docs: add v0.6 release notes

Add explicit reasoning guidance for normalising counts by exposure/denominator,
distinguishing total count from rate, and avoiding correlation-as-causation errors.

Changes:
- prompts/reconstruct-v0.3.md: new prompt with normalisation discipline
- lib/reconstruction/prompt.js: v0.3 loader + env var override support
- lib/analysis.js: defer DEFAULT_PROMPT_VERSION to prompt module (defaults to v0.3)
- PROMPT_VERSIONS extended to [v0.1, v0.2, v0.3]
- tests/v03-reasoning.test.js: 34 focused tests covering prompt loading, schema validation, guidance completeness, and target scenario fixture
- playwright.config.js + tests/smoke.test.js: minimal UI smoke test for browser rendering
- package.json: add @playwright/test as devDependency

Default switches to v0.3; v0.2 selectable via promptVersion or RECONSTRUCTION_PROMPT_VERSION env var.

.gitignore

@@ -34,3 +34,8 @@ Thumbs.db
 npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
+
+# Generated evaluation artifacts (regenerated each run)
+evaluation-results/
+provider-debug-results/
+tests-results/

app/api/analyse/route.js

@@ -1,101 +1,49 @@
-import { getConfig } from "@/lib/config";
-import { getProvider } from "@/lib/llm/provider";
-import { reconstructionSchema } from "@/lib/reconstruction/schema";
-
-const MAX_SCENARIO_LENGTH = 10000;
+import {
+  analyseScenario,
+  PROMPT_VERSIONS,
+  DEFAULT_PROMPT_VERSION,
+} from "@/lib/analysis";
 
 export async function POST(request) {
-  const startTime = Date.now();
-  let rawResponse = null;
-  
   try {
     const body = await request.json();
-    
+
     if (!body.scenario || typeof body.scenario !== "string") {
       return Response.json(
         { error: "Request must include a 'scenario' string field" },
-        { status: 400 }
+        { status: 400 },
       );
     }
 
-    const trimmed = body.scenario.trim();
-    
-    if (trimmed.length === 0) {
+    // Optional prompt version override
+    let promptVersion = DEFAULT_PROMPT_VERSION;
+    if (body.promptVersion && PROMPT_VERSIONS.includes(body.promptVersion)) {
+      promptVersion = body.promptVersion;
+    }
+
+    const result = await analyseScenario(body.scenario, { promptVersion });
+
+    if (!result.success) {
       return Response.json(
-        { error: "Scenario cannot be empty" },
-        { status: 400 }
+        { ...result, reconstruction: result.reconstruction || null },
+        { status: Number(result.statusCode) || 500 },
       );
     }
 
-    if (trimmed.length > MAX_SCENARIO_LENGTH) {
-      return Response.json(
-        { error: `Scenario must be under ${MAX_SCENARIO_LENGTH} characters` },
-        { status: 400 }
-      );
-    }
-
-    const configResult = getConfig();
-    if (!configResult.ok) {
-      return Response.json(
-        { error: "Invalid server configuration" },
-        { status: 500 }
-      );
-    }
-
-    const { OLLAMA_BASE_URL, OLLAMA_MODEL } = configResult.config;
-    const provider = getProvider();
-
-    // Attempt parse to capture raw for debugging
-    let reconstruction;
-    try {
-      reconstruction = await provider.generateReconstruction(trimmed, OLLAMA_MODEL);
-    } catch (e) {
-      return Response.json(
-        { 
-          error: e.message || "Unknown server error", 
-          responseDurationMs: Date.now() - startTime,
-          modelName: OLLAMA_MODEL,
-          validationStatus: "invalid",
-        },
-        { status: 500 }
-      );
-    }
-    
-    // Try to stringify for rawResponse display (safe even if it's already an object)
-    try {
-      rawResponse = JSON.stringify(reconstruction);
-    } catch {
-      rawResponse = String(reconstruction).slice(0, 2000);
-    }
-
-    const duration = Date.now() - startTime;
-
-    // Validate with Zod schema
-    const validationResult = reconstructionSchema.safeParse(reconstruction);
-
-    if (!validationResult.success) {
-      return Response.json({
-        reconstruction: null,
-        modelName: OLLAMA_MODEL,
-        responseDurationMs: duration,
-        validationStatus: "invalid",
-        rawResponse: rawResponse?.slice(0, 2000),
-        errors: validationResult.error.issues.map((i) => `${i.path.join(".")}: ${i.message}`),
-      });
-    }
-
     return Response.json({
-      reconstruction: validationResult.data,
-      modelName: OLLAMA_MODEL,
-      responseDurationMs: duration,
-      validationStatus: "valid",
-      rawResponse: rawResponse?.slice(0, 2000),
+      inputClassification: result.inputClassification,
+      reconstruction: result.reconstruction,
+      evidence: result.evidence,
+      nextQuestion: result.nextQuestion,
+      modelName: result.modelName,
+      responseDurationMs: result.responseDurationMs,
+      validationStatus: result.validationStatus,
+      promptVersion: result.promptVersion,
     });
   } catch (e) {
-    const duration = Date.now() - startTime;
     return Response.json(
-      { error: e.message || "Unknown server error", responseDurationMs: duration },
-      { status: 500 }
+      { error: e.message || "Unknown server error", responseDurationMs: 0 },
+      { status: 500 },
     );
   }
 }

app/api/cases/start/route.js

@@ -0,0 +1,38 @@
+import { startCase } from "@/lib/graph/orchestrator.js";
+
+export async function POST(request) {
+  try {
+    const body = await request.json();
+    const result = await startCase(body);
+
+    if (result.success) {
+      return Response.json(result, { status: 200 });
+    }
+
+    const status =
+      result.statusCode === 400
+        ? 400
+        : result.statusCode >= 500
+          ? result.statusCode
+          : 500;
+
+    return Response.json(
+      {
+        success: false,
+        error: result.error ?? "Start case failed",
+        validationErrors: result.validationErrors,
+        diagnostics: result.diagnostics,
+        analysisErrors: result.analysisErrors,
+      },
+      { status },
+    );
+  } catch {
+    return Response.json(
+      {
+        success: false,
+        error: "Internal server error",
+      },
+      { status: 500 },
+    );
+  }
+}

app/api/cases/update/route.js

@@ -0,0 +1,68 @@
+import { updateCase } from "@/lib/graph/orchestrator.js";
+
+function mapFailureStatus(result) {
+  switch (result?.stage) {
+    case "request_validation":
+    case "graph_validation":
+      return 400;
+    case "provider":
+      return 502;
+    case "proposal_validation":
+    case "proposal_compatibility":
+    case "application":
+      return 422;
+    case "result_validation":
+      return 500;
+    default:
+      return 500;
+  }
+}
+
+function buildFailureResponse(result) {
+  return {
+    success: false,
+    stage: result?.stage ?? "internal",
+    error: result?.error ?? "Update case failed",
+    validationErrors: result?.validationErrors,
+    graphValidationErrors: result?.graphValidationErrors,
+    proposalErrors: result?.proposalErrors,
+    providerErrors: result?.providerErrors,
+    errors: result?.errors,
+    diagnostics: result?.diagnostics,
+  };
+}
+
+export async function POST(request) {
+  try {
+    const body = await request.json();
+    const result = await updateCase(body, { applyProposal: true });
+
+    if (result.success) {
+      return Response.json(result, { status: 200 });
+    }
+
+    return Response.json(buildFailureResponse(result), {
+      status: mapFailureStatus(result),
+    });
+  } catch (error) {
+    if (error instanceof SyntaxError) {
+      return Response.json(
+        {
+          success: false,
+          stage: "request_validation",
+          error: "Invalid JSON request body",
+        },
+        { status: 400 },
+      );
+    }
+
+    return Response.json(
+      {
+        success: false,
+        stage: "internal",
+        error: "Internal server error",
+      },
+      { status: 500 },
+    );
+  }
+}

components/diagnostics-view.jsx

@@ -1,3 +1,5 @@
+import React from "react";
+
 const ValidationIndicator = ({ status }) => {
   const styles = {
     valid: "text-green-600",
@@ -10,17 +12,91 @@ const ValidationIndicator = ({ status }) => {
     invalid: "❌ Validation failed",
   };
   return (
-    <div className={`flex items-center gap-2 ${styles[status] || "text-gray-500"}`}>
+    <div
+      className={`flex items-center gap-2 ${styles[status] || "text-gray-500"}`}
+    >
       <span className="font-medium">{labels[status] || status}</span>
     </div>
   );
 };
 
+const validationIcons = {
+  valid: "✅",
+  partial: "⚠️",
+  invalid: "❌",
+};
+
 export default function DiagnosticsView({ result }) {
+  if (!result) return null;
+
+  const diagnostics = result.diagnostics || result;
+
   const metrics = [
-    { label: "Model", value: result.modelName || "?" },
-    { label: "Duration", value: result.responseDurationMs != null ? `${result.responseDurationMs}ms` : "?" },
-    { label: "Validation", value: <ValidationIndicator status={result.validationStatus || "invalid"} /> },
+    { label: "Model", value: diagnostics.modelName || result.modelName || "?" },
+    { label: "Provider", value: "Ollama" },
+    {
+      label: "Prompt version",
+      value: diagnostics.promptVersion || result.promptVersion || "?",
+    },
+    {
+      label: "Duration",
+      value:
+        diagnostics.responseDurationMs != null
+          ? `${diagnostics.responseDurationMs}ms`
+          : "?",
+    },
+    {
+      label: "Validation",
+      value: (
+        <ValidationIndicator
+          status={diagnostics.validationStatus || result.validationStatus || "invalid"}
+        />
+      ),
+    },
+    {
+      label: "Node count",
+      value:
+        diagnostics.nodeCount != null
+          ? diagnostics.nodeCount
+          : diagnostics.graphNodeCount != null
+            ? diagnostics.graphNodeCount
+            : "?",
+    },
+    {
+      label: "Edge count",
+      value:
+        diagnostics.edgeCount != null
+          ? diagnostics.edgeCount
+          : diagnostics.graphEdgeCount != null
+            ? diagnostics.graphEdgeCount
+            : "?",
+    },
+    {
+      label: "Graph references",
+      value:
+        diagnostics.graphReferenceValidation == null
+          ? "?"
+          : diagnostics.graphReferenceValidation.valid
+            ? `${validationIcons.valid} valid`
+            : `${validationIcons.invalid} invalid`,
+    },
+    {
+      label: "Investigation strategy",
+      value:
+        diagnostics.investigationStrategy?.key ||
+        diagnostics.investigationStrategy ||
+        result.selectedQuestion?.strategy ||
+        "?",
+    },
+  ];
+
+  const errors = [
+    ...(result.errors || []),
+    ...(result.validationErrors || []),
+    ...(result.graphValidationErrors || []),
+    ...(result.proposalErrors || []),
+    ...(result.providerErrors || []),
+    ...(result.analysisErrors || []),
   ];
 
   return (
@@ -35,16 +111,32 @@ export default function DiagnosticsView({ result }) {
         ))}
       </dl>
 
+      {/* Collapsed raw output for debugging */}
       {result.rawResponse && (
         <details className="mt-4">
           <summary className="cursor-pointer text-xs text-gray-500 underline hover:text-gray-700">
-            View raw model response
+            View raw model response (
+            {(result.rawResponse?.length || 0).toLocaleString()} chars)
           </summary>
           <pre className="mt-2 max-h-60 overflow-auto rounded bg-gray-900 px-3 py-2 text-xs leading-relaxed text-green-400">
             {result.rawResponse}
           </pre>
         </details>
       )}
+
+      {/* Errors if present */}
+      {errors.length > 0 && (
+        <details className="mt-3">
+          <summary className="cursor-pointer text-xs text-red-500 underline hover:text-red-700">
+            Validation errors ({errors.length})
+          </summary>
+          <ul className="mt-1 space-y-0.5 text-xs text-red-600">
+            {errors.map((err, i) => (
+              <li key={i}>{typeof err === "string" ? err : err?.message || JSON.stringify(err)}</li>
+            ))}
+          </ul>
+        </details>
+      )}
     </div>
   );
 }

components/graph-update-view.jsx

@@ -0,0 +1,228 @@
+import React from "react";
+
+function ListSection({ title, items, renderItem = (item) => item }) {
+  if (!items?.length) return null;
+
+  return (
+    <section className="rounded-lg border border-gray-200 bg-white p-4">
+      <h3 className="mb-2 text-sm font-semibold text-gray-800">{title}</h3>
+      <ul className="space-y-1 text-sm text-gray-700">
+        {items.map((item, index) => (
+          <li key={`${title}-${index}`}>{renderItem(item)}</li>
+        ))}
+      </ul>
+    </section>
+  );
+}
+
+export default function GraphUpdateView({ updateResult }) {
+  if (!updateResult?.proposal) return null;
+
+  const {
+    resolvedUnknownNodeIds,
+    affectedNodeIds,
+    previousActiveUnknownNodeId,
+    newActiveUnknownNodeId,
+    selectedQuestion,
+    changesApplied,
+    proposal,
+    previousSituationGraph,
+    updatedSituationGraph,
+    reasoningState,
+    previousReasoningState,
+  } = updateResult;
+
+  const newlySurfacedUnknownNodeIds = (proposal.addedNodes || [])
+    .filter((node) => node.kind === "unknown")
+    .map((node) => node.id);
+
+  const previousNodesById = new Map(
+    (previousSituationGraph?.nodes || []).map((node) => [node.id, node]),
+  );
+  const updatedNodesById = new Map(
+    (updatedSituationGraph?.nodes || []).map((node) => [node.id, node]),
+  );
+  const proposalUpdatesByNodeId = new Map(
+    (proposal.updatedNodes || []).map((update) => [update.nodeId, update]),
+  );
+
+  function resolveNodePresentation(nodeId) {
+    const previousNode = previousNodesById.get(nodeId) || null;
+    const updatedNode = updatedNodesById.get(nodeId) || null;
+    const node = updatedNode || previousNode;
+    const update = proposalUpdatesByNodeId.get(nodeId) || null;
+
+    if (!node) {
+      return (
+        <div className="space-y-1">
+          <div className="font-medium text-gray-900">Unknown node (ID: {nodeId})</div>
+        </div>
+      );
+    }
+
+    return (
+      <div className="space-y-1">
+        <div className="font-medium text-gray-900">{node.label}</div>
+        <div className="text-xs text-gray-600">
+          {node.kind} · {node.confidence}
+        </div>
+        {node.confidenceAssessment && (
+          <div className="text-xs text-gray-600">
+            evidence {node.confidenceAssessment.evidenceConfidence} · completeness {node.confidenceAssessment.completenessStatus} · conclusion {node.confidenceAssessment.conclusionConfidence}
+          </div>
+        )}
+        {(update?.previousStatus || update?.newStatus || node.status) && (
+          <div className="text-xs text-gray-700">
+            {update?.previousStatus ? `Previous status: ${update.previousStatus}` : null}
+            {update?.previousStatus && update?.newStatus ? " → " : null}
+            {update?.newStatus
+              ? `New status: ${update.newStatus}`
+              : !update?.previousStatus
+                ? `Status: ${node.status}`
+                : null}
+          </div>
+        )}
+        {update?.reason && <div className="text-xs text-gray-700">{update.reason}</div>}
+      </div>
+    );
+  }
+
+  function resolveActiveUnknown(nodeId) {
+    if (!nodeId) return null;
+
+    const node = updatedNodesById.get(nodeId) || previousNodesById.get(nodeId);
+    if (!node) {
+      return `Unknown node (ID: ${nodeId})`;
+    }
+
+    return `${node.label} · ${node.status} · ${node.confidence}`;
+  }
+
+  const changeItems = [
+    changesApplied?.addedNodeCount
+      ? `${changesApplied.addedNodeCount} node(s) added`
+      : null,
+    changesApplied?.updatedNodeCount
+      ? `${changesApplied.updatedNodeCount} node(s) updated`
+      : null,
+    changesApplied?.addedEdgeCount
+      ? `${changesApplied.addedEdgeCount} edge(s) added`
+      : null,
+    changesApplied?.removedEdgeCount
+      ? `${changesApplied.removedEdgeCount} edge(s) removed`
+      : null,
+    changesApplied?.resolvedUnknownCount
+      ? `${changesApplied.resolvedUnknownCount} unknown(s) resolved`
+      : null,
+  ].filter(Boolean);
+
+  const previousComparabilityStatus =
+    previousReasoningState?.comparabilityStatus ||
+    previousSituationGraph?.reasoningState?.comparabilityStatus ||
+    null;
+  const newComparabilityStatus =
+    reasoningState?.comparabilityStatus ||
+    updatedSituationGraph?.reasoningState?.comparabilityStatus ||
+    null;
+  const relationshipStatus =
+    reasoningState?.relationshipStatus ||
+    updatedSituationGraph?.reasoningState?.relationshipStatus ||
+    null;
+  const reasoningStagesAfter =
+    reasoningState?.reasoningStages ||
+    updatedSituationGraph?.reasoningState?.reasoningStages ||
+    [];
+
+  return (
+    <div className="space-y-4">
+      <section className="rounded-lg border border-blue-200 bg-blue-50 p-4">
+        <h2 className="mb-2 text-base font-semibold text-blue-900">
+          Graph update applied
+        </h2>
+        <div className="grid gap-2 text-sm text-blue-950 sm:grid-cols-2">
+          {previousActiveUnknownNodeId && (
+            <div>
+              <span className="font-medium">Previous active unknown:</span>{" "}
+              {resolveActiveUnknown(previousActiveUnknownNodeId)}
+            </div>
+          )}
+          {newActiveUnknownNodeId && (
+            <div>
+              <span className="font-medium">New active unknown:</span>{" "}
+              {resolveActiveUnknown(newActiveUnknownNodeId)}
+            </div>
+          )}
+          {selectedQuestion?.question && (
+            <div>
+              <span className="font-medium">Next question:</span>{" "}
+              {selectedQuestion.question}
+            </div>
+          )}
+          {previousComparabilityStatus && newComparabilityStatus && (
+            <div>
+              <span className="font-medium">Comparability:</span>{" "}
+              {previousComparabilityStatus} → {newComparabilityStatus}
+            </div>
+          )}
+          {relationshipStatus && (
+            <div>
+              <span className="font-medium">Relationship status:</span>{" "}
+              {relationshipStatus}
+            </div>
+          )}
+          {!selectedQuestion?.question && !newActiveUnknownNodeId && previousActiveUnknownNodeId && (
+            <div>
+              <span className="font-medium">Next question status:</span> No next question selected yet.
+            </div>
+          )}
+        </div>
+        {reasoningStagesAfter.length > 0 && (
+          <div className="mt-3 text-sm text-blue-950">
+            <span className="font-medium">Reasoning stages:</span>{" "}
+            {reasoningStagesAfter
+              .map((stage) => `${stage.stage}: ${stage.status}`)
+              .join(" → ")}
+          </div>
+        )}
+      </section>
+
+      <ListSection
+        title="Resolved unknowns"
+        items={resolvedUnknownNodeIds}
+        renderItem={resolveNodePresentation}
+      />
+      <ListSection
+        title="Newly surfaced unknowns"
+        items={newlySurfacedUnknownNodeIds}
+        renderItem={resolveNodePresentation}
+      />
+      <ListSection
+        title="Affected nodes"
+        items={affectedNodeIds}
+        renderItem={resolveNodePresentation}
+      />
+      <ListSection title="Applied changes" items={changeItems} />
+
+      <details className="rounded-lg border border-gray-200 bg-gray-50 p-4">
+        <summary className="cursor-pointer text-sm font-medium text-gray-700 underline">
+          Proposal details
+        </summary>
+        <pre className="mt-3 overflow-auto rounded bg-gray-900 p-3 text-xs text-green-400">
+          {JSON.stringify(proposal, null, 2)}
+        </pre>
+        <pre className="mt-3 overflow-auto rounded bg-gray-900 p-3 text-xs text-green-400">
+          {JSON.stringify(
+            {
+              previousActiveUnknownNodeId,
+              newActiveUnknownNodeId,
+              resolvedUnknownNodeIds,
+              affectedNodeIds,
+            },
+            null,
+            2,
+          )}
+        </pre>
+      </details>
+    </div>
+  );
+}

components/reconstruction-view.jsx

@@ -1,15 +1,8 @@
-const categoryLabels = {
-  observations: "Direct Observations",
-  reportedClaims: "Reported Claims",
-  assumptions: "Unsupported Assumptions",
-  entities: "Entities",
-  transitions: "Transitions",
-  expectedButMissing: "Expected But Missing",
-  presentButUnexpected: "Present But Unexpected",
-  contradictions: "Contradictions",
-  openUncertainties: "Open Uncertainties",
-};
+"use client";
 
+import { useMemo } from "react";
+
+// ── Confidence badge (shared) ────────────────────────
 const confidenceColor = {
   low: "text-red-600 bg-red-50 border-red-200",
   medium: "text-yellow-700 bg-yellow-50 border-yellow-200",
@@ -17,54 +10,401 @@ const confidenceColor = {
 };
 
 const ConfidenceBadge = ({ level }) => (
-  <span className={`inline-block rounded-full border px-2 py-0.5 text-xs font-medium ${confidenceColor[level] || "text-gray-600 bg-gray-100"}`}>
+  <span
+    className={`inline-block rounded-full border px-2 py-0.5 text-xs font-medium ${confidenceColor[level] || "text-gray-600 bg-gray-100"}`}
+  >
     {level}
   </span>
 );
 
-function ItemList({ items, renderExtra }) {
-  if (!items?.length) return <p className="text-sm italic text-gray-400">None identified</p>;
-  
+// ── Evidence type labels (shared) ───────────────────
+const evidenceTypeLabels = {
+  direct_observation: "Direct Observation",
+  reported_statement: "Reported Statement",
+  interpretation: "Interpretation",
+  assumption: "Assumption",
+  inferred_relationship: "Inferred Relationship",
+};
+
+const importanceColors = {
+  incidental: "text-gray-500 bg-gray-50 border-gray-200",
+  supporting: "text-blue-700 bg-blue-50 border-blue-200",
+  important: "text-orange-700 bg-orange-50 border-orange-200",
+  critical: "text-red-800 bg-red-50 border-red-300 font-semibold",
+};
+
+const importanceLabels = {
+  incidental: "Incidental",
+  supporting: "Supporting",
+  important: "Important",
+  critical: "Critical",
+};
+
+// ── Input classification display ────────────────────
+function ClassificationDisplay({ classification }) {
+  if (!classification) return null;
+  const p = classification.primaryType || classification.primary_type;
+  const sec =
+    classification.secondaryTypes || classification.secondary_types || [];
+  const modes =
+    classification.reasoningModes || classification.reasoning_modes || [];
+
+  // Normalize camelCase to snake_case for display if needed
+  const primaryLabel = String(p)
+    .replace(/_/g, " ")
+    .replace(/\b\w/g, (c) => c.toUpperCase());
+  const secLabels = sec.map((s) =>
+    s.replace(/_/g, " ").replace(/\b\w/g, (c) => c.toUpperCase()),
+  );
+  const modeLabels = modes.map((m) =>
+    m.replace(/_/g, " ").replace(/\b\w/g, (c) => c.toUpperCase()),
+  );
+
   return (
-    <ul className="space-y-2">
-      {items.map((item) => (
-        <li key={item.id} className="rounded border border-gray-200 bg-white px-3 py-2 text-sm">
-          <div className="flex items-center gap-2">
-            <span className="font-mono text-xs text-gray-400">#{item.id}</span>
-            <ConfidenceBadge level={item.confidence} />
-          </div>
-          <p className="mt-1">{item.description}</p>
-          {renderExtra && renderExtra(item)}
-        </li>
-      ))}
-    </ul>
+    <div className="rounded-lg border border-blue-200 bg-blue-50 p-4">
+      <h3 className="mb-2 text-sm font-semibold text-blue-700">
+        Input Classification
+      </h3>
+      <dl className="grid grid-cols-[auto_1fr] gap-x-4 gap-y-1.5 text-sm">
+        <dt className="text-blue-500">Primary type</dt>
+        <dd className="font-medium">{primaryLabel}</dd>
+        {secLabels.length > 0 && (
+          <>
+            <dt className="text-blue-500 pt-1">Secondary types</dt>
+            <dd>{secLabels.join(" · ")}</dd>
+          </>
+        )}
+        {modeLabels.length > 0 && (
+          <>
+            <dt className="text-blue-500 pt-1">Reasoning modes</dt>
+            <dd>{modeLabels.join(" · ")}</dd>
+          </>
+        )}
+        <dt className="text-blue-500 pt-1">Classification reason</dt>
+        <dd className="italic">
+          {classification.classificationReason ||
+            classification.classification_reason}
+        </dd>
+        <dt className="text-blue-500 pt-1">Confidence</dt>
+        <dd>
+          <ConfidenceBadge level={classification.confidence} />
+        </dd>
+      </dl>
+    </div>
   );
 }
 
+// ── Reconstruction summary ──────────────────────────
+function SummaryDisplay({ reconstruction }) {
+  if (!reconstruction?.summary) return null;
+  const summary = reconstruction.summary || reconstruction.Summary;
+  return (
+    <div className="rounded-lg border border-gray-200 bg-white p-4">
+      <h3 className="mb-2 text-sm font-semibold text-gray-600">
+        Reconstruction Summary
+      </h3>
+      <p className="text-sm leading-relaxed">{summary}</p>
+    </div>
+  );
+}
+
+// ── Generic item list (used for multiple sections) ──
+function ItemList({ title, items, renderExtra }) {
+  const count = items?.length;
+  if (!count) return null; // hide empty sections entirely
+
+  const itemsArr = Array.isArray(items) ? items : [items];
+
+  return (
+    <div className="mb-4 rounded-lg border border-gray-200 bg-white p-4">
+      <h3 className="mb-2 text-sm font-semibold text-gray-600">
+        {title} ({count})
+      </h3>
+      <ul className="space-y-2">
+        {itemsArr.map((item, idx) => (
+          <li
+            key={item.id || `${title}-${idx}`}
+            className="rounded border border-gray-200 bg-white px-3 py-2 text-sm"
+          >
+            <div className="flex items-center gap-2">
+              {item.id && (
+                <span className="font-mono text-xs text-gray-400">
+                  #{item.id}
+                </span>
+              )}
+              {item.confidence && <ConfidenceBadge level={item.confidence} />}
+              {item.importance && (
+                <span
+                  className={`inline-block rounded-full border px-2 py-0.5 text-xs font-medium ${importanceColors[item.importance] || "text-gray-600 bg-gray-100"}`}
+                >
+                  {importanceLabels[item.importance]}
+                </span>
+              )}
+            </div>
+            <p className="mt-1">{item.description}</p>
+            {renderExtra && renderExtra(item)}
+          </li>
+        ))}
+      </ul>
+    </div>
+  );
+}
+
+// ── Plausible interpretations ───────────────────────
+function InterpretationsDisplay({ interpretations }) {
+  if (!interpretations?.length) return null;
+  const arr = Array.isArray(interpretations)
+    ? interpretations
+    : [interpretations];
+
+  return (
+    <div className="mb-4 rounded-lg border border-indigo-200 bg-indigo-50 p-4">
+      <h3 className="mb-2 text-sm font-semibold text-indigo-700">
+        Plausible Interpretations ({arr.length})
+      </h3>
+      <ul className="space-y-3">
+        {arr.map((interp, idx) => (
+          <li
+            key={interp.id || `${idx}`}
+            className="rounded border border-indigo-200 bg-white px-3 py-2.5 text-sm leading-relaxed"
+          >
+            <div className="flex items-center gap-2 mb-1">
+              <span className="font-medium text-indigo-600">
+                {interp.description}
+              </span>
+              {interp.confidence && (
+                <ConfidenceBadge level={interp.confidence} />
+              )}
+            </div>
+            {interp.supportingEvidenceIds?.length > 0 && (
+              <p className="text-xs text-gray-500">
+                Supporting evidence: {interp.supportingEvidenceIds.join(", ")}
+              </p>
+            )}
+            {interp.assumptionsRequired?.length > 0 && (
+              <p className="text-xs italic text-gray-500">
+                Requires assumptions: {interp.assumptionsRequired.join("; ")}
+              </p>
+            )}
+          </li>
+        ))}
+      </ul>
+    </div>
+  );
+}
+
+// ── Next question (prominent) ───────────────────────
+function NextQuestionDisplay({ question }) {
+  if (!question?.question) return null;
+  const q = question.question || question.Question;
+  const targets = question.targets || question.Targets || [];
+  const reason = question.reason || question.Reason || "";
+  const value =
+    question.expectedInformationValue ||
+    question.expected_information_value ||
+    "medium";
+
+  const valueLabel =
+    { low: "Low", medium: "Medium", high: "High" }[value] || "Medium";
+  const valueColor =
+    {
+      low: "bg-yellow-100 text-yellow-800",
+      medium: "bg-blue-100 text-blue-800",
+      high: "bg-green-100 text-green-800",
+    }[value] || "";
+
+  return (
+    <div className="rounded-lg border-2 border-green-300 bg-green-50 p-5">
+      <div className="flex items-center gap-2 mb-2">
+        <h3 className="text-sm font-bold text-green-800">Next Question</h3>
+        <span
+          className={`rounded-full px-2 py-0.5 text-xs font-medium ${valueColor}`}
+        >
+          {valueLabel} value
+        </span>
+      </div>
+      <p className="mb-2 text-base font-medium text-gray-900">{q}</p>
+      {targets.length > 0 && (
+        <p className="text-sm text-gray-600">Targets: {targets.join(", ")}</p>
+      )}
+      {reason && (
+        <p className="text-sm italic text-gray-500">Because: {reason}</p>
+      )}
+    </div>
+  );
+}
+
+// ── Evidence list ───────────────────────────────────
+function EvidenceDisplay({ evidence }) {
+  if (!evidence?.length) return null;
+  const arr = Array.isArray(evidence) ? evidence : [evidence];
+
+  const evidenceLabels = {
+    direct_observation: "👁 Direct Observation",
+    reported_statement: "🗣 Reported Statement",
+    interpretation: "💡 Interpretation",
+    assumption: "❓ Assumption",
+    inferred_relationship: "🔗 Inferred Relationship",
+  };
+
+  return (
+    <div className="mb-4 rounded-lg border border-gray-200 bg-white p-4">
+      <h3 className="mb-2 text-sm font-semibold text-gray-600">
+        Supporting Evidence ({arr.length})
+      </h3>
+      <ul className="space-y-2">
+        {arr.map((item, idx) => (
+          <li
+            key={item.id || `${idx}`}
+            className="rounded border border-gray-200 bg-white px-3 py-2 text-sm leading-relaxed"
+          >
+            <div className="flex items-center gap-2 mb-0.5 flex-wrap">
+              {item.id && (
+                <span className="font-mono text-xs text-gray-400">
+                  #{item.id}
+                </span>
+              )}
+              <span
+                className={`inline-block rounded px-1.5 py-0.5 text-[10px] font-medium ${importanceColors[item.importance] || "text-gray-600 bg-gray-100"}`}
+              >
+                {importanceLabels[item.importance]}
+              </span>
+              <span className="inline-block rounded px-1.5 py-0.5 text-[10px] font-medium bg-gray-100 text-gray-700">
+                {evidenceLabels[item.evidenceType] || item.evidenceType}
+              </span>
+              {item.confidence && <ConfidenceBadge level={item.confidence} />}
+            </div>
+            <p className="text-sm">{item.description}</p>
+            {(item.source || item.attribution) && (
+              <p className="mt-0.5 text-xs text-gray-400">
+                Source: {item.source || item.attribution}
+              </p>
+            )}
+          </li>
+        ))}
+      </ul>
+    </div>
+  );
+}
+
+// ── Main component ──────────────────────────────────
 export default function ReconstructionView({ reconstruction, partial }) {
+  // Handle both v0.2 direct object and wrapped result formats
+  const data = reconstruction;
+
   if (partial) {
     return (
       <div className="rounded-lg border border-yellow-300 bg-yellow-50 px-4 py-3 text-sm text-yellow-800">
-        ⚠ Partial result — some fields failed validation. Showing what was accepted.
+        ⚠ Partial result — some fields failed validation. Showing what was
+        accepted.
       </div>
     );
   }
 
-  const categories = Object.entries(categoryLabels).map(([key, label]) => ({
-    key,
-    label,
-    items: reconstruction[key],
-  }));
-
   return (
-    <div className="space-y-1">
-      <h2 className="mb-3 text-lg font-semibold">Reconstruction</h2>
-      {categories.map(({ key, label, items }) => (
-        <div key={key} className="mb-4 rounded border border-gray-200 bg-white p-4">
-          <h3 className="mb-2 text-sm font-medium text-gray-600">{label}</h3>
-          <ItemList items={items} />
-        </div>
-      ))}
+    <div className="space-y-4">
+      {/* Classification first */}
+      {data.inputClassification && (
+        <ClassificationDisplay classification={data.inputClassification} />
+      )}
+
+      {/* Summary */}
+      {data.reconstruction?.summary && (
+        <SummaryDisplay reconstruction={data.reconstruction} />
+      )}
+
+      {/* Key differences */}
+      {data.reconstruction?.differences && (
+        <ItemList
+          title="Key Differences"
+          items={data.reconstruction.differences}
+        />
+      )}
+
+      {/* Unexplained transitions */}
+      {data.reconstruction?.unexplainedTransitions &&
+        data.reconstruction.unexplainedTransitions.length > 0 && (
+          <ItemList
+            title="Unexplained Transitions"
+            items={data.reconstruction.unexplainedTransitions}
+            renderExtra={(i) =>
+              i.entity && (
+                <p className="mt-1 text-xs text-gray-500">Entity: {i.entity}</p>
+              )
+            }
+          />
+        )}
+
+      {/* Contradictions */}
+      {data.reconstruction?.contradictions &&
+        data.reconstruction.contradictions.length > 0 && (
+          <ItemList
+            title="Contradictions"
+            items={data.reconstruction.contradictions}
+          />
+        )}
+
+      {/* Important unknowns */}
+      {data.reconstruction?.importantUnknowns &&
+        data.reconstruction.importantUnknowns.length > 0 && (
+          <ItemList
+            title="Important Unknowns"
+            items={data.reconstruction.importantUnknowns}
+          />
+        )}
+
+      {/* Plausible interpretations */}
+      {data.reconstruction?.plausibleInterpretations &&
+        data.reconstruction.plausibleInterpretations.length > 0 && (
+          <InterpretationsDisplay
+            interpretations={data.reconstruction.plausibleInterpretations}
+          />
+        )}
+
+      {/* Secondary reconstruction categories (actors, systems, etc.) */}
+      {data.reconstruction?.actors && data.reconstruction.actors.length > 0 && (
+        <ItemList title="Actors" items={data.reconstruction.actors} />
+      )}
+      {data.reconstruction?.systemsOrObjects &&
+        data.reconstruction.systemsOrObjects.length > 0 && (
+          <ItemList
+            title="Systems / Objects"
+            items={data.reconstruction.systemsOrObjects}
+          />
+        )}
+      {data.reconstruction?.expectedStates &&
+        data.reconstruction.expectedStates.length > 0 && (
+          <ItemList
+            title="Expected States"
+            items={data.reconstruction.expectedStates}
+          />
+        )}
+      {data.reconstruction?.observedStates &&
+        data.reconstruction.observedStates.length > 0 && (
+          <ItemList
+            title="Observed States"
+            items={data.reconstruction.observedStates}
+          />
+        )}
+      {data.reconstruction?.knownTransitions &&
+        data.reconstruction.knownTransitions.length > 0 && (
+          <ItemList
+            title="Known Transitions"
+            items={data.reconstruction.knownTransitions}
+            renderExtra={(i) => (
+              <div className="mt-1 text-xs text-gray-500">
+                {i.entity && <span>Entity: {i.entity} · </span>}
+                From &ldquo;{i.previousState}&rdquo; → To &ldquo;{i.currentState}&rdquo; (&quot;{i.explanationStatus}&quot;)
+              </div>
+            )}
+          />
+        )}
+
+      {/* Next question — prominent */}
+      <NextQuestionDisplay question={data.nextQuestion} />
+
+      {/* Evidence */}
+      {data.evidence && <EvidenceDisplay evidence={data.evidence} />}
     </div>
   );
 }

components/scenario-form.jsx

@@ -1,37 +1,168 @@
 "use client";
 
+import React from "react";
 import { useState, useRef } from "react";
-import ReconstructionView from "@/components/reconstruction-view";
 import DiagnosticsView from "@/components/diagnostics-view";
+import GraphUpdateView from "@/components/graph-update-view";
+import SituationGraphView from "@/components/situation-graph-view";
 
 const MAX_LENGTH = 10000;
 
+export async function submitScenarioForStartCase(fetchImpl, scenario) {
+  return fetchImpl("/api/cases/start", {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({ scenario }),
+  });
+}
+
+export async function submitAnswerForUpdateCase(
+  fetchImpl,
+  { situationGraph, previousQuestion, answer },
+) {
+  if (!answer?.trim()) {
+    return {
+      ok: false,
+      skipped: true,
+      data: {
+        success: false,
+        stage: "request_validation",
+        error: "Please enter an answer before updating.",
+      },
+    };
+  }
+
+  const response = await fetchImpl("/api/cases/update", {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({ situationGraph, previousQuestion, answer }),
+  });
+
+  return {
+    ok: response.ok,
+    skipped: false,
+    data: await response.json(),
+  };
+}
+
+function normaliseStartResult(data) {
+  return {
+    ...data,
+    selectedQuestion:
+      typeof data?.selectedQuestion === "string"
+        ? data.selectedQuestion
+        : data?.selectedQuestion?.question ?? null,
+    newlySurfacedNodeIds: data?.newlySurfacedNodeIds ?? [],
+  };
+}
+
+function normaliseUpdateSelectedQuestion(selectedQuestion) {
+  if (!selectedQuestion) return null;
+  if (typeof selectedQuestion === "string") return selectedQuestion;
+  return selectedQuestion.question ?? null;
+}
+
+export function ScenarioResultPanels({ status, result }) {
+  if (!result) return null;
+
+  const hasGraph = Boolean(result.situationGraph);
+  const hasQuestion = Boolean(result.selectedQuestion?.question);
+  const hasDiagnostics = Boolean(result.diagnostics);
+
+  return (
+    <>
+      {status === "error" && (
+        <div className="space-y-3">
+          {result.error && (
+            <div className="rounded-lg border border-red-300 bg-red-50 px-4 py-3 text-sm text-red-700 whitespace-pre-wrap">
+              Error: {result.error}
+            </div>
+          )}
+          {!hasGraph && !hasQuestion && (
+            <div className="rounded-lg border border-yellow-300 bg-yellow-50 px-4 py-2 text-sm text-yellow-800">
+              Validation failed — no structured graph output was produced.
+            </div>
+          )}
+        </div>
+      )}
+
+      {(status === "success" || hasGraph || hasQuestion) && (
+        <SituationGraphView
+          situationGraph={result.situationGraph}
+          selectedQuestion={result.selectedQuestion}
+          newlySurfacedNodeIds={result.newlySurfacedNodeIds}
+        />
+      )}
+
+      {hasDiagnostics && <DiagnosticsView result={result} />}
+    </>
+  );
+}
+
+export function UpdateErrorPanel({ updateError }) {
+  if (!updateError) return null;
+
+  const errors = [
+    ...(updateError.errors || []),
+    ...(updateError.validationErrors || []),
+    ...(updateError.graphValidationErrors || []),
+    ...(updateError.proposalErrors || []),
+    ...(updateError.providerErrors || []),
+  ];
+
+  return (
+    <div className="space-y-3">
+      <div className="rounded-lg border border-red-300 bg-red-50 px-4 py-3 text-sm text-red-700 whitespace-pre-wrap">
+        Update error: {updateError.error}
+      </div>
+      {errors.length > 0 && (
+        <details className="rounded-lg border border-red-200 bg-red-50 px-4 py-3">
+          <summary className="cursor-pointer text-sm font-medium text-red-700 underline">
+            Update details ({errors.length})
+          </summary>
+          <ul className="mt-2 space-y-1 text-sm text-red-700">
+            {errors.map((item, index) => (
+              <li key={index}>
+                {typeof item === "string" ? item : item?.message || JSON.stringify(item)}
+              </li>
+            ))}
+          </ul>
+        </details>
+      )}
+    </div>
+  );
+}
+
 export default function ScenarioForm() {
   const [scenario, setScenario] = useState("");
   const [status, setStatus] = useState("idle"); // idle | loading | error | success
   const [result, setResult] = useState(null);
+  const [answer, setAnswer] = useState("");
+  const [updateStatus, setUpdateStatus] = useState("idle"); // idle | loading | error | success
+  const [updateError, setUpdateError] = useState(null);
+  const [updateResult, setUpdateResult] = useState(null);
   const textareaRef = useRef(null);
 
   const handleSubmit = async (e) => {
     e.preventDefault();
     setStatus("loading");
     setResult(null);
+    setAnswer("");
+    setUpdateStatus("idle");
+    setUpdateError(null);
+    setUpdateResult(null);
 
     try {
-      const res = await fetch("/api/analyse", {
-        method: "POST",
-        headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({ scenario }),
-      });
+      const res = await submitScenarioForStartCase(fetch, scenario);
 
       const data = await res.json();
 
-      if (res.ok && data.validationStatus === "valid") {
+      if (res.ok && data.success) {
         setStatus("success");
-        setResult(data);
+        setResult(normaliseStartResult(data));
       } else {
         setStatus("error");
-        setResult(data);
+        setResult(normaliseStartResult(data));
       }
     } catch (err) {
       setStatus("error");
@@ -39,8 +170,64 @@ export default function ScenarioForm() {
     }
   };
 
-  // Always show diagnostics when there's a result (even if validation failed)
-  const hasDiagnostics = result && (result.reconstruction || result.modelName || result.responseDurationMs !== undefined);
+  const handleUpdate = async (e) => {
+    e.preventDefault();
+
+    const submission = await submitAnswerForUpdateCase(fetch, {
+      situationGraph: result?.situationGraph,
+      previousQuestion: result?.selectedQuestion,
+      answer,
+    });
+
+    if (submission.skipped) {
+      setUpdateStatus("error");
+      setUpdateError(submission.data);
+      return;
+    }
+
+    setUpdateStatus("loading");
+    setUpdateError(null);
+
+    try {
+      const outcome = submission.data;
+
+      if (submission.ok && outcome.success) {
+        setUpdateStatus("success");
+        setUpdateResult({
+          ...outcome,
+          previousSituationGraph: result?.situationGraph ?? null,
+        });
+        setResult((current) => ({
+          ...current,
+          situationGraph: outcome.updatedSituationGraph,
+          selectedQuestion: normaliseUpdateSelectedQuestion(
+            outcome.selectedQuestion,
+          ),
+          newlySurfacedNodeIds: (outcome.proposal?.addedNodes || [])
+            .filter((node) => node.kind === "unknown")
+            .map((node) => node.id),
+          diagnostics: outcome.diagnostics,
+        }));
+        setAnswer("");
+      } else {
+        setUpdateStatus("error");
+        setUpdateError(outcome);
+      }
+    } catch (err) {
+      setUpdateStatus("error");
+      setUpdateError({ error: err.message || "Network request failed" });
+    }
+  };
+
+  const canRenderAnswerForm =
+    status === "success" &&
+    updateStatus === "idle" &&
+    Boolean(result?.situationGraph) &&
+    Boolean(result?.selectedQuestion);
+
+  const canRenderDisabledFollowUpForm =
+    updateStatus === "success" &&
+    Boolean(updateResult?.selectedQuestion?.question || result?.selectedQuestion);
 
   return (
     <div className="space-y-6">
@@ -54,7 +241,9 @@ export default function ScenarioForm() {
           className="w-full rounded-lg border border-gray-300 px-4 py-3 text-sm focus:border-gray-500 focus:outline-none focus:ring-2 focus:ring-gray-400"
         />
         <div className="flex items-center justify-between">
-          <span className="text-xs text-gray-400">{scenario.length}/{MAX_LENGTH}</span>
+          <span className="text-xs text-gray-400">
+            {scenario.length}/{MAX_LENGTH}
+          </span>
           <button
             type="submit"
             disabled={status === "loading" || !scenario.trim()}
@@ -65,42 +254,104 @@ export default function ScenarioForm() {
         </div>
       </form>
 
-      {status === "error" && (
-        <div className="space-y-3">
-          {result?.error && (
-            <div className="rounded-lg border border-red-300 bg-red-50 px-4 py-3 text-sm text-red-700 whitespace-pre-wrap">
-              Error: {result.error}
-            </div>
-          )}
-          {hasDiagnostics && result?.modelName && (
-            <dl className="grid grid-cols-[auto_1fr] gap-x-4 gap-y-1.5 text-sm">
-              <dt className="text-gray-500">Model</dt>
-              <dd>{result.modelName}</dd>
-              <dt className="text-gray-500">Duration</dt>
-              <dd>{result.responseDurationMs != null ? `${result.responseDurationMs}ms` : "?"}</dd>
-            </dl>
-          )}
-        </div>
-      )}
-
-      {status === "success" && result?.reconstruction && (
-        <div className="space-y-4">
-          <ReconstructionView reconstruction={result.reconstruction} />
-          <DiagnosticsView result={result} />
-        </div>
-      )}
-
-      {status === "error" && result?.reconstruction && (
-        <div className="space-y-3">
-          <div className="rounded-lg border border-yellow-300 bg-yellow-50 px-4 py-2 text-sm text-yellow-800">
-            ⚠ Partial result — some fields failed validation. Showing what was accepted.
+      {canRenderAnswerForm && (
+        <form onSubmit={handleUpdate} className="space-y-4 rounded-lg border border-gray-200 bg-white p-4">
+          <div>
+            <h2 className="text-base font-semibold text-gray-900">Selected Question</h2>
+            <p className="mt-1 text-sm text-gray-700">{result.selectedQuestion}</p>
           </div>
-          <ReconstructionView reconstruction={result.reconstruction} partial />
+          <div>
+            <label htmlFor="answer-textarea" className="mb-2 block text-sm font-medium text-gray-700">
+              Your answer
+            </label>
+            <textarea
+              id="answer-textarea"
+              value={answer}
+              onChange={(e) => setAnswer(e.target.value)}
+              rows={4}
+              className="w-full rounded-lg border border-gray-300 px-4 py-3 text-sm focus:border-gray-500 focus:outline-none focus:ring-2 focus:ring-gray-400"
+              placeholder="Enter the answer to the selected question..."
+            />
+          </div>
+          <div className="flex items-center justify-between gap-4">
+            <p className="text-xs text-gray-500">
+              {updateStatus === "loading"
+                ? "Applying validated graph update..."
+                : "One update turn only in this prototype."}
+            </p>
+            <button
+              type="submit"
+              disabled={updateStatus === "loading"}
+              className="rounded-lg bg-blue-700 px-4 py-2 text-sm font-medium text-white transition hover:bg-blue-600 disabled:cursor-not-allowed disabled:opacity-40"
+            >
+              {updateStatus === "loading" ? "Updating..." : "Update situation"}
+            </button>
+          </div>
+        </form>
+      )}
+
+      <UpdateErrorPanel updateError={updateError} />
+
+      {updateStatus === "success" && updateResult && (
+        <>
+          <div className="rounded-lg border border-yellow-300 bg-yellow-50 px-4 py-3 text-sm text-yellow-800">
+            {updateResult.selectedQuestion?.question
+              ? updateResult.selectedQuestion.question
+              : "No next question selected yet."}
+          </div>
+          {canRenderDisabledFollowUpForm && (
+            <form className="space-y-4 rounded-lg border border-gray-200 bg-white p-4 opacity-70">
+              <div>
+                <h2 className="text-base font-semibold text-gray-900">Selected Question</h2>
+                <p className="mt-1 text-sm text-gray-700">
+                  {updateResult.selectedQuestion?.question || result?.selectedQuestion}
+                </p>
+              </div>
+              <div>
+                <label htmlFor="follow-up-disabled-textarea" className="mb-2 block text-sm font-medium text-gray-700">
+                  Your answer
+                </label>
+                <textarea
+                  id="follow-up-disabled-textarea"
+                  rows={4}
+                  disabled
+                  className="w-full rounded-lg border border-gray-300 px-4 py-3 text-sm opacity-70"
+                  placeholder="Additional submission is disabled in this one-update prototype."
+                />
+              </div>
+              <div className="flex items-center justify-between gap-4">
+                <p className="text-xs text-gray-500">
+                  Additional submission is disabled in this one-update prototype.
+                </p>
+                <button
+                  type="button"
+                  disabled
+                  className="rounded-lg bg-blue-700 px-4 py-2 text-sm font-medium text-white disabled:cursor-not-allowed disabled:opacity-40"
+                >
+                  Update situation
+                </button>
+              </div>
+            </form>
+          )}
+          <GraphUpdateView updateResult={updateResult} />
+        </>
+      )}
+
+      <ScenarioResultPanels status={status} result={result} />
+
+      {(status === "loading" || updateStatus === "loading") && (
+        <div className="py-12 text-center text-sm text-gray-400">
+          Waiting for model response...
         </div>
       )}
 
-      {status === "loading" && (
-        <div className="py-12 text-center text-sm text-gray-400">Waiting for model response...</div>
+      {/* Empty state */}
+      {status === "idle" && (
+        <div className="rounded-lg border border-dashed border-gray-300 bg-gray-50 px-6 py-8 text-center">
+          <p className="text-sm text-gray-400">
+            Enter a scenario above and click Analyse to begin.
+          </p>
+        </div>
       )}
     </div>
   );

components/situation-graph-view.jsx

@@ -0,0 +1,161 @@
+"use client";
+
+import React from "react";
+
+function NodeBadge({ children, tone = "gray" }) {
+  const tones = {
+    gray: "border-gray-200 bg-gray-50 text-gray-700",
+    blue: "border-blue-200 bg-blue-50 text-blue-700",
+    green: "border-green-200 bg-green-50 text-green-700",
+    yellow: "border-yellow-200 bg-yellow-50 text-yellow-700",
+    red: "border-red-200 bg-red-50 text-red-700",
+    purple: "border-purple-200 bg-purple-50 text-purple-700",
+  };
+
+  return (
+    <span className={`rounded-full border px-2 py-0.5 text-xs ${tones[tone] || tones.gray}`}>
+      {children}
+    </span>
+  );
+}
+
+function NodeGroup({
+  title,
+  nodes,
+  resolvedNodeIds = new Set(),
+  newlySurfacedNodeIds = new Set(),
+  activeUnknownNodeId = null,
+}) {
+  if (!nodes?.length) return null;
+
+  return (
+    <section className="rounded-lg border border-gray-200 bg-white p-4">
+      <h3 className="mb-3 text-sm font-semibold text-gray-700">
+        {title} ({nodes.length})
+      </h3>
+      <ul className="space-y-3">
+        {nodes.map((node) => (
+          <li key={node.id} className="rounded border border-gray-100 bg-gray-50 p-3 text-sm">
+            <div className="flex flex-wrap items-center gap-2">
+              <span className="font-medium text-gray-900">{node.label}</span>
+              <NodeBadge tone="blue">{node.status}</NodeBadge>
+              <NodeBadge tone="green">{node.confidence}</NodeBadge>
+              {node.confidenceAssessment?.completenessStatus && (
+                <NodeBadge tone="purple">
+                  completeness: {node.confidenceAssessment.completenessStatus}
+                </NodeBadge>
+              )}
+              {resolvedNodeIds.has(node.id) && (
+                <NodeBadge tone="red">resolved unknown</NodeBadge>
+              )}
+              {newlySurfacedNodeIds.has(node.id) && (
+                <NodeBadge tone="purple">newly surfaced unknown</NodeBadge>
+              )}
+              {activeUnknownNodeId === node.id && (
+                <NodeBadge tone="yellow">active unknown</NodeBadge>
+              )}
+              {node.value != null && (
+                <NodeBadge tone="yellow">
+                  {node.value}
+                  {node.unit ? ` ${node.unit}` : ""}
+                </NodeBadge>
+              )}
+            </div>
+            {node.description && node.description !== node.label && (
+              <p className="mt-1 text-gray-600">{node.description}</p>
+            )}
+            {node.confidenceAssessment && (
+              <p className="mt-1 text-xs text-gray-500">
+                evidence: {node.confidenceAssessment.evidenceConfidence} ·
+                conclusion: {node.confidenceAssessment.conclusionConfidence}
+              </p>
+            )}
+          </li>
+        ))}
+      </ul>
+    </section>
+  );
+}
+
+export default function SituationGraphView({
+  situationGraph,
+  selectedQuestion,
+  newlySurfacedNodeIds = [],
+}) {
+  if (!situationGraph) return null;
+
+  const selectedQuestionText =
+    typeof selectedQuestion === "string"
+      ? selectedQuestion
+      : selectedQuestion?.question ?? null;
+
+  const activeUnknown = situationGraph.activeUnknownNodeId
+    ? situationGraph.nodes.find((node) => node.id === situationGraph.activeUnknownNodeId)
+    : null;
+
+  const nodesByKind = situationGraph.nodes.reduce((acc, node) => {
+    if (!acc[node.kind]) acc[node.kind] = [];
+    acc[node.kind].push(node);
+    return acc;
+  }, {});
+
+  const resolvedNodeIdSet = new Set(situationGraph.resolvedNodeIds || []);
+  const newlySurfacedNodeIdSet = new Set(newlySurfacedNodeIds || []);
+
+  return (
+    <div className="space-y-4">
+      {selectedQuestionText && (
+        <section className="rounded-lg border-2 border-green-300 bg-green-50 p-5">
+          <h2 className="mb-2 text-base font-bold text-green-800">Selected Question</h2>
+          <p className="text-base font-medium text-gray-900">{selectedQuestionText}</p>
+        </section>
+      )}
+
+      <section className="rounded-lg border border-gray-200 bg-white p-4">
+        <h2 className="mb-2 text-base font-semibold text-gray-900">Situation Graph</h2>
+        <dl className="space-y-2 text-sm">
+          <div>
+            <dt className="text-gray-500">Central statement</dt>
+            <dd className="font-medium text-gray-900">{situationGraph.centralStatement}</dd>
+          </div>
+          {situationGraph.currentSummary && (
+            <div>
+              <dt className="text-gray-500">Current summary</dt>
+              <dd className="text-gray-800">{situationGraph.currentSummary}</dd>
+            </div>
+          )}
+          {activeUnknown && (
+            <div>
+              <dt className="text-gray-500">Active unknown</dt>
+              <dd className="text-gray-900">{activeUnknown.label}</dd>
+            </div>
+          )}
+          <div>
+            <dt className="text-gray-500">Edge count</dt>
+            <dd className="text-gray-900">{situationGraph.edges.length}</dd>
+          </div>
+        </dl>
+      </section>
+
+      {Object.entries(nodesByKind).map(([kind, nodes]) => (
+        <NodeGroup
+          key={kind}
+          title={kind.replace(/_/g, " ")}
+          nodes={nodes}
+          resolvedNodeIds={resolvedNodeIdSet}
+          newlySurfacedNodeIds={newlySurfacedNodeIdSet}
+          activeUnknownNodeId={situationGraph.activeUnknownNodeId}
+        />
+      ))}
+
+      <details className="rounded-lg border border-gray-200 bg-gray-50 p-4">
+        <summary className="cursor-pointer text-sm font-medium text-gray-700 underline">
+          Raw graph JSON
+        </summary>
+        <pre className="mt-3 overflow-auto rounded bg-gray-900 p-3 text-xs text-green-400">
+          {JSON.stringify(situationGraph, null, 2)}
+        </pre>
+      </details>
+    </div>
+  );
+}

docs/orchestrator-contract.md

@@ -0,0 +1,113 @@
+# Orchestrator Contract — Confidence Engine v0.4
+
+## 1. Exported Function Signatures & Shape (JavaScript)
+
+### lib/analysis.js
+
+```js
+export async function analyseScenario(scenario, opts = {})
+// @param {string} scenario
+// @param {{ promptVersion?: "v0.2" | "v0.3" }} [opts]
+// @returns {Promise<{ success: boolean, validationStatus: "valid"|"invalid",
+//     modelName: string|null, responseDurationMs: number, rawResponse: string|null,
+//     promptVersion: string|null, inputClassification: object|null, reconstruction: object|null,
+//     evidence: object[]|undefined, nextQuestion: string|undefined, errors: string[]|undefined,
+//     error: string|undefined, statusCode: number|undefined }>}
+
+export const PROMPT_VERSIONS    // { [key: string]: string }
+export const DEFAULT_PROMPT_VERSION  // "v0.2"
+```
+
+### lib/graph/schema.js
+
+```js
+export const SituationKind          // { observation, reported_claim, metric, state, transition, relationship, assumption, unknown, conclusion }
+export const SituationStatus        // { known, unknown, provisional, supported, weakened, contradicted, resolved }
+export const ConfidenceLevel        // { low, medium, high }
+export const SituationRelationship  // { supports, weakens, contradicts, depends_on, causes, may_cause, measures, compares_with, updates, other }
+
+export const situationNodeSchema    // Zod → {@typedef SituationNode}
+export const situationEdgeSchema    // Zod → {@typedef SituationEdge}
+export const situationGraphSchema   // Zod → {@typedef SituationGraph}
+export const graphUpdateSchema      // Zod → {@typedef GraphUpdate}
+export const startCaseRequestSchema // { scenario: string (1-10000), promptVersion?: string }
+export const updateCaseRequestSchema// { situationGraph: SituationGraph, previousQuestion: string, answer: string (1-5000), promptVersion?: string }
+
+/** @param {string} label */ /** @returns {string} */ export function makeNodeId(label)
+/** @param {{ id?, label, description, kind?, status?, confidence?, value?, unit?, ... }} opts */ /** @returns {SituationNode} */ export function makeNode(opts)
+/** @param {{ id?, fromNodeId, toNodeId, relationship?, confidence?, description? }} opts */ /** @returns {SituationEdge} */ export function makeEdge(opts)
+/** @param {{ centralStatement?, nodes?, edges?, activeUnknownNodeId?, resolvedNodeIds?, currentSummary? }} opts */ /** @returns {SituationGraph} */ export function makeGraph(opts)
+```
+
+### lib/graph/utils.js
+
+```js
+export function validateGraphReferences(graph)     // → { valid: boolean, errors: string[] }
+export function detectDuplicateNodeIds(nodes)      // → { nodeId, count }[]
+export function detectDuplicateEdges(edges)        // { edgeId, fromNodeId, toNodeId, relationship }[]
+export function findDependentNodes(graph, nodeId)  // → string[] (transitive)
+export function findAffectedNodes(graph, nodeId)   // → string[] (direct + indirect via affects/dependsOn)
+/** @param {SituationGraph} graph */ /** @param {string} nodeId */ /** @param {string} newStatus */ /** @param {*} newValue */ /** @param {string} reason */
+export function resolveUnknownNode(graph, nodeId, newStatus, newValue, reason)  // → { success, error?, previousStatus?, newStatus?, previousValue?, newValue?, reason?, affectedNodes? }
+export function selectActiveUnknownCandidate(graph, resolvedNodeIds)  // → { nodeId, label, score } | null
+/** @param {SituationGraph} graph */ /** @param {GraphUpdate} update */
+export function applyGraphUpdate(graph, update)  // → { success: boolean, errors?, nodes?, edges?, resolvedNodeIds? }
+/** @param {SituationGraph} graph */ /** @param {GraphUpdate} update */
+export function validateGraphUpdate(graph, update)  // → { valid: boolean, errors: string[] }
+```
+
+### lib/graph/builder.js
+
+```js
+export function buildInitialGraph(analysisData)  // @param {{ reconstruction, evidence? }} → { nodes: SituationNode[], edges: SituationEdge[] }
+export function buildMinimalGraph(scenario)       // @param {string} → { nodes, edges }
+export function describeGraph(graph)              // @param {{ nodes, edges }} → string (summary text)
+```
+
+## 2. Dependencies Between Files
+
+```
+lib/analysis.js
+  ├── getConfig()         from lib/config.js
+  ├── getProvider()       from lib/llm/provider.js   [EXTERNAL]
+  ├── buildPrompt()       from lib/reconstruction/prompt.js
+  └── reconstructionV2/V1Schema  from lib/reconstruction/schema.js
+
+lib/graph/utils.js      ← imports situationNodeSchema, situationEdgeSchema, situationGraphSchema from schema.js
+lib/graph/builder.js    ← imports situationNodeSchema, situationEdgeSchema, makeNodeId from schema.js
+docs/v0.4-handoff.md   → references CaseOrchestrator.startCase()/updateCase() (not in any inspected file)
+```
+
+## 3. Side Effects (LLM Calls)
+
+| Function | LLM Call? | Details |
+|---|---|---|
+| `analyseScenario()` | **Yes** | `provider.generateReconstruction(prompt, model)` — POST to configured LLM. Prompt from `buildPrompt(scenario, version)`. |
+| All graph functions (`schema.js`, `utils.js`, `builder.js`) | No | Pure/deterministic only. |
+| `startCase()` / `updateCase()` (per handoff) | **Yes** | startCase: calls analyseScenario. updateCase: calls LLM via buildUpdatePrompt context + provider for GraphUpdate, then applyGraphUpdate(). |
+
+## 4. Minimal Proposed Contract for API Functions
+
+### startCase(body)
+- **Input:** `{ scenario: string (1-10000), promptVersion?: string }` — validated by `startCaseRequestSchema`.
+- **Flow:** validate → `analyseScenario()` → if ok, `buildInitialGraph(result)`; on failure return minimal graph via `buildMinimalGraph()`.
+- **Output (success):** `{ success: true, graphSummary: string, nodeCount: number, edgeCount: number, activeUnknownNodeId: string|undefined, nextQuestion: string }`
+- **Output (failure):** `{ success: false, error: string, graphSummary: string, nodeCount: number, edgeCount: number }`
+
+### updateCase(body)
+- **Input:** `{ situationGraph: SituationGraph, previousQuestion: string (1+), answer: string (1-5000), promptVersion?: string }` — validated by `updateCaseRequestSchema`.
+- **Flow:** validate → `buildUpdatePrompt(ctx)` → LLM call for GraphUpdate proposal → `validateGraphUpdate()` → `applyGraphUpdate()` → resolve unknowns via `resolveUnknownNode()` → pick next candidate via `selectActiveUnknownCandidate()`.
+- **Output (success):** `{ success: true, graphSummary: string, nodeChanges: { added, updated, removed }, edgeChanges: { added, removed }, resolvedNodes: string[], nextQuestion: string|null }`
+- **Output (failure):** `{ success: false, error: string, graphSummary: string, nodeChanges: {}, edgeChanges: {}, resolvedNodes: [], nextQuestion: null }`
+
+## 5. Missing Interfaces — TODO
+
+1. **[TODO]** `CaseOrchestrator` class described in handoff but absent from all five inspected files. startCase()/updateCase() wrappers need implementation per above contract.
+2. **[TODO]** `buildUpdatePrompt(ctx)` (per handoff lives in prompt-builder.js) — not reviewed; input/output needs a separate doc once the file is available.
+3. **[TODO]** LLM provider interface (`getProvider()`, `generateReconstruction(prompt, model)`) — external dependency. Assumes rawResponse is parseable JSON matching v0.2/v0.1 schema; needs explicit contract.
+4. **[TODO]** Error handling for updateCase() on malformed LLM JSON — handoff notes "generic 500"; needs structured retry/error contract.
+5. **[TODO]** Completion heuristic `getCompletionStatus()` referenced in handoff but absent; needs contract (e.g., "complete" when no unresolved unknown nodes).
+
+---
+
+*End of contract.*

docs/v0.4-handoff.md

@@ -0,0 +1,258 @@
+# v0.4 Handoff — Confidence Engine (confidence-engine)
+
+**Date:** 2026-08-01
+**Branch:** `feature/reconstruction-v0.3`
+**Parent branch:** `main`
+
+---
+
+## 1. What This Project Is
+
+A Next.js app that performs evidence-based situation reconstruction on user-supplied scenarios. An LLM analyses the scenario, builds a directed graph of actors, systems, unknowns and relationships, then iteratively refines the graph through multi-turn Q&A with the user.
+
+---
+
+## 2. Recent Commit History
+
+| Commit | Message |
+|--------|---------|
+| `79ea2f6` | feat: add v0.3 normalised comparison reasoning |
+| `d72c7c5` | chore: establish clean v0.2 baseline |
+| `a2f9e47` | chore: preserve initial reconstruction prototype |
+
+Only **one commit** ahead of `main`: `79ea2f6` — the v0.3 normalised comparison reasoning work.
+
+---
+
+## 3. Current State Summary
+
+### What's done and committed to this branch
+
+1. **v0.3 prompt** (`prompts/reconstruct-v0.3.md`) — a full LLM system prompt that adds:
+   - Normalisation / rate reasoning guidance (distinguishing absolute counts from per-unit rates)
+   - Interpretation discipline (empty array when evidence is too thin; no speculative filler)
+   - "Exactly one next question" constraint (no compound questions)
+   - Evidence type classification: `direct_observation`, `reported_statement`, `interpretation`, `assumption`, `inferred_relationship`
+   - Importance and confidence scales
+   - A strict camelCase JSON output schema with four top-level keys: `inputClassification`, `reconstruction`, `evidence`, `nextQuestion`
+
+2. **v0.3 prompt versioning** (`lib/reconstruction/prompt.js`) — exports `PROMPT_VERSIONS`, `DEFAULT_PROMPT_VERSION ("v0.3")`, and `buildPrompt(scenario, version)` for loading prompt templates from disk with scenario substitution.
+
+3. **Schema validation** (`lib/reconstruction/schema.js`) — Zod schemas for v0.2 output (`reconstructionV2Schema`). A `parseReconstructionV2(rawString)` helper is used in the analysis pipeline.
+
+4. **v0.3 reasoning tests** (`tests/v03-reasoning.test.js`) — extensive test suite covering:
+   - Prompt version registration and loading
+   - v0.3 guidance completeness (normalisation, rate vs count, correlation-vs-causation)
+   - Schema validation with a realistic "production/complaints" fixture
+   - Parse helper tests
+
+5. **Graph library** (`lib/graph/`) — the multi-turn reconstruction pipeline:
+
+   | File | Purpose |
+   |------|---------|
+   | `schema.js` | Zod schemas for SituationNode, SituationEdge, SituationGraph, GraphUpdate; helpers like `makeNodeId`, `makeNode`, `makeEdge`, `makeGraph` |
+   | `builder.js` | `buildInitialGraph(reconstruction, evidence)` — converts v0.2/v0.3 analysis output into a SituationGraph with deterministic nodes/edges; `buildMinimalGraph(scenario)` for fallback; `describeGraph(graph)` for display |
+   | `orchestrator.js` | `CaseOrchestrator` class managing the full multi-turn lifecycle (idle → building → active); exports `startCase(body)` and `updateCase(body)` convenience functions for API routes |
+   | `prompt-builder.js` | `buildUpdatePrompt(ctx)` — formats current graph state + Q&A context into a system prompt for the LLM update-evaluation turn |
+   | `utils.js` | Deterministic graph operations: `validateGraphReferences`, `detectDuplicateNodeIds`, `detectDuplicateEdges`, `findDependentNodes`, `findAffectedNodes`, `resolveUnknownNode`, `selectActiveUnknownCandidate`, `applyGraphUpdate`, `validateGraphUpdate` |
+
+6. **API routes** (`app/api/`)
+
+   | Route | Purpose |
+   |-------|---------|
+   | `POST /api/start-case` | Start a new reconstruction case — accepts `{ scenario, promptVersion? }`, returns graph summary, node/edge counts, next question |
+   | `POST /api/update-case` | Process a turn — accepts `{ scenario, graph, answer, currentQuestion?, turnCount?, modelName? }`, returns updated graph summary, next question, changes summary |
+
+7. **Smoke test** (`tests/smoke.test.js`) — basic integration test for the start-case API route.
+
+### What's NOT yet committed (untracked files from git status)
+
+| File | Description |
+|------|-------------|
+| `lib/graph/` (full directory) | The multi-turn graph library — built but NOT yet committed to any branch. These are the new untracked files: `builder.js`, `orchestrator.js`, `prompt-builder.js`, `schema.js`, `utils.js` |
+| `tests/graph/` (full directory) | Tests for the graph library — also untracked: `builder.test.js`, `orchestrator.test.js`, `prompt-builder.test.js`, `schema.test.js`, `utils.test.js` |
+| `app/api/start-case/route.js` | New API route (untracked) |
+| `app/api/update-case/route.js` | New API route (untracked) |
+
+> **Important:** The git status shows these files as untracked (`??`). They exist on disk but have never been staged or committed. You need to decide whether to commit them now or integrate them differently.
+
+---
+
+## 4. Test Status
+
+```
+Test Files:  4 failed | 4 passed (8)
+Tests:       5 failed | 216 passed (221)
+```
+
+### Known failures
+
+The failures cluster in `tests/graph/`:
+- **`prompt-builder.test.js`** — test expects the literal string `"Existing or newly added nodes"` but the prompt template currently says `"existing or newly added nodes"` (case mismatch). The SYSTEM_PROMPT_HEADER constant uses lowercase.
+- Other graph tests likely have similar fixture/reference issues.
+
+Run `npx vitest run tests/graph/ --reporter=verbose` for full details.
+
+---
+
+## 5. Architecture Overview
+
+```
+User scenario
+      │
+      ▼
+┌──────────────┐     ┌─────────────────┐     ┌──────────────┐
+│ analyseScenario│──▶│ buildPrompt     │──▶│ LLM (v0.3)   │
+│  (lib/analysis.js) │  (reconstruction/prompt.js) │              │
+└──────────────┘     └─────────────────┘     └──────┬───────┘
+                                                      │
+                                                      ▼
+                                              ┌──────────────┐
+                                              │ Parse output │
+                                              │ (Zod/parse   │
+                                              │  Reconstruction│
+                                              │  V2)          │
+                                              └──────┬───────┘
+                                                     │
+                     ┌───────────────────────────────┤
+                     ▼                               ▼
+              ┌──────────────┐           ┌──────────────────┐
+              │buildInitialGraph│         │ buildMinimalGraph │
+              │  (graph/builder)│         │  (fallback)       │
+              └──────┬─────────┘           └──────────────────┘
+                     │
+                     ▼
+              ┌──────────────┐
+              │SituationGraph │  ← Zod-validated graph structure
+              │  {nodes, edges}│     nodes: observation/metric/unknown/...
+              └──────┬───────┘     edges: supports/weakens/causes/...
+                     │
+          (multi-turn loop via updateCase)
+                     │
+           ┌─────────▼─────────┐
+           │buildUpdatePrompt  │  → LLM proposes GraphUpdate
+           │                   │
+           │applyGraphUpdate   │  → deterministic, validated
+           │validateGraphUpdate│     (no direct LLM mutation)
+           └───────────────────┘
+```
+
+---
+
+## 6. Key Design Decisions
+
+### Normalisation / rate reasoning (v0.3 focus)
+The v0.3 prompt explicitly instructs the model to:
+- Always consider whether a denominator/exposure metric is needed when counts change alongside scale
+- Distinguish absolute count from rate
+- Avoid treating two rising counts as causal evidence (production growth may outpace complaint growth)
+- Request the per-unit metric as the highest-value next question
+
+### Graph immutability
+LLM proposals are never applied directly. All mutations go through `applyGraphUpdate()` in `lib/graph/utils.js`, which:
+- Validates all node/edge references exist
+- Rejects duplicate IDs
+- Enforces a max graph size (500 nodes) and update size (100KB)
+- Returns the full new state for validation
+
+### Prompt versioning
+- Default is `"v0.3"` but `PROMPT_VERSIONS` includes `"v0.2"` for backward compatibility
+- `RECONSTRUCTION_PROMPT_VERSION` env var can override default at module load time
+- Prompts are loaded from `prompts/reconstruct-v0.{version}.md` on disk
+
+### Deterministic node IDs
+Node IDs are computed via a deterministic hash of the label: `makeNodeId(label)`. This avoids conflicts but means nodes must be created with consistent labels to get consistent IDs.
+
+---
+
+## 7. Open Questions / TODOs for Next Developer
+
+1. **Untracked graph library** — `lib/graph/` and `tests/graph/` are untracked on disk. Do we commit them as part of v0.4, or keep them in a separate branch?
+
+2. **Test failures** — 5 tests fail across the graph test suite. The prompt-builder case-sensitivity issue needs fixing. Review all failing tests before merging.
+
+3. **Missing `RECONSTRUCTION_PROMPT_VERSION` env var docs** — The system uses an env var override but it's not documented in `.env.example`. Add it if it's intended to be configurable.
+
+4. **Provider integration** — `lib/llm/provider.js` is imported by the orchestrator (`getProvider()`, `generateReconstruction()`). Verify the provider implementation matches what this code expects.
+
+5. **Graph completeness heuristic** — `CaseOrchestrator.getCompletionStatus()` returns `"complete"` when no unknown nodes remain, but doesn't consider whether all important observations have been verified.
+
+6. **Error resilience in update flow** — If the LLM returns malformed JSON, the update route returns a 500 with a generic error message. Consider retry logic or structured error parsing.
+
+7. **`buildUpdatePrompt` SYSTEM_PROMPT_HEADER is a module-level constant** — it's hardcoded and never versioned. If v0.5 changes the update-evaluation prompt style, this will need to become a template.
+
+8. **The `nextQuestion` field on `/api/start-case` response** includes the adapted question (original + active unknown label appended). The client may want the original and adapted separately.
+
+---
+
+## 8. File Inventory (new / changed files on this branch)
+
+### Prompts
+- `prompts/reconstruct-v0.3.md` — **NEW** — v0.3 system prompt (161 lines)
+- `prompts/reconstruct-v0.2.md` — **existing** — baseline prompt
+
+### Core library
+- `lib/analysis.js` — **MODIFIED** — analyseScenario function (uses v0.3 prompt by default)
+- `lib/reconstruction/prompt.js` — **MODIFIED** — prompt versioning exports
+- `lib/reconstruction/schema.js` — **existing** — Zod schemas + parseReconstructionV2
+
+### Graph library (untracked on disk)
+- `lib/graph/builder.js` — buildInitialGraph, buildMinimalGraph, describeGraph
+- `lib/graph/orchestrator.js` — CaseOrchestrator class, startCase, updateCase
+- `lib/graph/prompt-builder.js` — buildUpdatePrompt + SYSTEM_PROMPT_HEADER
+- `lib/graph/schema.js` — SituationNode/Edge/Graph/Update Zod schemas
+- `lib/graph/utils.js` — validation, dedup, dependency, and apply utilities
+
+### API routes (untracked on disk)
+- `app/api/start-case/route.js`
+- `app/api/update-case/route.js`
+
+### Tests (untracked on disk)
+- `tests/graph/builder.test.js`
+- `tests/graph/orchestrator.test.js`
+- `tests/graph/prompt-builder.test.js`
+- `tests/graph/schema.test.js`
+- `tests/graph/utils.test.js`
+- `tests/v03-reasoning.test.js` — **committed** to current branch
+- `tests/smoke.test.js`
+
+### Config changes
+- `package.json` — added dependency (verify which one)
+- `playwright.config.js` — added/modified for integration testing
+- `.env.local` — exists locally (not committed)
+
+---
+
+## 9. How to Run
+
+```bash
+# Install dependencies
+npm install
+
+# Unit tests
+npx vitest run
+
+# Graph library tests (has 5 failures)
+npx vitest run tests/graph/ --reporter=verbose
+
+# Start dev server
+npm run dev
+
+# API endpoints
+# POST /api/start-case    → { scenario: "..." }
+# POST /api/update-case   → { graph: {...}, answer: "...", ... }
+```
+
+---
+
+## 10. What to Do First (Recommended Priorities)
+
+1. **Review and fix the 5 failing tests** — likely simple string/fixture issues
+2. **Decide on the untracked files** — commit them, or create a v0.4 branch from this point
+3. **Verify the LLM provider integration** — ensure `getProvider()` and `generateReconstruction()` are wired up correctly
+4. **Add env var documentation** for `RECONSTRUCTION_PROMPT_VERSION` to `.env.example`
+5. **Smoke test end-to-end** — call `/api/start-case` with a real scenario and verify the full flow
+
+---
+
+*End of handoff.*

docs/v0.4-route-status.md

@@ -0,0 +1,25 @@
+# v0.4 Route Status
+
+- `app/api/cases/start/route.js`
+  - Current tracked start-case route for the v0.4 graph orchestration path.
+  - Covered by `tests/app/api/cases-start-route.test.js`.
+
+- `app/api/cases/update/route.js`
+  - Current tracked update-case route for the v0.4 graph orchestration path.
+  - Delegates to `updateCase(body, { applyProposal: true })`.
+  - Covered by `tests/app/api/cases-update-route.test.js`.
+
+- `app/api/start-case/route.js`
+  - Earlier experiment / duplicate start route.
+  - No repository UI/test references were found.
+  - Deleted from the working tree during UI connection cleanup.
+
+- `app/api/update-case/route.js`
+  - Earlier experimental duplicate update route.
+  - Removed from the working tree during route consolidation.
+
+- Current UI status
+  - `components/scenario-form.jsx` now calls `/api/cases/start` for the main experimental flow.
+  - `/api/cases/update` is the active tracked update route.
+  - `/api/analyse` remains available for legacy one-shot analysis.
+  - No UI changes were required for this route milestone.

docs/v0.5-question-priority-generalisation.md

@@ -0,0 +1,48 @@
+# v0.5 Question Priority Generalisation
+
+## Hypothesis
+
+The current deterministic unknown selector and graph-context question formulator should generalise across several decision types by selecting a foundational unknown before downstream implementation or pricing leaves.
+
+## Scenarios
+
+1. Should we hire another engineer?
+2. Should we replace the delivery vans?
+3. Should we launch in another country?
+4. Should we continue a project that is over budget?
+5. Should we introduce a paid support tier?
+
+## Results
+
+| Scenario                     | Selected unknown            | Strategy             | Pass/Fail |
+| ---------------------------- | --------------------------- | -------------------- | --------- |
+| Hire another engineer        | `hire-success-criteria`     | `decision criterion` | Pass      |
+| Replace the delivery vans    | `van-reliability-threshold` | `decision criterion` | Pass      |
+| Launch in another country    | `country-value-threshold`   | `actor/customer`     | Pass      |
+| Continue over-budget project | `project-benefit-threshold` | `decision criterion` | Pass      |
+| Introduce paid support tier  | `support-value-threshold`   | `actor/customer`     | Pass      |
+
+## Repeated failure patterns
+
+Two repeated structural formulation failures appeared before the final pass:
+
+1. **Constraint language in surrounding graph context outranked node-local decision-threshold language** in more than one case.
+2. **Baseline language in surrounding graph context outranked node-local threshold language** in more than one case.
+
+Both failures affected formulation strategy, not deterministic unknown selection.
+
+## Code change made
+
+A small deterministic change was made in `lib/graph/question-formulator.js`:
+
+- prefer node-local `definition` language before broader criterion inference
+- prefer node-local `decision criterion` language before context-only `constraint` inference
+- only treat `baseline` or `constraint` as primary when the selected node itself carries that language, otherwise allow them as fallback strategies later
+
+No architecture, UI, persistence, prompt, scoring, additional model turns, or provider calls were added.
+
+## Remaining limitations
+
+- In two passing cases, the selector chose a threshold-style foundational node while the formulator still used an `actor/customer` strategy because related context strongly referenced customers or recipients.
+- This experiment is fixture-driven and deterministic; it is useful for regression protection, not scientific validation.
+- The suite exercises the production path without model calls, but it does not prove behaviour over arbitrary real-world graph structures.

docs/v0.5-release-notes.md

@@ -0,0 +1,58 @@
+# v0.5 Release Notes
+
+## Purpose of v0.5
+
+v0.5 stabilises the graph-backed one-turn update flow so the engine can resolve an answered unknown, surface consequential new unknowns, prioritise the next unknown deterministically, and formulate a deterministic follow-up question without changing the UI or adding more model turns.
+
+## Capabilities proven
+
+v0.5 includes:
+
+- resolving an existing unknown
+- surfacing consequential new unknowns
+- limiting emergent unknowns
+- deterministic information-value prioritisation
+- deterministic question formulation
+- generalisation across five decision types
+- graph-backed one-turn UI update
+
+## Five-case generalisation result
+
+All five deterministic fixture scenarios passed:
+
+1. Should we hire another engineer?
+2. Should we replace the delivery vans?
+3. Should we launch in another country?
+4. Should we continue a project that is over budget?
+5. Should we introduce a paid support tier?
+
+The selector chose a foundational unknown first in each case, avoided the downstream leaf first, required no model call, and preserved graph immutability during question formulation.
+
+## Key deterministic safeguards
+
+- proposal application re-selects the active unknown deterministically after validation
+- information-value scoring penalises downstream or prerequisite-blocked unknowns
+- emergent unknown validation limits additions and requires explicit answer-derived linkage
+- final question wording is reformulated from graph context without an extra model turn
+- question validation rejects compound, awkward, or pricing-led fallback phrasing
+
+## Known limitation
+
+A correctly selected threshold node can still be phrased using an actor/customer strategy when surrounding graph context strongly references customers or value recipients.
+
+This limitation is recorded for the next experiment and is not being fixed in the v0.5 release-prep task.
+
+## Deliberately excluded work
+
+- no reasoning-logic expansion beyond the small deterministic formulation fixes already landed on the branch
+- no new features
+- no UI changes
+- no persistence
+- no additional model turn
+- no Ollama calls for validation
+- no evaluator-suite runs
+- no Playwright runs
+
+## Next experimental question
+
+Can the question formulation strategy remain aligned with the selected node's role when surrounding graph context contains competing signals?

docs/v0.6-ambiguity-generalisation.md

@@ -0,0 +1,40 @@
+# v0.6 Ambiguity Generalisation
+
+## Hypothesis
+
+If the selector truly handles unjustified contradiction ties generically, it should return ambiguity across multiple domains without preferring one explanation by wording alone.
+
+## Scenarios
+
+1. Revenue increased by 18%, but cash in the bank fell over the same period.
+2. Customer satisfaction scores increased, but complaints also increased.
+3. Average delivery time decreased by 25%, but order cancellations increased.
+4. Website traffic doubled, but sales remained unchanged.
+5. Production output increased by 30%, but quality defects also increased.
+
+## Observed behaviour
+
+All five fixtures produced the same pattern:
+
+- candidate count: 2
+- selector status: `ambiguous`
+- tie reason: `No justified distinction between leading unknowns.`
+- no explanation was favoured
+- one broad investigation question was produced from the central contradiction
+- neutral label renaming did not collapse ambiguity into a winner
+
+## Repeated failure patterns
+
+None observed across two or more scenarios.
+
+The current ambiguity handling generalised cleanly across the five contradiction fixtures.
+
+## Corrections
+
+No production correction was required in this task.
+
+## Lessons learned
+
+- The current ambiguity path appears domain-agnostic when structure and semantic weights remain intentionally non-discriminating.
+- Central-statement-based tie questions are broad enough to avoid prematurely backing one branch.
+- The most useful regression signal is whether ambiguity survives neutral relabelling, not whether one label sorts ahead of another in display order.

docs/v0.6-atomicity-experiment.md

@@ -0,0 +1,211 @@
+# v0.6 Atomicity Experiment
+
+## Hypothesis
+
+After deterministic unknown selection, the engine should assess whether the selected unknown is already atomic or is still too composite to ask directly.
+
+If the unknown is atomic, the engine should proceed exactly as before.
+
+If the unknown is composite, the engine should not ask that parent unknown directly. Instead, it should decompose it into a small set of explicit child unknowns representing broad, independent candidate dimensions that a non-expert could understand.
+
+## Constraints
+
+- No graph redesign
+- No persistence
+- No UI redesign
+- No selection-weight tuning
+- No Ollama calls in unit tests
+
+## Deterministic rule introduced
+
+Atomicity assessment is **not** a new investigation strategy.
+
+It runs in the graph update path at this seam:
+
+```text
+unknown selection -> atomicity assessment -> optional decomposition -> deterministic reselection -> question formulation
+```
+
+The implementation uses deterministic text and graph-shape checks:
+
+- focused unknowns like denominator / threshold / definition / baseline / evidence remain **atomic**
+- broad relationship-explanation unknowns and broad “possible causes / what changed / explanation for why X but Y” unknowns become **composite**
+
+## Decomposition behavior
+
+When a selected unknown is composite:
+
+1. The parent unknown remains unresolved.
+2. Between 2 and 5 child unknowns are created or reused deterministically.
+3. Children become explicit graph nodes.
+4. Children link back to the parent with existing `depends_on` edges.
+5. Children inherit the same “why it matters” discipline in their descriptions.
+6. Deterministic selection reruns across the updated graph.
+
+For the current relationship-explanation experiment, the broad child dimensions are:
+
+- Whether the two observations reflect different timing
+- How the two observations were measured
+- Change affecting signal A more than signal B
+- Change affecting signal B more than signal A
+- One-off event during the period
+
+These are intentionally non-jargon and broad enough to generalise across scenarios like:
+
+- Revenue up / Cash down
+- Customer satisfaction up / Complaints up
+- Delivery time down / Cancellations up
+- Traffic up / Sales flat
+- Production up / Defects up
+
+## Diagnostics added
+
+The orchestrator now reports:
+
+- `atomicityAssessment`
+- `atomicityDecisionReason`
+- `decompositionDepth`
+- `decompositionAttempted`
+- `decompositionAccepted`
+- `decompositionStoppedReason`
+- `proposedChildCount`
+- `acceptedChildCount`
+- `rejectedChildren`
+- `selectedChildNodeId`
+- `childQualitySummary`
+- `propagationPerformed`
+- `resolvedChildNodeId`
+- `parentNodeId`
+- `parentStatusBefore`
+- `parentStatusAfter`
+- `parentConfidenceBefore`
+- `parentConfidenceAfter`
+- `affectedAncestorIds`
+- `nextSelectedSibling`
+- `parentResolved`
+- `decompositionPerformed`
+- `childUnknownCount`
+- `childNodeIds`
+- `atomicityReason`
+
+This sits alongside the existing explicit-emergent-unknown diagnostics.
+
+## Observed outcome
+
+The experiment was useful.
+
+Before this change, the engine could select a broad explanation unknown and ask it directly.
+
+After this change:
+
+- the broad explanation parent remains explicit in the graph
+- the engine decomposes it into child unknowns first
+- the next asked question is backed by a more focused child unknown
+- repeated updates reuse the same decomposition children deterministically
+- child-quality checks reject compound or duplicate children before they enter the graph
+- decomposition stops deterministically once a selected child is directly answerable
+- resolving one child does not resolve the parent immediately
+- resolved child evidence now propagates upward to the parent and ancestor chain deterministically
+- parent status and confidence change conservatively after child resolution
+- the next sibling becomes eligible for normal deterministic selection without recreating the resolved child
+
+In the revenue-versus-cash case, the selected next question becomes:
+
+> What evidence would clarify how the two observations were measured?
+
+rather than asking the full broad explanation node directly.
+
+## Upward propagation and reconstruction
+
+Recursive reasoning is complete only when decomposition and reconstruction are both deterministic.
+
+Confidence must not outrun completeness or evidence.
+
+For this experiment, reconstruction now behaves as follows:
+
+- when a child unknown resolves, that child keeps its own resolved status and answer evidence
+- the parent is updated, but remains unresolved unless the deterministic completion rule is satisfied
+- only the ancestor chain connected to that child is updated
+- unrelated branches remain unchanged
+- the deterministic selector then chooses the next justified unresolved sibling or related follow-up
+
+For the current conservative completion rule:
+
+- **one resolved child** → parent becomes `provisional` with higher confidence, but remains unresolved
+- **all direct child unknowns resolved** → parent resolves deterministically with `high` confidence
+
+The confidence model is now explicitly separated into:
+
+- **evidence confidence**: how trustworthy the currently attached support is
+- **completeness**: whether the required direct child structure is empty, partial, or complete
+- **conclusion confidence**: how strongly the current parent state is justified given both evidence and completeness
+
+Deterministic propagation rules now enforce:
+
+- one resolved child may raise evidence confidence
+- unresolved direct children cap conclusion confidence
+- contradictory direct children block high conclusion confidence
+- duplicate evidence does not increase confidence
+- status changes do not raise confidence on their own
+- parent resolution still requires the separate completion rule
+
+## Cross-branch corroboration
+
+The next confidence experiment adds deterministic branch interaction checks without changing the graph model.
+
+The engine now distinguishes between:
+
+- **multiple evidence**: more than one branch exists
+- **independent corroboration**: distinct resolved branches support the same parent without sharing the same evidence key
+- **duplicate evidence**: the same evidence key appears through multiple branches and must not be double-counted
+- **conflicting evidence**: branches support incompatible positions, such as `recognised correctly` vs `recognised incorrectly`
+
+Deterministic branch rules:
+
+- corroboration only counts when branches are distinct and their evidence sources differ
+- duplicate evidence groups never count as corroboration
+- conflicts cap conclusion confidence and prevent a higher confidence upgrade
+- independent branches remain interaction-neutral
+
+Additional diagnostics now expose:
+
+- `corroboratingBranchCount`
+- `conflictingBranchCount`
+- `duplicateEvidenceCount`
+- `independentBranchCount`
+- `interactionSummary`
+- `confidenceAdjustmentReason`
+
+Observed effect:
+
+- independent corroboration can raise `evidenceConfidence`
+- duplicate evidence produces no extra confidence increase
+- conflicting evidence lowers or caps `conclusionConfidence`
+- completeness rules still dominate whether a parent may become highly justified
+
+Example progression:
+
+- parent before: `unknown`, `medium`
+- after resolving `How the two observations were measured`: parent becomes `provisional`, `medium`
+- evidence confidence becomes `high`, completeness becomes `partial`, conclusion confidence becomes `medium`
+- next sibling becomes selectable and the engine moves on without recreating the resolved child
+
+## Interpretation
+
+This supports the idea that recursive decomposition is a fundamental part of graph-backed questioning, not just a prompt refinement.
+
+The main remaining limitation is that sibling selection still inherits the existing deterministic scorer. That means some domains may advance to a justified sibling that is not the intuitively expected next child, even though the propagation itself remains deterministic and graph-valid.
+
+## Validation run
+
+Covered by:
+
+- `tests/graph/atomicity-assessment.test.js`
+- `tests/graph/decomposition-quality.test.js`
+- `tests/graph/upward-propagation.test.js`
+- `tests/graph/apply-proposal.test.js`
+- `tests/graph/orchestrator.test.js`
+- `tests/graph/question-formulator.test.js`
+- `tests/ui/scenario-form.test.jsx`
+
+And then by the broader requested validation pass with lint and build.

docs/v0.6-comparability-experiment.md

@@ -0,0 +1,48 @@
+# v0.6 Comparability Experiment
+
+## Hypothesis
+
+The engine should confirm that observations are comparable before treating their difference as a contradiction that needs explanatory follow-up.
+
+## Fixtures
+
+1. Revenue increased by 18%, but cash in the bank fell over the same period.
+2. Complaints increased. Production increased.
+3. Average delivery time decreased by 25%, but order cancellations increased.
+4. Customer satisfaction increased, but complaints increased.
+5. Temperature increased. Ice melted.
+6. Sales doubled. Sales doubled.
+
+## Results
+
+- The first four scenarios repeated the same failure pattern: contradiction-level investigation could begin before comparability was established.
+- A deterministic comparability gate corrected that by producing one comparison question first.
+- Confirmed comparability did not by itself imply contradiction.
+- Temperature increased / Ice melted was reclassified as a compatible relationship, so no contradiction question was asked.
+- Sales doubled / Sales doubled was reclassified as duplicate observations, so no follow-up question was asked.
+
+## Relationship classification stage
+
+After comparability assessment, observations now pass through a deterministic relationship classification stage:
+
+- `contradictory`
+- `compatible`
+- `potentially_related`
+- `duplicate`
+- `insufficient_information`
+
+## Whether comparability should become a permanent reasoning stage
+
+Yes, in minimal deterministic form.
+
+The repeated pattern appeared in four scenarios, so a small pre-contradiction comparability assessment is justified.
+
+## Two-step experiment result
+
+A comparison question is useful only if its answer advances the reasoning stage rather than merely adding more text.
+
+In the revenue-versus-cash scenario, the first question now confirms whether the figures are comparable, and the answer resolves that existing uncertainty instead of creating a parallel note. After that update, the engine progresses from comparability assessment to cautious relationship assessment and can select one broad non-expert follow-up question.
+
+Every justified next question should correspond to an explicit unresolved graph node.
+
+The earlier fallback-only path has now been removed from the normal successful progression. After comparability is resolved and a further investigation question is justified, the engine creates or reuses an explicit unresolved reasoning unknown and lets deterministic selection and question formulation proceed through the standard graph pipeline. A fallback is now only acceptable as an explicit failure case, not as the normal source of the next question.

docs/v0.6-reasoning-architecture.md

@@ -0,0 +1,375 @@
+# v0.6 Reasoning Architecture
+
+## Purpose
+
+This document describes the implemented deterministic reasoning architecture on branch `feature/question-strategy-alignment-v0.6`.
+
+It is written for future developers who need to understand how v0.6 actually executes, what invariants it relies on, where the recursive loops are, and what the system deliberately does **not** attempt to do.
+
+## End-to-end pipeline
+
+The implemented runtime pipeline is:
+
+```text
+Scenario input
+↓
+LLM analysis / reconstruction
+↓
+Initial graph build
+↓
+Deterministic unknown selection
+↓
+Selected question
+↓
+User answer
+↓
+LLM graph-update proposal
+↓
+Proposal parsing / normalisation
+↓
+Proposal compatibility validation
+↓
+Deterministic graph update application
+↓
+Reasoning-state rebuild
+↓
+Comparability assessment
+↓
+Relationship classification
+↓
+Explicit emergent unknown creation / reuse (if required)
+↓
+Deterministic reselection
+↓
+Atomicity assessment
+↓
+Optional decomposition into child unknowns
+↓
+Deterministic reselection
+↓
+Resolved-child propagation upward
+↓
+Confidence / completeness / corroboration update
+↓
+Next active unknown
+↓
+Question formulation
+```
+
+## Deterministic stages
+
+### 1. Scenario analysis / reconstruction
+
+- **Purpose**: obtain structured reconstruction material from scenario text
+- **Input**: scenario, prompt version
+- **Output**: analysis payload containing reconstruction, evidence, diagnostics, and optional next question
+- **Why it exists**: provides the initial structured substrate from which the graph is built
+- **What breaks if removed**: the graph builder has no structured reconstruction to convert into nodes and edges
+
+### 2. Initial graph build
+
+- **Purpose**: convert reconstruction output into an initial `SituationGraph`
+- **Input**: reconstruction + evidence
+- **Output**: graph nodes and edges, then `makeGraph(...)` wraps them with active/resolved/summary state
+- **Why it exists**: all later reasoning is graph-based, not free text
+- **What breaks if removed**: no explicit unknown nodes, no deterministic selection, no validated update loop
+
+### 3. Deterministic unknown selection
+
+- **Purpose**: choose the next active unknown from unresolved graph nodes
+- **Input**: graph, resolved node IDs
+- **Output**: selected candidate or explicit ambiguity result
+- **Why it exists**: the system needs a deterministic next investigation target
+- **What breaks if removed**: question ordering becomes arbitrary or hidden in prompts
+
+### 4. Selected question exposure
+
+- **Purpose**: expose the chosen unknown as the next question to the user
+- **Input**: selected unknown + question formulation or tie-resolution logic
+- **Output**: selected question object
+- **Why it exists**: the user-facing loop must ask a concrete next question
+- **What breaks if removed**: the system can build a graph but cannot continue interaction coherently
+
+### 5. LLM graph-update proposal
+
+- **Purpose**: transform a user answer into a proposed graph change set
+- **Input**: current graph, previous question, answer, prompt version
+- **Output**: raw JSON-like proposal
+- **Why it exists**: the LLM is limited to proposing changes; it does not mutate the graph directly
+- **What breaks if removed**: answers cannot affect the graph except through manual hard-coded logic
+
+### 6. Proposal parsing / normalisation
+
+- **Purpose**: parse JSON, remove null array items, apply known aliases, fill omitted optional fields
+- **Input**: raw model response
+- **Output**: validated `graphUpdateSchema` payload or structured parser failure
+- **Why it exists**: model outputs are not trusted as-is
+- **What breaks if removed**: malformed or partially missing model output would reach graph logic directly
+
+### 7. Proposal compatibility validation
+
+- **Purpose**: ensure the proposal is graph-safe and semantically valid before application
+- **Input**: current graph + proposed update
+- **Output**: accepted proposal or compatibility errors
+- **Why it exists**: protects graph integrity and reasoning invariants
+- **What breaks if removed**: duplicate IDs, missing references, fake selected questions, and no-op updates could corrupt the graph
+
+### 8. Deterministic graph update application
+
+- **Purpose**: apply only validated graph changes to a copied graph
+- **Input**: graph + validated proposal
+- **Output**: updated nodes, edges, resolved node IDs
+- **Why it exists**: separates safe application from generation
+- **What breaks if removed**: no explicit, replayable state transition exists
+
+### 9. Reasoning-state rebuild
+
+- **Purpose**: derive fresh comparability/relationship state from the updated graph
+- **Input**: updated graph + optional override state
+- **Output**: `reasoningState`
+- **Why it exists**: reasoning stages are derived from graph state, not stored blindly
+- **What breaks if removed**: comparability and relationship decisions drift from actual graph contents
+
+### 10. Comparability assessment
+
+- **Purpose**: decide whether supported observations are comparable enough for relationship reasoning
+- **Input**: graph observations + central statement + optional stored override
+- **Output**: comparability status/reason + contradiction permission
+- **Why it exists**: relationship reasoning is gated by comparability
+- **What breaks if removed**: contradiction or relationship reasoning would run over incomparable observations
+
+### 11. Relationship classification
+
+- **Purpose**: classify observation relationships once comparability permits it
+- **Input**: graph + comparability result
+- **Output**: relationship status, reason, whether a follow-up question is justified
+- **Why it exists**: determines whether explanation-style follow-up is needed
+- **What breaks if removed**: the system cannot distinguish compatible, duplicate, insufficient, and contradiction-adjacent observation sets
+
+### 12. Explicit emergent unknown creation / reuse
+
+- **Purpose**: ensure any justified relationship follow-up is represented by an explicit unresolved graph node
+- **Input**: provisional graph + relationship assessment
+- **Output**: reused or newly added explanation unknown and edges
+- **Why it exists**: preserves the invariant that a question must originate from an explicit unknown
+- **What breaks if removed**: relationship follow-up would revert to fallback-only question text not backed by the graph
+
+### 13. Atomicity assessment
+
+- **Purpose**: determine whether the selected unknown is directly investigable or too composite
+- **Input**: selected unknown + graph context
+- **Output**: `atomic` or `composite` decision with decomposition kind/reason
+- **Why it exists**: prevents asking broad explanation unknowns directly
+- **What breaks if removed**: the system asks high-level composite unknowns instead of decomposing them first
+
+### 14. Optional decomposition
+
+- **Purpose**: split a composite unknown into deterministic child unknowns
+- **Input**: composite selected unknown + graph context
+- **Output**: 2–5 child unknowns, edges, quality summary, rejection diagnostics
+- **Why it exists**: narrows broad unknowns into explicit candidate dimensions
+- **What breaks if removed**: recursive reasoning stops at broad parents and loses graph-backed substructure
+
+### 15. Resolved-child propagation upward
+
+- **Purpose**: move resolved child effects to parent and ancestor chain without prematurely resolving them
+- **Input**: updated graph + proposal snapshot
+- **Output**: parent/ancestor status and confidence updates, additional diagnostics
+- **Why it exists**: decomposition requires deterministic reconstruction as well as decomposition
+- **What breaks if removed**: child answers stay local and parents never become progressively better-supported
+
+### 16. Confidence / completeness / corroboration update
+
+- **Purpose**: derive parent-level `confidenceAssessment` from resolved children and branch interactions
+- **Input**: parent child set + branch evidence/status interactions
+- **Output**: `evidenceConfidence`, `completenessStatus`, `conclusionConfidence`, plus derived display `confidence`
+- **Why it exists**: reasoning support must be separated from completion and contradiction state
+- **What breaks if removed**: parent confidence collapses back into vague status-driven heuristics
+
+### 17. Next active unknown + question formulation
+
+- **Purpose**: reselect the next unresolved unknown and formulate a concrete next question
+- **Input**: updated graph + selection state + graph context
+- **Output**: next active unknown and question object
+- **Why it exists**: closes the recursive interaction loop
+- **What breaks if removed**: the system updates the graph but cannot continue investigation deterministically
+
+## Architectural invariants
+
+The current implementation enforces these invariants:
+
+1. **A question must originate from an explicit unresolved unknown node.**
+2. **Unknown selection is deterministic.**
+3. **Alphabetical ordering is not treated as reasoning.**
+4. **Relationship reasoning does not precede comparability.**
+5. **The LLM never mutates the graph directly; it only proposes updates.**
+6. **All graph updates are schema-validated before application.**
+7. **All node/edge references must resolve to existing nodes.**
+8. **Duplicate node IDs are rejected.**
+9. **Duplicate added edge IDs are rejected.**
+10. **A selected question cannot target a resolved unknown.**
+11. **A resolved unknown updated to `resolved` must also appear in `resolvedUnknownNodeIds`.**
+12. **A proposal must contain a meaningful change.**
+13. **Every newly added unknown must include why-it-matters language.**
+14. **Every newly added unknown must be explicitly connected to answer-derived graph structure.**
+15. **Composite selected unknowns are decomposed before direct questioning when atomicity rules require it.**
+16. **Parent unknowns remain unresolved until completion rules are satisfied.**
+17. **Confidence must not outrun completeness.**
+18. **Duplicate evidence cannot increase confidence.**
+19. **Conflicting evidence caps conclusion confidence.**
+20. **Cross-branch corroboration only counts for distinct branches with distinct evidence keys.**
+21. **Ambiguous leading unknowns remain explicit ambiguity, not silent forced choice.**
+
+## Recursive loops and stopping rules
+
+### Main investigation loop
+
+```text
+Unknown
+↓
+Question
+↓
+Answer
+↓
+Proposal
+↓
+Graph update
+↓
+Propagation
+↓
+Next unknown
+```
+
+- **Exit condition**: no unresolved candidates remain, or no next question is justified, or proposal/application fails
+- **Stopping rule**: deterministic selection returns `null` or explicit ambiguity, or update validation blocks progress
+- **Completion behaviour**: continues only while the graph contains justified unresolved unknowns
+
+### Decomposition loop
+
+```text
+Selected unknown
+↓
+Atomicity assessment
+↓
+If composite: decompose
+↓
+Reselect child
+↓
+Atomicity assessment again
+```
+
+- **Exit condition**: selected child is atomic; parent already has children; max decomposition depth reached; or decomposition quality fails
+- **Stopping rule**: `MAX_DECOMPOSITION_DEPTH`, reuse instead of regeneration, or inability to produce enough valid child unknowns
+- **Completion behaviour**: deterministic and bounded; no infinite recursive decomposition path is intentionally allowed
+
+### Propagation loop
+
+```text
+Resolved child
+↓
+Ancestor chain walk
+↓
+Recompute parent state
+↓
+Stop when no ancestor state changes
+```
+
+- **Exit condition**: no more parents in the ancestor chain or no state change
+- **Stopping rule**: ancestor chain is explicit and finite; propagation does not invent new ancestors
+- **Completion behaviour**: deterministic upward traversal with explicit stop on unchanged state
+
+### Potential infinite loops reviewed
+
+- **Unknown/question recursion**: bounded by unresolved unknown set, proposal validation, and explicit no-candidate states
+- **Decomposition recursion**: bounded by max depth and child reuse rules
+- **Propagation recursion**: bounded by finite ancestor chain and no-change stop condition
+
+No intentional infinite reasoning loop is present in the implemented architecture.
+
+## Graph lifecycle summary
+
+### Node lifecycle
+
+1. node created by `buildInitialGraph` or later proposal/decomposition/emergent-unknown logic
+2. node validated by schema
+3. node may become active unknown
+4. node may be updated by proposal application
+5. unknown node may become `resolved`, `provisional`, `contradicted`, or remain `unknown`
+6. resolved unknown ID is tracked in `resolvedNodeIds`
+
+### Edge lifecycle
+
+1. edge created in initial graph or by deterministic proposal augmentation
+2. edge validated against existing node IDs
+3. edge may be removed only through explicit `removedEdgeIds`
+4. edge relationships also update `dependsOn` / `childIds` projections during application
+
+### Unknown lifecycle
+
+1. initial unknown discovered from reconstruction
+2. selected deterministically or left ambiguous
+3. may be decomposed if composite
+4. may be resolved directly by answer
+5. may cause emergent reasoning unknown creation when relationship reasoning demands a new explicit question target
+
+### Resolved lifecycle
+
+1. proposal marks unresolved unknown resolved
+2. reconciliation ensures resolution semantics are explicit
+3. `resolvedUnknownNodeIds` feed graph application
+4. propagation may resolve parent only when completion rule is met
+
+### Confidence lifecycle
+
+1. nodes begin with base `confidence`
+2. parent/ancestor propagation derives `confidenceAssessment`
+3. display `confidence` is derived from `conclusionConfidence`
+4. completeness, duplicate evidence, contradiction, and corroboration constrain the result
+
+### Question lifecycle
+
+1. selected unknown becomes question target
+2. `formulateQuestion` or tie-resolution logic produces question text
+3. answer returns through update route
+4. proposal may select a new question target or leave reselection to deterministic logic
+
+Every major transition above is explicit in the current codebase rather than implicit in model text alone.
+
+## Duplicated or overlapping concepts
+
+The following concepts are intentionally close and may look duplicated:
+
+- **status vs confidence**: status captures lifecycle/progression; confidence captures support strength
+- **confidence vs confidenceAssessment**: `confidence` is now a derived display field, while `confidenceAssessment` carries separated reasoning dimensions
+- **resolvedNodeIds vs node.status === resolved**: both are maintained; the first is a graph-level index, the second is node-local state
+- **selectedQuestion in proposal vs selectedQuestion in final result**: proposal may omit or propose one, final result recomputes deterministic selection/questioning after graph logic
+- **comparability state in reasoningState vs derived comparability from graph**: overrides may carry forward prior confirmed reasoning, but `buildReasoningState` still rebuilds from graph + override context
+
+These are not necessarily defects, but they are the main places where future simplification pressure is likely.
+
+## Known boundaries and deliberate exclusions
+
+v0.6 deliberately does **not** attempt the following:
+
+- probabilistic reasoning
+- Bayesian inference
+- persistence
+- semantic embeddings
+- fuzzy semantic similarity
+- autonomous exploration outside explicit user answers
+- multi-hop corroboration across unrelated subtrees without a shared direct parent
+- expert-only jargon-specific reasoning modes
+- UI-heavy reasoning visualisation beyond existing graph/update displays
+- arbitrary non-deterministic tie breaking
+
+## Defects found during this review
+
+No new production defect was intentionally introduced or fixed as part of this architecture review.
+
+## Developer notes
+
+- `startCase` owns reconstruction → graph build → first deterministic selection.
+- `updateCaseWithDependencies` owns proposal generation / parsing and delegates deterministic graph semantics to `applyValidatedProposal`.
+- `applyValidatedProposal` is the main reasoning pipeline coordinator for update-time graph evolution.
+- `question-formulator.js` owns comparability, relationship classification, atomicity assessment, investigation strategy selection, and question formulation.
+- `utils.js` owns selection scoring, ordering, graph validation, and safe graph update application.

docs/v0.6-release-notes.md

@@ -0,0 +1,89 @@
+# v0.6 Release Notes
+
+## Purpose
+
+v0.6 turns the engine into a deterministic recursive reasoning system that keeps next questions, decomposition, propagation, and confidence updates explicitly grounded in the situation graph.
+
+## Capabilities added
+
+- deterministic unknown selection explanations
+- explicit ambiguity handling instead of silent tie-breaking
+- comparability assessment before relationship reasoning
+- relationship classification after comparability
+- reasoning-stage progression after comparability answers
+- graph-backed next questions via explicit unknown nodes
+- investigation-strategy-based question formulation
+- atomicity assessment for selected unknowns
+- composite-unknown decomposition into child unknowns
+- child-quality validation for decomposition outputs
+- upward propagation from resolved children to parents and ancestors
+- separation of evidence confidence, completeness, and conclusion confidence
+- deterministic cross-branch corroboration, conflict, and duplicate-evidence handling
+- developer-facing reasoning architecture documentation
+
+## Reasoning pipeline summary
+
+```text
+Scenario
+→ Reconstruction
+→ Initial graph
+→ Deterministic unknown selection
+→ Question
+→ Answer
+→ Proposal
+→ Proposal parsing / validation
+→ Graph update
+→ Reasoning-state rebuild
+→ Comparability assessment
+→ Relationship classification
+→ Emergent unknown creation / reuse
+→ Atomicity assessment
+→ Optional decomposition
+→ Propagation
+→ Confidence / completeness / corroboration update
+→ Next active unknown
+→ Next question
+```
+
+## Core invariants
+
+- every asked question must originate from an explicit unresolved unknown
+- unknown selection is deterministic
+- ambiguity is preserved explicitly when no justified distinction exists
+- relationship reasoning cannot precede comparability
+- parent nodes cannot resolve before completion rules are met
+- confidence cannot outrun completeness
+- duplicate evidence cannot increase confidence
+- conflicting evidence caps conclusion confidence
+- cross-branch corroboration only counts for distinct branches with distinct evidence keys
+- the LLM proposes updates but does not mutate the graph directly
+
+## What v0.6 proved
+
+- graph-backed questioning works better when every justified next question maps to an explicit unresolved node
+- broad unknowns can be decomposed deterministically before direct questioning
+- resolved child evidence can be propagated upward without prematurely resolving parent reasoning
+- confidence becomes easier to reason about when evidence quality, completeness, and conclusion strength are separated
+- deterministic cross-branch corroboration can improve support without double-counting repeated evidence
+
+## Known limitations
+
+- sibling selection still depends on the existing deterministic scorer and may choose a justified next branch that is not always the intuitively expected one
+- cross-branch corroboration is limited to direct child branches of the same parent
+- no multi-hop corroboration exists across unrelated subtrees
+- reasoning remains bounded to explicitly represented graph structure and user-provided answers
+
+## Deliberate exclusions
+
+- no persistence
+- no autonomous exploration
+- no probabilistic reasoning
+- no Bayesian reasoning
+- no semantic embeddings
+- no expert mode
+- no multi-hop corroboration across unrelated subtrees
+- no heavy graph visualisation
+
+## Next experimental question
+
+`Can the engine preserve and reuse successful reasoning structures across separate cases without turning prior experience into unquestioned assumptions?`

docs/v0.6-selection-influence-experiment.md

@@ -0,0 +1,50 @@
+# v0.6 Selection Influence Experiment
+
+## Hypothesis
+
+The initial unknown selected for the revenue-versus-cash scenario may be driven more by graph structure, more by semantic keyword matches, or by both together.
+
+## Scenario
+
+`Revenue increased by 18%, but cash in the bank fell over the same period.`
+
+## Actual selected node
+
+- Node ID: `nqdzobz`
+- Label: `Magnitude and nature of cash outflows (operating expenses, debt repayments, capex, or working capital shifts).`
+- Deterministic investigation strategy: `definition`
+- Deterministic question: `What evidence would resolve whether magnitude and nature of cash outflows (operating expenses, debt repayments, capex, or working capital shifts). is true?`
+
+## Structural contribution
+
+- Downstream dependency count: `0`
+- Prerequisite position: no unresolved prerequisites; count `0`
+- Dependency ordering / centrality: no candidate had downstream dependants or dependency depth advantage in the live graph
+
+## Semantic contribution
+
+- Objective: false
+- Actor: false
+- Criteria: false
+- Measurement: false
+- Terminology: false
+- Constraint: false
+- Pricing: false
+- Implementation: false
+- Optimisation: false
+- Speculative: false
+- Contribution list: only `downstream_dependencies` was present, with delta `0`
+
+## Counterfactual results
+
+- Live-shaped ordering: `nqdzobz` ranked above `niewza`, but both had score `0`, downstream `0`, and unresolved prerequisites `0`
+- Links removed: ordering stayed the same, because the live graph already provided no differentiating structure between the two unknowns
+- Wording neutralised: ordering flipped to the first unknown by neutral label order (`Unknown A` before `Unknown B`), showing the outcome remained tie-break-driven rather than structure-driven
+
+## Conclusion
+
+For this scenario, the actual winner was not selected because of graph structure and not selected because of semantic keyword weights. The live diagnostics show a complete tie on score, downstream influence, and prerequisite position, with every semantic match category false for both candidates. The winner was therefore chosen by the final tie-break rule, `label_asc`.
+
+## Is a scoring change justified?
+
+Not from this single experiment alone. The result shows a diagnostic gap for this scenario, but this task does not justify a scoring change by itself, and no scoring change is made.

lib/analysis.js

@@ -0,0 +1,242 @@
+/**
+ * Core analysis pipeline — shared by API routes and evaluation harness.
+ * Calls the provider, parses output, validates against Zod schemas (v0.2 first, v0.1 fallback).
+ */
+
+import { getConfig } from "../lib/config.js";
+import { getProvider } from "../lib/llm/provider.js";
+import {
+  buildPrompt,
+  PROMPT_VERSIONS,
+  DEFAULT_PROMPT_VERSION,
+} from "../lib/reconstruction/prompt.js";
+import { normaliseAnalysisResponse } from "../lib/reconstruction/compatibility.js";
+import {
+  reconstructionV2Schema,
+  reconstructionSchema as reconstructionV1Schema,
+} from "../lib/reconstruction/schema.js";
+
+const MAX_SCENARIO_LENGTH = 10000;
+
+/**
+ * Analyse a scenario string through the full pipeline.
+ * @param {string} scenario - The scenario text to analyse
+ * @param {object} [opts]
+ * @param {"v0.1" | "v0.2"} [opts.promptVersion="v0.2"] - Prompt version to use
+ * @returns {Promise<object>} Analysis result with diagnostics
+ */
+export async function analyseScenario(scenario, opts = {}) {
+  const startTime = Date.now();
+
+  // ── Input validation ───────────────────────────────
+  if (typeof scenario !== "string") {
+    return buildErrorResponse("Input must be a string", startTime);
+  }
+
+  const trimmed = scenario.trim();
+  if (trimmed.length === 0) {
+    return buildErrorResponse("Scenario cannot be empty", startTime);
+  }
+  if (trimmed.length > MAX_SCENARIO_LENGTH) {
+    return buildErrorResponse(
+      `Scenario must be under ${MAX_SCENARIO_LENGTH} characters`,
+      startTime,
+    );
+  }
+
+  // ── Configuration check ────────────────────────────
+  const configResult = getConfig();
+  if (!configResult.ok) {
+    return buildErrorResponse("Invalid server configuration", startTime, "500");
+  }
+
+  const { OLLAMA_BASE_URL: _ignored, OLLAMA_MODEL } = configResult.config;
+  const promptVersion = opts.promptVersion || DEFAULT_PROMPT_VERSION;
+
+  // ── Build prompt ───────────────────────────────────
+  let promptObj;
+  try {
+    promptObj = await buildPrompt(trimmed, promptVersion);
+  } catch (e) {
+    return buildErrorResponse(
+      `Failed to build prompt: ${e.message}`,
+      startTime,
+    );
+  }
+
+  // ── Call provider ──────────────────────────────────
+  const provider = getProvider();
+  let rawResponse;
+  try {
+    rawResponse = await provider.generateReconstruction(
+      promptObj.prompt,
+      OLLAMA_MODEL,
+    );
+  } catch (e) {
+    return buildErrorResponse(
+      e.message || "Provider error during analysis",
+      Date.now() - startTime,
+    );
+  }
+
+  const duration = Date.now() - startTime;
+
+  // Try to capture raw response for diagnostics
+  let rawResponseStr;
+  try {
+    rawResponseStr = JSON.stringify(rawResponse);
+  } catch {
+    rawResponseStr = String(rawResponse).slice(0, 2000);
+  }
+
+  const compatibility = normaliseAnalysisResponse(rawResponse);
+  const candidateResponse = compatibility.normalised;
+
+  // ── Validate against v0.2 schema (preferred) ──────
+  const resultV2 = tryValidateAgainstSchema(
+    candidateResponse,
+    reconstructionV2Schema,
+  );
+  if (resultV2.valid) {
+    return buildSuccessResultV2(
+      resultV2.data,
+      OLLAMA_MODEL,
+      duration,
+      promptVersion,
+      compatibility,
+    );
+  }
+
+  // ── Fallback to v0.1 schema ────────────────────────
+  const resultV1 = tryValidateAgainstSchema(
+    candidateResponse,
+    reconstructionV1Schema,
+  );
+  if (resultV1.valid) {
+    return buildSuccessResultV1(
+      resultV1.data,
+      OLLAMA_MODEL,
+      duration,
+      promptVersion,
+      compatibility,
+    );
+  }
+
+  // ── Neither schema matched — partial failure ───────
+  return buildPartialResult(
+    rawResponseStr?.slice(0, 2000),
+    resultV2.error ?? resultV1.error,
+    OLLAMA_MODEL,
+    duration,
+    promptVersion,
+    compatibility,
+  );
+}
+
+/** Attempt validation against a Zod schema */
+function tryValidateAgainstSchema(data, schema) {
+  if (!schema.safeParse) {
+    return {
+      valid: false,
+      error: new Error("Schema does not support safeParse"),
+    };
+  }
+  const result = schema.safeParse(data);
+  return result.success
+    ? { valid: true, data: result.data }
+    : { valid: false, error: result.error };
+}
+
+// ── Result builders ──────────────────────────────────
+
+function buildErrorResponse(message, elapsed, statusCode = 500) {
+  return {
+    success: false,
+    error: message,
+    modelName: null,
+    responseDurationMs: elapsed,
+    validationStatus: "invalid",
+    rawResponse: null,
+    promptVersion: null,
+    statusCode,
+  };
+}
+
+function buildCompatibilityDiagnostics(compatibility) {
+  return {
+    compatibilityApplied: compatibility.changesApplied.length > 0,
+    compatibilityChanges: compatibility.changesApplied,
+    compatibilityWarnings: compatibility.warnings,
+  };
+}
+
+function buildSuccessResultV2(data, model, duration, version, compatibility) {
+  return {
+    success: true,
+    validationStatus: "valid",
+    modelName: model,
+    responseDurationMs: duration,
+    rawResponse: JSON.stringify(data).slice(0, 3000),
+    promptVersion: version,
+    inputClassification: data.inputClassification,
+    reconstruction: data.reconstruction,
+    evidence: data.evidence,
+    nextQuestion: data.nextQuestion,
+    errors: undefined,
+    ...buildCompatibilityDiagnostics(compatibility),
+  };
+}
+
+function buildSuccessResultV1(data, model, duration, version, compatibility) {
+  return {
+    success: true,
+    validationStatus: "valid",
+    modelName: model,
+    responseDurationMs: duration,
+    rawResponse: JSON.stringify(data).slice(0, 3000),
+    promptVersion: version,
+    inputClassification: null,
+    reconstruction: data,
+    evidence: undefined,
+    nextQuestion: undefined,
+    errors: undefined,
+    ...buildCompatibilityDiagnostics(compatibility),
+  };
+}
+
+function buildPartialResult(
+  rawResp,
+  error,
+  model,
+  duration,
+  version,
+  compatibility,
+) {
+  let errors = [];
+  if (error && typeof error.flatten === "function") {
+    errors = error.flatten().fieldErrors
+      ? Object.entries(error.flatten().fieldErrors).flatMap(([k, v]) => [
+          `${k}: ${v.join(", ")}`,
+        ])
+      : [String(error)];
+  } else if (error) {
+    errors = [String(error).slice(0, 500)];
+  }
+
+  return {
+    success: false,
+    validationStatus: "invalid",
+    modelName: model,
+    responseDurationMs: duration,
+    rawResponse: rawResp?.slice(0, 2000),
+    promptVersion: version,
+    inputClassification: null,
+    reconstruction: null,
+    evidence: undefined,
+    nextQuestion: undefined,
+    errors,
+    ...buildCompatibilityDiagnostics(compatibility),
+  };
+}
+
+export { PROMPT_VERSIONS, DEFAULT_PROMPT_VERSION };

lib/graph/builder.js

@@ -0,0 +1,305 @@
+/**
+ * Deterministic situation graph builder — builds initial graph from scenario text.
+ * Takes v0.2/v0.3 analysis output (from analyseScenario) and constructs a SituationGraph.
+ */
+
+import {
+  situationNodeSchema,
+  situationEdgeSchema,
+  makeNodeId,
+} from "./schema.js";
+
+/**
+ * Build an initial situation graph from a v0.3 reconstruction result.
+ * @param {{ reconstruction: object, evidence: object[] | undefined }} analysisData
+ * @returns {{ nodes: import("./schema.js").SituationNode[], edges: import("./schema.js").SituationEdge[] }}
+ */
+export function buildInitialGraph(analysisData) {
+  const { reconstruction, evidence = [] } = analysisData;
+
+  if (!reconstruction || !reconstruction.summary) {
+    return { nodes: [], edges: [] };
+  }
+
+  const nodeMap = new Map(); // label -> node
+
+  // ── Helper: register or get a node by label ────────────
+
+  function ensureNode(
+    label,
+    kind,
+    status,
+    description,
+    value,
+    unit,
+    confidence,
+  ) {
+    if (nodeMap.has(label)) return nodeMap.get(label);
+
+    const id = makeNodeId(label);
+    const node = situationNodeSchema.parse({
+      id,
+      label,
+      description: description ?? label,
+      kind,
+      status,
+      confidence,
+      value: value ?? null,
+      unit: unit ?? null,
+      evidenceIds: [],
+      dependsOn: [],
+      affects: [],
+      parentId: null,
+      childIds: [],
+    });
+    nodeMap.set(label, node);
+    return node;
+  }
+
+  // ── Evidence lookup ────────────────────────────────────
+
+  const evidenceMap = new Map();
+  for (const ev of evidence) {
+    if (ev.id) evidenceMap.set(ev.id, ev);
+  }
+
+  function addEvidenceToNode(nodeId, evidenceId) {
+    const node = Object.values(nodeMap).find((n) => n.id === nodeId);
+    if (node && !node.evidenceIds.includes(evidenceId)) {
+      node.evidenceIds.push(evidenceId);
+    }
+  }
+
+  // ── Extract observed states as nodes ────────────────────
+
+  const summaryNode = ensureNode(
+    reconstruction.summary || "Situation Summary",
+    "state",
+    "provisional",
+    "Summary of the situation from the scenario text",
+    null,
+    null,
+    "medium",
+  );
+
+  // Collect all observable quantities as metric nodes
+  const metrics = new Map();
+
+  if (reconstruction.observedStates) {
+    for (const obs of reconstruction.observedStates) {
+      const node = ensureNode(
+        obs.description || obs.label,
+        "observation",
+        "supported",
+        obs.description || obs.label,
+        null,
+        null,
+        obs.confidence || "medium",
+      );
+
+      if (obs.id) node.evidenceIds.push(obs.id);
+    }
+  }
+
+  // Actors as states/nodes
+  if (reconstruction.actors) {
+    for (const actor of reconstruction.actors) {
+      ensureNode(
+        actor.description || actor.label,
+        "observation",
+        "supported",
+        actor.description || actor.label,
+        null,
+        null,
+        actor.confidence || "medium",
+      );
+    }
+  }
+
+  if (reconstruction.systemsOrObjects) {
+    for (const sys of reconstruction.systemsOrObjects) {
+      ensureNode(
+        sys.description || sys.label,
+        "metric",
+        "known",
+        sys.description || sys.label,
+        null,
+        null,
+        sys.confidence || "medium",
+      );
+    }
+  }
+
+  // Differences as relationship nodes
+  if (reconstruction.differences) {
+    for (const diff of reconstruction.differences) {
+      const node = ensureNode(
+        diff.description || "Difference",
+        "relationship",
+        "supported",
+        diff.description || "Difference",
+        null,
+        null,
+        diff.confidence || "medium",
+      );
+    }
+  }
+
+  // Contradictions as nodes
+  if (reconstruction.contradictions) {
+    for (const c of reconstruction.contradictions) {
+      const node = ensureNode(
+        c.description || c.label,
+        "relationship",
+        "supported",
+        c.description || c.label,
+        null,
+        null,
+        c.confidence || "medium",
+      );
+    }
+  }
+
+  // Important unknowns as unknown nodes
+  const unknownNodes = [];
+  if (reconstruction.importantUnknowns) {
+    for (const unk of reconstruction.importantUnknowns) {
+      const node = ensureNode(
+        unk.description || unk.label,
+        "unknown",
+        "unknown",
+        unk.description || "Unknown factor in the situation",
+        null,
+        null,
+        unk.confidence || "low",
+      );
+      unknownNodes.push(node);
+    }
+  }
+
+  // Plausible interpretations
+  if (reconstruction.plausibleInterpretations) {
+    for (const interp of reconstruction.plausibleInterpretations) {
+      ensureNode(
+        interp.description || interp.label,
+        "assumption",
+        "provisional",
+        interp.description || "Plausible interpretation",
+        null,
+        null,
+        interp.confidence || "low",
+      );
+    }
+  }
+
+  // Known transitions
+  if (reconstruction.knownTransitions) {
+    for (const trans of reconstruction.knownTransitions) {
+      ensureNode(
+        `${trans.entity}: ${trans.previousState} → ${trans.currentState}`,
+        "transition",
+        trans.explanationStatus === "confirmed" ? "known" : "provisional",
+        trans.description ||
+          `Transition: ${trans.entity} from ${trans.previousState} to ${trans.currentState}`,
+        null,
+        null,
+        trans.confidence || "medium",
+      );
+    }
+  }
+
+  // ── Build edges between nodes ────────────────────────
+
+  const nodeArr = Array.from(nodeMap.values());
+  const edges = [];
+
+  // Link actors → observed states as measures relationships
+  let actorNodes = [];
+  let metricNodes = [];
+  let unknownNodeIds = [];
+
+  for (const n of nodeArr) {
+    if (n.kind === "observation" && n.status === "supported") {
+      // These are observations — link to summary
+      edges.push(
+        situationEdgeSchema.parse({
+          id: `e-sum-${n.id}`,
+          fromNodeId: n.id,
+          toNodeId: summaryNode.id,
+          relationship: "supports",
+          confidence: n.confidence || "medium",
+          description: `${n.label} supports the summary`,
+        }),
+      );
+    }
+    if (n.kind === "unknown") {
+      unknownNodeIds.push(n.id);
+      edges.push(
+        situationEdgeSchema.parse({
+          id: `e-unk-${n.id}`,
+          fromNodeId: n.id,
+          toNodeId: summaryNode.id,
+          relationship: "depends_on",
+          confidence: n.confidence || "low",
+          description: `${n.label} is an unresolved factor for this situation`,
+        }),
+      );
+    }
+  }
+
+  return { nodes: nodeArr, edges };
+}
+
+/**
+ * Build a minimal starting graph for any scenario.
+ * Used when analysis has no reconstruction data (e.g., error state).
+ */
+export function buildMinimalGraph(scenario) {
+  const shortLabel = scenario.slice(0, 80);
+
+  return {
+    nodes: [
+      situationNodeSchema.parse({
+        id: "n0",
+        label: shortLabel,
+        description: `Initial situation from: "${scenario.slice(0, 200)}"`,
+        kind: "state",
+        status: "provisional",
+        confidence: "low",
+        value: null,
+        unit: null,
+        evidenceIds: [],
+        dependsOn: [],
+        affects: [],
+        parentId: null,
+        childIds: [],
+      }),
+    ],
+    edges: [],
+  };
+}
+
+/**
+ * Convert graph nodes/edges to a human-readable summary for display.
+ */
+export function describeGraph(graph) {
+  const parts = [];
+
+  // Count by kind
+  const byKind = {};
+  for (const n of graph.nodes) {
+    byKind[n.kind] = (byKind[n.kind] || 0) + 1;
+  }
+
+  parts.push(
+    `Nodes: ${Object.entries(byKind)
+      .map(([k, v]) => `${v} ${k}`)
+      .join(", ")}`,
+  );
+  parts.push(`Edges: ${graph.edges.length} total`);
+  parts.push(
+    `Unknowns: ${graph.nodes.filter((n) => n.status === "unknown").length} unresolved`,
+  );
+
+  return parts.join(" | ");
+}

lib/graph/orchestrator.js

@@ -0,0 +1,660 @@
+/**
+ * Situation Graph Case Orchestrator — manages the lifecycle of a case.
+ * startCase builds initial graph from analysis; updateCase applies answers.
+ */
+
+import { analyseScenario } from "../analysis.js";
+import { assertConfig } from "../config.js";
+import { getProvider } from "../llm/provider.js";
+import {
+  makeGraph,
+  startCaseRequestSchema,
+  situationGraphSchema,
+  updateCaseRequestSchema,
+} from "./schema.js";
+import { buildInitialGraph, describeGraph } from "./builder.js";
+import { applyValidatedProposal } from "./apply-proposal.js";
+import { buildGraphUpdatePrompt } from "./prompt-builder.js";
+import {
+  buildReasoningState,
+  formulateTieResolutionQuestion,
+} from "./question-formulator.js";
+import { parseGraphUpdateProposal } from "./update-proposal.js";
+import {
+  explainUnknownSelection,
+  selectActiveUnknownCandidate,
+  validateGraphReferences,
+} from "./utils.js";
+
+function toValidationErrors(error) {
+  return (
+    error?.errors?.map((issue) => ({
+      path: issue.path,
+      message: issue.message,
+      code: issue.code,
+    })) ?? [{ message: "Validation failed" }]
+  );
+}
+
+function buildDiagnostics({
+  analysis,
+  graph,
+  graphReferenceValidation,
+  unknownSelectionExplanation,
+}) {
+  return {
+    promptVersion: analysis?.promptVersion ?? null,
+    modelName: analysis?.modelName ?? null,
+    responseDurationMs: analysis?.responseDurationMs ?? null,
+    validationStatus: analysis?.validationStatus ?? "invalid",
+    nodeCount: graph?.nodes?.length ?? 0,
+    edgeCount: graph?.edges?.length ?? 0,
+    graphReferenceValidation,
+    compatibilityApplied: analysis?.compatibilityApplied ?? false,
+    compatibilityChanges: analysis?.compatibilityChanges ?? [],
+    compatibilityWarnings: analysis?.compatibilityWarnings ?? [],
+    unknownSelectionExplanation: unknownSelectionExplanation ?? null,
+  };
+}
+
+function buildUnknownSelectionDiagnostics(
+  graph,
+  resolvedNodeIds = [],
+  selectedQuestion = null,
+) {
+  const explanation = explainUnknownSelection(graph, resolvedNodeIds);
+  if (explanation.status === "ambiguous") {
+    return {
+      ...explanation,
+      tieResolutionQuestion:
+        selectedQuestion?.selectionStatus === "ambiguous"
+          ? selectedQuestion.question
+          : formulateTieResolutionQuestion({ graph }).question,
+      alphabeticalUsedAsReasoning: false,
+    };
+  }
+
+  return explanation;
+}
+
+function buildUpdateDiagnostics({
+  promptVersion,
+  modelName,
+  responseDurationMs,
+  normalisationsApplied,
+  graph,
+  graphReferenceValidation,
+  selectedQuestion,
+  unknownSelectionExplanation,
+  previousReasoningState,
+  reasoningState,
+  resolvedReasoningNodeIds,
+  emergentReasoningNodeCreated,
+  emergentReasoningNodeId,
+  emergentReasoningNodeReason,
+  atomicityAssessment,
+  atomicityDecisionReason,
+  decompositionDepth,
+  decompositionAttempted,
+  decompositionAccepted,
+  decompositionStoppedReason,
+  proposedChildCount,
+  acceptedChildCount,
+  rejectedChildren,
+  selectedChildNodeId,
+  childQualitySummary,
+  propagationPerformed,
+  resolvedChildNodeId,
+  parentNodeId,
+  parentStatusBefore,
+  parentStatusAfter,
+  parentConfidenceBefore,
+  parentConfidenceAfter,
+  evidenceConfidenceBefore,
+  evidenceConfidenceAfter,
+  completenessBefore,
+  completenessAfter,
+  conclusionConfidenceBefore,
+  conclusionConfidenceAfter,
+  resolvedDirectChildren,
+  unresolvedDirectChildren,
+  contradictoryDirectChildren,
+  corroboratingBranchCount,
+  conflictingBranchCount,
+  duplicateEvidenceCount,
+  independentBranchCount,
+  interactionSummary,
+  confidenceCapReason,
+  ancestorPropagationStoppedReason,
+  affectedAncestorIds,
+  nextSelectedSibling,
+  parentResolved,
+  decompositionPerformed,
+  childUnknownCount,
+  childNodeIds,
+  atomicityReason,
+}) {
+  return {
+    promptVersion: promptVersion ?? "v0.4",
+    modelName: modelName ?? null,
+    responseDurationMs: responseDurationMs ?? null,
+    validationStatus: "valid",
+    nodeCount: graph?.nodes?.length ?? 0,
+    edgeCount: graph?.edges?.length ?? 0,
+    graphReferenceValidation: graphReferenceValidation ?? {
+      valid: true,
+      errors: [],
+    },
+    normalisationsApplied: normalisationsApplied ?? [],
+    investigationStrategy:
+      selectedQuestion?.investigationStrategy ??
+      selectedQuestion?.strategy ??
+      null,
+    previousComparabilityStatus:
+      previousReasoningState?.comparabilityStatus ?? null,
+    comparabilityStatus: reasoningState?.comparabilityStatus ?? null,
+    relationshipStatus: reasoningState?.relationshipStatus ?? null,
+    relationshipAssessed: reasoningState?.relationshipAssessed ?? null,
+    reasoningStagesBefore: previousReasoningState?.reasoningStages ?? [],
+    reasoningStagesAfter: reasoningState?.reasoningStages ?? [],
+    resolvedReasoningNodeIds: resolvedReasoningNodeIds ?? [],
+    emergentReasoningNodeCreated: emergentReasoningNodeCreated ?? false,
+    emergentReasoningNodeId: emergentReasoningNodeId ?? null,
+    emergentReasoningNodeReason: emergentReasoningNodeReason ?? null,
+    atomicityAssessment: atomicityAssessment ?? null,
+    atomicityDecisionReason: atomicityDecisionReason ?? null,
+    decompositionDepth: decompositionDepth ?? 0,
+    decompositionAttempted: decompositionAttempted ?? false,
+    decompositionAccepted: decompositionAccepted ?? false,
+    decompositionStoppedReason: decompositionStoppedReason ?? null,
+    proposedChildCount: proposedChildCount ?? 0,
+    acceptedChildCount: acceptedChildCount ?? 0,
+    rejectedChildren: rejectedChildren ?? [],
+    selectedChildNodeId: selectedChildNodeId ?? null,
+    childQualitySummary: childQualitySummary ?? [],
+    propagationPerformed: propagationPerformed ?? false,
+    resolvedChildNodeId: resolvedChildNodeId ?? null,
+    parentNodeId: parentNodeId ?? null,
+    parentStatusBefore: parentStatusBefore ?? null,
+    parentStatusAfter: parentStatusAfter ?? null,
+    parentConfidenceBefore: parentConfidenceBefore ?? null,
+    parentConfidenceAfter: parentConfidenceAfter ?? null,
+    evidenceConfidenceBefore: evidenceConfidenceBefore ?? null,
+    evidenceConfidenceAfter: evidenceConfidenceAfter ?? null,
+    completenessBefore: completenessBefore ?? null,
+    completenessAfter: completenessAfter ?? null,
+    conclusionConfidenceBefore: conclusionConfidenceBefore ?? null,
+    conclusionConfidenceAfter: conclusionConfidenceAfter ?? null,
+    resolvedDirectChildren: resolvedDirectChildren ?? 0,
+    unresolvedDirectChildren: unresolvedDirectChildren ?? 0,
+    contradictoryDirectChildren: contradictoryDirectChildren ?? 0,
+    corroboratingBranchCount: corroboratingBranchCount ?? 0,
+    conflictingBranchCount: conflictingBranchCount ?? 0,
+    duplicateEvidenceCount: duplicateEvidenceCount ?? 0,
+    independentBranchCount: independentBranchCount ?? 0,
+    interactionSummary: interactionSummary ?? null,
+    confidenceCapReason: confidenceCapReason ?? null,
+    ancestorPropagationStoppedReason: ancestorPropagationStoppedReason ?? null,
+    affectedAncestorIds: affectedAncestorIds ?? [],
+    nextSelectedSibling: nextSelectedSibling ?? null,
+    parentResolved: parentResolved ?? false,
+    decompositionPerformed: decompositionPerformed ?? false,
+    childUnknownCount: childUnknownCount ?? 0,
+    childNodeIds: childNodeIds ?? [],
+    atomicityReason: atomicityReason ?? null,
+    unknownSelectionExplanation: unknownSelectionExplanation ?? null,
+  };
+}
+
+export async function startCase(body) {
+  const parsedRequest = startCaseRequestSchema.safeParse(body);
+
+  if (!parsedRequest.success) {
+    return {
+      success: false,
+      error: "Invalid start-case request",
+      validationErrors: toValidationErrors(parsedRequest.error),
+      statusCode: 400,
+    };
+  }
+
+  const { scenario, promptVersion } = parsedRequest.data;
+  const analysis = await analyseScenario(scenario, { promptVersion });
+
+  if (!analysis.success) {
+    return {
+      success: false,
+      error: analysis.error ?? "Scenario analysis failed",
+      diagnostics: buildDiagnostics({
+        analysis,
+        graph: null,
+        graphReferenceValidation: null,
+      }),
+      analysisErrors: analysis.errors ?? undefined,
+      rawResponse: analysis.rawResponse ?? undefined,
+      statusCode: Number(analysis.statusCode) || 502,
+    };
+  }
+
+  const initialGraph = buildInitialGraph({
+    reconstruction: analysis.reconstruction,
+    evidence: analysis.evidence,
+  });
+
+  const currentSummary = describeGraph(initialGraph);
+  const deterministicSelection = selectActiveUnknownCandidate(
+    {
+      ...initialGraph,
+      resolvedNodeIds: [],
+    },
+    [],
+  );
+  const activeUnknownNodeId =
+    deterministicSelection?.status === "selected"
+      ? deterministicSelection.nodeId
+      : null;
+
+  const situationGraph = makeGraph({
+    centralStatement: scenario,
+    nodes: initialGraph.nodes,
+    edges: initialGraph.edges,
+    activeUnknownNodeId,
+    resolvedNodeIds: [],
+    currentSummary,
+    reasoningState: buildReasoningState({
+      centralStatement: scenario,
+      nodes: initialGraph.nodes,
+      edges: initialGraph.edges,
+      resolvedNodeIds: [],
+    }),
+  });
+
+  situationGraphSchema.parse(situationGraph);
+
+  const graphReferenceValidation = validateGraphReferences(situationGraph);
+  const selectedQuestion =
+    deterministicSelection?.status === "ambiguous"
+      ? {
+          id: "q_tie_resolution",
+          ...formulateTieResolutionQuestion({ graph: situationGraph }),
+          tiedCandidateIds: deterministicSelection.tiedCandidateIds,
+        }
+      : (analysis.nextQuestion ?? null);
+  const unknownSelectionExplanation = buildUnknownSelectionDiagnostics(
+    situationGraph,
+    [],
+    selectedQuestion,
+  );
+  if (!graphReferenceValidation.valid) {
+    return {
+      success: false,
+      error: "Situation graph reference validation failed",
+      diagnostics: buildDiagnostics({
+        analysis,
+        graph: situationGraph,
+        graphReferenceValidation,
+        unknownSelectionExplanation,
+      }),
+      validationErrors: graphReferenceValidation.errors,
+      statusCode: 500,
+    };
+  }
+
+  return {
+    success: true,
+    situationGraph,
+    selectedQuestion,
+    diagnostics: buildDiagnostics({
+      analysis,
+      graph: situationGraph,
+      graphReferenceValidation,
+      unknownSelectionExplanation,
+    }),
+  };
+}
+
+export async function updateCase() {
+  return updateCaseWithDependencies(...arguments);
+}
+
+function sanitiseErrorMessage(error, fallbackMessage) {
+  if (typeof error?.message === "string" && error.message.trim().length > 0) {
+    return error.message;
+  }
+
+  return fallbackMessage;
+}
+
+async function updateCaseWithDependencies(body, dependencies = {}) {
+  const parsedRequest = updateCaseRequestSchema.safeParse(body);
+
+  if (!parsedRequest.success) {
+    return {
+      success: false,
+      stage: "request_validation",
+      error: "Invalid update-case request",
+      validationErrors: toValidationErrors(parsedRequest.error),
+      statusCode: 400,
+    };
+  }
+
+  const { situationGraph, previousQuestion, answer, promptVersion } =
+    parsedRequest.data;
+
+  const graphSchemaValidation = situationGraphSchema.safeParse(situationGraph);
+  const graphReferenceValidation = validateGraphReferences(situationGraph);
+
+  if (!graphSchemaValidation.success || !graphReferenceValidation.valid) {
+    return {
+      success: false,
+      stage: "graph_validation",
+      error: "Invalid situation graph",
+      graphValidationErrors: [
+        ...(!graphSchemaValidation.success
+          ? toValidationErrors(graphSchemaValidation.error)
+          : []),
+        ...(!graphReferenceValidation.valid
+          ? graphReferenceValidation.errors
+          : []),
+      ],
+      statusCode: 400,
+    };
+  }
+
+  const buildPrompt =
+    dependencies.buildGraphUpdatePrompt ?? buildGraphUpdatePrompt;
+  const parseProposal =
+    dependencies.parseGraphUpdateProposal ?? parseGraphUpdateProposal;
+  const applyProposalUpdate =
+    dependencies.applyValidatedProposal ?? applyValidatedProposal;
+  const shouldApplyProposal = dependencies.applyProposal === true;
+
+  let modelName = null;
+  let rawResponse;
+  const startedAt = Date.now();
+
+  try {
+    const config = dependencies.config ?? assertConfig();
+    modelName = config.OLLAMA_MODEL;
+
+    const prompt = buildPrompt({
+      situationGraph,
+      previousQuestion,
+      answer,
+      promptVersion,
+    });
+
+    const provider = dependencies.provider ?? getProvider();
+    rawResponse = await provider.generateReconstruction(prompt, modelName);
+  } catch (error) {
+    return {
+      success: false,
+      stage: "provider",
+      error: "Graph update proposal generation failed",
+      providerErrors: [
+        sanitiseErrorMessage(
+          error,
+          "Provider failed to generate graph update proposal",
+        ),
+      ],
+      diagnostics: {
+        promptVersion: promptVersion ?? null,
+        modelName,
+        responseDurationMs: Date.now() - startedAt,
+        normalisationsApplied: [],
+      },
+      statusCode: 502,
+    };
+  }
+
+  const parsedProposal = parseProposal(rawResponse);
+  const responseDurationMs = Date.now() - startedAt;
+
+  if (!parsedProposal.success) {
+    return {
+      success: false,
+      stage: "proposal_validation",
+      error: "Invalid graph update proposal",
+      proposalErrors: parsedProposal.errors,
+      diagnostics: {
+        promptVersion: promptVersion ?? null,
+        modelName,
+        responseDurationMs,
+        normalisationsApplied: parsedProposal.normalisationsApplied,
+      },
+      statusCode: 502,
+    };
+  }
+
+  if (shouldApplyProposal) {
+    const applicationResult = applyProposalUpdate({
+      situationGraph,
+      proposal: parsedProposal.proposal,
+      previousQuestion,
+      answer,
+    });
+
+    if (!applicationResult.success) {
+      return {
+        success: false,
+        stage: applicationResult.stage,
+        errors: applicationResult.errors,
+        diagnostics: {
+          ...buildUpdateDiagnostics({
+            promptVersion,
+            modelName,
+            responseDurationMs,
+            normalisationsApplied: parsedProposal.normalisationsApplied,
+            graph: situationGraph,
+            graphReferenceValidation: graphReferenceValidation,
+            selectedQuestion: null,
+            previousReasoningState: buildReasoningState(situationGraph),
+            reasoningState: buildReasoningState(situationGraph),
+            resolvedReasoningNodeIds: [],
+            emergentReasoningNodeCreated: false,
+            emergentReasoningNodeId: null,
+            emergentReasoningNodeReason: null,
+            atomicityAssessment: null,
+            atomicityDecisionReason: null,
+            decompositionDepth: 0,
+            decompositionAttempted: false,
+            decompositionAccepted: false,
+            decompositionStoppedReason: null,
+            proposedChildCount: 0,
+            acceptedChildCount: 0,
+            rejectedChildren: [],
+            selectedChildNodeId: null,
+            childQualitySummary: [],
+            propagationPerformed: false,
+            resolvedChildNodeId: null,
+            parentNodeId: null,
+            parentStatusBefore: null,
+            parentStatusAfter: null,
+            parentConfidenceBefore: null,
+            parentConfidenceAfter: null,
+            evidenceConfidenceBefore: null,
+            evidenceConfidenceAfter: null,
+            completenessBefore: null,
+            completenessAfter: null,
+            conclusionConfidenceBefore: null,
+            conclusionConfidenceAfter: null,
+            resolvedDirectChildren: 0,
+            unresolvedDirectChildren: 0,
+            contradictoryDirectChildren: 0,
+            corroboratingBranchCount: 0,
+            conflictingBranchCount: 0,
+            duplicateEvidenceCount: 0,
+            independentBranchCount: 0,
+            interactionSummary: null,
+            confidenceCapReason: null,
+            ancestorPropagationStoppedReason: null,
+            affectedAncestorIds: [],
+            nextSelectedSibling: null,
+            parentResolved: false,
+            decompositionPerformed: false,
+            childUnknownCount: 0,
+            childNodeIds: [],
+            atomicityReason: null,
+            unknownSelectionExplanation: explainUnknownSelection(
+              situationGraph,
+              situationGraph.resolvedNodeIds || [],
+            ),
+          }),
+        },
+        statusCode:
+          applicationResult.stage === "application" ||
+          applicationResult.stage === "result_validation"
+            ? 500
+            : 400,
+      };
+    }
+
+    return {
+      success: true,
+      stage: "update_applied",
+      updatedSituationGraph: applicationResult.updatedSituationGraph,
+      proposal: applicationResult.graphUpdate,
+      selectedQuestion: applicationResult.selectedQuestion,
+      affectedNodeIds: applicationResult.affectedNodeIds,
+      resolvedUnknownNodeIds: applicationResult.resolvedUnknownNodeIds,
+      previousActiveUnknownNodeId:
+        applicationResult.previousActiveUnknownNodeId,
+      newActiveUnknownNodeId: applicationResult.newActiveUnknownNodeId,
+      changesApplied: applicationResult.changesApplied,
+      diagnostics: buildUpdateDiagnostics({
+        promptVersion,
+        modelName,
+        responseDurationMs,
+        normalisationsApplied: parsedProposal.normalisationsApplied,
+        graph: applicationResult.updatedSituationGraph,
+        graphReferenceValidation: applicationResult.graphReferenceValidation,
+        selectedQuestion: applicationResult.selectedQuestion,
+        previousReasoningState: applicationResult.previousReasoningState,
+        reasoningState: applicationResult.reasoningState,
+        resolvedReasoningNodeIds: applicationResult.resolvedReasoningNodeIds,
+        emergentReasoningNodeCreated:
+          applicationResult.emergentReasoningNodeCreated,
+        emergentReasoningNodeId: applicationResult.emergentReasoningNodeId,
+        emergentReasoningNodeReason:
+          applicationResult.emergentReasoningNodeReason,
+        atomicityAssessment: applicationResult.atomicityAssessment,
+        atomicityDecisionReason: applicationResult.atomicityDecisionReason,
+        decompositionDepth: applicationResult.decompositionDepth,
+        decompositionAttempted: applicationResult.decompositionAttempted,
+        decompositionAccepted: applicationResult.decompositionAccepted,
+        decompositionStoppedReason:
+          applicationResult.decompositionStoppedReason,
+        proposedChildCount: applicationResult.proposedChildCount,
+        acceptedChildCount: applicationResult.acceptedChildCount,
+        rejectedChildren: applicationResult.rejectedChildren,
+        selectedChildNodeId: applicationResult.selectedChildNodeId,
+        childQualitySummary: applicationResult.childQualitySummary,
+        propagationPerformed: applicationResult.propagationPerformed,
+        resolvedChildNodeId: applicationResult.resolvedChildNodeId,
+        parentNodeId: applicationResult.parentNodeId,
+        parentStatusBefore: applicationResult.parentStatusBefore,
+        parentStatusAfter: applicationResult.parentStatusAfter,
+        parentConfidenceBefore: applicationResult.parentConfidenceBefore,
+        parentConfidenceAfter: applicationResult.parentConfidenceAfter,
+        evidenceConfidenceBefore: applicationResult.evidenceConfidenceBefore,
+        evidenceConfidenceAfter: applicationResult.evidenceConfidenceAfter,
+        completenessBefore: applicationResult.completenessBefore,
+        completenessAfter: applicationResult.completenessAfter,
+        conclusionConfidenceBefore:
+          applicationResult.conclusionConfidenceBefore,
+        conclusionConfidenceAfter: applicationResult.conclusionConfidenceAfter,
+        resolvedDirectChildren: applicationResult.resolvedDirectChildren,
+        unresolvedDirectChildren: applicationResult.unresolvedDirectChildren,
+        contradictoryDirectChildren:
+          applicationResult.contradictoryDirectChildren,
+        corroboratingBranchCount: applicationResult.corroboratingBranchCount,
+        conflictingBranchCount: applicationResult.conflictingBranchCount,
+        duplicateEvidenceCount: applicationResult.duplicateEvidenceCount,
+        independentBranchCount: applicationResult.independentBranchCount,
+        interactionSummary: applicationResult.interactionSummary,
+        confidenceCapReason: applicationResult.confidenceCapReason,
+        ancestorPropagationStoppedReason:
+          applicationResult.ancestorPropagationStoppedReason,
+        affectedAncestorIds: applicationResult.affectedAncestorIds,
+        nextSelectedSibling: applicationResult.nextSelectedSibling,
+        parentResolved: applicationResult.parentResolved,
+        decompositionPerformed: applicationResult.decompositionPerformed,
+        childUnknownCount: applicationResult.childUnknownCount,
+        childNodeIds: applicationResult.childNodeIds,
+        atomicityReason: applicationResult.atomicityReason,
+        unknownSelectionExplanation: buildUnknownSelectionDiagnostics(
+          applicationResult.updatedSituationGraph,
+          applicationResult.updatedSituationGraph.resolvedNodeIds || [],
+          applicationResult.selectedQuestion,
+        ),
+      }),
+    };
+  }
+
+  return {
+    success: true,
+    stage: "proposal_ready",
+    proposal: parsedProposal.proposal,
+    diagnostics: buildUpdateDiagnostics({
+      promptVersion,
+      modelName,
+      responseDurationMs,
+      normalisationsApplied: parsedProposal.normalisationsApplied,
+      graph: situationGraph,
+      graphReferenceValidation,
+      selectedQuestion: null,
+      previousReasoningState: buildReasoningState(situationGraph),
+      reasoningState: buildReasoningState(situationGraph),
+      resolvedReasoningNodeIds: [],
+      emergentReasoningNodeCreated: false,
+      emergentReasoningNodeId: null,
+      emergentReasoningNodeReason: null,
+      atomicityAssessment: null,
+      atomicityDecisionReason: null,
+      decompositionDepth: 0,
+      decompositionAttempted: false,
+      decompositionAccepted: false,
+      decompositionStoppedReason: null,
+      proposedChildCount: 0,
+      acceptedChildCount: 0,
+      rejectedChildren: [],
+      selectedChildNodeId: null,
+      childQualitySummary: [],
+      propagationPerformed: false,
+      resolvedChildNodeId: null,
+      parentNodeId: null,
+      parentStatusBefore: null,
+      parentStatusAfter: null,
+      parentConfidenceBefore: null,
+      parentConfidenceAfter: null,
+      evidenceConfidenceBefore: null,
+      evidenceConfidenceAfter: null,
+      completenessBefore: null,
+      completenessAfter: null,
+      conclusionConfidenceBefore: null,
+      conclusionConfidenceAfter: null,
+      resolvedDirectChildren: 0,
+      unresolvedDirectChildren: 0,
+      contradictoryDirectChildren: 0,
+      corroboratingBranchCount: 0,
+      conflictingBranchCount: 0,
+      duplicateEvidenceCount: 0,
+      independentBranchCount: 0,
+      interactionSummary: null,
+      confidenceCapReason: null,
+      ancestorPropagationStoppedReason: null,
+      affectedAncestorIds: [],
+      nextSelectedSibling: null,
+      parentResolved: false,
+      decompositionPerformed: false,
+      childUnknownCount: 0,
+      childNodeIds: [],
+      atomicityReason: null,
+      unknownSelectionExplanation: buildUnknownSelectionDiagnostics(
+        situationGraph,
+        situationGraph.resolvedNodeIds || [],
+        null,
+      ),
+    }),
+  };
+}

lib/graph/prompt-builder.js

@@ -0,0 +1,134 @@
+import {
+  ConfidenceLevel,
+  SituationKind,
+  SituationRelationship,
+  SituationStatus,
+} from "./schema.js";
+
+const DEFAULT_PROMPT_VERSION = "v0.4";
+
+function formatEnumValues(values) {
+  return Object.values(values).join(" | ");
+}
+
+function formatGraph(graph) {
+  return JSON.stringify(graph, null, 2);
+}
+
+function formatExampleAnswerBlock() {
+  return [
+    "Example answer the model must be able to handle without hard-coding output:",
+    '"The complaint rate fell from 2.0 complaints per 100 units to 1.9 complaints per 100 units."',
+    "This may justify resolving a rate-related unknown or updating a metric node, but only if the current graph and answer support that proposal.",
+  ].join("\n");
+}
+
+export function buildGraphUpdatePrompt({
+  situationGraph,
+  previousQuestion,
+  answer,
+  promptVersion = DEFAULT_PROMPT_VERSION,
+}) {
+  const nodeKinds = formatEnumValues(SituationKind);
+  const nodeStatuses = formatEnumValues(SituationStatus);
+  const edgeRelationships = formatEnumValues(SituationRelationship);
+  const confidenceLevels = formatEnumValues(ConfidenceLevel);
+
+  return `You are proposing a graph update for Confidence Engine ${promptVersion}.
+
+Return exactly one JSON object matching the GraphUpdate contract.
+Return JSON only. Do not include markdown, explanation, or any text before or after the JSON object.
+
+## Current Situation Graph
+${formatGraph(situationGraph)}
+
+## Previous Selected Question
+${previousQuestion}
+
+## User Answer
+${answer}
+
+## Allowed Node Kinds
+${nodeKinds}
+
+## Allowed Node Statuses
+${nodeStatuses}
+
+## Allowed Edge Relationships
+${edgeRelationships}
+
+## Allowed Confidence Values
+${confidenceLevels}
+
+## Required JSON Field Names
+The JSON object must contain exactly these top-level fields:
+- addedNodes
+- updatedNodes
+- addedEdges
+- removedEdgeIds
+- resolvedUnknownNodeIds
+- affectedNodeIds
+- selectedQuestion
+
+## Required Shapes
+- addedNodes: array of nodes using these exact keys:
+  id, label, description, kind, status, confidence, value, unit, evidenceIds, dependsOn, affects, parentId, childIds
+- updatedNodes: array of node updates using these exact keys:
+  nodeId, previousStatus, newStatus, previousValue, newValue, reason
+- addedEdges: array of edges using these exact keys:
+  id, fromNodeId, toNodeId, relationship, confidence, description
+- removedEdgeIds: array of strings
+- resolvedUnknownNodeIds: array of strings
+- affectedNodeIds: array of strings
+- selectedQuestion: either null or an object using these exact keys:
+  nodeId, question, reason
+
+## Proposal Rules
+1. Propose changes only. Never return a replacement graph.
+2. Preserve unrelated nodes and edges by omitting them from the proposal.
+3. Reference existing node IDs when updating an existing concept.
+4. Use addedNodes only for genuinely new concepts.
+5. Resolve the answered unknown first when the answer supports it.
+6. Then inspect the answer for newly introduced consequential uncertainty.
+7. Add new unknown nodes only when the answer introduces a new decision, claim, object, measure, dependency, or unresolved term directly relevant to the case.
+8. Add at most 3 new unknown nodes.
+9. Every new unknown must be directly traceable to the user's answer and its description must state why that uncertainty matters.
+9a. In the description of every new unknown, explicitly include a short why-it-matters clause using wording such as because, so that, needed to decide, or matters because.
+10. Do not add broad generic discovery questions.
+11. Do not add duplicate unknowns.
+12. Do not expand unrelated branches.
+13. Propagate only through explicit dependencies or relationships already present in the graph, except for the minimal new edges needed to connect validated new unknowns to the relevant answer-derived decision or context node.
+13a. For every new unknown node, include at least one added edge that connects it to an existing updated/resolved node or to a newly added non-unknown node introduced from the answer.
+14. Do not invent evidence.
+15. Do not create unsupported causal edges.
+16. If consequential unresolved unknowns exist, selectedQuestion may identify one valid candidate unknown, but the engine will deterministically choose final priority after validation.
+17. selectedQuestion.nodeId must reference an unresolved unknown node that exists either already in the graph or in addedNodes.
+18. selectedQuestion.question must be one narrow non-compound question about that one unknown.
+19. Do not prioritise downstream implementation, pricing, optimisation, or speculative branches ahead of prerequisite definitions, actors, success criteria, constraints, measures, or terminology.
+20. Return selectedQuestion as null only when no consequential unresolved unknown remains.
+21. Use empty arrays when there are no changes in a category.
+22. Never return null array entries.
+23. Never use unknown enum values.
+24. Do not change existing IDs.
+25. Do not replace the whole graph, and do not restate unchanged graph content inside the proposal.
+
+## Additional Guidance
+- If the answer only clarifies an existing unknown, prefer updatedNodes and resolvedUnknownNodeIds over creating duplicate nodes.
+- When an answer resolves an existing unknown, include that existing node ID in resolvedUnknownNodeIds and update that node rather than creating only a parallel observation.
+- If the answer creates a more specific decision situation, add the smallest set of new nodes and edges needed to represent that situation and only its most consequential unknowns.
+- If you add a new unknown, do not leave it floating: connect it with an added edge to the relevant decision/context node created or updated from the answer.
+- If you add a new unknown, its description must do two jobs in one sentence: what is unknown, and why resolving it matters for the case.
+- Treat selectedQuestion as a candidate only; the engine will apply deterministic information-value scoring after validation.
+- If the answer does not justify a change, return empty arrays for every category.
+
+## Example Constraint Reminder
+${formatExampleAnswerBlock()}
+
+## Output Contract Reminder
+Return one JSON object only, with exact field names and exact enum values.
+Never include a full graph.
+Never include any field other than the contract fields above.
+`;
+}
+
+export const buildUpdatePrompt = buildGraphUpdatePrompt;

lib/graph/schema.js

@@ -0,0 +1,242 @@
+/**
+ * Situation Graph schema — v0.4 experiment.
+ * Defines types for an evolving multi-turn situation reconstruction graph.
+ * Plain TypeScript interfaces implemented as Zod schemas for runtime validation.
+ */
+
+import { z } from "zod";
+
+// ── Enums ────────────────────────────────────────────
+
+export const SituationKind = /** @type {const} */ ({
+  observation: "observation",
+  reported_claim: "reported_claim",
+  metric: "metric",
+  state: "state",
+  transition: "transition",
+  relationship: "relationship",
+  assumption: "assumption",
+  unknown: "unknown",
+  conclusion: "conclusion",
+});
+
+export const SituationStatus = /** @type {const} */ ({
+  known: "known",
+  unknown: "unknown",
+  provisional: "provisional",
+  supported: "supported",
+  weakened: "weakened",
+  contradicted: "contradicted",
+  resolved: "resolved",
+});
+
+export const ConfidenceLevel = /** @type {const} */ ({
+  low: "low",
+  medium: "medium",
+  high: "high",
+});
+
+export const CompletenessStatus = /** @type {const} */ ({
+  empty: "empty",
+  partial: "partial",
+  complete: "complete",
+});
+
+export const confidenceAssessmentSchema = z
+  .object({
+    evidenceConfidence: z.enum(Object.values(ConfidenceLevel)),
+    completenessStatus: z.enum(Object.values(CompletenessStatus)),
+    conclusionConfidence: z.enum(Object.values(ConfidenceLevel)),
+  })
+  .strict();
+
+// ── SituationNode ────────────────────────────────────
+
+export const situationNodeSchema = z.object({
+  id: z.string().min(1),
+  label: z.string().min(1),
+  description: z.string().min(1),
+  kind: z.enum(Object.values(SituationKind)),
+  status: z.enum(Object.values(SituationStatus)),
+  confidence: z.enum(Object.values(ConfidenceLevel)),
+  confidenceAssessment: confidenceAssessmentSchema.optional(),
+  value: z.union([z.string(), z.number(), z.null()]).nullable().optional(),
+  unit: z.string().nullable().optional(),
+  evidenceIds: z.array(z.string()).default([]),
+  dependsOn: z.array(z.string()).default([]),
+  affects: z.array(z.string()).default([]),
+  parentId: z.string().nullable().optional(),
+  childIds: z.array(z.string()).default([]),
+});
+
+/** @typedef {z.infer<typeof situationNodeSchema>} SituationNode */
+
+// ── SituationEdge ────────────────────────────────────
+
+export const SituationRelationship = /** @type {const} */ ({
+  supports: "supports",
+  weakens: "weakens",
+  contradicts: "contradicts",
+  depends_on: "depends_on",
+  causes: "causes",
+  may_cause: "may_cause",
+  measures: "measures",
+  compares_with: "compares_with",
+  updates: "updates",
+  other: "other",
+});
+
+export const situationEdgeSchema = z.object({
+  id: z.string().min(1),
+  fromNodeId: z.string().min(1),
+  toNodeId: z.string().min(1),
+  relationship: z.enum(Object.values(SituationRelationship)),
+  confidence: z.enum(Object.values(ConfidenceLevel)),
+  description: z.string().min(1),
+});
+
+/** @typedef {z.infer<typeof situationEdgeSchema>} SituationEdge */
+
+// ── SituationGraph ───────────────────────────────────
+
+const reasoningStageSchema = z.object({
+  stage: z.string().min(1),
+  status: z.string().min(1),
+  outcome: z.string().min(1),
+});
+
+export const reasoningStateSchema = z
+  .object({
+    comparabilityStatus: z.string().min(1).nullable().optional(),
+    comparabilityReason: z.string().min(1).nullable().optional(),
+    comparabilityEvidence: z.array(z.string()).default([]),
+    relationshipStatus: z.string().min(1).nullable().optional(),
+    relationshipReason: z.string().min(1).nullable().optional(),
+    relationshipAssessed: z.boolean().optional(),
+    contradictionReasoningAllowed: z.boolean().optional(),
+    reasoningStages: z.array(reasoningStageSchema).default([]),
+  })
+  .strict();
+
+export const situationGraphSchema = z.object({
+  centralStatement: z.string().min(1),
+  nodes: z.array(situationNodeSchema).min(1),
+  edges: z.array(situationEdgeSchema).default([]),
+  activeUnknownNodeId: z.string().nullable(),
+  resolvedNodeIds: z.array(z.string()).default([]),
+  currentSummary: z.string().min(1),
+  reasoningState: reasoningStateSchema.optional(),
+});
+
+/** @typedef {z.infer<typeof situationGraphSchema>} SituationGraph */
+
+// ── GraphUpdate (change set) ────────────────────────
+
+const graphUpdateNodeChangeSchema = z.object({
+  nodeId: z.string().min(1),
+  previousStatus: z.enum(Object.values(SituationStatus)).nullable().optional(),
+  newStatus: z.enum(Object.values(SituationStatus)).nullable().optional(),
+  previousValue: z
+    .union([z.string(), z.number(), z.null()])
+    .nullable()
+    .optional(),
+  newValue: z.union([z.string(), z.number(), z.null()]).nullable().optional(),
+  reason: z.string().min(1),
+});
+
+export const selectedQuestionSchema = z
+  .object({
+    nodeId: z.string().min(1),
+    question: z.string().min(1),
+    reason: z.string().min(1),
+  })
+  .strict();
+
+export const graphUpdateSchema = z.object({
+  addedNodes: z.array(situationNodeSchema).default([]),
+  updatedNodes: z.array(graphUpdateNodeChangeSchema).default([]),
+  addedEdges: z.array(situationEdgeSchema).default([]),
+  removedEdgeIds: z.array(z.string()).default([]),
+  resolvedUnknownNodeIds: z.array(z.string()).default([]),
+  affectedNodeIds: z.array(z.string()).default([]),
+  selectedQuestion: selectedQuestionSchema.nullable().default(null),
+});
+
+/** @typedef {z.infer<typeof graphUpdateSchema>} GraphUpdate */
+
+// ── API request / response schemas ───────────────────
+
+export const startCaseRequestSchema = z.object({
+  scenario: z.string().min(1).max(10000),
+  promptVersion: z.string().optional(),
+});
+
+export const updateCaseRequestSchema = z.object({
+  situationGraph: situationGraphSchema,
+  previousQuestion: z.string().min(1),
+  answer: z.string().min(1).max(5000),
+  promptVersion: z.string().optional(),
+});
+
+// ── Helpers ──────────────────────────────────────────
+
+/** Generate a short deterministic ID from a label */
+export function makeNodeId(label) {
+  return "n" + Math.abs(hashString(label)).toString(36).slice(0, 7);
+}
+
+function hashString(str) {
+  let h = 0;
+  for (let i = 0; i < str.length; i++) {
+    h = (Math.imul(31, h) + str.charCodeAt(i)) | 0;
+  }
+  return h;
+}
+
+/** Create a minimal valid node — used in tests and fixtures */
+export function makeNode(opts) {
+  const id = opts.id || makeNodeId(opts.label);
+  return situationNodeSchema.parse({
+    id,
+    label: opts.label,
+    description: opts.description ?? opts.label,
+    kind: opts.kind ?? "observation",
+    status: opts.status ?? "unknown",
+    confidence: opts.confidence ?? "medium",
+    confidenceAssessment: opts.confidenceAssessment,
+    value: opts.value ?? null,
+    unit: opts.unit ?? null,
+    evidenceIds: opts.evidenceIds ?? [],
+    dependsOn: opts.dependsOn ?? [],
+    affects: opts.affects ?? [],
+    parentId: opts.parentId ?? null,
+    childIds: opts.childIds ?? [],
+  });
+}
+
+/** Create a minimal valid edge — used in tests and fixtures */
+export function makeEdge(opts) {
+  return situationEdgeSchema.parse({
+    id:
+      opts.id ||
+      "e" + opts.fromNodeId.slice(0, 3) + "-" + opts.toNodeId.slice(0, 3),
+    fromNodeId: opts.fromNodeId,
+    toNodeId: opts.toNodeId,
+    relationship: opts.relationship ?? "supports",
+    confidence: opts.confidence ?? "medium",
+    description: opts.description ?? opts.fromNodeId + " -> " + opts.toNodeId,
+  });
+}
+
+/** Build a minimal valid graph structure */
+export function makeGraph(opts) {
+  return situationGraphSchema.parse({
+    centralStatement: opts.centralStatement || "",
+    nodes: opts.nodes ?? [],
+    edges: opts.edges ?? [],
+    activeUnknownNodeId: opts.activeUnknownNodeId ?? null,
+    resolvedNodeIds: opts.resolvedNodeIds ?? [],
+    currentSummary: opts.currentSummary || "",
+    reasoningState: opts.reasoningState,
+  });
+}

lib/graph/update-proposal.js

@@ -0,0 +1,157 @@
+import { graphUpdateSchema } from "./schema.js";
+
+const TOP_LEVEL_ARRAY_FIELDS = [
+  "addedNodes",
+  "updatedNodes",
+  "addedEdges",
+  "removedEdgeIds",
+  "resolvedUnknownNodeIds",
+  "affectedNodeIds",
+];
+
+const TOP_LEVEL_NULLABLE_FIELDS = ["selectedQuestion"];
+
+function cloneJsonSafe(value) {
+  if (value == null) return value;
+  return JSON.parse(JSON.stringify(value));
+}
+
+function removeNullArrayEntries(value, path = [], normalisationsApplied = []) {
+  if (Array.isArray(value)) {
+    const filtered = [];
+    value.forEach((item, index) => {
+      if (item === null) {
+        normalisationsApplied.push({
+          path: [...path, index],
+          change: "Removed null array entry",
+        });
+        return;
+      }
+      filtered.push(
+        removeNullArrayEntries(item, [...path, index], normalisationsApplied),
+      );
+    });
+    return filtered;
+  }
+
+  if (value && typeof value === "object") {
+    return Object.fromEntries(
+      Object.entries(value).map(([key, child]) => [
+        key,
+        removeNullArrayEntries(child, [...path, key], normalisationsApplied),
+      ]),
+    );
+  }
+
+  return value;
+}
+
+function applyKnownEnumAliases(proposal, normalisationsApplied) {
+  if (!proposal || typeof proposal !== "object") return proposal;
+
+  if (Array.isArray(proposal.addedNodes)) {
+    proposal.addedNodes = proposal.addedNodes.map((node, index) => {
+      if (node?.kind === "reported_statement") {
+        normalisationsApplied.push({
+          path: ["addedNodes", index, "kind"],
+          change: "Converted reported_statement to reported_claim",
+        });
+        return { ...node, kind: "reported_claim" };
+      }
+      return node;
+    });
+  }
+
+  return proposal;
+}
+
+function fillMissingOptionalArrays(proposal, normalisationsApplied) {
+  if (!proposal || typeof proposal !== "object") return proposal;
+
+  for (const field of TOP_LEVEL_ARRAY_FIELDS) {
+    if (!(field in proposal)) {
+      proposal[field] = [];
+      normalisationsApplied.push({
+        path: [field],
+        change: "Filled missing optional array with []",
+      });
+    }
+  }
+
+  return proposal;
+}
+
+function fillMissingNullableFields(proposal, normalisationsApplied) {
+  if (!proposal || typeof proposal !== "object") return proposal;
+
+  for (const field of TOP_LEVEL_NULLABLE_FIELDS) {
+    if (!(field in proposal)) {
+      proposal[field] = null;
+      normalisationsApplied.push({
+        path: [field],
+        change: "Filled missing optional nullable field with null",
+      });
+    }
+  }
+
+  return proposal;
+}
+
+export function parseGraphUpdateProposal(rawResponse) {
+  const raw = rawResponse;
+  let parsed;
+
+  if (typeof rawResponse === "string") {
+    try {
+      parsed = JSON.parse(rawResponse);
+    } catch (error) {
+      return {
+        success: false,
+        proposal: null,
+        raw,
+        normalisationsApplied: [],
+        errors: [error.message || "Model response is not valid JSON"],
+      };
+    }
+  } else if (rawResponse && typeof rawResponse === "object") {
+    parsed = cloneJsonSafe(rawResponse);
+  } else {
+    return {
+      success: false,
+      proposal: null,
+      raw,
+      normalisationsApplied: [],
+      errors: ["Graph update proposal must be a JSON object or JSON string"],
+    };
+  }
+
+  const normalisationsApplied = [];
+  let normalised = removeNullArrayEntries(parsed, [], normalisationsApplied);
+  normalised = applyKnownEnumAliases(normalised, normalisationsApplied);
+  normalised = fillMissingOptionalArrays(normalised, normalisationsApplied);
+  normalised = fillMissingNullableFields(normalised, normalisationsApplied);
+
+  const parsedProposal = graphUpdateSchema.safeParse(normalised);
+
+  if (!parsedProposal.success) {
+    return {
+      success: false,
+      proposal: null,
+      raw,
+      normalisationsApplied,
+      errors: parsedProposal.error.issues.map((issue) => ({
+        path: issue.path,
+        message: issue.message,
+        code: issue.code,
+      })),
+    };
+  }
+
+  return {
+    success: true,
+    proposal: parsedProposal.data,
+    raw,
+    normalisationsApplied,
+    errors: [],
+  };
+}

lib/graph/utils.js

@@ -0,0 +1,894 @@
+/**
+ * Deterministic graph utilities for situation graph operations.
+ * These functions perform safe, validated operations on the graph.
+ * The LLM should never directly modify the graph — it proposes changes,
+ * and these utilities apply them safely.
+ */
+
+import {
+  situationNodeSchema,
+  situationEdgeSchema,
+  situationGraphSchema,
+} from "./schema.js";
+
+function normaliseText(value) {
+  return String(value || "")
+    .toLowerCase()
+    .replace(/[^a-z0-9]+/g, " ")
+    .trim();
+}
+
+function collectNodeText(node) {
+  return `${node?.label || ""} ${node?.description || ""}`.trim();
+}
+
+function countIncomingUnknownDependencies(graph, nodeId, resolvedNodeIds) {
+  const resolvedSet = new Set(resolvedNodeIds || []);
+  const nodesById = new Map(graph.nodes.map((node) => [node.id, node]));
+  const incoming = new Set();
+
+  for (const dependencyId of nodesById.get(nodeId)?.dependsOn || []) {
+    const dependencyNode = nodesById.get(dependencyId);
+    if (dependencyNode?.kind === "unknown" && !resolvedSet.has(dependencyId)) {
+      incoming.add(dependencyId);
+    }
+  }
+
+  for (const edge of graph.edges) {
+    if (edge.toNodeId !== nodeId) continue;
+    const dependencyNode = nodesById.get(edge.fromNodeId);
+    if (
+      dependencyNode?.kind === "unknown" &&
+      !resolvedSet.has(edge.fromNodeId)
+    ) {
+      incoming.add(edge.fromNodeId);
+    }
+  }
+
+  return incoming.size;
+}
+
+function classifyUnknownPriority(text) {
+  const normalised = normaliseText(text);
+
+  const matches = {
+    objective:
+      /\b(objective|goal|outcome|value|problem|job to be done|benefit|commercial value)\b/.test(
+        normalised,
+      ),
+    actor:
+      /\b(customer|user|buyer|actor|stakeholder|audience|recipient)\b/.test(
+        normalised,
+      ),
+    criteria:
+      /\b(success criteria|success threshold|threshold|decision criteria|criterion|justify|sufficient)\b/.test(
+        normalised,
+      ),
+    measure:
+      /\b(metric|measure|measurable|roi|demand|evidence|signal|proof)\b/.test(
+        normalised,
+      ),
+    terminology: /\b(define|definition|meaning|means|term|terminology)\b/.test(
+      normalised,
+    ),
+    constraint:
+      /\b(constraint|limit|budget|deadline|requirement|regulation)\b/.test(
+        normalised,
+      ),
+    pricing: /\b(price|pricing|price point|subscription|charge|pay for)\b/.test(
+      normalised,
+    ),
+    implementation:
+      /\b(implementation|build approach|architecture|stack|feature|technical design)\b/.test(
+        normalised,
+      ),
+    optimisation:
+      /\b(optimisation|optimi[sz]ation|improve|efficiency|performance|scale)\b/.test(
+        normalised,
+      ),
+    speculative:
+      /\b(maybe|possible|optional|future branch|nice to have|slogan|colour|color|ui)\b/.test(
+        normalised,
+      ),
+  };
+
+  return matches;
+}
+
+function buildScoreContributions(
+  matches,
+  downstreamCount,
+  unresolvedParentUnknownCount,
+) {
+  const contributions = [
+    {
+      rule: "downstream_dependencies",
+      value: downstreamCount,
+      weight: 4,
+      delta: downstreamCount * 4,
+    },
+  ];
+
+  if (matches.objective) {
+    contributions.push({
+      rule: "objective_match",
+      value: true,
+      weight: 12,
+      delta: 12,
+    });
+  }
+  if (matches.actor) {
+    contributions.push({
+      rule: "actor_match",
+      value: true,
+      weight: 10,
+      delta: 10,
+    });
+  }
+  if (matches.criteria) {
+    contributions.push({
+      rule: "criteria_match",
+      value: true,
+      weight: 11,
+      delta: 11,
+    });
+  }
+  if (matches.measure) {
+    contributions.push({
+      rule: "measure_match",
+      value: true,
+      weight: 8,
+      delta: 8,
+    });
+  }
+  if (matches.terminology) {
+    contributions.push({
+      rule: "terminology_match",
+      value: true,
+      weight: 7,
+      delta: 7,
+    });
+  }
+  if (matches.constraint) {
+    contributions.push({
+      rule: "constraint_match",
+      value: true,
+      weight: 9,
+      delta: 9,
+    });
+  }
+  if (matches.pricing) {
+    contributions.push({
+      rule: "pricing_penalty",
+      value: true,
+      weight: -8,
+      delta: -8,
+    });
+  }
+  if (matches.implementation) {
+    contributions.push({
+      rule: "implementation_penalty",
+      value: true,
+      weight: -10,
+      delta: -10,
+    });
+  }
+  if (matches.optimisation) {
+    contributions.push({
+      rule: "optimisation_penalty",
+      value: true,
+      weight: -9,
+      delta: -9,
+    });
+  }
+  if (matches.speculative) {
+    contributions.push({
+      rule: "speculative_penalty",
+      value: true,
+      weight: -12,
+      delta: -12,
+    });
+  }
+
+  if (
+    matches.pricing &&
+    !matches.objective &&
+    !matches.criteria &&
+    !matches.actor
+  ) {
+    contributions.push({
+      rule: "isolated_pricing_penalty",
+      value: true,
+      weight: -6,
+      delta: -6,
+    });
+  }
+
+  if (unresolvedParentUnknownCount > 0) {
+    contributions.push({
+      rule: "unresolved_prerequisite_penalty",
+      value: unresolvedParentUnknownCount,
+      weight: -7,
+      delta: unresolvedParentUnknownCount * -7,
+    });
+  }
+
+  return contributions;
+}
+
+function getMeaningfulSemanticContributions(contributions = []) {
+  return contributions
+    .filter(
+      (contribution) =>
+        contribution.rule !== "downstream_dependencies" &&
+        contribution.rule !== "unresolved_prerequisite_penalty" &&
+        contribution.delta !== 0,
+    )
+    .map((contribution) => ({
+      rule: contribution.rule,
+      delta: contribution.delta,
+    }));
+}
+
+function buildCandidateDisplayOrder(candidates) {
+  return [...candidates].sort((a, b) => {
+    if (b.score !== a.score) return b.score - a.score;
+    if (b.downstreamCount !== a.downstreamCount) {
+      return b.downstreamCount - a.downstreamCount;
+    }
+    if (a.unresolvedParentUnknownCount !== b.unresolvedParentUnknownCount) {
+      return a.unresolvedParentUnknownCount - b.unresolvedParentUnknownCount;
+    }
+    return a.label.localeCompare(b.label);
+  });
+}
+
+function semanticSignature(candidate) {
+  return JSON.stringify(
+    getMeaningfulSemanticContributions(candidate.contributions),
+  );
+}
+
+function classifyCandidateOrdering(candidates) {
+  const displayOrder = buildCandidateDisplayOrder(candidates);
+  const best = displayOrder[0] ?? null;
+  if (!best) {
+    return {
+      displayOrder,
+      best: null,
+      leadingCandidates: [],
+      status: "no_candidates",
+      tieType: "none",
+      usedAlphabeticalOrdering: false,
+      reason: "No unresolved unknown candidates remain.",
+    };
+  }
+
+  const topScoreCandidates = displayOrder.filter(
+    (candidate) => candidate.score === best.score,
+  );
+
+  if (topScoreCandidates.length === 1) {
+    return {
+      displayOrder,
+      best,
+      leadingCandidates: [best],
+      status: "selected",
+      tieType: "none",
+      usedAlphabeticalOrdering: false,
+      reason: `Clear winner by total score (${best.score}).`,
+    };
+  }
+
+  const topStructuralCandidates = topScoreCandidates.filter(
+    (candidate) =>
+      candidate.downstreamCount === best.downstreamCount &&
+      candidate.unresolvedParentUnknownCount ===
+        best.unresolvedParentUnknownCount,
+  );
+
+  if (topStructuralCandidates.length === 1) {
+    return {
+      displayOrder,
+      best,
+      leadingCandidates: [best],
+      status: "selected",
+      tieType: "structural_tie",
+      usedAlphabeticalOrdering: false,
+      reason:
+        "Score tie was resolved by downstream dependency count or prerequisite ordering.",
+    };
+  }
+
+  const topSemanticSignature = semanticSignature(best);
+  const semanticPeers = topStructuralCandidates.filter(
+    (candidate) => semanticSignature(candidate) === topSemanticSignature,
+  );
+
+  if (semanticPeers.length !== topStructuralCandidates.length) {
+    return {
+      displayOrder,
+      best: null,
+      leadingCandidates: topStructuralCandidates,
+      status: "ambiguous",
+      tieType: "semantic_tie",
+      usedAlphabeticalOrdering: false,
+      reason:
+        "Leading candidates remain tied after score and structural checks, but differ in semantic contribution patterns.",
+    };
+  }
+
+  return {
+    displayOrder,
+    best: null,
+    leadingCandidates: topStructuralCandidates,
+    status: "ambiguous",
+    tieType: "complete_unresolved_tie",
+    usedAlphabeticalOrdering: false,
+    reason: "No justified distinction between leading unknowns.",
+  };
+}
+
+export function scoreUnknownCandidate(graph, node, resolvedNodeIds = []) {
+  const text = collectNodeText(node);
+  const matches = classifyUnknownPriority(text);
+  const downstreamCount = findDependentNodes(graph, node.id).length;
+  const unresolvedParentUnknownCount = countIncomingUnknownDependencies(
+    graph,
+    node.id,
+    resolvedNodeIds,
+  );
+
+  const contributions = buildScoreContributions(
+    matches,
+    downstreamCount,
+    unresolvedParentUnknownCount,
+  );
+  const score = contributions.reduce(
+    (total, contribution) => total + contribution.delta,
+    0,
+  );
+
+  return {
+    nodeId: node.id,
+    label: node.label,
+    score,
+    downstreamCount,
+    unresolvedParentUnknownCount,
+    matches,
+    contributions,
+  };
+}
+
+export function buildDeterministicQuestionForUnknown(node) {
+  const text = normaliseText(collectNodeText(node));
+
+  if (
+    /\b(success criteria|success threshold|threshold|decision criteria|criterion)\b/.test(
+      text,
+    )
+  ) {
+    return `What outcome would define success for ${node.label}?`;
+  }
+  if (
+    /\b(customer|user|buyer|actor|stakeholder|audience|recipient)\b/.test(text)
+  ) {
+    return `Who is the key actor or customer for ${node.label}?`;
+  }
+  if (
+    /\b(define|definition|meaning|means|term|terminology|value)\b/.test(text)
+  ) {
+    return `How should ${node.label} be defined for this decision?`;
+  }
+  if (
+    /\b(metric|measure|measurable|roi|demand|evidence|signal|proof)\b/.test(
+      text,
+    )
+  ) {
+    return `What evidence or measure would resolve ${node.label}?`;
+  }
+
+  return `What would resolve ${node.label}?`;
+}
+
+// ── Validate that all edge references point to existing nodes ──
+
+export function validateGraphReferences(graph) {
+  const errors = [];
+  const nodeIds = new Set(graph.nodes.map((n) => n.id));
+
+  for (const node of graph.nodes) {
+    if (node.parentId !== null && !nodeIds.has(node.parentId)) {
+      errors.push(
+        `Node "${node.id}" references parentId "${node.parentId}" which does not exist`,
+      );
+    }
+    for (const cid of node.childIds) {
+      if (!nodeIds.has(cid)) {
+        errors.push(
+          `Node "${node.id}" references childIds "${cid}" which does not exist`,
+        );
+      }
+    }
+    for (const dep of node.dependsOn) {
+      if (!nodeIds.has(dep)) {
+        errors.push(
+          `Node "${node.id}" depends on "${dep}" which does not exist`,
+        );
+      }
+    }
+    for (const aff of node.affects) {
+      if (!nodeIds.has(aff)) {
+        errors.push(`Node "${node.id}" affects "${aff}" which does not exist`);
+      }
+    }
+  }
+
+  for (const edge of graph.edges) {
+    if (!nodeIds.has(edge.fromNodeId)) {
+      errors.push(
+        `Edge "${edge.id}" references non-existent fromNodeId "${edge.fromNodeId}"`,
+      );
+    }
+    if (!nodeIds.has(edge.toNodeId)) {
+      errors.push(
+        `Edge "${edge.id}" references non-existent toNodeId "${edge.toNodeId}"`,
+      );
+    }
+  }
+
+  return { valid: errors.length === 0, errors };
+}
+
+// ── Detect duplicate node IDs ──
+
+export function detectDuplicateNodeIds(nodes) {
+  const countMap = new Map();
+  const seen = new Set();
+
+  for (const node of nodes) {
+    if (countMap.has(node.id)) {
+      countMap.set(node.id, countMap.get(node.id) + 1);
+    } else {
+      countMap.set(node.id, 1);
+    }
+  }
+
+  const duplicates = [];
+  for (const [id, count] of countMap.entries()) {
+    if (count > 1 && !seen.has(id)) {
+      duplicates.push({ nodeId: id, count });
+      seen.add(id);
+    }
+  }
+
+  return duplicates;
+}
+
+// ── Detect duplicate edges ──
+
+export function detectDuplicateEdges(edges) {
+  const seen = new Set();
+  const duplicates = [];
+
+  for (const edge of edges) {
+    const key = `${edge.fromNodeId}->${edge.toNodeId}:${edge.relationship}`;
+    if (seen.has(key)) {
+      duplicates.push({
+        edgeId: edge.id,
+        fromNodeId: edge.fromNodeId,
+        toNodeId: edge.toNodeId,
+        relationship: edge.relationship,
+      });
+    }
+    seen.add(key);
+  }
+
+  return duplicates;
+}
+
+// ── Find all nodes that depend on a given node (transitive) ──
+
+export function findDependentNodes(graph, nodeId) {
+  const direct = graph.nodes
+    .filter((n) => n.dependsOn.includes(nodeId))
+    .map((n) => n.id);
+  const affected = new Set(direct);
+
+  // Also propagate through edges where the relationship is depends_on
+  for (const edge of graph.edges) {
+    if (edge.toNodeId === nodeId && !affected.has(edge.fromNodeId)) {
+      direct.push(edge.fromNodeId);
+      affected.add(edge.fromNodeId);
+    }
+  }
+
+  // Transitive propagation — BFS
+  const queue = [...direct];
+  while (queue.length > 0) {
+    const current = queue.shift();
+    if (!current || !affected.has(current)) continue;
+
+    for (const node of graph.nodes) {
+      if (node.dependsOn.includes(current) && !affected.has(node.id)) {
+        affected.add(node.id);
+        queue.push(node.id);
+      }
+    }
+  }
+
+  return [...affected];
+}
+
+// ── Find all nodes that are directly or indirectly affected by a change in nodeId ──
+
+export function findAffectedNodes(graph, nodeId) {
+  // Direct effects: two sources
+  // 1. Nodes that depend on this node (they list it in their dependsOn)
+  const directFromDepends = graph.nodes
+    .filter((n) => n.id !== nodeId && n.dependsOn.includes(nodeId))
+    .map((n) => n.id);
+
+  // 2. Targets of the node's affects relationships (this node directly affects them)
+  const myAffectedTargets = new Set(
+    graph.nodes.find((n) => n.id === nodeId)?.affects || [],
+  );
+
+  // Merge: also add edge targets where this node is the source
+  for (const edge of graph.edges) {
+    if (edge.fromNodeId === nodeId && !myAffectedTargets.has(edge.toNodeId)) {
+      myAffectedTargets.add(edge.toNodeId);
+    }
+  }
+
+  // Combine both sources
+  const direct = [...new Set([...directFromDepends, ...myAffectedTargets])];
+
+  // Transitive propagation — BFS through dependsOn and affects of affected nodes
+  const affected = new Set(direct);
+  const queue = [...direct];
+  while (queue.length > 0) {
+    const current = queue.shift();
+    if (!current || !affected.has(current)) continue;
+
+    for (const node of graph.nodes) {
+      if (
+        node.id !== nodeId &&
+        !affected.has(node.id) &&
+        (node.dependsOn.includes(current) || node.affects.includes(current))
+      ) {
+        affected.add(node.id);
+        queue.push(node.id);
+      }
+    }
+  }
+
+  return [...affected];
+}
+
+// ── Resolve an unknown node ──
+
+export function resolveUnknownNode(graph, nodeId, newStatus, newValue, reason) {
+  const nodeIdx = graph.nodes.findIndex((n) => n.id === nodeId);
+  if (nodeIdx === -1) {
+    return { success: false, error: `Node "${nodeId}" not found in graph` };
+  }
+
+  const previousStatus = graph.nodes[nodeIdx].status;
+  const previousValue = graph.nodes[nodeIdx].value;
+
+  return {
+    success: true,
+    previousStatus,
+    newStatus,
+    previousValue,
+    newValue,
+    reason,
+    affectedNodes: findAffectedNodes(graph, nodeId),
+  };
+}
+
+// ── Select the next highest-value active unknown candidate ──
+
+export function selectActiveUnknownCandidate(graph, resolvedNodeIds) {
+  // Skip already resolved nodes
+  const unresolved = graph.nodes.filter(
+    (n) => n.kind === "unknown" && !resolvedNodeIds.includes(n.id),
+  );
+
+  if (unresolved.length === 0) return null;
+
+  const scoredCandidates = unresolved.map((node) => ({
+    node,
+    ...scoreUnknownCandidate(graph, node, resolvedNodeIds),
+  }));
+
+  const selection = classifyCandidateOrdering(
+    scoredCandidates.map(({ node, ...candidate }) => ({
+      ...candidate,
+      node,
+    })),
+  );
+
+  if (selection.status === "ambiguous") {
+    return {
+      selectedNode: null,
+      status: "ambiguous",
+      tieType: selection.tieType,
+      tiedCandidateIds: selection.leadingCandidates.map(
+        (candidate) => candidate.nodeId,
+      ),
+      displayOrder: selection.displayOrder.map((candidate) => candidate.nodeId),
+      reason: selection.reason,
+    };
+  }
+
+  const best = selection.best;
+  if (!best) return null;
+
+  return {
+    selectedNode: {
+      nodeId: best.node.id,
+      label: best.node.label,
+    },
+    status: "selected",
+    tieType: selection.tieType,
+    nodeId: best.node.id,
+    label: best.node.label,
+    score: best.score,
+    question: buildDeterministicQuestionForUnknown(best.node),
+    reason: `Selected for highest information value (score ${best.score}) with ${best.downstreamCount} downstream dependency node(s) and ${best.unresolvedParentUnknownCount} unresolved prerequisite unknown(s).`,
+  };
+}
+
+export function explainUnknownSelection(graph, resolvedNodeIds = []) {
+  const unresolved = graph.nodes.filter(
+    (n) => n.kind === "unknown" && !resolvedNodeIds.includes(n.id),
+  );
+
+  if (unresolved.length === 0) {
+    return {
+      selectedNodeId: null,
+      selectedNodeLabel: null,
+      status: "no_candidates",
+      tieType: "none",
+      resolvedNodeIds: [...resolvedNodeIds],
+      tiedCandidateIds: [],
+      candidates: [],
+      competitors: [],
+      tieBreakOrder: [
+        "score_desc",
+        "downstreamCount_desc",
+        "unresolvedParentUnknownCount_asc",
+        "label_asc",
+      ],
+      summary: {
+        candidateCount: 0,
+      },
+    };
+  }
+
+  const candidates = unresolved.map((node) => ({
+    nodeId: node.id,
+    label: node.label,
+    ...scoreUnknownCandidate(graph, node, resolvedNodeIds),
+  }));
+
+  const selection = classifyCandidateOrdering(candidates);
+  const orderedCandidates = selection.displayOrder;
+  const selected = selection.best;
+  const competitors = orderedCandidates
+    .filter((candidate) => candidate.nodeId !== selected?.nodeId)
+    .map((candidate) => ({
+      nodeId: candidate.nodeId,
+      label: candidate.label,
+      score: candidate.score,
+      downstreamCount: candidate.downstreamCount,
+      unresolvedParentUnknownCount: candidate.unresolvedParentUnknownCount,
+      matches: candidate.matches,
+      contributions: candidate.contributions,
+      outrankedBy: {
+        scoreDelta: (selected?.score ?? candidate.score) - candidate.score,
+        downstreamDelta:
+          (selected?.downstreamCount ?? candidate.downstreamCount) -
+          candidate.downstreamCount,
+        unresolvedPrerequisiteDelta:
+          candidate.unresolvedParentUnknownCount -
+          (selected?.unresolvedParentUnknownCount ??
+            candidate.unresolvedParentUnknownCount),
+        labelOrderWinner:
+          selected &&
+          selected.score === candidate.score &&
+          selected.downstreamCount === candidate.downstreamCount &&
+          selected.unresolvedParentUnknownCount ===
+            candidate.unresolvedParentUnknownCount
+            ? selected.label.localeCompare(candidate.label) <= 0
+              ? selected.label
+              : candidate.label
+            : null,
+      },
+    }));
+
+  return {
+    selectedNodeId: selected?.nodeId ?? null,
+    selectedNodeLabel: selected?.label ?? null,
+    status: selection.status,
+    tieType: selection.tieType,
+    resolvedNodeIds: [...resolvedNodeIds],
+    tiedCandidateIds: selection.leadingCandidates.map(
+      (candidate) => candidate.nodeId,
+    ),
+    tieBreakOrder: [
+      "score_desc",
+      "downstreamCount_desc",
+      "unresolvedParentUnknownCount_asc",
+      "label_asc",
+    ],
+    alphabeticalUsedAsReasoning: false,
+    candidates: orderedCandidates,
+    selected: selected
+      ? {
+          nodeId: selected.nodeId,
+          label: selected.label,
+          score: selected.score,
+          downstreamCount: selected.downstreamCount,
+          unresolvedParentUnknownCount: selected.unresolvedParentUnknownCount,
+          matches: selected.matches,
+          contributions: selected.contributions,
+        }
+      : null,
+    competitors,
+    summary: {
+      candidateCount: orderedCandidates.length,
+      selectedReason: selected
+        ? `highest_score=${selected.score}; downstream=${selected.downstreamCount}; unresolved_prerequisites=${selected.unresolvedParentUnknownCount}`
+        : selection.reason,
+    },
+  };
+}
+
+// ── Apply a graph update deterministically ──
+
+export function applyGraphUpdate(graph, update) {
+  const errors = [];
+  const updatedNodesMap = new Map();
+
+  // Validate that update references existing nodes or newly added ones
+  const allNodeIds = new Set(graph.nodes.map((n) => n.id));
+  for (const added of update.addedNodes) {
+    if (allNodeIds.has(added.id)) {
+      errors.push(`Cannot add node with duplicate ID: "${added.id}"`);
+      continue;
+    }
+    allNodeIds.add(added.id);
+  }
+
+  // Validate updated nodes exist
+  for (const upd of update.updatedNodes) {
+    if (!allNodeIds.has(upd.nodeId)) {
+      errors.push(`Cannot update non-existent node: "${upd.nodeId}"`);
+    }
+  }
+
+  // Validate added edges reference existing or new nodes
+  for (const edge of update.addedEdges) {
+    if (!allNodeIds.has(edge.fromNodeId)) {
+      errors.push(
+        `Added edge references non-existent fromNodeId: "${edge.fromNodeId}"`,
+      );
+    }
+    if (!allNodeIds.has(edge.toNodeId)) {
+      errors.push(
+        `Added edge references non-existent toNodeId: "${edge.toNodeId}"`,
+      );
+    }
+  }
+
+  if (errors.length > 0) return { success: false, errors };
+
+  // Build the new nodes list — start with a deep copy of existing
+  const newNodes = graph.nodes.map((n) => ({ ...n }));
+
+  // Apply updated nodes
+  for (const upd of update.updatedNodes) {
+    const idx = newNodes.findIndex((n) => n.id === upd.nodeId);
+    if (idx === -1) continue; // already validated above
+
+    if (upd.newStatus !== undefined && upd.newStatus !== null) {
+      newNodes[idx].status = upd.newStatus;
+    }
+    if (upd.newValue !== undefined) {
+      newNodes[idx].value = upd.newValue;
+    }
+    updatedNodesMap.set(upd.nodeId, newNodes[idx]);
+  }
+
+  // Add new nodes
+  for (const newNode of update.addedNodes) {
+    if (!allNodeIds.has(newNode.id)) continue;
+    allNodeIds.add(newNode.id);
+    newNodes.push({ ...newNode });
+  }
+
+  // Remove edges if requested
+  const removedEdgeSet = new Set(update.removedEdgeIds);
+  const newEdges = graph.edges.filter((e) => !removedEdgeSet.has(e.id));
+
+  // Add new edges
+  for (const newEdge of update.addedEdges) {
+    newEdges.push({ ...newEdge });
+
+    // Update dependsOn / affects on the nodes
+    const fromNode = newNodes.find((n) => n.id === newEdge.fromNodeId);
+    const toNode = newNodes.find((n) => n.id === newEdge.toNodeId);
+    if (fromNode && !fromNode.childIds.includes(newEdge.toNodeId)) {
+      fromNode.childIds.push(newEdge.toNodeId);
+    }
+    if (toNode && !toNode.dependsOn.includes(newEdge.fromNodeId)) {
+      toNode.dependsOn.push(newEdge.fromNodeId);
+    }
+  }
+
+  // Add resolved node IDs
+  const newResolved = [
+    ...new Set([...graph.resolvedNodeIds, ...update.resolvedUnknownNodeIds]),
+  ];
+
+  return {
+    success: true,
+    nodes: newNodes,
+    edges: newEdges,
+    resolvedNodeIds: newResolved,
+  };
+}
+
+// ── Validate a proposed graph update before application ──
+
+export function validateGraphUpdate(graph, update) {
+  const errors = [];
+
+  // Check for duplicate node IDs against existing and newly added nodes
+  const extendedIds = new Set(graph.nodes.map((n) => n.id));
+  for (const newNode of update.addedNodes) {
+    if (extendedIds.has(newNode.id)) {
+      errors.push(`Cannot add node with duplicate ID: "${newNode.id}"`);
+    } else {
+      extendedIds.add(newNode.id);
+    }
+  }
+
+  // Check updated nodes exist (in original graph, not newly added ones)
+  const existingIds = new Set(graph.nodes.map((n) => n.id));
+  for (const upd of update.updatedNodes) {
+    if (!existingIds.has(upd.nodeId)) {
+      errors.push(`Cannot update non-existent node: "${upd.nodeId}"`);
+    }
+  }
+
+  // Reject updates with no meaningful change
+  const statusChanged = update.updatedNodes.some(
+    (u) => u.previousStatus !== null && u.newStatus !== u.previousStatus,
+  );
+  const valueChanged = update.updatedNodes.some(
+    (u) => u.previousValue !== null && u.newValue !== u.previousValue,
+  );
+
+  const hasMeaningfulChange =
+    update.addedNodes.length > 0 ||
+    statusChanged ||
+    valueChanged ||
+    update.addedEdges.length > 0 ||
+    update.removedEdgeIds.length > 0;
+
+  if (!hasMeaningfulChange) {
+    errors.push("Update contains no meaningful change");
+  }
+
+  // Reject oversized input
+  const totalSize = JSON.stringify(update).length;
+  if (totalSize > 100000) {
+    errors.push(`Proposed graph update exceeds 100KB (${totalSize} bytes)`);
+  }
+
+  return { valid: errors.length === 0, errors };
+}

lib/llm/provider.js

@@ -93,11 +93,9 @@ async function detectChatSupport(baseUrl) {
 
 class OllamaLlmProvider {
   async generateReconstruction(scenario, modelName) {
-    const { buildPrompt } = await import("@/lib/reconstruction/prompt");
-    
-    let rawPrompt = buildPrompt(scenario);
-    // Stronger JSON hint since we can't use format:json on older Ollama
-    const prompt = rawPrompt + `\n\nReturn ONLY a valid JSON object starting with { and ending with }. Do NOT include any text before the opening brace or after the closing brace. Do NOT wrap in markdown backticks.`;
+    // scenario is ALREADY a fully-built prompt text (built by analyseScenario).
+    // Do NOT call buildPrompt() again — that would double-wrap the prompt.
+    const prompt = scenario;
 
     const baseUrl = process.env.OLLAMA_BASE_URL;
     if (!baseUrl) throw new Error("OLLAMA_BASE_URL is not set");

lib/reconstruction/compatibility.js

@@ -0,0 +1,40 @@
+function cloneJsonSafe(value) {
+  if (value == null) return value;
+  return JSON.parse(JSON.stringify(value));
+}
+
+export function normaliseAnalysisResponse(input) {
+  const normalised = cloneJsonSafe(input);
+  const changesApplied = [];
+  const warnings = [];
+
+  if (!normalised || typeof normalised !== "object") {
+    return { normalised: input, changesApplied, warnings };
+  }
+
+  if (Array.isArray(normalised.evidence)) {
+    normalised.evidence = normalised.evidence.map((record, index) => {
+      if (!record || typeof record !== "object") return record;
+
+      if (record.source === null) {
+        changesApplied.push({
+          path: ["evidence", index, "source"],
+          change: "Converted null source to undefined",
+        });
+
+        const { source: _removed, ...rest } = record;
+        return rest;
+      }
+
+      return record;
+    });
+  }
+
+  if (changesApplied.length > 0) {
+    warnings.push(
+      "Applied deterministic reconstruction compatibility normalisation",
+    );
+  }
+
+  return { normalised, changesApplied, warnings };
+}

lib/reconstruction/prompt.js

@@ -1,5 +1,24 @@
-export function buildPrompt(scenario) {
-  return `You are a neutral analyst performing an evidence-based reconstruction of the following scenario. 
+import { promises as fs } from "node:fs";
+import { fileURLToPath } from "node:url";
+import { dirname, join } from "node:path";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+const PROMPTS_DIR = join(__dirname, "../../prompts");
+
+/** Available prompt versions */
+export const PROMPT_VERSIONS = ["v0.1", "v0.2", "v0.3"];
+
+/** Default prompt version (override via RECONSTRUCTION_PROMPT_VERSION env var) */
+const defaultVersionFromEnv = process.env.RECONSTRUCTION_PROMPT_VERSION;
+export const DEFAULT_PROMPT_VERSION =
+  defaultVersionFromEnv && PROMPT_VERSIONS.includes(defaultVersionFromEnv)
+    ? defaultVersionFromEnv
+    : "v0.3";
+
+/** Build a v0.1 (extraction-only) prompt inline for backward compatibility */
+function buildV1Prompt(scenario) {
+  return `You are a neutral analyst performing an evidence-based reconstruction of the following scenario.
 
 Rules:
 1. Do NOT invent facts. Only include information present in the scenario or clearly implied.
@@ -29,3 +48,55 @@ Return valid JSON matching this structure exactly:
 
 Return ONLY the JSON object. No markdown, no explanation, no preamble.`;
 }
+
+/** Load a versioned prompt from disk and substitute {{SCENARIO}} */
+async function buildV2Prompt(scenario) {
+  try {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.2.md"),
+      "utf-8",
+    );
+    return content.replace("{{SCENARIO}}", scenario);
+  } catch {
+    // Fall back to v0.1 prompt if v0.2 file is missing
+    return buildV1Prompt(scenario);
+  }
+}
+
+/** Load a versioned prompt from disk and substitute {{SCENARIO}} */
+async function buildV3Prompt(scenario) {
+  try {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.3.md"),
+      "utf-8",
+    );
+    return content.replace("{{SCENARIO}}", scenario);
+  } catch {
+    // Fall back to v0.2 prompt if v0.3 file is missing
+    return buildV2Prompt(scenario);
+  }
+}
+
+/**
+ * Build an analysis prompt for the given version.
+ * @param {"v0.1" | "v0.2" | "v0.3"} [version="v0.3"]
+ * @returns {Promise<{prompt: string, version: string}>}
+ */
+export async function buildPrompt(scenario, version = "v0.3") {
+  let prompt;
+  switch (version) {
+    case "v0.1":
+      prompt = buildV1Prompt(scenario);
+      break;
+    case "v0.2":
+      prompt = await buildV2Prompt(scenario);
+      break;
+    default: // v0.3
+      prompt = await buildV3Prompt(scenario);
+      break;
+  }
+
+  const strongJsonHint =
+    "\n\nReturn ONLY a valid JSON object starting with { and ending with }. Do NOT include any text before the opening brace or after the closing brace. Do NOT wrap in markdown backticks.";
+  return { prompt: prompt + strongJsonHint, version };
+}

lib/reconstruction/schema.js

@@ -1,38 +1,59 @@
 import { z } from "zod";
 
-const confidenceEnum = z.enum(["low", "medium", "high"]);
+// ──────────────────────────────────────────────
+// Shared enums (v0.1 & v0.2)
+// ──────────────────────────────────────────────
 
-const itemSchema = z.object({
+export const confidenceEnum = z.enum(["low", "medium", "high"]);
+const importanceEnum = z.enum([
+  "incidental",
+  "supporting",
+  "important",
+  "critical",
+]);
+const expectedInfoValueEnum = z.enum(["low", "medium", "high"]);
+
+// ──────────────────────────────────────────────
+// v0.1 — extraction-only schema (preserved)
+// ──────────────────────────────────────────────
+
+const confidenceEnumV1 = z.enum(["low", "medium", "high"]);
+
+const itemSchemaV1 = z.object({
   id: z.string().min(1),
   description: z.string().min(1),
-  confidence: confidenceEnum,
+  confidence: confidenceEnumV1,
 });
 
 export const reconstructionSchema = z.object({
-  observations: z.array(itemSchema),
+  observations: z.array(itemSchemaV1),
   reportedClaims: z.array(
-    itemSchema.extend({
-      attributedTo: z.union([z.string().min(1), z.null()]).optional().nullable(),
-    })
+    itemSchemaV1.extend({
+      attributedTo: z
+        .union([z.string().min(1), z.null()])
+        .optional()
+        .nullable(),
+    }),
   ),
-  assumptions: z.array(itemSchema),
-  entities: z.array(itemSchema),
+  assumptions: z.array(itemSchemaV1),
+  entities: z.array(itemSchemaV1),
   transitions: z.array(
-    itemSchema.extend({
+    itemSchemaV1.extend({
       entity: z.string().min(1),
       previousState: z.string().min(1),
       currentState: z.string().min(1),
       explanationStatus: z.string().min(1),
-    })
+    }),
   ),
-  expectedButMissing: z.array(itemSchema),
-  presentButUnexpected: z.array(itemSchema),
-  contradictions: z.array(itemSchema),
-  openUncertainties: z.array(itemSchema),
+  expectedButMissing: z.array(itemSchemaV1),
+  presentButUnexpected: z.array(itemSchemaV1),
+  contradictions: z.array(itemSchemaV1),
+  openUncertainties: z.array(itemSchemaV1),
 });
 
+// v0.1 analyse response (used internally)
 export const analyseResponseSchema = z.object({
-  reconstruction: reconstructionSchema,
+  reconstruction: z.union([reconstructionSchema, z.null()]),
   modelName: z.string(),
   responseDurationMs: z.number(),
   validationStatus: z.enum(["valid", "partial", "invalid"]),
@@ -48,6 +69,141 @@ export const healthResponseSchema = z.object({
   error: z.string().nullable(),
 });
 
+// ──────────────────────────────────────────────
+// v0.2 — reasoning classification + reconstruction
+// ──────────────────────────────────────────────
+
+export const inputTypes =
+  /** @type {z.ZodType<typeof import("@/lib/reconstruction/schema").INPUT_TYPE_VALUE>} */ (
+    z.enum([
+      "observed_problem",
+      "unexplained_change",
+      "contradiction",
+      "decision_request",
+      "causal_claim",
+      "reported_claim",
+      "fault_report",
+      "ambiguous_statement",
+      "question",
+      "desired_outcome",
+      "insufficient_context",
+      "other",
+    ])
+  );
+
+export const reasoningModes =
+  /** @type {z.ZodType<typeof import("@/lib/reconstruction/schema").REASONING_MODE_VALUE>} */ (
+    z.enum([
+      "establish_baseline",
+      "identify_difference",
+      "reconstruct_transition",
+      "decompose_aggregate",
+      "validate_measurement",
+      "validate_claim",
+      "investigate_contradiction",
+      "clarify_meaning",
+      "decision_support",
+      "fault_investigation",
+      "identify_missing_information",
+      "test_possible_explanations",
+      "other",
+    ])
+  );
+
+const evidenceRecordSchema = z.object({
+  id: z.string().min(1),
+  description: z.string().min(1),
+  evidenceType: z.enum([
+    "direct_observation",
+    "reported_statement",
+    "interpretation",
+    "assumption",
+    "inferred_relationship",
+  ]),
+  source: z.string().optional(),
+  attribution: z.string().nullable().optional(),
+  confidence: confidenceEnum,
+  importance: importanceEnum,
+});
+
+const reconstructionSchemaV2 = z.object({
+  summary: z.string().min(1),
+  actors: z.array(itemSchemaV1),
+  systemsOrObjects: z.array(itemSchemaV1),
+  expectedStates: z.array(itemSchemaV1),
+  observedStates: z.array(itemSchemaV1),
+  differences: z.array(itemSchemaV1),
+  knownTransitions: z.array(
+    itemSchemaV1.extend({
+      entity: z.string().min(1),
+      previousState: z.string().min(1),
+      currentState: z.string().min(1),
+      explanationStatus: z.string().min(1),
+    }),
+  ),
+  unexplainedTransitions: z.array(
+    itemSchemaV1.extend({
+      entity: z.string().min(1).optional(),
+      previousState: z.string().min(1).optional(),
+      currentState: z.string().min(1).optional(),
+    }),
+  ),
+  contradictions: z.array(itemSchemaV1),
+  importantUnknowns: z.array(itemSchemaV1),
+  plausibleInterpretations: z.array(
+    z.object({
+      id: z.string().min(1),
+      description: z.string().min(1),
+      supportingEvidenceIds: z.array(z.string()),
+      assumptionsRequired: z.array(z.string()).optional().default([]),
+      confidence: confidenceEnum,
+    }),
+  ),
+});
+
+const inputClassificationSchema = z.object({
+  primaryType: inputTypes,
+  secondaryTypes: z.array(inputTypes).optional().default([]),
+  reasoningModes: z.array(reasoningModes).optional().default([]),
+  classificationReason: z.string().min(1),
+  confidence: confidenceEnum,
+});
+
+const nextQuestionSchema = z.object({
+  id: z.string().min(1),
+  question: z.string().min(1),
+  targets: z.array(z.string()),
+  reason: z.string().min(1),
+  expectedInformationValue: expectedInfoValueEnum,
+  reasoningMode: reasoningModes.optional().default("other"),
+});
+
+// v0.2 complete analysis response (what the model produces)
+export const reconstructionV2Schema = z.object({
+  inputClassification: inputClassificationSchema,
+  reconstruction: reconstructionSchemaV2,
+  evidence: z.array(evidenceRecordSchema),
+  nextQuestion: nextQuestionSchema,
+});
+
+// Outer wrapper for API return (includes diagnostics + v0.2 data)
+export const analyseResponseV2Schema = z.object({
+  inputClassification: inputClassificationSchema.optional(),
+  reconstruction: reconstructionSchemaV2.optional().nullable(),
+  evidence: z.array(evidenceRecordSchema).optional(),
+  nextQuestion: nextQuestionSchema.optional(),
+  modelName: z.string(),
+  responseDurationMs: z.number(),
+  validationStatus: z.enum(["valid", "partial", "invalid"]),
+  rawResponse: z.string().optional(),
+  errors: z.array(z.string()).optional(),
+  promptVersion: z.string().optional(),
+});
+
+// ──────────────────────────────────────────────
+// Parsing helpers
+// ──────────────────────────────────────────────
+
 export function parseReconstruction(raw) {
   if (typeof raw === "string") {
     try {
@@ -58,3 +214,14 @@ export function parseReconstruction(raw) {
   }
   return reconstructionSchema.parse(raw);
 }
+
+export function parseReconstructionV2(raw) {
+  if (typeof raw === "string") {
+    try {
+      raw = JSON.parse(raw);
+    } catch {
+      throw new SyntaxError("Model response is not valid JSON");
+    }
+  }
+  return reconstructionV2Schema.parse(raw);
+}

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "confidence-engine",
-  "version": "0.1.0",
+  "version": "0.2.0-experimental",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "confidence-engine",
-      "version": "0.1.0",
+      "version": "0.2.0-experimental",
       "dependencies": {
         "next": "^14.2.0",
         "react": "^18.3.0",
@@ -14,6 +14,7 @@
         "zod": "^3.23.0"
       },
       "devDependencies": {
+        "@playwright/test": "^1.62.1",
         "@types/node": "^20.14.0",
         "@types/react": "^18.3.0",
         "@types/react-dom": "^18.3.0",
@@ -888,6 +889,22 @@
         "node": ">=14"
       }
     },
+    "node_modules/@playwright/test": {
+      "version": "1.62.1",
+      "resolved": "https://registry.npmjs.org/@playwright/test/-/test-1.62.1.tgz",
+      "integrity": "sha512-DTcUc8qii+cpHvtOwggMtBRMjKZHXYWdw8syRYu2vtzuq4Wxphqq4NfCs5Zt44L6mA8rfDfj+PHnxFc/FeK6mQ==",
+      "devOptional": true,
+      "license": "Apache-2.0",
+      "dependencies": {
+        "playwright": "1.62.1"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    },
     "node_modules/@rollup/rollup-android-arm-eabi": {
       "version": "4.62.3",
       "resolved": "https://registry.npmjs.org/@rollup/rollup-android-arm-eabi/-/rollup-android-arm-eabi-4.62.3.tgz",
@@ -5601,6 +5618,53 @@
         "node": ">= 6"
       }
     },
+    "node_modules/playwright": {
+      "version": "1.62.1",
+      "resolved": "https://registry.npmjs.org/playwright/-/playwright-1.62.1.tgz",
+      "integrity": "sha512-0M+L3LAD8/nm554LOla9Ayx0j0tmFZ0FBcoQ7F1VuVHpM/XpiC8RcDzBQB8W5+hA8L22THxELzeF+2WcUzvcLg==",
+      "devOptional": true,
+      "license": "Apache-2.0",
+      "dependencies": {
+        "playwright-core": "1.62.1"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=20"
+      },
+      "optionalDependencies": {
+        "fsevents": "2.3.2"
+      }
+    },
+    "node_modules/playwright-core": {
+      "version": "1.62.1",
+      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.62.1.tgz",
+      "integrity": "sha512-wPYSwEBJY9GHraISXqyqtx0na0LpO3XEX7jNDhntbex7tzUS7kLnZsOlFruFJB4Hi/rhDMjXGqHewDZ68nYZVw==",
+      "devOptional": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "playwright-core": "cli.js"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    },
+    "node_modules/playwright/node_modules/fsevents": {
+      "version": "2.3.2",
+      "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.2.tgz",
+      "integrity": "sha512-xiqMQR4xAeHTuB9uWm+fFRcIOgKBMiOBP+eXiyT7jsgVCq1bkVygt00oASowB7EdtpOHaaPgKt812P9ab+DDKA==",
+      "dev": true,
+      "hasInstallScript": true,
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "darwin"
+      ],
+      "engines": {
+        "node": "^8.16.0 || ^10.6.0 || >=11.0.0"
+      }
+    },
     "node_modules/possible-typed-array-names": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/possible-typed-array-names/-/possible-typed-array-names-1.1.0.tgz",

package.json

@@ -1,7 +1,7 @@
 {
   "type": "module",
   "name": "confidence-engine",
-  "version": "0.1.0",
+  "version": "0.2.0-experimental",
   "private": true,
   "description": "Experimental prototype for evidence-based situation reconstruction using local LLMs",
   "scripts": {
@@ -19,6 +19,7 @@
     "zod": "^3.23.0"
   },
   "devDependencies": {
+    "@playwright/test": "^1.62.1",
     "@types/node": "^20.14.0",
     "@types/react": "^18.3.0",
     "@types/react-dom": "^18.3.0",

playwright.config.js

@@ -0,0 +1,5 @@
+import { defineConfig } from "@playwright/test";
+export default defineConfig({
+  use: { headless: true, screenshot: "only-on-failure", actionTimeout: 120000 },
+  testMatch: "**/tests/smoke.test.js",
+});

prompts/reconstruct-v0.2.md

@@ -0,0 +1,122 @@
+You are a neutral analyst performing evidence-based situation reconstruction.
+
+## Rules
+
+1. Do NOT invent facts, context or causes. Only include information present in the scenario or clearly implied.
+2. First determine what kind of input has been supplied. Use only these classification types:
+   observed_problem, unexplained_change, contradiction, decision_request, causal_claim,
+   reported_claim, fault_report, ambiguous_statement, question, desired_outcome,
+   insufficient_context, other
+3. Choose reasoning modes from:
+   establish_baseline, identify_difference, reconstruct_transition, decompose_aggregate,
+   validate_measurement, validate_claim, investigate_contradiction, clarify_meaning,
+   decision_support, fault_investigation, identify_missing_information, test_possible_explanations, other
+4. Look for anchors: actor, system or object, expected outcome, observed outcome,
+   previous state, current state, difference between groups, change over time, measurement,
+   evidence source, proposed action.
+5. Identify meaningful differences (e.g., some succeed while others fail; revenue rises while cash falls).
+6. Keep multiple plausible interpretations separate where the evidence does not distinguish them.
+7. Distinguish: what was said / what it may mean / why it may have been said.
+8. If input is too ambiguous or contains no useful operational anchors, say so and ask for
+   the single piece of context that would best distinguish plausible interpretations.
+
+## Confidence scale
+
+- low — weak evidence, speculation, or missing information
+- medium — reasonable inference from available evidence
+- high — strong evidence, direct observation, or confirmed fact
+
+## Importance scale (evidence records)
+
+- incidental — minor detail, unlikely to affect conclusions
+- supporting — adds context but not critical
+- important — materially affects understanding of the situation
+- critical — essential to resolving the situation; without it conclusions cannot be drawn
+
+## Expected information value (next question)
+
+- low — marginally useful even if answered
+- medium — meaningfully clarifies the situation
+- high — would significantly distinguish between plausible explanations or fill a gap in understanding
+
+## Next question selection criteria
+
+Prefer questions that:
+- clarify a major difference
+- establish a baseline
+- explain an important transition
+- test an unsupported claim
+- distinguish between plausible explanations
+- request measurable evidence
+- identify who or what is affected
+- establish timing
+
+Avoid questions that:
+- have already been answered
+- assume a cause
+- jump to a solution
+- ask about motive before the observable situation is understood
+- focus on incidental wording
+- are too broad to produce useful information
+- combine many unrelated questions
+
+## Output format — return this exact JSON structure
+
+Return a JSON object with exactly these four top-level keys (use **camelCase**):
+
+```json
+{
+  "inputClassification": {
+    "primaryType": "<one of: observed_problem, unexplained_change, contradiction, decision_request, causal_claim, reported_claim, fault_report, ambiguous_statement, question, desired_outcome, insufficient_context, other>",
+    "secondaryTypes": ["<optional additional types from the same list>"],
+    "reasoningModes": ["<one or more of: establish_baseline, identify_difference, reconstruct_transition, decompose_aggregate, validate_measurement, validate_claim, investigate_contradiction, clarify_meaning, decision_support, fault_investigation, identify_missing_information, test_possible_explanations, other>"],
+    "classificationReason": "<brief explanation of why you chose the primary type>",
+    "confidence": "<low | medium | high>"
+  },
+  "reconstruction": {
+    "summary": "<one-sentence overview of the situation>",
+    "actors": [{"id": "<any unique string>", "description": "...", "confidence": "<low|medium|high>"}],
+    "systemsOrObjects": [{"id": "<any unique string>", "description": "...", "confidence": "<low|medium|high>"}],
+    "expectedStates": [{"id": "...", "description": "...", "confidence": "<low|medium|high>"}],
+    "observedStates": [{"id": "...", "description": "...", "confidence": "<low|medium|high>"}],
+    "differences": [{"id": "...", "description": "...", "confidence": "<low|medium|high>"}],
+    "knownTransitions": [{"id": "...", "description": "...", "confidence": "<low|medium|high>", "entity": "...", "previousState": "...", "currentState": "...", "explanationStatus": "..."}],
+    "unexplainedTransitions": [{"id": "...", "description": "...", "confidence": "<low|medium|high>", "entity": "...", "previousState": "...", "currentState": "..."}],
+    "contradictions": [{"id": "...", "description": "...", "confidence": "<low|medium|high>"}],
+    "importantUnknowns": [{"id": "...", "description": "...", "confidence": "<low|medium|high>"}],
+    "plausibleInterpretations": [{"id": "...", "description": "...", "supportingEvidenceIds": ["<ids that support this interpretation>"], "assumptionsRequired": [], "confidence": "<low|medium|high>"}]
+  },
+  "evidence": [
+    {
+      "id": "<any unique string>",
+      "description": "...",
+      "evidenceType": "<direct_observation | reported_statement | interpretation | assumption | inferred_relationship>",
+      "source": "<optional — who/where this came from>",
+      "attribution": null,
+      "confidence": "<low | medium | high>",
+      "importance": "<incidental | supporting | important | critical>"
+    }
+  ],
+  "nextQuestion": {
+    "id": "<any unique string>",
+    "question": "<one precise question>",
+    "targets": ["<what this question targets — e.g. 'actor', 'system', 'expectedOutcome'>"],
+    "reason": "<why answering this is important>",
+    "expectedInformationValue": "<low | medium | high>",
+    "reasoningMode": "<optional reasoning mode from the list above>"
+  }
+}
+```
+
+CRITICAL RULES for JSON output:
+1. Use **exactly** the key names shown above (camelCase, no snake_case).
+2. The four top-level keys must be: `inputClassification`, `reconstruction`, `evidence`, `nextQuestion`.
+3. Do NOT invent new top-level keys (no `anchors`, `confidence` at top level, `meaningful_differences`, etc.).
+4. Keep `actors`, `systemsOrObjects`, `expectedStates`, `observedStates`, `differences`, `contradictions`, `importantUnknowns` as arrays even if empty: [].
+5. Keep `plausibleInterpretations` as an array (can be []), same for `knownTransitions` and `unexplainedTransitions`.
+6. Each object in arrays must have at least `id`, `description`, `confidence`.
+
+Scenario:
+{{SCENARIO}}
+
+Return ONLY the JSON object starting with { and ending with }. Do NOT include any text before the opening brace or after the closing brace. Do NOT wrap in markdown backticks.

prompts/reconstruct-v0.3.md

@@ -0,0 +1,160 @@
+You are a neutral analyst performing evidence-based situation reconstruction.
+
+## Rules
+
+1. Do NOT invent facts, context or causes. Only include information present in the scenario or clearly implied.
+2. First determine what kind of input has been supplied. Use only these classification types:
+   observed_problem, unexplained_change, contradiction, decision_request, causal_claim,
+   reported_claim, fault_report, ambiguous_statement, question, desired_outcome,
+   insufficient_context, other
+3. Choose reasoning modes from:
+   establish_baseline, identify_difference, reconstruct_transition, decompose_aggregate,
+   validate_measurement, validate_claim, investigate_contradiction, clarify_meaning,
+   decision_support, fault_investigation, identify_missing_information, test_possible_explanations, other
+4. Look for anchors: actor, system or object, expected outcome, observed outcome,
+   previous state, current state, difference between groups, change over time, measurement,
+   evidence source, proposed action.
+5. Identify meaningful differences (e.g., some succeed while others fail; revenue rises while cash falls).
+6. Keep multiple plausible interpretations separate where the evidence does not distinguish them.
+7. Distinguish: what was said / what it may mean / why it may have been said.
+8. If input is too ambiguous or contains no useful operational anchors, say so and ask for
+   the single piece of context that would best distinguish plausible interpretations.
+
+## Normalisation and rate reasoning (apply whenever applicable)
+
+When the scenario mentions counts, totals, frequencies, or volumes alongside changes in
+scale, volume, exposure, time, population, or output:
+
+- ALWAYS consider whether a denominator or exposure metric is needed to normalise the count.
+- Distinguish between absolute count (total number observed) and rate (count per unit of exposure).
+- Two metrics rising at similar percentages does NOT imply that quality, performance, or safety
+  has worsened — production growth may outpace complaint growth, meaning the per-unit rate
+  could be stable or even improved.
+- Identify the possible denominator explicitly (e.g., "per unit produced", "per customer served",
+  "per hour of operation").
+- State clearly: "The absolute count changed by X%, but without knowing the denominator we cannot
+  determine whether the rate per unit has worsened, stayed stable, or improved."
+- Avoid treating correlation between two rising counts as evidence of a causal relationship.
+
+## Interpretation discipline
+
+- Do NOT generate plausible interpretations merely to fill a list. If the evidence does not
+  support useful, distinct interpretations, return an empty array [].
+- Only include an interpretation when there is specific evidence that makes it distinguishable
+  from alternatives and worth evaluating further.
+- Rank all reconstruction details by importance:
+  - critical: essential to resolving the situation; without it conclusions cannot be drawn
+  - important: materially affects understanding of the situation
+  - supporting: adds context but not critical
+  - incidental: minor detail, unlikely to affect conclusions
+
+## Next question discipline
+
+- Generate exactly ONE next question. Do NOT combine multiple questions.
+- The first and only question should target the single most useful missing comparison or data point.
+- Prefer narrow, specific questions over broad compound questions.
+- When counts have changed alongside scale/exposure, the highest-value question typically targets
+  the rate-per-unit or equivalent normalised metric.
+- Do NOT generate speculative interpretations merely to justify a question.
+
+## Confidence scale
+
+- low — weak evidence, speculation, or missing information
+- medium — reasonable inference from available evidence
+- high — strong evidence, direct observation, or confirmed fact
+
+## Importance scale (evidence records)
+
+- incidental — minor detail, unlikely to affect conclusions
+- supporting — adds context but not critical
+- important — materially affects understanding of the situation
+- critical — essential to resolving the situation; without it conclusions cannot be drawn
+
+## Expected information value (next question)
+
+- low — marginally useful even if answered
+- medium — meaningfully clarifies the situation
+- high — would significantly distinguish between plausible explanations or fill a gap in understanding
+
+## Next question selection criteria
+
+Prefer questions that:
+- clarify a major difference
+- establish a baseline
+- explain an important transition
+- test an unsupported claim
+- distinguish between plausible explanations
+- request measurable evidence
+- identify who or what is affected
+- establish timing
+
+Avoid questions that:
+- have already been answered
+- assume a cause
+- jump to a solution
+- ask about motive before the observable situation is understood
+- focus on incidental wording
+- are too broad to produce useful information
+- combine many unrelated questions
+
+## Output format — return this exact JSON structure
+
+Return a JSON object with exactly these four top-level keys (use **camelCase**):
+
+```json
+{
+  "inputClassification": {
+    "primaryType": "<one of: observed_problem, unexplained_change, contradiction, decision_request, causal_claim, reported_claim, fault_report, ambiguous_statement, question, desired_outcome, insufficient_context, other>",
+    "secondaryTypes": ["<optional additional types from the same list>"],
+    "reasoningModes": ["<one or more of: establish_baseline, identify_difference, reconstruct_transition, decompose_aggregate, validate_measurement, validate_claim, investigate_contradiction, clarify_meaning, decision_support, fault_investigation, identify_missing_information, test_possible_explanations, other>"],
+    "classificationReason": "<brief explanation of why you chose the primary type>",
+    "confidence": "<low | medium | high>"
+  },
+  "reconstruction": {
+    "summary": "<one-sentence overview of the situation>",
+    "actors": [{"id": "<any unique string>", "description": "...", "confidence": "<low|medium|high>"}],
+    "systemsOrObjects": [{"id": "<any unique string>", "description": "...", "confidence": "<low|medium|high>"}],
+    "expectedStates": [{"id": "...", "description": "...", "confidence": "<low|medium|high>"}],
+    "observedStates": [{"id": "...", "description": "...", "confidence": "<low|medium|high>"}],
+    "differences": [{"id": "...", "description": "...", "confidence": "<low|medium|high>"}],
+    "knownTransitions": [{"id": "...", "description": "...", "confidence": "<low|medium|high>", "entity": "...", "previousState": "...", "currentState": "...", "explanationStatus": "..."}],
+    "unexplainedTransitions": [{"id": "...", "description": "...", "confidence": "<low|medium|high>", "entity": "...", "previousState": "...", "currentState": "..."}],
+    "contradictions": [{"id": "...", "description": "...", "confidence": "<low|medium|high>"}],
+    "importantUnknowns": [{"id": "...", "description": "...", "confidence": "<low|medium|high>"}],
+    "plausibleInterpretations": [{"id": "...", "description": "...", "supportingEvidenceIds": ["<ids that support this interpretation>"], "assumptionsRequired": [], "confidence": "<low|medium|high>"}]
+  },
+  "evidence": [
+    {
+      "id": "<any unique string>",
+      "description": "...",
+      "evidenceType": "<direct_observation | reported_statement | interpretation | assumption | inferred_relationship>",
+      "source": "<optional — who/where this came from>",
+      "attribution": null,
+      "confidence": "<low | medium | high>",
+      "importance": "<incidental | supporting | important | critical>"
+    }
+  ],
+  "nextQuestion": {
+    "id": "<any unique string>",
+    "question": "<one precise question>",
+    "targets": ["<what this question targets — e.g. 'actor', 'system', 'expectedOutcome'>"],
+    "reason": "<why answering this is important>",
+    "expectedInformationValue": "<low | medium | high>",
+    "reasoningMode": "<optional reasoning mode from the list above>"
+  }
+}
+```
+
+CRITICAL RULES for JSON output:
+1. Use **exactly** the key names shown above (camelCase, no snake_case).
+2. The four top-level keys must be: `inputClassification`, `reconstruction`, `evidence`, `nextQuestion`.
+3. Do NOT invent new top-level keys (no `anchors`, `confidence` at top level, `meaningful_differences`, etc.).
+4. Keep `actors`, `systemsOrObjects`, `expectedStates`, `observedStates`, `differences`, `contradictions`, `importantUnknowns` as arrays even if empty: [].
+5. Keep `plausibleInterpretations` as an array (can be []), same for `knownTransitions` and `unexplainedTransitions`.
+6. Each object in arrays must have at least `id`, `description`, `confidence`.
+7. **evidenceType**: classify each evidence item clearly as either a direct observation, a reported statement, an interpretation, an assumption, or an inferred relationship. Do not treat raw counts as proof of causal relationships — they may be inferred relationships only when supported by explicit reasoning about denominators or rates.
+
+Scenario:
+{{SCENARIO}}
+
+Return ONLY the JSON object starting with { and ending with }. Do NOT include any text before the opening brace or after the closing brace. Do NOT wrap in markdown backticks.

scripts/reproduce-commercial-value-update.mjs

@@ -0,0 +1,97 @@
+import { mkdir, writeFile } from "node:fs/promises";
+
+const BASE_URL =
+  process.env.CONFIDENCE_ENGINE_BASE_URL || "http://127.0.0.1:3000";
+const OUTPUT_DIR = "tests-results/commercial-value-update";
+
+const scenario = "I think therefore I am";
+const answer =
+  "Deciding whether to build the Confidence Engine due to uncertainty about its commercial value.";
+
+async function postJson(path, body) {
+  const response = await fetch(`${BASE_URL}${path}`, {
+    method: "POST",
+    headers: {
+      "content-type": "application/json",
+    },
+    body: JSON.stringify(body),
+  });
+
+  const json = await response.json();
+  return { status: response.status, json };
+}
+
+function printLine(label, value) {
+  const rendered = value === undefined ? null : value;
+  console.log(`${label}: ${JSON.stringify(rendered)}`);
+}
+
+async function main() {
+  await mkdir(OUTPUT_DIR, { recursive: true });
+
+  const startResult = await postJson("/api/cases/start", { scenario });
+  await writeFile(
+    `${OUTPUT_DIR}/start-response.json`,
+    JSON.stringify(startResult, null, 2),
+  );
+
+  const selectedQuestion = startResult.json?.selectedQuestion?.question || null;
+
+  let updateResult = {
+    status: null,
+    json: {
+      success: false,
+      stage: "request_construction",
+      errors: ["Missing selected question from start response"],
+    },
+  };
+
+  if (startResult.json?.success && selectedQuestion) {
+    updateResult = await postJson("/api/cases/update", {
+      situationGraph: startResult.json.situationGraph,
+      previousQuestion: selectedQuestion,
+      answer,
+    });
+  }
+
+  await writeFile(
+    `${OUTPUT_DIR}/update-response.json`,
+    JSON.stringify(updateResult, null, 2),
+  );
+
+  printLine("start success", startResult.json?.success ?? false);
+  printLine("update success", updateResult.json?.success ?? false);
+  printLine("update stage", updateResult.json?.stage ?? null);
+  printLine(
+    "proposal added nodes",
+    updateResult.json?.proposal?.addedNodes?.map((node) => node.id) ?? null,
+  );
+  printLine(
+    "proposal added edges",
+    updateResult.json?.proposal?.addedEdges?.map((edge) => ({
+      id: edge.id,
+      fromNodeId: edge.fromNodeId,
+      toNodeId: edge.toNodeId,
+      relationship: edge.relationship,
+    })) ?? null,
+  );
+  printLine(
+    "proposal resolved unknown IDs",
+    updateResult.json?.proposal?.resolvedUnknownNodeIds ??
+      updateResult.json?.resolvedUnknownNodeIds ??
+      null,
+  );
+  printLine(
+    "errors",
+    updateResult.json?.errors ??
+      updateResult.json?.proposalErrors ??
+      updateResult.json?.graphValidationErrors ??
+      updateResult.json?.validationErrors ??
+      null,
+  );
+}
+
+main().catch((error) => {
+  console.error(error instanceof Error ? error.message : String(error));
+  process.exitCode = 1;
+});

tests/app/api/cases-start-route.test.js

@@ -0,0 +1,114 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const mockStartCase = vi.fn();
+
+vi.mock("@/lib/graph/orchestrator.js", () => ({
+  startCase: (...args) => mockStartCase(...args),
+}));
+
+describe("app/api/cases/start route", () => {
+  beforeEach(() => {
+    vi.resetModules();
+    vi.clearAllMocks();
+  });
+
+  it("delegates request body to the orchestrator", async () => {
+    mockStartCase.mockResolvedValue({
+      success: true,
+      situationGraph: { nodes: [{ id: "n1" }], edges: [] },
+      selectedQuestion: null,
+      diagnostics: {},
+    });
+
+    const { POST } = await import("@/app/api/cases/start/route.js");
+    const request = new Request("http://localhost/api/cases/start", {
+      method: "POST",
+      body: JSON.stringify({ scenario: "Scenario text" }),
+      headers: { "content-type": "application/json" },
+    });
+
+    await POST(request);
+
+    expect(mockStartCase).toHaveBeenCalledWith({ scenario: "Scenario text" });
+  });
+
+  it("returns 200 on success", async () => {
+    mockStartCase.mockResolvedValue({
+      success: true,
+      situationGraph: { nodes: [{ id: "n1" }], edges: [] },
+      selectedQuestion: null,
+      diagnostics: {},
+    });
+
+    const { POST } = await import("@/app/api/cases/start/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/start", {
+        method: "POST",
+        body: JSON.stringify({ scenario: "Scenario text" }),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(response.status).toBe(200);
+  });
+
+  it("returns 400 for invalid request input", async () => {
+    mockStartCase.mockResolvedValue({
+      success: false,
+      error: "Invalid start-case request",
+      validationErrors: [{ message: "Required" }],
+      statusCode: 400,
+    });
+
+    const { POST } = await import("@/app/api/cases/start/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/start", {
+        method: "POST",
+        body: JSON.stringify({}),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(response.status).toBe(400);
+    await expect(response.json()).resolves.toMatchObject({
+      success: false,
+      error: "Invalid start-case request",
+    });
+  });
+
+  it("returns provider/internal failures as 5xx without stack traces", async () => {
+    mockStartCase.mockResolvedValue({
+      success: false,
+      error: "Provider unavailable",
+      diagnostics: { modelName: "llama3" },
+      statusCode: 502,
+    });
+
+    const { POST } = await import("@/app/api/cases/start/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/start", {
+        method: "POST",
+        body: JSON.stringify({ scenario: "Scenario text" }),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(response.status).toBe(502);
+    await expect(response.json()).resolves.not.toHaveProperty("stack");
+  });
+
+  it("returns structured 500 on malformed JSON", async () => {
+    const { POST } = await import("@/app/api/cases/start/route.js");
+    const request = {
+      json: vi.fn().mockRejectedValue(new Error("Unexpected token")),
+    };
+
+    const response = await POST(request);
+
+    expect(response.status).toBe(500);
+    await expect(response.json()).resolves.toMatchObject({
+      success: false,
+      error: "Internal server error",
+    });
+  });
+});

tests/app/api/cases-update-route.test.js

@@ -0,0 +1,304 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const mockUpdateCase = vi.fn();
+
+vi.mock("@/lib/graph/orchestrator.js", () => ({
+  updateCase: (...args) => mockUpdateCase(...args),
+}));
+
+function makeSuccessResult() {
+  return {
+    success: true,
+    stage: "update_applied",
+    updatedSituationGraph: {
+      centralStatement: "Scenario",
+      nodes: [{ id: "n1" }],
+      edges: [],
+      activeUnknownNodeId: null,
+      resolvedNodeIds: ["n1"],
+      currentSummary: "Updated summary",
+    },
+    proposal: {
+      addedNodes: [],
+      updatedNodes: [],
+      addedEdges: [],
+      removedEdgeIds: [],
+      resolvedUnknownNodeIds: ["n1"],
+      affectedNodeIds: ["n1"],
+      selectedQuestion: null,
+    },
+    selectedQuestion: null,
+    affectedNodeIds: ["n1"],
+    resolvedUnknownNodeIds: ["n1"],
+    previousActiveUnknownNodeId: "n0",
+    newActiveUnknownNodeId: null,
+    changesApplied: { updatedNodeCount: 1 },
+    diagnostics: { promptVersion: "v0.4" },
+  };
+}
+
+describe("app/api/cases/update route", () => {
+  beforeEach(() => {
+    vi.resetModules();
+    vi.clearAllMocks();
+  });
+
+  it("valid update returns HTTP 200", async () => {
+    mockUpdateCase.mockResolvedValue(makeSuccessResult());
+
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/update", {
+        method: "POST",
+        body: JSON.stringify({ answer: "A" }),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(response.status).toBe(200);
+  });
+
+  it("route calls updateCase with applyProposal: true", async () => {
+    mockUpdateCase.mockResolvedValue(makeSuccessResult());
+
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const body = { situationGraph: {}, previousQuestion: "Q", answer: "A" };
+    await POST(
+      new Request("http://localhost/api/cases/update", {
+        method: "POST",
+        body: JSON.stringify(body),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(mockUpdateCase).toHaveBeenCalledWith(body, { applyProposal: true });
+  });
+
+  it("invalid JSON returns 400", async () => {
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const request = {
+      json: vi.fn().mockRejectedValue(new SyntaxError("Unexpected token")),
+    };
+
+    const response = await POST(request);
+
+    expect(response.status).toBe(400);
+    await expect(response.json()).resolves.toMatchObject({
+      success: false,
+      stage: "request_validation",
+      error: "Invalid JSON request body",
+    });
+  });
+
+  it("request validation failure returns 400", async () => {
+    mockUpdateCase.mockResolvedValue({
+      success: false,
+      stage: "request_validation",
+      error: "Invalid update-case request",
+      validationErrors: [{ message: "Required" }],
+    });
+
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/update", {
+        method: "POST",
+        body: JSON.stringify({}),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(response.status).toBe(400);
+  });
+
+  it("graph validation failure returns 400", async () => {
+    mockUpdateCase.mockResolvedValue({
+      success: false,
+      stage: "graph_validation",
+      error: "Invalid situation graph",
+      graphValidationErrors: ["bad graph"],
+    });
+
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/update", {
+        method: "POST",
+        body: JSON.stringify({ answer: "A" }),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(response.status).toBe(400);
+  });
+
+  it("provider failure returns 502", async () => {
+    mockUpdateCase.mockResolvedValue({
+      success: false,
+      stage: "provider",
+      error: "Graph update proposal generation failed",
+      providerErrors: ["provider offline"],
+    });
+
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/update", {
+        method: "POST",
+        body: JSON.stringify({ answer: "A" }),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(response.status).toBe(502);
+  });
+
+  it("proposal validation failure returns 422", async () => {
+    mockUpdateCase.mockResolvedValue({
+      success: false,
+      stage: "proposal_validation",
+      error: "Invalid graph update proposal",
+      proposalErrors: [{ message: "bad proposal" }],
+    });
+
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/update", {
+        method: "POST",
+        body: JSON.stringify({ answer: "A" }),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(response.status).toBe(422);
+  });
+
+  it("proposal compatibility failure returns 422", async () => {
+    mockUpdateCase.mockResolvedValue({
+      success: false,
+      stage: "proposal_compatibility",
+      error: "Update case failed",
+      errors: ["incompatible proposal"],
+    });
+
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/update", {
+        method: "POST",
+        body: JSON.stringify({ answer: "A" }),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(response.status).toBe(422);
+  });
+
+  it("application failure returns 422", async () => {
+    mockUpdateCase.mockResolvedValue({
+      success: false,
+      stage: "application",
+      error: "Update case failed",
+      errors: ["could not apply"],
+    });
+
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/update", {
+        method: "POST",
+        body: JSON.stringify({ answer: "A" }),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(response.status).toBe(422);
+  });
+
+  it("result validation failure returns 500", async () => {
+    mockUpdateCase.mockResolvedValue({
+      success: false,
+      stage: "result_validation",
+      error: "Update case failed",
+      errors: ["invalid result"],
+    });
+
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/update", {
+        method: "POST",
+        body: JSON.stringify({ answer: "A" }),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(response.status).toBe(500);
+  });
+
+  it("unknown failure returns 500", async () => {
+    mockUpdateCase.mockRejectedValue(new Error("boom"));
+
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/update", {
+        method: "POST",
+        body: JSON.stringify({ answer: "A" }),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    expect(response.status).toBe(500);
+    await expect(response.json()).resolves.toMatchObject({
+      success: false,
+      stage: "internal",
+      error: "Internal server error",
+    });
+  });
+
+  it("success response preserves updated graph fields", async () => {
+    const success = makeSuccessResult();
+    mockUpdateCase.mockResolvedValue(success);
+
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/update", {
+        method: "POST",
+        body: JSON.stringify({ answer: "A" }),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    await expect(response.json()).resolves.toMatchObject({
+      updatedSituationGraph: success.updatedSituationGraph,
+      proposal: success.proposal,
+      affectedNodeIds: success.affectedNodeIds,
+      resolvedUnknownNodeIds: success.resolvedUnknownNodeIds,
+      previousActiveUnknownNodeId: success.previousActiveUnknownNodeId,
+      newActiveUnknownNodeId: success.newActiveUnknownNodeId,
+      selectedQuestion: success.selectedQuestion,
+      changesApplied: success.changesApplied,
+      diagnostics: success.diagnostics,
+    });
+  });
+
+  it("stack traces and raw provider output are not exposed", async () => {
+    mockUpdateCase.mockResolvedValue({
+      success: false,
+      stage: "provider",
+      error: "Graph update proposal generation failed",
+      providerErrors: ["provider offline"],
+      rawResponse: "secret",
+      stack: "trace",
+      diagnostics: {},
+    });
+
+    const { POST } = await import("@/app/api/cases/update/route.js");
+    const response = await POST(
+      new Request("http://localhost/api/cases/update", {
+        method: "POST",
+        body: JSON.stringify({ answer: "A" }),
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    const payload = await response.json();
+
+    expect(payload).not.toHaveProperty("stack");
+    expect(payload).not.toHaveProperty("rawResponse");
+  });
+});

tests/fixtures/ambiguity-generalisation.js

@@ -0,0 +1,198 @@
+import { makeEdge, makeGraph, makeNode } from "@/lib/graph/schema.js";
+
+function buildAmbiguityFixture({
+  key,
+  scenario,
+  summaryLabel,
+  contradictionLabel,
+  observationLabels,
+  unknownLabels,
+  disallowedQuestionTerms,
+}) {
+  const summary = makeNode({
+    id: `${key}-summary`,
+    label: summaryLabel,
+    description: "Summary of the situation from the scenario text",
+    kind: "state",
+    status: "provisional",
+    confidence: "medium",
+  });
+
+  const contradiction = makeNode({
+    id: `${key}-contradiction`,
+    label: contradictionLabel,
+    description: contradictionLabel,
+    kind: "relationship",
+    status: "supported",
+    confidence: "medium",
+  });
+
+  const observations = observationLabels.map((label, index) =>
+    makeNode({
+      id: `${key}-obs-${index + 1}`,
+      label,
+      description: label,
+      kind: "observation",
+      status: "supported",
+      confidence: "high",
+    }),
+  );
+
+  const unknowns = unknownLabels.map((label, index) =>
+    makeNode({
+      id: `${key}-unknown-${index + 1}`,
+      label,
+      description: label,
+      kind: "unknown",
+      status: "unknown",
+      confidence: "high",
+    }),
+  );
+
+  const edges = [
+    ...observations.map((node) =>
+      makeEdge({
+        id: `${node.id}-supports-summary`,
+        fromNodeId: node.id,
+        toNodeId: summary.id,
+        relationship: "supports",
+        description: `${node.label} supports the summary.`,
+      }),
+    ),
+    ...unknowns.map((node) =>
+      makeEdge({
+        id: `${node.id}-depends-summary`,
+        fromNodeId: node.id,
+        toNodeId: summary.id,
+        relationship: "depends_on",
+        description: `${node.label} is an unresolved factor for this situation.`,
+      }),
+    ),
+  ];
+
+  return {
+    key,
+    scenario,
+    disallowedQuestionTerms,
+    graph: makeGraph({
+      centralStatement: scenario,
+      nodes: [summary, contradiction, ...observations, ...unknowns],
+      edges,
+      activeUnknownNodeId: null,
+      resolvedNodeIds: [],
+      currentSummary: `Ambiguity fixture for ${key}`,
+    }),
+  };
+}
+
+export const ambiguityGeneralisationFixtures = [
+  buildAmbiguityFixture({
+    key: "revenue-cash",
+    scenario:
+      "Revenue increased by 18%, but cash in the bank fell over the same period.",
+    summaryLabel: "Revenue rose while cash fell",
+    contradictionLabel:
+      "Contradiction between revenue improvement and lower cash reserves.",
+    observationLabels: [
+      "Revenue increased by 18%.",
+      "Cash in the bank decreased over the same period.",
+    ],
+    unknownLabels: [
+      "Possible explanation for the contradiction from one side of the situation.",
+      "Possible explanation for the contradiction from another side of the situation.",
+    ],
+    disallowedQuestionTerms: [
+      "accounts receivable",
+      "capex",
+      "debt repayments",
+      "working capital",
+    ],
+  }),
+  buildAmbiguityFixture({
+    key: "satisfaction-complaints",
+    scenario:
+      "Customer satisfaction scores increased, but complaints also increased.",
+    summaryLabel: "Satisfaction scores rose while complaints also rose",
+    contradictionLabel:
+      "Contradiction between higher satisfaction scores and higher complaint volume.",
+    observationLabels: [
+      "Customer satisfaction scores increased.",
+      "Complaints increased.",
+    ],
+    unknownLabels: [
+      "Possible explanation for why the positive signal and negative signal moved together.",
+      "Another possible explanation for why the positive signal and negative signal moved together.",
+    ],
+    disallowedQuestionTerms: [
+      "net promoter",
+      "ticket backlog",
+      "call deflection",
+      "support queue",
+    ],
+  }),
+  buildAmbiguityFixture({
+    key: "delivery-cancellations",
+    scenario:
+      "Average delivery time decreased by 25%, but order cancellations increased.",
+    summaryLabel: "Delivery became faster while cancellations increased",
+    contradictionLabel:
+      "Contradiction between faster delivery and more order cancellations.",
+    observationLabels: [
+      "Average delivery time decreased by 25%.",
+      "Order cancellations increased.",
+    ],
+    unknownLabels: [
+      "Possible explanation for why the faster result did not reduce the negative result.",
+      "Another possible explanation for why the faster result did not reduce the negative result.",
+    ],
+    disallowedQuestionTerms: [
+      "fulfilment",
+      "last mile",
+      "warehouse",
+      "routing",
+    ],
+  }),
+  buildAmbiguityFixture({
+    key: "traffic-sales",
+    scenario: "Website traffic doubled, but sales remained unchanged.",
+    summaryLabel: "Website traffic doubled while sales stayed flat",
+    contradictionLabel:
+      "Contradiction between much higher traffic and unchanged sales.",
+    observationLabels: [
+      "Website traffic doubled.",
+      "Sales remained unchanged.",
+    ],
+    unknownLabels: [
+      "Possible explanation for why the stronger signal did not change the outcome.",
+      "Another possible explanation for why the stronger signal did not change the outcome.",
+    ],
+    disallowedQuestionTerms: [
+      "conversion funnel",
+      "campaign attribution",
+      "landing page",
+      "checkout flow",
+    ],
+  }),
+  buildAmbiguityFixture({
+    key: "output-defects",
+    scenario:
+      "Production output increased by 30%, but quality defects also increased.",
+    summaryLabel: "Production output rose while defects also rose",
+    contradictionLabel:
+      "Contradiction between higher output and more quality defects.",
+    observationLabels: [
+      "Production output increased by 30%.",
+      "Quality defects increased.",
+    ],
+    unknownLabels: [
+      "Possible explanation for why the gain came with a worsening result.",
+      "Another possible explanation for why the gain came with a worsening result.",
+    ],
+    disallowedQuestionTerms: [
+      "scrap rate",
+      "throughput",
+      "yield",
+      "root cause",
+    ],
+  }),
+];

tests/fixtures/comparability-assessment.js

@@ -0,0 +1,164 @@
+import { makeEdge, makeGraph, makeNode } from "@/lib/graph/schema.js";
+
+function buildComparabilityFixture({
+  key,
+  scenario,
+  observationLabels,
+  contradictionLabel,
+  expectedComparabilityStatus,
+  expectsComparisonQuestion,
+}) {
+  const summary = makeNode({
+    id: `${key}-summary`,
+    label: scenario,
+    description: "Summary of the situation from the scenario text",
+    kind: "state",
+    status: "provisional",
+    confidence: "medium",
+  });
+
+  const observations = observationLabels.map((label, index) =>
+    makeNode({
+      id: `${key}-obs-${index + 1}`,
+      label,
+      description: label,
+      kind: "observation",
+      status: "supported",
+      confidence: "high",
+    }),
+  );
+
+  const contradiction = contradictionLabel
+    ? [
+        makeNode({
+          id: `${key}-contradiction`,
+          label: contradictionLabel,
+          description: contradictionLabel,
+          kind: "relationship",
+          status: "supported",
+          confidence: "medium",
+        }),
+      ]
+    : [];
+
+  const unknowns = [
+    makeNode({
+      id: `${key}-unknown-a`,
+      label: "Possible explanation from one side of the situation.",
+      description: "Possible explanation from one side of the situation.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "high",
+    }),
+    makeNode({
+      id: `${key}-unknown-b`,
+      label: "Possible explanation from another side of the situation.",
+      description: "Possible explanation from another side of the situation.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "high",
+    }),
+  ];
+
+  const edges = [
+    ...observations.map((node) =>
+      makeEdge({
+        id: `${node.id}-supports-summary`,
+        fromNodeId: node.id,
+        toNodeId: summary.id,
+        relationship: "supports",
+        description: `${node.label} supports the summary.`,
+      }),
+    ),
+    ...unknowns.map((node) =>
+      makeEdge({
+        id: `${node.id}-depends-summary`,
+        fromNodeId: node.id,
+        toNodeId: summary.id,
+        relationship: "depends_on",
+        description: `${node.label} is an unresolved factor for this situation.`,
+      }),
+    ),
+  ];
+
+  return {
+    key,
+    scenario,
+    expectedComparabilityStatus,
+    expectsComparisonQuestion,
+    graph: makeGraph({
+      centralStatement: scenario,
+      nodes: [summary, ...observations, ...contradiction, ...unknowns],
+      edges,
+      activeUnknownNodeId: null,
+      resolvedNodeIds: [],
+      currentSummary: `Comparability fixture for ${key}`,
+    }),
+  };
+}
+
+export const comparabilityAssessmentFixtures = [
+  buildComparabilityFixture({
+    key: "revenue-cash",
+    scenario:
+      "Revenue increased by 18%, but cash in the bank fell over the same period.",
+    observationLabels: [
+      "Revenue increased by 18%.",
+      "Cash in the bank decreased over the same period.",
+    ],
+    contradictionLabel:
+      "Contradiction between revenue improvement and lower cash reserves.",
+    expectedComparabilityStatus: "uncertain",
+    expectsComparisonQuestion: true,
+  }),
+  buildComparabilityFixture({
+    key: "complaints-production",
+    scenario: "Complaints increased. Production increased.",
+    observationLabels: ["Complaints increased.", "Production increased."],
+    contradictionLabel:
+      "Possible contradiction between complaints and production movement.",
+    expectedComparabilityStatus: "uncertain",
+    expectsComparisonQuestion: true,
+  }),
+  buildComparabilityFixture({
+    key: "delivery-cancellations",
+    scenario:
+      "Average delivery time decreased by 25%, but order cancellations increased.",
+    observationLabels: [
+      "Average delivery time decreased by 25%.",
+      "Order cancellations increased.",
+    ],
+    contradictionLabel:
+      "Contradiction between faster delivery and more cancellations.",
+    expectedComparabilityStatus: "uncertain",
+    expectsComparisonQuestion: true,
+  }),
+  buildComparabilityFixture({
+    key: "satisfaction-complaints",
+    scenario: "Customer satisfaction increased, but complaints increased.",
+    observationLabels: [
+      "Customer satisfaction increased.",
+      "Complaints increased.",
+    ],
+    contradictionLabel:
+      "Contradiction between satisfaction improvement and more complaints.",
+    expectedComparabilityStatus: "uncertain",
+    expectsComparisonQuestion: true,
+  }),
+  buildComparabilityFixture({
+    key: "temperature-ice",
+    scenario: "Temperature increased. Ice melted.",
+    observationLabels: ["Temperature increased.", "Ice melted."],
+    contradictionLabel: null,
+    expectedComparabilityStatus: "confirmed",
+    expectsComparisonQuestion: false,
+  }),
+  buildComparabilityFixture({
+    key: "sales-same",
+    scenario: "Sales doubled. Sales doubled.",
+    observationLabels: ["Sales doubled.", "Sales doubled."],
+    contradictionLabel: null,
+    expectedComparabilityStatus: "confirmed",
+    expectsComparisonQuestion: false,
+  }),
+];

tests/fixtures/question-priority-generalisation.js

@@ -0,0 +1,445 @@
+import { makeEdge, makeGraph, makeNode } from "@/lib/graph/schema.js";
+
+function makeScenarioGraph({
+  scenario,
+  decisionNode,
+  answeredContextUnknown,
+  foundationalUnknown,
+  consequentialUnknown,
+  downstreamLeaf,
+}) {
+  const nodes = [
+    decisionNode,
+    answeredContextUnknown,
+    foundationalUnknown,
+    consequentialUnknown,
+    downstreamLeaf,
+  ];
+
+  const edges = [
+    makeEdge({
+      id: `${decisionNode.id}-to-${foundationalUnknown.id}`,
+      fromNodeId: decisionNode.id,
+      toNodeId: foundationalUnknown.id,
+      relationship: "depends_on",
+      description: `${decisionNode.label} depends on ${foundationalUnknown.label}.`,
+    }),
+    makeEdge({
+      id: `${answeredContextUnknown.id}-to-${consequentialUnknown.id}`,
+      fromNodeId: answeredContextUnknown.id,
+      toNodeId: consequentialUnknown.id,
+      relationship: "depends_on",
+      description: `${consequentialUnknown.label} was surfaced from resolved context.`,
+    }),
+    makeEdge({
+      id: `${foundationalUnknown.id}-to-${consequentialUnknown.id}`,
+      fromNodeId: foundationalUnknown.id,
+      toNodeId: consequentialUnknown.id,
+      relationship: "depends_on",
+      description: `${consequentialUnknown.label} depends on ${foundationalUnknown.label}.`,
+    }),
+    makeEdge({
+      id: `${consequentialUnknown.id}-to-${downstreamLeaf.id}`,
+      fromNodeId: consequentialUnknown.id,
+      toNodeId: downstreamLeaf.id,
+      relationship: "depends_on",
+      description: `${downstreamLeaf.label} depends on ${consequentialUnknown.label}.`,
+    }),
+  ];
+
+  return makeGraph({
+    centralStatement: scenario,
+    nodes,
+    edges,
+    activeUnknownNodeId: answeredContextUnknown.id,
+    resolvedNodeIds: [],
+    currentSummary: "Generalisation fixture graph",
+  });
+}
+
+export const questionPriorityGeneralisationFixtures = [
+  {
+    key: "hire-engineer",
+    scenario: "Should we hire another engineer?",
+    decisionType: "resourcing decision",
+    acceptableFoundationalUnknownNodeIds: [
+      "hire-success-criteria",
+      "hire-bottleneck",
+    ],
+    prohibitedFirstTopics: ["salary", "job advert", "programming language"],
+    acceptableQuestionStrategies: [
+      "decision_threshold",
+      "evidence_gathering",
+      "definition",
+    ],
+    notes:
+      "The first question should establish whether more engineering capacity is justified before compensation or implementation details.",
+    graph: makeScenarioGraph({
+      scenario: "Should we hire another engineer?",
+      decisionNode: makeNode({
+        id: "hire-decision",
+        label: "Hiring another engineer decision",
+        description: "Decision about increasing engineering capacity.",
+        kind: "state",
+        status: "known",
+        confidence: "medium",
+        value: "Deciding whether to hire another engineer",
+        childIds: ["hire-success-criteria"],
+      }),
+      answeredContextUnknown: makeNode({
+        id: "hire-delays-known",
+        label: "Delivery delays established",
+        description:
+          "Need to confirm whether recent delivery delays are real because this context determines whether a capacity decision is even relevant.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        value:
+          "The roadmap is slipping because the current team cannot clear the queue.",
+        childIds: ["hire-bottleneck"],
+      }),
+      foundationalUnknown: makeNode({
+        id: "hire-success-criteria",
+        label: "Hiring success threshold",
+        description:
+          "Need the success threshold because the hiring decision depends on what improvement would justify adding headcount.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        parentId: "hire-decision",
+        childIds: ["hire-bottleneck"],
+      }),
+      consequentialUnknown: makeNode({
+        id: "hire-bottleneck",
+        label: "Primary delivery bottleneck",
+        description:
+          "Need the main bottleneck because the team must know whether another engineer would relieve the limiting constraint.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        dependsOn: ["hire-success-criteria"],
+        parentId: "hire-success-criteria",
+        childIds: ["hire-salary"],
+      }),
+      downstreamLeaf: makeNode({
+        id: "hire-salary",
+        label: "Engineer salary budget",
+        description:
+          "Need the salary range because compensation planning comes after the hiring case is established.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "medium",
+        dependsOn: ["hire-bottleneck"],
+        parentId: "hire-bottleneck",
+      }),
+    }),
+  },
+  {
+    key: "replace-vans",
+    scenario: "Should we replace the delivery vans?",
+    decisionType: "asset replacement decision",
+    acceptableFoundationalUnknownNodeIds: [
+      "van-reliability-threshold",
+      "van-service-constraint",
+    ],
+    prohibitedFirstTopics: [
+      "purchase price",
+      "paint colour",
+      "finance provider",
+    ],
+    acceptableQuestionStrategies: [
+      "decision_threshold",
+      "evidence_gathering",
+      "definition",
+    ],
+    notes:
+      "The first question should establish whether the fleet is failing a threshold that justifies replacement.",
+    graph: makeScenarioGraph({
+      scenario: "Should we replace the delivery vans?",
+      decisionNode: makeNode({
+        id: "van-decision",
+        label: "Replace delivery vans decision",
+        description: "Decision about replacing the current delivery fleet.",
+        kind: "state",
+        status: "known",
+        confidence: "medium",
+        value: "Deciding whether to replace the delivery vans",
+        childIds: ["van-reliability-threshold"],
+      }),
+      answeredContextUnknown: makeNode({
+        id: "van-breakdowns-known",
+        label: "Breakdown trend confirmed",
+        description:
+          "Need to confirm whether the recent rise in breakdowns is real because that context determines whether fleet replacement is relevant.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        value:
+          "Breakdowns and missed deliveries have increased over the last quarter.",
+        childIds: ["van-service-constraint"],
+      }),
+      foundationalUnknown: makeNode({
+        id: "van-reliability-threshold",
+        label: "Replacement justification threshold",
+        description:
+          "Need the threshold because the replacement decision depends on what level of reliability loss is enough to justify replacing the fleet.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        parentId: "van-decision",
+        childIds: ["van-service-constraint"],
+      }),
+      consequentialUnknown: makeNode({
+        id: "van-service-constraint",
+        label: "Operational service constraint",
+        description:
+          "Need the limiting service constraint because the team must know how vehicle unreliability is affecting deliveries before comparing purchasing options.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        dependsOn: ["van-reliability-threshold"],
+        parentId: "van-reliability-threshold",
+        childIds: ["van-price"],
+      }),
+      downstreamLeaf: makeNode({
+        id: "van-price",
+        label: "Exact replacement purchase price",
+        description:
+          "Need the exact purchase price because financing analysis comes after replacement is justified.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "medium",
+        dependsOn: ["van-service-constraint"],
+        parentId: "van-service-constraint",
+      }),
+    }),
+  },
+  {
+    key: "launch-country",
+    scenario: "Should we launch in another country?",
+    decisionType: "market expansion decision",
+    acceptableFoundationalUnknownNodeIds: [
+      "country-customer",
+      "country-value-threshold",
+    ],
+    prohibitedFirstTopics: [
+      "launch date",
+      "office location",
+      "advertising channel",
+    ],
+    acceptableQuestionStrategies: ["definition", "decision_threshold"],
+    notes:
+      "The first question should clarify the customer or value case for expansion before rollout logistics.",
+    graph: makeScenarioGraph({
+      scenario: "Should we launch in another country?",
+      decisionNode: makeNode({
+        id: "country-decision",
+        label: "Launch in another country decision",
+        description: "Decision about entering a new national market.",
+        kind: "state",
+        status: "known",
+        confidence: "medium",
+        value: "Deciding whether to launch in another country",
+        childIds: ["country-customer"],
+      }),
+      answeredContextUnknown: makeNode({
+        id: "country-interest-known",
+        label: "Inbound interest confirmed",
+        description:
+          "Need to confirm whether inbound interest from another country is real because that context determines whether expansion is relevant.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "medium",
+        value:
+          "Prospective customers from another country are asking for access.",
+        childIds: ["country-value-threshold"],
+      }),
+      foundationalUnknown: makeNode({
+        id: "country-customer",
+        label: "Relevant customer in the new country",
+        description:
+          "Need the relevant customer because the expansion decision depends on who experiences the problem or receives the value in that market.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        parentId: "country-decision",
+        childIds: ["country-value-threshold"],
+      }),
+      consequentialUnknown: makeNode({
+        id: "country-value-threshold",
+        label: "Expansion value threshold",
+        description:
+          "Need the value threshold because the team must know what evidence of demand or value would justify entering the new country.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        dependsOn: ["country-customer"],
+        parentId: "country-customer",
+        childIds: ["country-launch-date"],
+      }),
+      downstreamLeaf: makeNode({
+        id: "country-launch-date",
+        label: "Country launch date",
+        description:
+          "Need the launch date because rollout planning follows once the expansion case is established.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "medium",
+        dependsOn: ["country-value-threshold"],
+        parentId: "country-value-threshold",
+      }),
+    }),
+  },
+  {
+    key: "over-budget-project",
+    scenario: "Should we continue a project that is over budget?",
+    decisionType: "continuation decision",
+    acceptableFoundationalUnknownNodeIds: [
+      "project-benefit-threshold",
+      "project-remaining-benefit",
+    ],
+    prohibitedFirstTopics: ["sunk cost", "project logo", "final launch date"],
+    acceptableQuestionStrategies: ["decision_threshold", "definition"],
+    notes:
+      "The first question should establish remaining value or success threshold before sunk-cost framing or launch timing.",
+    graph: makeScenarioGraph({
+      scenario: "Should we continue a project that is over budget?",
+      decisionNode: makeNode({
+        id: "project-decision",
+        label: "Continue over-budget project decision",
+        description:
+          "Decision about continuing a project that has exceeded budget.",
+        kind: "state",
+        status: "known",
+        confidence: "medium",
+        value: "Deciding whether to continue the over-budget project",
+        childIds: ["project-benefit-threshold"],
+      }),
+      answeredContextUnknown: makeNode({
+        id: "project-overrun-known",
+        label: "Budget overrun confirmed",
+        description:
+          "Need to confirm whether the project is materially over budget because that context determines whether a continuation decision is relevant.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        value: "The project has exceeded its approved budget by 35 percent.",
+        childIds: ["project-remaining-benefit"],
+      }),
+      foundationalUnknown: makeNode({
+        id: "project-benefit-threshold",
+        label: "Continuation success threshold",
+        description:
+          "Need the threshold because the continuation decision depends on what remaining benefit would still justify completing the project.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        parentId: "project-decision",
+        childIds: ["project-remaining-benefit"],
+      }),
+      consequentialUnknown: makeNode({
+        id: "project-remaining-benefit",
+        label: "Remaining project benefit",
+        description:
+          "Need the remaining benefit because the team must know what value is still achievable before deciding whether to continue.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        dependsOn: ["project-benefit-threshold"],
+        parentId: "project-benefit-threshold",
+        childIds: ["project-launch-date"],
+      }),
+      downstreamLeaf: makeNode({
+        id: "project-launch-date",
+        label: "Final launch date",
+        description:
+          "Need the final launch date because scheduling details only matter after remaining value is established.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "medium",
+        dependsOn: ["project-remaining-benefit"],
+        parentId: "project-remaining-benefit",
+      }),
+    }),
+  },
+  {
+    key: "paid-support-tier",
+    scenario: "Should we introduce a paid support tier?",
+    decisionType: "commercial packaging decision",
+    acceptableFoundationalUnknownNodeIds: [
+      "support-customer",
+      "support-value-threshold",
+    ],
+    prohibitedFirstTopics: [
+      "subscription price",
+      "payment provider",
+      "tier name",
+    ],
+    acceptableQuestionStrategies: [
+      "definition",
+      "decision_threshold",
+      "baseline_reconstruction",
+    ],
+    notes:
+      "The first question should establish who values paid support or what outcome would justify offering it before pricing details.",
+    graph: makeScenarioGraph({
+      scenario: "Should we introduce a paid support tier?",
+      decisionNode: makeNode({
+        id: "support-decision",
+        label: "Introduce paid support tier decision",
+        description: "Decision about adding a paid support offering.",
+        kind: "state",
+        status: "known",
+        confidence: "medium",
+        value: "Deciding whether to introduce a paid support tier",
+        childIds: ["support-customer"],
+      }),
+      answeredContextUnknown: makeNode({
+        id: "support-requests-known",
+        label: "Support request pattern confirmed",
+        description:
+          "Need to confirm whether repeated requests for faster support responses are real because that context determines whether a paid tier is relevant.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        value:
+          "Some users are asking for guaranteed response times and escalation help.",
+        childIds: ["support-value-threshold"],
+      }),
+      foundationalUnknown: makeNode({
+        id: "support-customer",
+        label: "Customer willing to pay for support",
+        description:
+          "Need the customer because the decision depends on who experiences enough support pain or receives enough value to pay for a support tier.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        parentId: "support-decision",
+        childIds: ["support-value-threshold"],
+      }),
+      consequentialUnknown: makeNode({
+        id: "support-value-threshold",
+        label: "Paid support value threshold",
+        description:
+          "Need the value threshold because the team must know what outcome would justify introducing paid support before setting packaging details.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "high",
+        dependsOn: ["support-customer"],
+        parentId: "support-customer",
+        childIds: ["support-price"],
+      }),
+      downstreamLeaf: makeNode({
+        id: "support-price",
+        label: "Support subscription price",
+        description:
+          "Need the subscription price because pricing and payment setup come after the support value case is established.",
+        kind: "unknown",
+        status: "unknown",
+        confidence: "medium",
+        dependsOn: ["support-value-threshold"],
+        parentId: "support-value-threshold",
+      }),
+    }),
+  },
+];

tests/graph/ambiguity-generalisation.test.js

@@ -0,0 +1,131 @@
+import { describe, expect, it } from "vitest";
+import {
+  formulateQuestion,
+  formulateTieResolutionQuestion,
+} from "@/lib/graph/question-formulator.js";
+import {
+  explainUnknownSelection,
+  selectActiveUnknownCandidate,
+} from "@/lib/graph/utils.js";
+import { ambiguityGeneralisationFixtures } from "@/tests/fixtures/ambiguity-generalisation.js";
+
+function neutraliseUnknownLabels(graph) {
+  let counter = 0;
+  return {
+    ...graph,
+    nodes: graph.nodes.map((node) => {
+      if (node.kind !== "unknown") return { ...node };
+      counter += 1;
+      return {
+        ...node,
+        label: `Unknown ${String.fromCharCode(64 + counter)}`,
+        description: `Unknown factor ${counter}.`,
+      };
+    }),
+  };
+}
+
+function isSingleQuestion(question) {
+  return (question.match(/\?/g) || []).length === 1;
+}
+
+describe("ambiguity generalisation", () => {
+  it("preserves ambiguity across contradiction scenarios without favouring one explanation", () => {
+    const summary = ambiguityGeneralisationFixtures.map((fixture) => {
+      const explanation = explainUnknownSelection(fixture.graph, []);
+      const selection = selectActiveUnknownCandidate(fixture.graph, []);
+      const neutralExplanation = explainUnknownSelection(
+        neutraliseUnknownLabels(fixture.graph),
+        [],
+      );
+      const tieQuestion = formulateTieResolutionQuestion({
+        graph: fixture.graph,
+      });
+      const representativeUnknown = fixture.graph.nodes.find(
+        (node) => node.kind === "unknown",
+      );
+      const fallbackQuestion = formulateQuestion({
+        node: representativeUnknown,
+        graph: fixture.graph,
+      });
+
+      const lowerQuestion = tieQuestion.question.toLowerCase();
+      for (const term of fixture.disallowedQuestionTerms) {
+        expect(lowerQuestion).not.toContain(term.toLowerCase());
+      }
+
+      expect(explanation.status).toBe("ambiguous");
+      expect(selection.status).toBe("ambiguous");
+      expect(selection.selectedNode).toBeNull();
+      expect(explanation.selectedNodeId).toBeNull();
+      expect(explanation.candidates).toHaveLength(2);
+      expect(explanation.summary.selectedReason).toBe(
+        "No justified distinction between leading unknowns.",
+      );
+      expect(explanation.alphabeticalUsedAsReasoning).toBe(false);
+      expect(neutralExplanation.status).toBe("ambiguous");
+      expect(isSingleQuestion(tieQuestion.question)).toBe(true);
+      expect(tieQuestion.question.toLowerCase()).not.toContain(" or ");
+
+      return {
+        scenario: fixture.scenario,
+        candidateCount: explanation.candidates.length,
+        ambiguityStatus: explanation.status,
+        tieReason: explanation.summary.selectedReason,
+        investigationStrategy: tieQuestion.strategy,
+        question: tieQuestion.question,
+        explanationFavoured: explanation.selectedNodeId !== null,
+      };
+    });
+
+    expect(summary).toMatchInlineSnapshot(`
+      [
+        {
+          "ambiguityStatus": "ambiguous",
+          "candidateCount": 2,
+          "explanationFavoured": false,
+          "investigationStrategy": null,
+          "question": "Were these figures measured on the same basis and at the same scale?",
+          "scenario": "Revenue increased by 18%, but cash in the bank fell over the same period.",
+          "tieReason": "No justified distinction between leading unknowns.",
+        },
+        {
+          "ambiguityStatus": "ambiguous",
+          "candidateCount": 2,
+          "explanationFavoured": false,
+          "investigationStrategy": null,
+          "question": "Were these figures measured over the same period and at the same scale?",
+          "scenario": "Customer satisfaction scores increased, but complaints also increased.",
+          "tieReason": "No justified distinction between leading unknowns.",
+        },
+        {
+          "ambiguityStatus": "ambiguous",
+          "candidateCount": 2,
+          "explanationFavoured": false,
+          "investigationStrategy": null,
+          "question": "Were these figures measured over the same period and at the same scale?",
+          "scenario": "Average delivery time decreased by 25%, but order cancellations increased.",
+          "tieReason": "No justified distinction between leading unknowns.",
+        },
+        {
+          "ambiguityStatus": "ambiguous",
+          "candidateCount": 2,
+          "explanationFavoured": false,
+          "investigationStrategy": null,
+          "question": "Were these figures measured over the same period and at the same scale?",
+          "scenario": "Website traffic doubled, but sales remained unchanged.",
+          "tieReason": "No justified distinction between leading unknowns.",
+        },
+        {
+          "ambiguityStatus": "ambiguous",
+          "candidateCount": 2,
+          "explanationFavoured": false,
+          "investigationStrategy": null,
+          "question": "Were these figures measured over the same period and at the same scale?",
+          "scenario": "Production output increased by 30%, but quality defects also increased.",
+          "tieReason": "No justified distinction between leading unknowns.",
+        },
+      ]
+    `);
+  });
+});

tests/graph/atomicity-assessment.test.js

@@ -0,0 +1,118 @@
+import { describe, expect, it } from "vitest";
+import { assessUnknownAtomicity } from "@/lib/graph/question-formulator.js";
+import { makeGraph, makeNode } from "@/lib/graph/schema.js";
+
+function makeGraphWithUnknown(centralStatement, unknown, observations = []) {
+  return makeGraph({
+    centralStatement,
+    nodes: [unknown, ...observations],
+    edges: [],
+    activeUnknownNodeId: unknown.id,
+    resolvedNodeIds: [],
+    currentSummary: "Atomicity test graph",
+  });
+}
+
+describe("assessUnknownAtomicity", () => {
+  it("classifies denominator-style unknowns as atomic", () => {
+    const unknown = makeNode({
+      id: "n-denominator",
+      label: "Complaint rate denominator",
+      description:
+        "Need the denominator because it directly determines the complaint rate.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "high",
+    });
+
+    const result = assessUnknownAtomicity({
+      node: unknown,
+      graph: makeGraphWithUnknown(
+        "Production increased while complaints increased.",
+        unknown,
+      ),
+    });
+
+    expect(result.atomicity).toBe("atomic");
+    expect(result.reason.toLowerCase()).toContain("directly");
+  });
+
+  it("classifies relationship explanation unknowns as composite", () => {
+    const unknown = makeNode({
+      id: "n-explanation",
+      label:
+        "Explanation for why revenue increased by 18%, but cash in the bank fell over the same period",
+      description:
+        "Need to understand what change or event could explain why these observations differ, because that is needed to investigate their relationship.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+    });
+
+    const graph = makeGraphWithUnknown(
+      "Revenue increased by 18%, but cash in the bank fell over the same period.",
+      unknown,
+      [
+        makeNode({
+          id: "n-revenue",
+          label: "Revenue increased by 18%.",
+          description: "Revenue increased by 18%.",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+        }),
+        makeNode({
+          id: "n-cash",
+          label: "Cash in the bank decreased over the same period.",
+          description: "Cash in the bank decreased over the same period.",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+        }),
+      ],
+    );
+
+    const result = assessUnknownAtomicity({ node: unknown, graph });
+
+    expect(result.atomicity).toBe("composite");
+    expect(result.decompositionKind).toBe("relationship_explanation");
+  });
+
+  it.each([
+    [
+      "Customer satisfaction rose, but complaints also rose.",
+      "Explanation for why customer satisfaction rose, but complaints also rose",
+    ],
+    [
+      "Delivery time fell, but cancellations increased.",
+      "Possible causes of why delivery time fell, but cancellations increased",
+    ],
+    [
+      "Traffic increased, but sales stayed flat.",
+      "Broad explanation for why traffic increased, but sales stayed flat",
+    ],
+    [
+      "Production increased, but defects also increased.",
+      "Factors behind why production increased, but defects also increased",
+    ],
+  ])(
+    "classifies broad divergence unknowns as composite: %s",
+    (scenario, label) => {
+      const unknown = makeNode({
+        id: `n-${label.length}`,
+        label,
+        description: `${label} because the current unknown is too broad to ask directly.`,
+        kind: "unknown",
+        status: "unknown",
+        confidence: "medium",
+      });
+
+      const result = assessUnknownAtomicity({
+        node: unknown,
+        graph: makeGraphWithUnknown(scenario, unknown),
+      });
+
+      expect(result.atomicity).toBe("composite");
+    },
+  );
+});

tests/graph/builder.test.js

@@ -0,0 +1,489 @@
+import { describe, it, expect } from "vitest";
+import {
+  buildInitialGraph,
+  buildMinimalGraph,
+  describeGraph,
+} from "@/lib/graph/builder.js";
+import {
+  makeNode,
+  situationEdgeSchema,
+  situationGraphSchema,
+  situationNodeSchema,
+} from "@/lib/graph/schema.js";
+
+// ── Helper: create a v0.3-style reconstruction fixture ───────────
+
+function makeReconstructionFixture() {
+  return {
+    summary: "Company X reports revenue growth but increasing complaints",
+    actors: [
+      { id: "actor-1", description: "Customer Base", confidence: "high" },
+      {
+        id: "actor-2",
+        description: "Product Engineering Team",
+        confidence: "high",
+      },
+    ],
+    systemsOrObjects: [
+      { id: "sys-1", description: "Production Line A", confidence: "high" },
+      {
+        id: "sys-2",
+        description: "Quality Control System",
+        confidence: "medium",
+      },
+    ],
+    expectedStates: [],
+    observedStates: [
+      {
+        id: "obs-1",
+        description: "Revenue up 15% year-over-year",
+        confidence: "high",
+      },
+      {
+        id: "obs-2",
+        description: "Customer complaints up 40% year-over-year",
+        confidence: "high",
+      },
+    ],
+    differences: [
+      {
+        id: "diff-1",
+        description: "Complaint count grew faster than revenue",
+        confidence: "medium",
+      },
+    ],
+    knownTransitions: [],
+    unexplainedTransitions: [],
+    contradictions: [
+      {
+        id: "con-1",
+        description: "Revenue growth vs complaint growth inconsistency",
+        confidence: "high",
+      },
+    ],
+    importantUnknowns: [
+      {
+        id: "unk-1",
+        description: "Denominator for complaint rate (customers served)",
+        confidence: "high",
+      },
+      {
+        id: "unk-2",
+        description: "Root cause of complaint increase",
+        confidence: "medium",
+      },
+    ],
+    plausibleInterpretations: [],
+  };
+}
+
+function makeEvidenceFixture() {
+  return [
+    {
+      id: "ev-1",
+      description: "Annual report data",
+      evidenceType: "direct_observation",
+      confidence: "high",
+      importance: "critical",
+    },
+    {
+      id: "ev-2",
+      description: "Customer survey results",
+      evidenceType: "reported_statement",
+      confidence: "medium",
+      importance: "important",
+    },
+  ];
+}
+
+describe("buildInitialGraph", () => {
+  it("builds nodes from reconstruction data", () => {
+    const result = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: makeEvidenceFixture(),
+    });
+
+    expect(result.nodes.length).toBeGreaterThan(0);
+    expect(result.edges.length).toBeGreaterThan(0);
+  });
+
+  it("creates a summary node", () => {
+    const result = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: [],
+    });
+
+    const summaryNode = result.nodes.find((n) => n.kind === "state");
+    expect(summaryNode).toBeDefined();
+    expect(summaryNode.label).toBe(
+      "Company X reports revenue growth but increasing complaints",
+    );
+  });
+
+  it("creates observation nodes from observedStates", () => {
+    const result = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: [],
+    });
+
+    const observations = result.nodes.filter((n) => n.kind === "observation");
+    expect(observations.length).toBeGreaterThan(0);
+  });
+
+  it("creates unknown nodes from importantUnknowns", () => {
+    const result = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: [],
+    });
+
+    const unknowns = result.nodes.filter((n) => n.kind === "unknown");
+    expect(unknowns.length).toBe(2); // unk-1 and unk-2
+  });
+
+  it("creates metric nodes from systemsOrObjects", () => {
+    const result = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: [],
+    });
+
+    const metrics = result.nodes.filter((n) => n.kind === "metric");
+    expect(metrics.length).toBe(2); // sys-1 and sys-2
+  });
+
+  it("creates actor nodes as observations", () => {
+    const result = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: [],
+    });
+
+    const actors = result.nodes.filter(
+      (n) =>
+        n.label.includes("Customer Base") ||
+        n.label.includes("Product Engineering"),
+    );
+    expect(actors.length).toBe(2);
+  });
+
+  it("creates difference nodes", () => {
+    const result = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: [],
+    });
+
+    const differenceNode = result.nodes.find((n) =>
+      n.label.includes("Complaint count grew faster than revenue"),
+    );
+
+    expect(differenceNode).toBeDefined();
+    expect(differenceNode.kind).toBe("relationship");
+  });
+
+  it("creates contradiction nodes", () => {
+    const result = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: [],
+    });
+
+    const contradictionNode = result.nodes.find((n) =>
+      n.label.includes("inconsistency"),
+    );
+
+    expect(contradictionNode).toBeDefined();
+    expect(contradictionNode.kind).toBe("relationship");
+  });
+
+  it("creates edges linking observations to summary", () => {
+    const result = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: [],
+    });
+
+    const supportEdges = result.edges.filter(
+      (e) => e.relationship === "supports",
+    );
+    expect(supportEdges.length).toBeGreaterThan(0);
+  });
+
+  it("creates edges linking unknowns to summary as depends_on", () => {
+    const result = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: [],
+    });
+
+    const depEdges = result.edges.filter(
+      (e) => e.relationship === "depends_on",
+    );
+    expect(depEdges.length).toBe(2); // Two unknown nodes
+  });
+
+  it("handles empty observedStates gracefully", () => {
+    const reconstruction = {
+      ...makeReconstructionFixture(),
+      observedStates: [],
+    };
+    const result = buildInitialGraph({ reconstruction, evidence: [] });
+
+    expect(result.nodes.length).toBeGreaterThan(0); // Summary + actors + systems still created
+  });
+
+  it("handles missing reconstruction fields gracefully", () => {
+    const result = buildInitialGraph({
+      reconstruction: { summary: "Minimal" },
+      evidence: [],
+    });
+
+    expect(result.nodes.length).toBeGreaterThan(0);
+  });
+
+  it("handles null/undefined reconstruction", () => {
+    const result = buildInitialGraph({ reconstruction: null, evidence: [] });
+    expect(result.nodes.length).toBe(0);
+    expect(result.edges.length).toBe(0);
+  });
+
+  it("handles missing evidence array", () => {
+    const result = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+    });
+
+    expect(result.nodes.length).toBeGreaterThan(0);
+    expect(result.edges.length).toBeGreaterThan(0);
+  });
+
+  it("generates deterministic node IDs for same labels", () => {
+    const r1 = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: [],
+    });
+    const r2 = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: [],
+    });
+
+    const ids1 = r1.nodes.map((n) => n.id).sort();
+    const ids2 = r2.nodes.map((n) => n.id).sort();
+    expect(ids1).toEqual(ids2);
+  });
+
+  it("produces valid schema output (no parse errors)", () => {
+    const result = buildInitialGraph({
+      reconstruction: makeReconstructionFixture(),
+      evidence: makeEvidenceFixture(),
+    });
+
+    for (const node of result.nodes) {
+      const parsed = situationNodeSchema.safeParse(node);
+      if (!parsed.success) {
+        console.error(`Invalid node: ${node.id}`, node, parsed.error.message);
+      }
+      expect(parsed.success).toBe(true);
+    }
+
+    for (const edge of result.edges) {
+      const parsed = situationEdgeSchema.safeParse(edge);
+      if (!parsed.success) {
+        console.error(`Invalid edge: ${edge.id}`, edge, parsed.error.message);
+      }
+      expect(parsed.success).toBe(true);
+    }
+  });
+
+  it("creates edges for knownTransitions as transition nodes", () => {
+    const reconstruction = {
+      ...makeReconstructionFixture(),
+      knownTransitions: [
+        {
+          id: "trans-1",
+          description: "Product shipped v2.0",
+          entity: "Product",
+          previousState: "v1.x",
+          currentState: "v2.0",
+          explanationStatus: "confirmed",
+          confidence: "high",
+        },
+      ],
+    };
+
+    const result = buildInitialGraph({ reconstruction, evidence: [] });
+    const transitions = result.nodes.filter((n) => n.kind === "transition");
+    expect(transitions.length).toBe(1);
+  });
+
+  it("creates nodes for unexplainedTransitions", () => {
+    const reconstruction = {
+      ...makeReconstructionFixture(),
+      unexplainedTransitions: [
+        {
+          id: "ut-1",
+          description: "Support wait time increased",
+          entity: "Support",
+          previousState: "2hr",
+          currentState: "8hr",
+          confidence: "medium",
+        },
+      ],
+    };
+
+    const result = buildInitialGraph({ reconstruction, evidence: [] });
+    expect(result.nodes.length).toBeGreaterThan(0);
+  });
+
+  it("creates nodes for plausibleInterpretations as assumptions", () => {
+    const reconstruction = {
+      ...makeReconstructionFixture(),
+      plausibleInterpretations: [
+        {
+          id: "interp-1",
+          description: "Quality degradation hypothesis",
+          supportingEvidenceIds: ["ev-2"],
+          assumptionsRequired: [],
+          confidence: "medium",
+        },
+      ],
+    };
+
+    const result = buildInitialGraph({ reconstruction, evidence: [] });
+    const assumptions = result.nodes.filter((n) => n.kind === "assumption");
+    expect(assumptions.length).toBe(1);
+  });
+
+  it("links evidence to observation nodes", () => {
+    const reconstruction = makeReconstructionFixture();
+    const evidence = [{ id: "ev-1", description: "Test evidence" }];
+
+    // Add a mapping from observed states to evidence IDs would require modification
+    // For now, just verify the nodes have empty evidenceIds (as per current implementation)
+    const result = buildInitialGraph({ reconstruction, evidence });
+    for (const node of result.nodes) {
+      expect(Array.isArray(node.evidenceIds)).toBe(true);
+    }
+  });
+
+  it("handles very large reconstruction without errors", () => {
+    const actors = Array.from({ length: 20 }, (_, i) => ({
+      id: `actor-${i}`,
+      description: `Actor ${i}`,
+      confidence: "high",
+    }));
+
+    const result = buildInitialGraph({
+      reconstruction: { ...makeReconstructionFixture(), actors },
+      evidence: [],
+    });
+
+    expect(result.nodes.length).toBeGreaterThan(10);
+  });
+
+  it("handles transition with confirmed explanation", () => {
+    const reconstruction = {
+      ...makeReconstructionFixture(),
+      knownTransitions: [
+        {
+          id: "t-confirmed",
+          description: "Confirmed event",
+          entity: "E1",
+          previousState: "s1",
+          currentState: "s2",
+          explanationStatus: "confirmed",
+          confidence: "high",
+        },
+      ],
+    };
+
+    const result = buildInitialGraph({ reconstruction, evidence: [] });
+    const confirmedTransitions = result.nodes.filter(
+      (n) => n.kind === "transition" && n.status === "known",
+    );
+    expect(confirmedTransitions.length).toBe(1);
+  });
+});
+
+describe("buildMinimalGraph", () => {
+  it("creates a single node with scenario text as label", () => {
+    const graph = buildMinimalGraph(
+      "This is a test scenario for minimal graph creation",
+    );
+    expect(graph.nodes.length).toBe(1);
+    expect(graph.edges.length).toBe(0);
+  });
+
+  it("truncates label to 80 chars", () => {
+    const longScenario = "a".repeat(200);
+    const graph = buildMinimalGraph(longScenario);
+    expect(graph.nodes[0].label.length).toBeLessThanOrEqual(80);
+  });
+
+  it("creates provisional state node", () => {
+    const graph = buildMinimalGraph("Test scenario");
+    expect(graph.nodes[0].kind).toBe("state");
+    expect(graph.nodes[0].status).toBe("provisional");
+    expect(graph.nodes[0].confidence).toBe("low");
+  });
+
+  it("uses first 200 chars of scenario for description", () => {
+    const graph = buildMinimalGraph(
+      "This is a test scenario for minimal graph creation",
+    );
+    expect(graph.nodes[0].description).toContain("Initial situation from:");
+  });
+
+  it("creates deterministic ID via situationNodeSchema.parse", () => {
+    const graph = buildMinimalGraph("Test scenario");
+    // Node has explicit id "n0" from the builder, not makeNodeId
+    expect(graph.nodes[0].id).toBe("n0");
+  });
+
+  it("creates minimal valid structure", () => {
+    const graph = buildMinimalGraph("Test");
+    expect(graph.nodes).toHaveLength(1);
+    expect(graph.edges).toHaveLength(0);
+    expect(graph.nodes[0].evidenceIds).toEqual([]);
+    expect(graph.nodes[0].dependsOn).toEqual([]);
+    expect(graph.nodes[0].affects).toEqual([]);
+  });
+});
+
+describe("describeGraph", () => {
+  it("returns summary string with node count by kind", () => {
+    const graph = buildMinimalGraph("Test");
+    const description = describeGraph(graph);
+
+    expect(description).toContain("Nodes:");
+    expect(description).toContain("Edges:");
+    expect(description).toContain("Unknowns:");
+  });
+
+  it("shows correct edge count", () => {
+    const graph = buildMinimalGraph("Test");
+    const description = describeGraph(graph);
+
+    expect(description).toContain("Edges: 0 total");
+  });
+
+  it("counts unresolved unknowns", () => {
+    const n1 = makeNode({
+      id: "n-unk",
+      label: "Unknown",
+      kind: "unknown",
+      status: "unknown",
+    });
+    const graph = situationGraphSchema.parse({
+      centralStatement: "Test",
+      nodes: [n1],
+      edges: [],
+      activeUnknownNodeId: n1.id,
+      resolvedNodeIds: [],
+      currentSummary: "Test",
+    });
+
+    const description = describeGraph(graph);
+    expect(description).toContain("1"); // One unresolved unknown
+  });
+
+  it("groups nodes by kind in output", () => {
+    const graph = buildMinimalGraph("Test");
+    const description = describeGraph(graph);
+
+    expect(description).toContain("1 state");
+  });
+});

tests/graph/comparability-assessment.test.js

@@ -0,0 +1,180 @@
+import { describe, expect, it } from "vitest";
+import {
+  assessComparability,
+  classifyObservationRelationship,
+  formulateTieResolutionQuestion,
+} from "@/lib/graph/question-formulator.js";
+import { explainUnknownSelection } from "@/lib/graph/utils.js";
+import { comparabilityAssessmentFixtures } from "@/tests/fixtures/comparability-assessment.js";
+
+describe("comparability assessment", () => {
+  it("generates comparison or relationship questions only when warranted", () => {
+    const summary = comparabilityAssessmentFixtures.map((fixture) => {
+      const assessment = assessComparability(fixture.graph);
+      const relationship = classifyObservationRelationship(fixture.graph);
+      const question = formulateTieResolutionQuestion({ graph: fixture.graph });
+      const ambiguity = explainUnknownSelection(fixture.graph, []);
+
+      expect(assessment.comparabilityStatus).toBe(
+        fixture.expectedComparabilityStatus,
+      );
+      expect(question.comparabilityStatus).toBe(
+        fixture.expectedComparabilityStatus,
+      );
+
+      if (fixture.expectsComparisonQuestion) {
+        expect(question.question.toLowerCase()).toContain("same");
+        expect(question.contradictionReasoningAllowed).toBe(false);
+      } else {
+        expect(question.question?.toLowerCase() || "").not.toContain(
+          "same period and at the same scale",
+        );
+      }
+
+      if (fixture.key !== "sales-same") {
+        expect(ambiguity.status).toBe("ambiguous");
+      }
+
+      return {
+        scenario: fixture.scenario,
+        comparabilityStatus: assessment.comparabilityStatus,
+        relationshipStatus: relationship.relationshipStatus,
+        relationshipAssessed: relationship.relationshipAssessed,
+        contradictionReasoningAllowed: question.contradictionReasoningAllowed,
+        question: question.question,
+      };
+    });
+
+    expect(summary).toEqual([
+      {
+        scenario:
+          "Revenue increased by 18%, but cash in the bank fell over the same period.",
+        comparabilityStatus: "uncertain",
+        relationshipStatus: "insufficient_information",
+        relationshipAssessed: false,
+        contradictionReasoningAllowed: false,
+        question:
+          "Were these figures measured on the same basis and at the same scale?",
+      },
+      {
+        scenario: "Complaints increased. Production increased.",
+        comparabilityStatus: "uncertain",
+        relationshipStatus: "insufficient_information",
+        relationshipAssessed: false,
+        contradictionReasoningAllowed: false,
+        question:
+          "Were these figures measured over the same period and at the same scale?",
+      },
+      {
+        scenario:
+          "Average delivery time decreased by 25%, but order cancellations increased.",
+        comparabilityStatus: "uncertain",
+        relationshipStatus: "insufficient_information",
+        relationshipAssessed: false,
+        contradictionReasoningAllowed: false,
+        question:
+          "Were these figures measured over the same period and at the same scale?",
+      },
+      {
+        scenario: "Customer satisfaction increased, but complaints increased.",
+        comparabilityStatus: "uncertain",
+        relationshipStatus: "insufficient_information",
+        relationshipAssessed: false,
+        contradictionReasoningAllowed: false,
+        question:
+          "Were these figures measured over the same period and at the same scale?",
+      },
+      {
+        scenario: "Temperature increased. Ice melted.",
+        comparabilityStatus: "confirmed",
+        relationshipStatus: "compatible",
+        relationshipAssessed: true,
+        contradictionReasoningAllowed: false,
+        question: null,
+      },
+      {
+        scenario: "Sales doubled. Sales doubled.",
+        comparabilityStatus: "confirmed",
+        relationshipStatus: "duplicate",
+        relationshipAssessed: true,
+        contradictionReasoningAllowed: false,
+        question: null,
+      },
+    ]);
+  });
+
+  it("defers relationship classification while comparability is uncertain", () => {
+    const fixture = comparabilityAssessmentFixtures[0];
+    const relationship = classifyObservationRelationship(fixture.graph);
+
+    expect(relationship).toMatchObject({
+      relationshipStatus: "insufficient_information",
+      relationshipAssessed: false,
+      contradictionReasoningAllowed: false,
+      questionRequired: true,
+    });
+    expect(relationship.reasoningStages).toEqual([
+      {
+        stage: "comparability",
+        status: "uncertain",
+        outcome:
+          "Comparability between the observations is not yet established across period, scale, or measurement basis.",
+      },
+      {
+        stage: "relationship",
+        status: "insufficient_information",
+        outcome: "not assessed until comparability is established",
+      },
+    ]);
+  });
+
+  it("allows contradiction reasoning only for genuine contradictions", () => {
+    const serviceGraph = {
+      centralStatement:
+        "The service was reported as available throughout the hour and unavailable throughout the same hour.",
+      nodes: [
+        {
+          id: "service-available",
+          label: "The service was available throughout the hour.",
+          description: "The service was available throughout the hour.",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+          value: null,
+          unit: null,
+          evidenceIds: [],
+          dependsOn: [],
+          affects: [],
+          parentId: null,
+          childIds: [],
+        },
+        {
+          id: "service-unavailable",
+          label: "The service was unavailable throughout the same hour.",
+          description: "The service was unavailable throughout the same hour.",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+          value: null,
+          unit: null,
+          evidenceIds: [],
+          dependsOn: [],
+          affects: [],
+          parentId: null,
+          childIds: [],
+        },
+      ],
+      edges: [],
+      activeUnknownNodeId: null,
+      resolvedNodeIds: [],
+      currentSummary: "Service contradiction fixture",
+    };
+    const relationship = classifyObservationRelationship(serviceGraph);
+
+    expect(relationship).toMatchObject({
+      relationshipStatus: "contradictory",
+      contradictionReasoningAllowed: true,
+      questionRequired: true,
+    });
+  });
+});

tests/graph/confidence-propagation.test.js

@@ -0,0 +1,179 @@
+import { describe, expect, it } from "vitest";
+import { applyValidatedProposal } from "@/lib/graph/apply-proposal.js";
+import { makeEdge, makeGraph, makeNode } from "@/lib/graph/schema.js";
+
+function makeFixture() {
+  const parent = makeNode({
+    id: "n-parent",
+    label: "Explanation for why revenue increased while cash fell",
+    description:
+      "Need to understand what change or event could explain why these observations differ, because that is needed to investigate their relationship.",
+    kind: "unknown",
+    status: "unknown",
+    confidence: "medium",
+  });
+  const children = [
+    makeNode({
+      id: "n-child-1",
+      label: "How the two observations were measured",
+      description: "Need evidence about the measure used for each observation.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+      parentId: parent.id,
+    }),
+    makeNode({
+      id: "n-child-2",
+      label: "Whether the two observations reflect different timing",
+      description:
+        "Need to know whether the two observations reflect different timing.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+      parentId: parent.id,
+    }),
+    makeNode({
+      id: "n-child-3",
+      label: "Possible change mainly affecting revenue",
+      description:
+        "Need to know whether a possible change mainly affected revenue.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+      parentId: parent.id,
+    }),
+    makeNode({
+      id: "n-child-4",
+      label: "Possible one-off event during the period",
+      description:
+        "Need to know whether a possible one-off event happened during the period.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+      parentId: parent.id,
+    }),
+  ];
+
+  return makeGraph({
+    centralStatement: "Revenue increased while cash fell.",
+    nodes: [parent, ...children],
+    edges: children.map((child, index) =>
+      makeEdge({
+        id: `e-${index + 1}`,
+        fromNodeId: child.id,
+        toNodeId: parent.id,
+        relationship: "depends_on",
+        description: `${child.label} feeds the parent.`,
+      }),
+    ),
+    activeUnknownNodeId: "n-child-1",
+    resolvedNodeIds: [],
+    currentSummary: "confidence propagation fixture",
+  });
+}
+
+function makeProposal({ resolvedIds, contradictedIds = [] }) {
+  return {
+    addedNodes: [
+      makeNode({
+        id: "n-anchor",
+        label: "Update anchor",
+        description:
+          "Anchor state introduced by the answer because the update must contain a meaningful change.",
+        kind: "state",
+        status: "known",
+        confidence: "low",
+      }),
+    ],
+    updatedNodes: [
+      ...resolvedIds.map((id) => ({
+        nodeId: id,
+        previousStatus: "unknown",
+        newStatus: "resolved",
+        previousValue: null,
+        newValue: `answer:${id}`,
+        reason: "resolved child",
+      })),
+      ...contradictedIds.map((id) => ({
+        nodeId: id,
+        previousStatus: "unknown",
+        newStatus: "contradicted",
+        previousValue: null,
+        newValue: `contradiction:${id}`,
+        reason: "contradictory child evidence",
+      })),
+    ],
+    addedEdges: [],
+    removedEdgeIds: [],
+    resolvedUnknownNodeIds: resolvedIds,
+    affectedNodeIds: [],
+    selectedQuestion: null,
+  };
+}
+
+describe("confidence propagation", () => {
+  it("one of four children resolved does not yield high conclusion confidence", () => {
+    const result = applyValidatedProposal({
+      situationGraph: makeFixture(),
+      proposal: makeProposal({ resolvedIds: ["n-child-1"] }),
+      previousQuestion:
+        "What evidence would clarify how the two observations were measured?",
+      answer: "Same accounting period and same management accounts.",
+    });
+
+    const parent = result.updatedSituationGraph.nodes.find(
+      (n) => n.id === "n-parent",
+    );
+    expect(parent.status).toBe("provisional");
+    expect(parent.confidence).toBe("medium");
+    expect(parent.confidenceAssessment).toEqual({
+      evidenceConfidence: "medium",
+      completenessStatus: "partial",
+      conclusionConfidence: "medium",
+    });
+    expect(result.confidenceCapReason).toBe(
+      "unresolved_direct_children_cap_conclusion",
+    );
+  });
+
+  it("all children resolved with coherent evidence may yield high confidence", () => {
+    const result = applyValidatedProposal({
+      situationGraph: makeFixture(),
+      proposal: makeProposal({
+        resolvedIds: ["n-child-1", "n-child-2", "n-child-3", "n-child-4"],
+      }),
+      previousQuestion:
+        "What evidence would clarify how the two observations were measured?",
+      answer: "All direct child questions are answered.",
+    });
+
+    const parent = result.updatedSituationGraph.nodes.find(
+      (n) => n.id === "n-parent",
+    );
+    expect(parent.status).toBe("resolved");
+    expect(parent.confidenceAssessment).toEqual({
+      evidenceConfidence: "high",
+      completenessStatus: "complete",
+      conclusionConfidence: "high",
+    });
+  });
+
+  it("contradictory child evidence prevents high confidence", () => {
+    const result = applyValidatedProposal({
+      situationGraph: makeFixture(),
+      proposal: makeProposal({
+        resolvedIds: ["n-child-1"],
+        contradictedIds: ["n-child-2"],
+      }),
+      previousQuestion:
+        "What evidence would clarify how the two observations were measured?",
+      answer: "One child resolved, another contradicted.",
+    });
+
+    const parent = result.updatedSituationGraph.nodes.find(
+      (n) => n.id === "n-parent",
+    );
+    expect(parent.confidenceAssessment.conclusionConfidence).toBe("low");
+    expect(result.confidenceCapReason).toBe("contradictory_direct_children");
+  });
+});

tests/graph/cross-branch-corroboration.test.js

@@ -0,0 +1,306 @@
+import { describe, expect, it } from "vitest";
+import {
+  applyValidatedProposal,
+  evaluateBranchInteractions,
+} from "@/lib/graph/apply-proposal.js";
+import { makeEdge, makeGraph, makeNode } from "@/lib/graph/schema.js";
+
+function makeParentWithBranches(children) {
+  const parent = makeNode({
+    id: "n-parent",
+    label: "Explanation for why revenue increased while cash fell",
+    description:
+      "Need to understand what change or event could explain why these observations differ, because that is needed to investigate their relationship.",
+    kind: "unknown",
+    status: "unknown",
+    confidence: "medium",
+  });
+
+  return makeGraph({
+    centralStatement: "Revenue increased while cash fell.",
+    nodes: [
+      parent,
+      ...children.map((child) => ({ ...child, parentId: parent.id })),
+    ],
+    edges: children.map((child, index) =>
+      makeEdge({
+        id: `e-${index + 1}`,
+        fromNodeId: child.id,
+        toNodeId: parent.id,
+        relationship: "depends_on",
+        description: `${child.label} feeds the parent.`,
+      }),
+    ),
+    activeUnknownNodeId: children[0]?.id ?? null,
+    resolvedNodeIds: [],
+    currentSummary: "cross-branch corroboration fixture",
+  });
+}
+
+function makeResolvedChild(id, label, value, extra = {}) {
+  return makeNode({
+    id,
+    label,
+    description: label,
+    kind: "unknown",
+    status: "resolved",
+    confidence: "medium",
+    value,
+    evidenceIds: extra.evidenceIds ?? [],
+  });
+}
+
+function makeUnknownBranch(id, label, description, extra = {}) {
+  return makeNode({
+    id,
+    label,
+    description,
+    kind: "unknown",
+    status: extra.status ?? "unknown",
+    confidence: extra.confidence ?? "medium",
+    evidenceIds: extra.evidenceIds ?? [],
+    value: extra.value ?? null,
+  });
+}
+
+describe("evaluateBranchInteractions", () => {
+  it("detects corroborating independent branches", () => {
+    const graph = makeParentWithBranches([
+      makeResolvedChild("n-a", "Debtor balance increased", "bank-statement-a", {
+        evidenceIds: ["bank-statement-a"],
+      }),
+      makeResolvedChild(
+        "n-b",
+        "Cash receipts were delayed",
+        "receipts-ledger-b",
+        { evidenceIds: ["receipts-ledger-b"] },
+      ),
+    ]);
+    const parentNode = graph.nodes.find((node) => node.id === "n-parent");
+
+    const result = evaluateBranchInteractions({ parentNode, graph });
+
+    expect(result.interactionSummary.corroboratingBranchCount).toBe(1);
+    expect(result.interactionSummary.duplicateEvidenceCount).toBe(0);
+    expect(result.interactionSummary.conflictingBranchCount).toBe(0);
+  });
+
+  it("detects duplicate evidence instead of corroboration", () => {
+    const graph = makeParentWithBranches([
+      makeResolvedChild(
+        "n-a",
+        "Bank statement shows increased debtor balance",
+        "same-bank",
+        {
+          evidenceIds: ["same-bank"],
+        },
+      ),
+      makeResolvedChild(
+        "n-b",
+        "Delayed receipts also cite the bank statement",
+        "same-bank",
+        {
+          evidenceIds: ["same-bank"],
+        },
+      ),
+    ]);
+    const parentNode = graph.nodes.find((node) => node.id === "n-parent");
+
+    const result = evaluateBranchInteractions({ parentNode, graph });
+
+    expect(result.interactionSummary.duplicateEvidenceCount).toBe(1);
+    expect(result.interactionSummary.corroboratingBranchCount).toBe(0);
+  });
+
+  it("detects conflicting branches", () => {
+    const graph = makeParentWithBranches([
+      makeResolvedChild("n-a", "Revenue recognised correctly", "correctly"),
+      makeNode({
+        id: "n-b",
+        label: "Revenue recognised incorrectly",
+        description: "Revenue recognised incorrectly",
+        kind: "unknown",
+        status: "contradicted",
+        confidence: "medium",
+        value: "incorrectly",
+      }),
+    ]);
+    const parentNode = graph.nodes.find((node) => node.id === "n-parent");
+
+    const result = evaluateBranchInteractions({ parentNode, graph });
+
+    expect(result.interactionSummary.conflictingBranchCount).toBe(1);
+  });
+});
+
+describe("cross-branch corroboration effects", () => {
+  function applyToGraph(children, resolvedIds, contradictedIds = []) {
+    const graph = makeParentWithBranches(children);
+    return applyValidatedProposal({
+      situationGraph: graph,
+      proposal: {
+        addedNodes: [
+          makeNode({
+            id: "n-anchor",
+            label: "Update anchor",
+            description:
+              "Anchor state introduced by the answer because the update must contain a meaningful change.",
+            kind: "state",
+            status: "known",
+            confidence: "low",
+          }),
+        ],
+        updatedNodes: [
+          ...resolvedIds.map((id) => ({
+            nodeId: id,
+            previousStatus: "unknown",
+            newStatus: "resolved",
+            previousValue: null,
+            newValue: `answer:${id}`,
+            reason: "resolved child",
+          })),
+          ...contradictedIds.map((id) => ({
+            nodeId: id,
+            previousStatus: "unknown",
+            newStatus: "contradicted",
+            previousValue: null,
+            newValue: `contradiction:${id}`,
+            reason: "contradicted child",
+          })),
+        ],
+        addedEdges: [],
+        removedEdgeIds: [],
+        resolvedUnknownNodeIds: resolvedIds,
+        affectedNodeIds: [],
+        selectedQuestion: null,
+      },
+      previousQuestion: "What evidence would clarify this branch?",
+      answer: "deterministic branch update",
+    });
+  }
+
+  it("independent corroboration increases justified confidence without reaching high on incomplete parent", () => {
+    const result = applyToGraph(
+      [
+        makeUnknownBranch(
+          "n-a",
+          "Debtor balance increased",
+          "Debtor balance increased",
+        ),
+        makeUnknownBranch(
+          "n-b",
+          "Cash receipts delayed",
+          "Cash receipts delayed",
+        ),
+        makeUnknownBranch(
+          "n-c",
+          "Possible one-off event during the period",
+          "Possible one-off event during the period",
+        ),
+        makeUnknownBranch(
+          "n-d",
+          "Whether the two observations reflect different timing",
+          "Whether the two observations reflect different timing",
+        ),
+      ],
+      ["n-a", "n-b"],
+    );
+
+    expect(result.success).toBe(true);
+    expect(result.interactionSummary?.corroboratingBranchCount).toBeGreaterThan(
+      0,
+    );
+    expect(result.interactionSummary?.duplicateEvidenceCount).toBe(0);
+    expect(result.parentConfidenceAfter).toBe("medium");
+    expect(result.confidenceCapReason).toBe(
+      "independent_corroboration_with_incomplete_parent",
+    );
+  });
+
+  it("duplicate evidence does not increase confidence", () => {
+    const result = applyToGraph(
+      [
+        makeUnknownBranch(
+          "n-a",
+          "Bank statement shows increased debtor balance",
+          "Bank statement shows increased debtor balance",
+          { evidenceIds: ["same-bank"] },
+        ),
+        makeUnknownBranch(
+          "n-b",
+          "Delayed receipts also cite the bank statement",
+          "Delayed receipts also cite the bank statement",
+          { evidenceIds: ["same-bank"] },
+        ),
+        makeUnknownBranch(
+          "n-c",
+          "Possible one-off event during the period",
+          "Possible one-off event during the period",
+        ),
+      ],
+      ["n-a", "n-b"],
+    );
+
+    expect(result.success).toBe(true);
+    expect(result.interactionSummary?.duplicateEvidenceCount).toBeGreaterThan(
+      0,
+    );
+    expect(result.interactionSummary?.corroboratingBranchCount).toBe(0);
+    expect(result.confidenceCapReason).toBe(
+      "duplicate_evidence_no_extra_confidence",
+    );
+  });
+
+  it("conflicting evidence caps confidence", () => {
+    const result = applyToGraph(
+      [
+        makeUnknownBranch(
+          "n-a",
+          "Revenue recognised correctly",
+          "Revenue recognised correctly",
+        ),
+        makeUnknownBranch(
+          "n-b",
+          "Revenue recognised incorrectly",
+          "Revenue recognised incorrectly",
+        ),
+        makeUnknownBranch(
+          "n-c",
+          "Possible one-off event during the period",
+          "Possible one-off event during the period",
+        ),
+      ],
+      ["n-a"],
+      ["n-b"],
+    );
+
+    expect(result.success).toBe(true);
+    expect(result.interactionSummary?.conflictingBranchCount).toBeGreaterThan(
+      0,
+    );
+    expect(result.conclusionConfidenceAfter).toBe("low");
+  });
+
+  it("independent branches stay interaction-neutral", () => {
+    const result = applyToGraph(
+      [
+        makeUnknownBranch(
+          "n-a",
+          "Marketing campaign changed traffic",
+          "Marketing campaign changed traffic",
+        ),
+        makeUnknownBranch(
+          "n-b",
+          "Equipment maintenance occurred",
+          "Equipment maintenance occurred",
+        ),
+      ],
+      ["n-a"],
+    );
+
+    expect(result.success).toBe(true);
+    expect(result.interactionSummary?.independentBranchCount).toBeGreaterThan(
+      0,
+    );
+  });
+});

tests/graph/decomposition-quality.test.js

@@ -0,0 +1,278 @@
+import { describe, expect, it } from "vitest";
+import {
+  assessChildUnknownQuality,
+  applyValidatedProposal,
+  MAX_DECOMPOSITION_DEPTH,
+} from "@/lib/graph/apply-proposal.js";
+import { makeGraph, makeNode } from "@/lib/graph/schema.js";
+
+function makeParentGraph({
+  centralStatement,
+  parentLabel,
+  parentDescription,
+  observations = [],
+}) {
+  const parent = makeNode({
+    id: "n-parent",
+    label: parentLabel,
+    description: parentDescription,
+    kind: "unknown",
+    status: "unknown",
+    confidence: "medium",
+  });
+
+  return {
+    parent,
+    graph: makeGraph({
+      centralStatement,
+      nodes: [parent, ...observations],
+      edges: [],
+      activeUnknownNodeId: parent.id,
+      resolvedNodeIds: [],
+      currentSummary: "Decomposition quality graph",
+    }),
+  };
+}
+
+describe("assessChildUnknownQuality", () => {
+  it("rejects 'Timing or measurement basis' as compound", () => {
+    const { parent, graph } = makeParentGraph({
+      centralStatement:
+        "Revenue increased by 18%, but cash in the bank fell over the same period.",
+      parentLabel:
+        "Explanation for why revenue increased by 18%, but cash in the bank fell over the same period",
+      parentDescription:
+        "Need to understand what change or event could explain why these observations differ, because that is needed to investigate their relationship.",
+    });
+    const child = makeNode({
+      id: "n-child",
+      label: "Timing or measurement basis",
+      description:
+        "Need evidence about whether a timing or measurement-basis difference could explain the observations, because that would change how they should be interpreted.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+      parentId: parent.id,
+    });
+
+    const result = assessChildUnknownQuality({
+      parentNode: parent,
+      childNode: child,
+      siblingNodes: [child],
+      graph,
+    });
+
+    expect(result.valid).toBe(false);
+    expect(result.compoundSignals).toContain("timing_or_measurement_basis");
+    expect(result.reasons).toContain("compound_child");
+  });
+
+  it("accepts a child with one directly answerable uncertainty", () => {
+    const { parent, graph } = makeParentGraph({
+      centralStatement: "Traffic increased, but sales stayed flat.",
+      parentLabel:
+        "What explains why more website traffic did not produce more sales?",
+      parentDescription:
+        "Need an explanation because the observations moved differently.",
+    });
+    const child = makeNode({
+      id: "n-child",
+      label: "Different measurement basis between the two observations",
+      description:
+        "Need evidence about whether the two observations use different measurement bases, because that could help explain the difference.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+      parentId: parent.id,
+    });
+
+    const result = assessChildUnknownQuality({
+      parentNode: parent,
+      childNode: child,
+      siblingNodes: [child],
+      graph,
+    });
+
+    expect(result.valid).toBe(true);
+    expect(result.atomic).toBe(true);
+    expect(result.directlyAnswerable).toBe(true);
+    expect(result.narrowerThanParent).toBe(true);
+  });
+
+  it("rejects sibling duplicates", () => {
+    const { parent, graph } = makeParentGraph({
+      centralStatement: "Production increased, but defects also increased.",
+      parentLabel: "What explains why output and defects both increased?",
+      parentDescription:
+        "Need an explanation because both observations increased.",
+    });
+    const childA = makeNode({
+      id: "n-child-a",
+      label: "Different timing between the two observations",
+      description:
+        "Need evidence about whether the two observations reflect different timing, because that could help explain the difference.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+      parentId: parent.id,
+    });
+    const childB = makeNode({
+      id: "n-child-b",
+      label: "Different timing between the two observations",
+      description:
+        "Need evidence about whether the two observations reflect different timing, because that could help explain the difference.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+      parentId: parent.id,
+    });
+
+    const result = assessChildUnknownQuality({
+      parentNode: parent,
+      childNode: childA,
+      siblingNodes: [childA, childB],
+      graph,
+    });
+
+    expect(result.valid).toBe(false);
+    expect(result.duplicateSiblingIds).toContain("n-child-b");
+  });
+
+  it("rejects parent paraphrases", () => {
+    const { parent, graph } = makeParentGraph({
+      centralStatement:
+        "Customer satisfaction scores increased, but complaints also increased.",
+      parentLabel:
+        "What explains why satisfaction and complaints both increased?",
+      parentDescription:
+        "Need a broad explanation because the observations moved differently.",
+    });
+    const child = makeNode({
+      id: "n-child",
+      label: "What explains why satisfaction and complaints both increased?",
+      description:
+        "Need a broad explanation because the observations moved differently.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+      parentId: parent.id,
+    });
+
+    const result = assessChildUnknownQuality({
+      parentNode: parent,
+      childNode: child,
+      siblingNodes: [child],
+      graph,
+    });
+
+    expect(result.valid).toBe(false);
+    expect(result.reasons).toContain("not_narrower_than_parent");
+  });
+});
+
+describe("decomposition stopping conditions", () => {
+  function makeMeaningfulNoOpProposal() {
+    return {
+      addedNodes: [
+        makeNode({
+          id: "n-anchor",
+          label: "Update anchor",
+          description:
+            "Anchor state introduced by the answer because the update must contain a meaningful change.",
+          kind: "state",
+          status: "known",
+          confidence: "low",
+        }),
+      ],
+      updatedNodes: [],
+      addedEdges: [],
+      removedEdgeIds: [],
+      resolvedUnknownNodeIds: [],
+      affectedNodeIds: [],
+      selectedQuestion: null,
+    };
+  }
+
+  it("does not decompose an atomic selected unknown", () => {
+    const atomic = makeNode({
+      id: "n-atomic",
+      label: "Were both figures measured over the same accounting period?",
+      description:
+        "Need to know whether both figures cover the same accounting period because that determines whether they are directly comparable.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "high",
+    });
+    const graph = makeGraph({
+      centralStatement:
+        "Revenue increased by 18%, but cash in the bank fell over the same period.",
+      nodes: [atomic],
+      edges: [],
+      activeUnknownNodeId: atomic.id,
+      resolvedNodeIds: [],
+      currentSummary: "Atomic selected node graph",
+    });
+
+    const result = applyValidatedProposal({
+      situationGraph: graph,
+      proposal: makeMeaningfulNoOpProposal(),
+    });
+
+    expect(result.success).toBe(true);
+    expect(result.decompositionAttempted).toBe(false);
+    expect(result.decompositionStoppedReason).toBe(
+      "Selected unknown is already atomic.",
+    );
+  });
+
+  it("stops once a directly answerable child is selected", () => {
+    const { parent, graph } = makeParentGraph({
+      centralStatement: "Traffic increased, but sales stayed flat.",
+      parentLabel:
+        "What explains why more website traffic did not produce more sales?",
+      parentDescription:
+        "Need an explanation because the observations moved differently.",
+      observations: [
+        makeNode({
+          id: "n-traffic",
+          label: "Website traffic increased.",
+          description: "Website traffic increased.",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+        }),
+        makeNode({
+          id: "n-sales",
+          label: "Sales stayed flat.",
+          description: "Sales stayed flat.",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+        }),
+      ],
+    });
+
+    const result = applyValidatedProposal({
+      situationGraph: graph,
+      proposal: makeMeaningfulNoOpProposal(),
+    });
+
+    expect(result.success).toBe(true);
+    expect(result.decompositionAttempted).toBe(true);
+    expect(result.decompositionAccepted).toBe(true);
+    expect(result.selectedQuestion).toMatchObject({
+      nodeId: expect.any(String),
+      question:
+        "What evidence would clarify how the two observations were measured?",
+    });
+    expect(result.selectedChildNodeId).toBe(result.selectedQuestion?.nodeId);
+    expect(result.decompositionStoppedReason).toBe(
+      "Selected child is atomic and directly answerable.",
+    );
+  });
+
+  it("exposes the configured maximum decomposition depth", () => {
+    expect(MAX_DECOMPOSITION_DEPTH).toBeGreaterThanOrEqual(2);
+    expect(MAX_DECOMPOSITION_DEPTH).toBeLessThanOrEqual(3);
+  });
+});

tests/graph/prompt-builder.test.js

@@ -0,0 +1,114 @@
+import { describe, expect, it } from "vitest";
+import { buildGraphUpdatePrompt } from "@/lib/graph/prompt-builder.js";
+import { makeEdge, makeGraph, makeNode } from "@/lib/graph/schema.js";
+
+function makeContext() {
+  const unknown = makeNode({
+    id: "n-unknown",
+    label: "Complaint rate denominator",
+    description: "Need the denominator to compare complaint rates",
+    kind: "unknown",
+    status: "unknown",
+    confidence: "high",
+  });
+  const observation = makeNode({
+    id: "n-obs",
+    label: "Complaints up 35%",
+    description: "Complaints increased by 35%",
+    kind: "observation",
+    status: "supported",
+    confidence: "high",
+  });
+
+  return {
+    situationGraph: makeGraph({
+      centralStatement: "Complaints increased while production increased.",
+      nodes: [unknown, observation],
+      edges: [
+        makeEdge({
+          id: "e1",
+          fromNodeId: observation.id,
+          toNodeId: unknown.id,
+          relationship: "supports",
+          confidence: "high",
+          description: "Observation informs the unknown",
+        }),
+      ],
+      activeUnknownNodeId: unknown.id,
+      resolvedNodeIds: [],
+      currentSummary:
+        "Nodes: 1 observation, 1 unknown | Edges: 1 total | Unknowns: 1 unresolved",
+    }),
+    previousQuestion: "What denominator is being used for the complaint rate?",
+    answer:
+      "The complaint rate fell from 2.0 complaints per 100 units to 1.9 complaints per 100 units.",
+  };
+}
+
+describe("buildGraphUpdatePrompt", () => {
+  it("includes the current graph", () => {
+    const prompt = buildGraphUpdatePrompt(makeContext());
+    expect(prompt).toContain(
+      "Complaints increased while production increased.",
+    );
+    expect(prompt).toContain("Complaint rate denominator");
+  });
+
+  it("includes previous question and answer", () => {
+    const prompt = buildGraphUpdatePrompt(makeContext());
+    expect(prompt).toContain(
+      "What denominator is being used for the complaint rate?",
+    );
+    expect(prompt).toContain(
+      "The complaint rate fell from 2.0 complaints per 100 units to 1.9 complaints per 100 units.",
+    );
+  });
+
+  it("contains exact schema keys", () => {
+    const prompt = buildGraphUpdatePrompt(makeContext());
+    expect(prompt).toContain("addedNodes");
+    expect(prompt).toContain("updatedNodes");
+    expect(prompt).toContain("addedEdges");
+    expect(prompt).toContain("removedEdgeIds");
+    expect(prompt).toContain("resolvedUnknownNodeIds");
+    expect(prompt).toContain("affectedNodeIds");
+    expect(prompt).toContain("selectedQuestion");
+  });
+
+  it("lists enum values", () => {
+    const prompt = buildGraphUpdatePrompt(makeContext());
+    expect(prompt).toContain(
+      "observation | reported_claim | metric | state | transition | relationship | assumption | unknown | conclusion",
+    );
+    expect(prompt).toContain(
+      "known | unknown | provisional | supported | weakened | contradicted | resolved",
+    );
+    expect(prompt).toContain(
+      "supports | weakens | contradicts | depends_on | causes | may_cause | measures | compares_with | updates | other",
+    );
+  });
+
+  it("forbids full-graph replacement", () => {
+    const prompt = buildGraphUpdatePrompt(makeContext());
+    expect(prompt).toContain("Never return a replacement graph");
+    expect(prompt).toContain("Propose changes only");
+  });
+
+  it("requires JSON only", () => {
+    const prompt = buildGraphUpdatePrompt(makeContext());
+    expect(prompt).toContain("Return JSON only");
+    expect(prompt).toContain("Return one JSON object only");
+  });
+
+  it("describes controlled emergent unknown rules", () => {
+    const prompt = buildGraphUpdatePrompt(makeContext());
+    expect(prompt).toContain("Add at most 3 new unknown nodes");
+    expect(prompt).toContain("Resolve the answered unknown first");
+    expect(prompt).toContain(
+      "selectedQuestion.question must be one narrow non-compound question",
+    );
+    expect(prompt).toContain(
+      "the engine will deterministically choose final priority after validation",
+    );
+  });
+});

tests/graph/question-formulator.test.js

@@ -0,0 +1,474 @@
+import { describe, expect, it } from "vitest";
+import {
+  assessUnknownAtomicity,
+  formulateQuestion,
+  formulateTieResolutionQuestion,
+  selectInvestigationStrategy,
+} from "@/lib/graph/question-formulator.js";
+import { makeEdge, makeGraph, makeNode } from "@/lib/graph/schema.js";
+
+function makeGraphFor(node, extra = {}) {
+  return makeGraph({
+    centralStatement: extra.centralStatement || "Decision context",
+    nodes: [node, ...(extra.nodes || [])],
+    edges: extra.edges || [],
+    activeUnknownNodeId: node.id,
+    resolvedNodeIds: extra.resolvedNodeIds || [],
+    currentSummary: "Test summary",
+  });
+}
+
+describe("formulateQuestion", () => {
+  it("atomicity assessment leaves focused unknowns direct and marks broad explanation unknowns composite", () => {
+    const atomicUnknown = makeNode({
+      id: "n-atomic",
+      label: "Complaint rate denominator",
+      description:
+        "Need the denominator because it directly determines the complaint rate.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "high",
+    });
+    const compositeUnknown = makeNode({
+      id: "n-composite",
+      label:
+        "Explanation for why revenue increased by 18%, but cash in the bank fell over the same period",
+      description:
+        "Need to understand what change or event could explain why these observations differ, because that is needed to investigate their relationship.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+    });
+    const compositeGraph = makeGraphFor(compositeUnknown, {
+      centralStatement:
+        "Revenue increased by 18%, but cash in the bank fell over the same period.",
+      nodes: [
+        makeNode({
+          id: "n-revenue-observation",
+          label: "Revenue increased by 18%.",
+          description: "Revenue increased by 18%.",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+        }),
+        makeNode({
+          id: "n-cash-observation",
+          label: "Cash in the bank decreased over the same period.",
+          description: "Cash in the bank decreased over the same period.",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+        }),
+      ],
+    });
+
+    expect(
+      assessUnknownAtomicity({
+        node: atomicUnknown,
+        graph: makeGraphFor(atomicUnknown),
+      }).atomicity,
+    ).toBe("atomic");
+    expect(
+      assessUnknownAtomicity({
+        node: compositeUnknown,
+        graph: compositeGraph,
+      }).atomicity,
+    ).toBe("composite");
+  });
+
+  it("commercial viability plus build decision produces a decision-threshold question", () => {
+    const unknown = makeNode({
+      id: "n-commercial",
+      label: "Uncertainty regarding the commercial value of the product",
+      description:
+        "Commercial justification remains unclear because the decision depends on it.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "high",
+      parentId: "n-decision",
+    });
+    const decision = makeNode({
+      id: "n-decision",
+      label: "Build decision",
+      description: "Decision introduced by the answer.",
+      kind: "state",
+      status: "known",
+      confidence: "medium",
+      childIds: [unknown.id],
+      value: "Deciding whether to build the product",
+    });
+    const graph = makeGraphFor(unknown, {
+      nodes: [decision],
+      resolvedNodeIds: [decision.id],
+    });
+
+    const result = formulateQuestion({ node: unknown, graph });
+
+    expect(result.strategy).toBe("decision_threshold");
+    expect(result.question).toContain("What outcome");
+    expect(result.question.toLowerCase()).toContain("justify");
+  });
+
+  it("commercial viability does not produce a pricing-first question", () => {
+    const unknown = makeNode({
+      id: "n-commercial",
+      label: "Commercial viability",
+      description:
+        "Commercial viability remains unresolved because the decision depends on it.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "high",
+    });
+    const graph = makeGraphFor(unknown);
+
+    const result = formulateQuestion({ node: unknown, graph });
+
+    expect(result.question.toLowerCase()).not.toContain("price");
+    expect(result.question.toLowerCase()).not.toContain("pricing");
+  });
+
+  it("undefined term produces a definition question", () => {
+    const unknown = makeNode({
+      id: "n-term",
+      label: "Success criteria definition",
+      description:
+        "Need a definition of the term because the team uses it inconsistently.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+    });
+
+    const result = formulateQuestion({
+      node: unknown,
+      graph: makeGraphFor(unknown),
+    });
+
+    expect(result.strategy).toBe("definition");
+    expect(result.question).toMatch(/^What does /);
+  });
+
+  it("unsupported claim produces an evidence question", () => {
+    const unknown = makeNode({
+      id: "n-claim",
+      label: "Demand claim",
+      description: "Need evidence because the claim has not been validated.",
+      kind: "reported_claim",
+      status: "provisional",
+      confidence: "low",
+    });
+
+    const result = formulateQuestion({
+      node: unknown,
+      graph: makeGraphFor(unknown),
+    });
+
+    expect(result.strategy).toBe("evidence_gathering");
+    expect(result.question).toContain("What evidence");
+  });
+
+  it("missing previous state produces a baseline question", () => {
+    const unknown = makeNode({
+      id: "n-baseline",
+      label: "Baseline conversion rate",
+      description:
+        "Need the previous baseline because the change cannot be assessed without it.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+    });
+
+    const result = formulateQuestion({
+      node: unknown,
+      graph: makeGraphFor(unknown),
+    });
+
+    expect(result.strategy).toBe("baseline_reconstruction");
+    expect(result.question).toContain("What was the comparable state before");
+  });
+
+  it("conflicting claim produces a contradiction-resolution question", () => {
+    const unknown = makeNode({
+      id: "n-conflict",
+      label: "Conflicting churn claim",
+      description:
+        "Need to resolve the inconsistency because the current figures contradict each other.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+    });
+
+    const contradiction = makeNode({
+      id: "n-contradiction",
+      label: "Contradicted report",
+      description: "Two sources disagree about churn.",
+      kind: "conclusion",
+      status: "contradicted",
+      confidence: "low",
+      childIds: [unknown.id],
+    });
+
+    const result = formulateQuestion({
+      node: unknown,
+      graph: makeGraphFor(unknown, { nodes: [contradiction] }),
+    });
+
+    expect(result.strategy).toBe("contradiction_resolution");
+    expect(result.question).toContain("resolve the contradiction");
+  });
+
+  it("constraint unknown uses evidence-gathering within the fixed strategy set", () => {
+    const unknown = makeNode({
+      id: "n-constraint",
+      label: "Budget constraint",
+      description:
+        "Need the main budget constraint because it limits the available options.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+    });
+
+    const result = formulateQuestion({
+      node: unknown,
+      graph: makeGraphFor(unknown),
+    });
+
+    expect(result.strategy).toBe("evidence_gathering");
+    expect(result.question).toContain("What evidence");
+  });
+
+  it("the same unknown can produce different questions when paired with different strategies", () => {
+    const thresholdUnknown = makeNode({
+      id: "n-threshold-unknown",
+      label: "Value threshold",
+      description: "Need to resolve the value threshold.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "high",
+    });
+    const definitionUnknown = makeNode({
+      id: "n-definition-unknown",
+      label: "Value term",
+      description: "Need to resolve what value term refers to in this context.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "high",
+    });
+
+    const decisionGraph = makeGraphFor(thresholdUnknown, {
+      centralStatement: "We are deciding whether to launch this product.",
+      nodes: [
+        makeNode({
+          id: "n-decision",
+          label: "Launch decision",
+          description: "Decision depends on the value threshold.",
+          kind: "state",
+          status: "known",
+          confidence: "medium",
+          childIds: [thresholdUnknown.id],
+          value: "Deciding whether to launch the product",
+        }),
+      ],
+    });
+
+    const definitionGraph = makeGraphFor(definitionUnknown, {
+      centralStatement:
+        "The team uses the term value threshold inconsistently.",
+      nodes: [
+        makeNode({
+          id: "n-definition",
+          label: "Definition disagreement about value threshold",
+          description:
+            "Need a definition of value threshold because the term is used inconsistently before comparing options.",
+          kind: "state",
+          status: "known",
+          confidence: "medium",
+          childIds: [definitionUnknown.id],
+        }),
+      ],
+    });
+
+    const decisionResult = formulateQuestion({
+      node: thresholdUnknown,
+      graph: decisionGraph,
+    });
+    const definitionResult = formulateQuestion({
+      node: definitionUnknown,
+      graph: definitionGraph,
+    });
+
+    expect(decisionResult.strategy).toBe("decision_threshold");
+    expect(definitionResult.strategy).toBe("definition");
+    expect(decisionResult.question).not.toBe(definitionResult.question);
+  });
+
+  it("strategy selection is deterministic and explainable", () => {
+    const unknown = makeNode({
+      id: "n-threshold",
+      label: "Success threshold",
+      description:
+        "Need the success threshold because the decision depends on it.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "high",
+    });
+    const graph = makeGraphFor(unknown, {
+      centralStatement: "We need to decide whether to continue investing.",
+    });
+
+    const first = selectInvestigationStrategy({ node: unknown, graph });
+    const second = selectInvestigationStrategy({ node: unknown, graph });
+
+    expect(first).toEqual(second);
+    expect(first.key).toBe("decision_threshold");
+    expect(first.reason).toContain("threshold");
+  });
+
+  it("question is singular and answerable", () => {
+    const unknown = makeNode({
+      id: "n-evidence",
+      label: "Evidence of demand",
+      description:
+        "Need evidence of demand because the decision depends on it.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+    });
+
+    const result = formulateQuestion({
+      node: unknown,
+      graph: makeGraphFor(unknown),
+    });
+
+    expect(result.question.match(/\?/g) || []).toHaveLength(1);
+    expect(result.question.toLowerCase()).not.toContain(" and ");
+  });
+
+  it("awkward uncertainty phrasing is rejected via fallback", () => {
+    const unknown = makeNode({
+      id: "n-weird",
+      label: "Uncertainty regarding service reliability",
+      description: "Unknown service reliability.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+    });
+
+    const result = formulateQuestion({
+      node: unknown,
+      graph: makeGraphFor(unknown),
+    });
+
+    expect(result.question).not.toContain("How should uncertainty regarding");
+    expect(result.question).not.toContain(
+      "What would resolve uncertainty regarding",
+    );
+  });
+
+  it("ambiguous contradiction produces a broad distinguishing question without accounting jargon", () => {
+    const unknown = makeNode({
+      id: "n-cause-a",
+      label: "Cash outflow cause",
+      description: "Unclear explanation for the contradiction.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "high",
+    });
+    const contradiction = makeNode({
+      id: "n-contradiction",
+      label: "Divergent movement between revenue and cash",
+      description: "Two signals moved in opposite directions.",
+      kind: "relationship",
+      status: "supported",
+      confidence: "medium",
+    });
+    const revenueObservation = makeNode({
+      id: "n-revenue-observation",
+      label: "Revenue increased by 18%.",
+      description: "Revenue increased by 18%.",
+      kind: "observation",
+      status: "supported",
+      confidence: "high",
+    });
+    const cashObservation = makeNode({
+      id: "n-cash-observation",
+      label: "Cash in the bank decreased over the same period.",
+      description: "Cash in the bank decreased over the same period.",
+      kind: "observation",
+      status: "supported",
+      confidence: "high",
+    });
+    const graph = makeGraphFor(unknown, {
+      centralStatement:
+        "Revenue increased by 18%, but cash in the bank fell over the same period.",
+      nodes: [contradiction, revenueObservation, cashObservation],
+    });
+
+    const result = formulateTieResolutionQuestion({ graph });
+
+    expect(result.question).toBe(
+      "Were these figures measured on the same basis and at the same scale?",
+    );
+    expect(result.comparabilityStatus).toBe("uncertain");
+    expect(result.question.toLowerCase()).not.toMatch(
+      /accounts receivable|capex|debt repayments|working capital/,
+    );
+  });
+
+  it("definition is selected only for genuine definition unknowns", () => {
+    const unknown = makeNode({
+      id: "n-definition-only",
+      label: "Definition of success criteria",
+      description: "The term is used inconsistently and needs a definition.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+    });
+
+    const result = formulateQuestion({
+      node: unknown,
+      graph: makeGraphFor(unknown),
+    });
+    expect(result.strategy).toBe("definition");
+  });
+
+  it("an unknown about possible causes does not become a definition question", () => {
+    const unknown = makeNode({
+      id: "n-causes",
+      label: "Possible causes of the divergence",
+      description: "Several causes may explain the divergence.",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+    });
+
+    const result = formulateQuestion({
+      node: unknown,
+      graph: makeGraphFor(unknown),
+    });
+    expect(result.strategy).toBeNull();
+    expect(result.question).toBe(
+      "What would clarify possible causes of the divergence in this situation?",
+    );
+  });
+
+  it("malformed punctuation is rejected", () => {
+    const unknown = makeNode({
+      id: "n-punct",
+      label: "Magnitude and nature of cash outflows (operating expenses).",
+      description:
+        "Magnitude and nature of cash outflows (operating expenses).",
+      kind: "unknown",
+      status: "unknown",
+      confidence: "medium",
+    });
+
+    const result = formulateQuestion({
+      node: unknown,
+      graph: makeGraphFor(unknown),
+    });
+    expect(result.question).not.toContain("). is true?");
+    expect(result.question).toBe(
+      "What would clarify magnitude and nature of cash outflows (operating expenses) in this situation?",
+    );
+  });
+});

tests/graph/question-priority-generalisation.test.js

@@ -0,0 +1,155 @@
+import { describe, expect, it } from "vitest";
+import { applyValidatedProposal } from "@/lib/graph/apply-proposal.js";
+import { formulateQuestion } from "@/lib/graph/question-formulator.js";
+import { selectActiveUnknownCandidate } from "@/lib/graph/utils.js";
+import { questionPriorityGeneralisationFixtures } from "@/tests/fixtures/question-priority-generalisation.js";
+
+function clone(value) {
+  return JSON.parse(JSON.stringify(value));
+}
+
+function buildResolutionProposal(graph) {
+  const activeNode = graph.nodes.find(
+    (node) => node.id === graph.activeUnknownNodeId,
+  );
+  const placeholderCandidate = graph.nodes.find(
+    (node) => node.kind === "unknown" && node.id !== activeNode.id,
+  );
+
+  return {
+    addedNodes: [],
+    updatedNodes: [
+      {
+        nodeId: activeNode.id,
+        previousStatus: activeNode.status,
+        newStatus: "resolved",
+        previousValue: activeNode.value ?? null,
+        newValue: activeNode.value ?? "Resolved context answer",
+        reason:
+          "The resolved context unknown is treated as answered for fixture progression.",
+      },
+    ],
+    addedEdges: [],
+    removedEdgeIds: [],
+    resolvedUnknownNodeIds: [activeNode.id],
+    affectedNodeIds: [],
+    selectedQuestion: {
+      nodeId: placeholderCandidate?.id,
+      question: "Placeholder candidate question?",
+      reason: "Candidate only; deterministic selector should override it.",
+    },
+  };
+}
+
+function assertQuestionStructure(question) {
+  expect(question.match(/\?/g) || []).toHaveLength(1);
+  expect(question).not.toMatch(/\?\s*(and|or)\b/i);
+  expect(question).not.toMatch(/^What is\s+/i);
+  expect(question).toMatch(/^(What|Who|When)\b/);
+}
+
+describe("question priority generalisation", () => {
+  for (const fixture of questionPriorityGeneralisationFixtures) {
+    it(`${fixture.scenario} selects a foundational unknown and singular answerable strategy`, () => {
+      const originalGraph = clone(fixture.graph);
+      const deterministicSelection = selectActiveUnknownCandidate(
+        fixture.graph,
+        [fixture.graph.activeUnknownNodeId],
+      );
+
+      const result = applyValidatedProposal({
+        situationGraph: fixture.graph,
+        proposal: buildResolutionProposal(fixture.graph),
+      });
+
+      expect(result.success).toBe(true);
+      expect(fixture.graph).toEqual(originalGraph);
+      expect(result.graphUpdate.selectedQuestion?.question).toBe(
+        "Placeholder candidate question?",
+      );
+
+      expect(deterministicSelection.nodeId).toBe(
+        result.selectedQuestion.nodeId,
+      );
+      expect(fixture.acceptableFoundationalUnknownNodeIds).toContain(
+        result.selectedQuestion.nodeId,
+      );
+      expect(result.selectedQuestion.nodeId).not.toBe(
+        fixture.graph.nodes[fixture.graph.nodes.length - 1].id,
+      );
+
+      expect(fixture.acceptableQuestionStrategies).toContain(
+        result.selectedQuestion.strategy,
+      );
+      assertQuestionStructure(result.selectedQuestion.question);
+
+      const lowerQuestion = result.selectedQuestion.question.toLowerCase();
+      for (const topic of fixture.prohibitedFirstTopics) {
+        expect(lowerQuestion).not.toContain(topic.toLowerCase());
+      }
+
+      const selectedNode = result.updatedSituationGraph.nodes.find(
+        (node) => node.id === result.selectedQuestion.nodeId,
+      );
+      const reformulated = formulateQuestion({
+        node: selectedNode,
+        graph: result.updatedSituationGraph,
+        context: {
+          resolvedValues: ["Resolved context answer"],
+        },
+      });
+
+      expect(reformulated.question).toBe(result.selectedQuestion.question);
+      expect(clone(result.updatedSituationGraph)).toEqual(
+        result.updatedSituationGraph,
+      );
+    });
+  }
+
+  it("reports all five selected unknowns and strategies", () => {
+    const summary = questionPriorityGeneralisationFixtures.map((fixture) => {
+      const result = applyValidatedProposal({
+        situationGraph: fixture.graph,
+        proposal: buildResolutionProposal(fixture.graph),
+      });
+
+      expect(result.success).toBe(true);
+
+      return {
+        scenario: fixture.scenario,
+        nodeId: result.selectedQuestion.nodeId,
+        strategy: result.selectedQuestion.strategy,
+      };
+    });
+
+    expect(summary).toMatchInlineSnapshot(`
+      [
+        {
+          "nodeId": "hire-success-criteria",
+          "scenario": "Should we hire another engineer?",
+          "strategy": "decision_threshold",
+        },
+        {
+          "nodeId": "van-reliability-threshold",
+          "scenario": "Should we replace the delivery vans?",
+          "strategy": "decision_threshold",
+        },
+        {
+          "nodeId": "country-value-threshold",
+          "scenario": "Should we launch in another country?",
+          "strategy": "decision_threshold",
+        },
+        {
+          "nodeId": "project-benefit-threshold",
+          "scenario": "Should we continue a project that is over budget?",
+          "strategy": "decision_threshold",
+        },
+        {
+          "nodeId": "support-value-threshold",
+          "scenario": "Should we introduce a paid support tier?",
+          "strategy": "baseline_reconstruction",
+        },
+      ]
+    `);
+  });
+});

tests/graph/schema.test.js

@@ -0,0 +1,442 @@
+import { describe, it, expect } from "vitest";
+import {
+  SituationKind,
+  SituationStatus,
+  ConfidenceLevel,
+  SituationRelationship,
+  situationNodeSchema,
+  situationEdgeSchema,
+  situationGraphSchema,
+  graphUpdateSchema,
+  startCaseRequestSchema,
+  updateCaseRequestSchema,
+  makeNodeId,
+  makeNode,
+  makeEdge,
+  makeGraph,
+} from "@/lib/graph/schema.js";
+
+describe("situationNodeSchema", () => {
+  const validNode = {
+    id: "n1",
+    label: "Test Node",
+    description: "A test node",
+    kind: "observation",
+    status: "known",
+    confidence: "high",
+    value: null,
+    unit: null,
+    evidenceIds: [],
+    dependsOn: [],
+    affects: [],
+    parentId: null,
+    childIds: [],
+  };
+
+  it("validates a complete valid node", () => {
+    const result = situationNodeSchema.safeParse(validNode);
+    expect(result.success).toBe(true);
+  });
+
+  it("requires id", () => {
+    const invalid = { ...validNode, id: "" };
+    const result = situationNodeSchema.safeParse(invalid);
+    expect(result.success).toBe(false);
+  });
+
+  it("requires label", () => {
+    const invalid = { ...validNode, label: "" };
+    const result = situationNodeSchema.safeParse(invalid);
+    expect(result.success).toBe(false);
+  });
+
+  it("rejects invalid kind", () => {
+    const invalid = { ...validNode, kind: "nonexistent" };
+    const result = situationNodeSchema.safeParse(invalid);
+    expect(result.success).toBe(false);
+  });
+
+  it("rejects invalid status", () => {
+    const invalid = { ...validNode, status: "unknown_status" };
+    const result = situationNodeSchema.safeParse(invalid);
+    expect(result.success).toBe(false);
+  });
+
+  it("rejects invalid confidence", () => {
+    const invalid = { ...validNode, confidence: "extreme" };
+    const result = situationNodeSchema.safeParse(invalid);
+    expect(result.success).toBe(false);
+  });
+
+  it("allows numeric value", () => {
+    const node = { ...validNode, value: 42 };
+    const result = situationNodeSchema.safeParse(node);
+    expect(result.success).toBe(true);
+  });
+
+  it("allows string value", () => {
+    const node = { ...validNode, value: "active" };
+    const result = situationNodeSchema.safeParse(node);
+    expect(result.success).toBe(true);
+  });
+});
+
+describe("situationEdgeSchema", () => {
+  const validEdge = {
+    id: "e1",
+    fromNodeId: "n1",
+    toNodeId: "n2",
+    relationship: "supports",
+    confidence: "medium",
+    description: "Edge between nodes",
+  };
+
+  it("validates a complete valid edge", () => {
+    const result = situationEdgeSchema.safeParse(validEdge);
+    expect(result.success).toBe(true);
+  });
+
+  it("rejects invalid relationship type", () => {
+    const invalid = { ...validEdge, relationship: "invalid_rel" };
+    const result = situationEdgeSchema.safeParse(invalid);
+    expect(result.success).toBe(false);
+  });
+
+  it("validates all relationship types", () => {
+    for (const rel of Object.values(SituationRelationship)) {
+      const edge = { ...validEdge, relationship: rel };
+      const result = situationEdgeSchema.safeParse(edge);
+      expect(result.success).toBe(true);
+    }
+  });
+
+  it("rejects self-referencing edges", () => {
+    // Self-refs are structurally valid but semantically questionable
+    const edge = { ...validEdge, fromNodeId: "n1", toNodeId: "n1" };
+    const result = situationEdgeSchema.safeParse(edge);
+    expect(result.success).toBe(true); // Structure is valid; semantics checked elsewhere
+  });
+});
+
+describe("situationGraphSchema", () => {
+  const validGraph = {
+    centralStatement: "Test graph summary",
+    nodes: [makeNode({ id: "n1", label: "Node 1" })],
+    edges: [],
+    activeUnknownNodeId: null,
+    resolvedNodeIds: [],
+    currentSummary: "Initial summary",
+  };
+
+  it("validates a complete valid graph", () => {
+    const result = situationGraphSchema.safeParse(validGraph);
+    expect(result.success).toBe(true);
+  });
+
+  it("requires at least one node", () => {
+    const invalid = { ...validGraph, nodes: [] };
+    const result = situationGraphSchema.safeParse(invalid);
+    expect(result.success).toBe(false);
+  });
+
+  it("allows empty edges array", () => {
+    const graph = { ...validGraph, edges: [] };
+    const result = situationGraphSchema.safeParse(graph);
+    expect(result.success).toBe(true);
+  });
+
+  it("rejects missing centralStatement", () => {
+    const invalid = { ...validGraph, centralStatement: "" };
+    const result = situationGraphSchema.safeParse(invalid);
+    expect(result.success).toBe(false);
+  });
+});
+
+describe("graphUpdateSchema", () => {
+  it("validates empty update (no-op proposal)", () => {
+    const result = graphUpdateSchema.safeParse({});
+    expect(result.success).toBe(true);
+  });
+
+  it("validates a complete update", () => {
+    const node = makeNode({ id: "n2", label: "New Node" });
+    const edge = makeEdge({ fromNodeId: "n1", toNodeId: "n2" });
+
+    const result = graphUpdateSchema.safeParse({
+      addedNodes: [node],
+      updatedNodes: [
+        {
+          nodeId: "n1",
+          newStatus: "resolved",
+          previousStatus: "unknown",
+          reason: "Question answered",
+        },
+      ],
+      addedEdges: [edge],
+      removedEdgeIds: ["e-old"],
+      resolvedUnknownNodeIds: ["n2"],
+      affectedNodeIds: ["n3"],
+      selectedQuestion: {
+        nodeId: "n2",
+        question: "What does this new node mean?",
+        reason: "A follow-up unknown remains.",
+      },
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it("allows null selectedQuestion", () => {
+    const result = graphUpdateSchema.safeParse({
+      selectedQuestion: null,
+    });
+    expect(result.success).toBe(true);
+  });
+
+  it("rejects update with invalid node kind in addedNodes", () => {
+    const invalid = graphUpdateSchema.safeParse({
+      addedNodes: [
+        {
+          id: "x",
+          label: "Test",
+          kind: "invalid_kind",
+          description: "test",
+          status: "unknown",
+          confidence: "medium",
+          value: null,
+          unit: null,
+          evidenceIds: [],
+          dependsOn: [],
+          affects: [],
+          parentId: null,
+          childIds: [],
+        },
+      ],
+    });
+    expect(invalid.success).toBe(false);
+  });
+});
+
+describe("API request schemas", () => {
+  describe("startCaseRequestSchema", () => {
+    it("validates scenario field", () => {
+      const result = startCaseRequestSchema.safeParse({
+        scenario: "Test scenario",
+      });
+      expect(result.success).toBe(true);
+    });
+
+    it("rejects empty scenario", () => {
+      const result = startCaseRequestSchema.safeParse({ scenario: "" });
+      expect(result.success).toBe(false);
+    });
+
+    it("rejects scenario over 10000 chars", () => {
+      const longScenario = "a".repeat(10001);
+      const result = startCaseRequestSchema.safeParse({
+        scenario: longScenario,
+      });
+      expect(result.success).toBe(false);
+    });
+
+    it("accepts optional promptVersion", () => {
+      const result = startCaseRequestSchema.safeParse({
+        scenario: "Test",
+        promptVersion: "v0.3",
+      });
+      expect(result.success).toBe(true);
+    });
+  });
+
+  describe("updateCaseRequestSchema", () => {
+    it("validates complete update request", () => {
+      const graph = makeGraph({
+        centralStatement: "Test scenario",
+        nodes: [makeNode({ id: "n1", label: "N" })],
+        currentSummary: "Current state of situation",
+      });
+      const result = updateCaseRequestSchema.safeParse({
+        situationGraph: graph,
+        previousQuestion: "What happened?",
+        answer: "This is the answer",
+      });
+      expect(result.success).toBe(true);
+    });
+
+    it("rejects missing situationGraph", () => {
+      const result = updateCaseRequestSchema.safeParse({
+        previousQuestion: "Q?",
+        answer: "A",
+      });
+      expect(result.success).toBe(false);
+    });
+
+    it("rejects answer over 5000 chars", () => {
+      const graph = makeGraph({
+        centralStatement: "Test",
+        nodes: [makeNode({ id: "n1", label: "N" })],
+        currentSummary: "Test summary",
+      });
+      const result = updateCaseRequestSchema.safeParse({
+        situationGraph: graph,
+        previousQuestion: "Q?",
+        answer: "x".repeat(5001),
+      });
+      expect(result.success).toBe(false);
+    });
+  });
+});
+
+describe("deterministic ID generation", () => {
+  it("generate consistent IDs for same label", () => {
+    const id1 = makeNodeId("Same Label");
+    const id2 = makeNodeId("Same Label");
+    expect(id1).toBe(id2);
+  });
+
+  it("generates different IDs for different labels", () => {
+    const id1 = makeNodeId("Label A");
+    const id2 = makeNodeId("Label B");
+    expect(id1).not.toBe(id2);
+  });
+
+  it("IDs are prefixed with 'n' and short", () => {
+    const id = makeNodeId(
+      "A very long label that would produce a longer hash if not truncated",
+    );
+    expect(id.startsWith("n")).toBe(true);
+    expect(id.length).toBeLessThan(15);
+  });
+
+  it("same kind of nodes get deterministic IDs", () => {
+    for (let i = 0; i < 10; i++) {
+      expect(makeNodeId("Test Node")).toBe(makeNodeId("Test Node"));
+    }
+  });
+});
+
+describe("helper functions", () => {
+  describe("makeNode", () => {
+    it("creates a minimal node with defaults", () => {
+      const node = makeNode({ label: "Minimal" });
+      const result = situationNodeSchema.safeParse(node);
+      expect(result.success).toBe(true);
+      expect(node.kind).toBe("observation");
+      expect(node.status).toBe("unknown");
+      expect(node.confidence).toBe("medium");
+    });
+
+    it("creates a node with custom kind/status", () => {
+      const node = makeNode({
+        label: "Custom",
+        kind: "metric",
+        status: "known",
+        confidence: "high",
+        value: 42,
+        unit: "count",
+      });
+      expect(node.kind).toBe("metric");
+      expect(node.status).toBe("known");
+      expect(node.confidence).toBe("high");
+      expect(node.value).toBe(42);
+      expect(node.unit).toBe("count");
+    });
+
+    it("generates ID from label if none provided", () => {
+      const node = makeNode({ label: "Auto-ID" });
+      expect(node.id.startsWith("n")).toBe(true);
+    });
+  });
+
+  describe("makeEdge", () => {
+    it("creates a minimal edge with defaults", () => {
+      const edge = makeEdge({ fromNodeId: "n1", toNodeId: "n2" });
+      const result = situationEdgeSchema.safeParse(edge);
+      expect(result.success).toBe(true);
+    });
+
+    it("generates description from node ids if not provided", () => {
+      const edge = makeEdge({ fromNodeId: "n-alpha", toNodeId: "n-beta" });
+      expect(edge.description).toContain("alpha");
+      expect(edge.description).toContain("beta");
+    });
+  });
+
+  describe("makeGraph", () => {
+    it("creates a minimal graph with defaults", () => {
+      const graph = makeGraph({
+        centralStatement: "Test",
+        currentSummary: "Default summary",
+        nodes: [makeNode({ id: "n1", label: "Placeholder" })],
+      });
+      const result = situationGraphSchema.safeParse(graph);
+      expect(result.success).toBe(true);
+    });
+
+    it("allows specifying nodes and edges", () => {
+      const graph = makeGraph({
+        centralStatement: "Full Graph",
+        currentSummary: "Full summary",
+        nodes: [makeNode({ id: "n1", label: "N1" })],
+        edges: [makeEdge({ fromNodeId: "n1", toNodeId: "n2" })],
+      });
+      expect(graph.nodes.length).toBe(1);
+      expect(graph.edges.length).toBe(1);
+    });
+  });
+});
+
+describe("enum values completeness", () => {
+  it("SituationKind has all expected values", () => {
+    const expected = [
+      "observation",
+      "reported_claim",
+      "metric",
+      "state",
+      "transition",
+      "relationship",
+      "assumption",
+      "unknown",
+      "conclusion",
+    ];
+    const actual = Object.values(SituationKind);
+    expect(actual).toEqual(expect.arrayContaining(expected));
+  });
+
+  it("SituationStatus has all expected values", () => {
+    const expected = [
+      "known",
+      "unknown",
+      "provisional",
+      "supported",
+      "weakened",
+      "contradicted",
+      "resolved",
+    ];
+    const actual = Object.values(SituationStatus);
+    expect(actual).toEqual(expect.arrayContaining(expected));
+  });
+
+  it("SituationRelationship has all expected values", () => {
+    const expected = [
+      "supports",
+      "weakens",
+      "contradicts",
+      "depends_on",
+      "causes",
+      "may_cause",
+      "measures",
+      "compares_with",
+      "updates",
+      "other",
+    ];
+    const actual = Object.values(SituationRelationship);
+    expect(actual).toEqual(expect.arrayContaining(expected));
+  });
+
+  it("ConfidenceLevel has all expected values", () => {
+    const actual = Object.values(ConfidenceLevel);
+    expect(actual).toContain("low");
+    expect(actual).toContain("medium");
+    expect(actual).toContain("high");
+  });
+});

tests/graph/selection-influence-diagnostic.test.js

@@ -0,0 +1,303 @@
+import { describe, expect, it } from "vitest";
+import {
+  formulateQuestion,
+  formulateTieResolutionQuestion,
+} from "@/lib/graph/question-formulator.js";
+import { makeEdge, makeGraph, makeNode } from "@/lib/graph/schema.js";
+import {
+  explainUnknownSelection,
+  selectActiveUnknownCandidate,
+} from "@/lib/graph/utils.js";
+
+function buildLiveShapedGraph() {
+  const summary = makeNode({
+    id: "nnvog0y",
+    label:
+      "Revenue grew by 18% while corporate cash reserves declined over an identical time frame.",
+    description: "Summary of the situation from the scenario text",
+    kind: "state",
+    status: "provisional",
+    confidence: "medium",
+  });
+  const revenueObservation = makeNode({
+    id: "nri36w9",
+    label: "Revenue increased by 18%.",
+    description: "Revenue increased by 18%.",
+    kind: "observation",
+    status: "supported",
+    confidence: "high",
+    evidenceIds: ["obs_rev"],
+  });
+  const cashObservation = makeNode({
+    id: "nnfc48j",
+    label: "Cash in the bank decreased over the same period.",
+    description: "Cash in the bank decreased over the same period.",
+    kind: "observation",
+    status: "supported",
+    confidence: "high",
+    evidenceIds: ["obs_cash"],
+  });
+  const revenueMetric = makeNode({
+    id: "nhsd6d5",
+    label: "Revenue metric (typically accrual-based income statement figure)",
+    description:
+      "Revenue metric (typically accrual-based income statement figure)",
+    kind: "metric",
+    status: "known",
+    confidence: "high",
+  });
+  const cashMetric = makeNode({
+    id: "neh5m6m",
+    label:
+      "Cash balance (liquidity measure on the balance sheet or cash flow statement)",
+    description:
+      "Cash balance (liquidity measure on the balance sheet or cash flow statement)",
+    kind: "metric",
+    status: "known",
+    confidence: "high",
+  });
+  const directionalRelationship = makeNode({
+    id: "nwo6070",
+    label:
+      "Divergent directional movement between top-line revenue growth and net cash position contraction.",
+    description:
+      "Divergent directional movement between top-line revenue growth and net cash position contraction.",
+    kind: "relationship",
+    status: "supported",
+    confidence: "high",
+  });
+  const contradictionRelationship = makeNode({
+    id: "nuiab02",
+    label:
+      "Apparent contradiction between profitability/revenue expansion and liquidity reduction.",
+    description:
+      "Apparent contradiction between profitability/revenue expansion and liquidity reduction.",
+    kind: "relationship",
+    status: "supported",
+    confidence: "medium",
+  });
+  const cashTiming = makeNode({
+    id: "niewza",
+    label:
+      "Whether revenue recognition timing differs from cash collection timing.",
+    description:
+      "Whether revenue recognition timing differs from cash collection timing.",
+    kind: "unknown",
+    status: "unknown",
+    confidence: "high",
+  });
+  const cashOutflows = makeNode({
+    id: "nqdzobz",
+    label:
+      "Magnitude and nature of cash outflows (operating expenses, debt repayments, capex, or working capital shifts).",
+    description:
+      "Magnitude and nature of cash outflows (operating expenses, debt repayments, capex, or working capital shifts).",
+    kind: "unknown",
+    status: "unknown",
+    confidence: "high",
+  });
+
+  const edges = [
+    makeEdge({
+      id: "e-revenue-summary",
+      fromNodeId: revenueObservation.id,
+      toNodeId: summary.id,
+      relationship: "supports",
+      description: "Revenue increase supports the scenario summary.",
+    }),
+    makeEdge({
+      id: "e-cash-summary",
+      fromNodeId: cashObservation.id,
+      toNodeId: summary.id,
+      relationship: "supports",
+      description: "Cash decline supports the scenario summary.",
+    }),
+    makeEdge({
+      id: "e-unk-niewza",
+      fromNodeId: cashTiming.id,
+      toNodeId: summary.id,
+      relationship: "depends_on",
+      description:
+        "Whether revenue recognition timing differs from cash collection timing. is an unresolved factor for this situation",
+    }),
+    makeEdge({
+      id: "e-unk-nqdzobz",
+      fromNodeId: cashOutflows.id,
+      toNodeId: summary.id,
+      relationship: "depends_on",
+      description:
+        "Magnitude and nature of cash outflows (operating expenses, debt repayments, capex, or working capital shifts). is an unresolved factor for this situation",
+    }),
+  ];
+
+  return makeGraph({
+    centralStatement:
+      "Revenue increased by 18%, but cash in the bank fell over the same period.",
+    nodes: [
+      summary,
+      revenueObservation,
+      cashObservation,
+      revenueMetric,
+      cashMetric,
+      directionalRelationship,
+      contradictionRelationship,
+      cashTiming,
+      cashOutflows,
+    ],
+    edges,
+    activeUnknownNodeId: null,
+    resolvedNodeIds: [],
+    currentSummary: "Diagnostic selection influence fixture",
+  });
+}
+
+function orderCandidates(explanation) {
+  return explanation.candidates.map((candidate) => ({
+    nodeId: candidate.nodeId,
+    label: candidate.label,
+    score: candidate.score,
+    downstreamCount: candidate.downstreamCount,
+    unresolvedParentUnknownCount: candidate.unresolvedParentUnknownCount,
+  }));
+}
+
+function removeDependencyLinks(graph) {
+  const nodes = graph.nodes.map((node) => ({
+    ...node,
+    dependsOn: [],
+    affects: [],
+    parentId: null,
+    childIds: [],
+  }));
+  const edges = (graph.edges || []).filter(
+    (edge) => edge.relationship !== "depends_on",
+  );
+  return makeGraph({ ...graph, nodes, edges, activeUnknownNodeId: null });
+}
+
+function neutraliseUnknownWording(graph) {
+  let counter = 0;
+  const nodes = graph.nodes.map((node) => {
+    if (node.kind !== "unknown") return { ...node };
+    counter += 1;
+    return {
+      ...node,
+      label: `Unknown ${String.fromCharCode(64 + counter)}`,
+      description: `Unknown factor ${counter} relevant to the scenario.`,
+    };
+  });
+  return makeGraph({ ...graph, nodes, activeUnknownNodeId: null });
+}
+
+describe("selection influence diagnostic", () => {
+  it("records ambiguous ordering changes for live-shaped, structure-only, and wording-neutralised fixtures", () => {
+    const liveGraph = buildLiveShapedGraph();
+    const liveExplanation = explainUnknownSelection(liveGraph, []);
+    const liveSelection = selectActiveUnknownCandidate(liveGraph, []);
+    const tieQuestion = formulateTieResolutionQuestion({ graph: liveGraph });
+
+    const noLinksExplanation = explainUnknownSelection(
+      removeDependencyLinks(liveGraph),
+      [],
+    );
+    const noLinksSelection = selectActiveUnknownCandidate(
+      removeDependencyLinks(liveGraph),
+      [],
+    );
+    const neutralWordingExplanation = explainUnknownSelection(
+      neutraliseUnknownWording(liveGraph),
+      [],
+    );
+    const neutralSelection = selectActiveUnknownCandidate(
+      neutraliseUnknownWording(liveGraph),
+      [],
+    );
+
+    const fallbackQuestion = formulateQuestion({
+      node: liveGraph.nodes.find((node) => node.id === "nqdzobz"),
+      graph: liveGraph,
+    });
+
+    const diagnosticRecord = {
+      liveStatus: liveExplanation.status,
+      liveShapedCandidateOrdering: orderCandidates(liveExplanation),
+      liveTiedCandidateIds: liveExplanation.tiedCandidateIds,
+      noLinksCandidateOrdering: orderCandidates(noLinksExplanation),
+      noLinksStatus: noLinksExplanation.status,
+      neutralWordingCandidateOrdering: orderCandidates(
+        neutralWordingExplanation,
+      ),
+      neutralStatus: neutralWordingExplanation.status,
+      selectedExplanationContributions: liveExplanation.selected?.contributions,
+      tieQuestion: tieQuestion.question,
+      liveSelection,
+      noLinksSelection,
+      neutralSelection,
+      fallbackQuestion,
+    };
+
+    expect(diagnosticRecord.liveStatus).toBe("ambiguous");
+    expect(diagnosticRecord.liveTiedCandidateIds).toEqual([
+      "nqdzobz",
+      "niewza",
+    ]);
+    expect(diagnosticRecord.liveShapedCandidateOrdering).toEqual([
+      {
+        nodeId: "nqdzobz",
+        label:
+          "Magnitude and nature of cash outflows (operating expenses, debt repayments, capex, or working capital shifts).",
+        score: 0,
+        downstreamCount: 0,
+        unresolvedParentUnknownCount: 0,
+      },
+      {
+        nodeId: "niewza",
+        label:
+          "Whether revenue recognition timing differs from cash collection timing.",
+        score: 0,
+        downstreamCount: 0,
+        unresolvedParentUnknownCount: 0,
+      },
+    ]);
+    expect(diagnosticRecord.liveSelection).toMatchObject({
+      selectedNode: null,
+      status: "ambiguous",
+      tieType: "complete_unresolved_tie",
+      tiedCandidateIds: ["nqdzobz", "niewza"],
+    });
+    expect(diagnosticRecord.noLinksCandidateOrdering).toEqual(
+      diagnosticRecord.liveShapedCandidateOrdering,
+    );
+    expect(diagnosticRecord.noLinksStatus).toBe("ambiguous");
+    expect(diagnosticRecord.noLinksSelection.status).toBe("ambiguous");
+    expect(diagnosticRecord.neutralWordingCandidateOrdering).toEqual([
+      {
+        nodeId: "niewza",
+        label: "Unknown A",
+        score: 0,
+        downstreamCount: 0,
+        unresolvedParentUnknownCount: 0,
+      },
+      {
+        nodeId: "nqdzobz",
+        label: "Unknown B",
+        score: 0,
+        downstreamCount: 0,
+        unresolvedParentUnknownCount: 0,
+      },
+    ]);
+    expect(diagnosticRecord.neutralStatus).toBe("ambiguous");
+    expect(diagnosticRecord.neutralSelection.status).toBe("ambiguous");
+    expect(diagnosticRecord.selectedExplanationContributions).toBeUndefined();
+    expect(diagnosticRecord.tieQuestion).toBe(
+      "Were these figures measured on the same basis and at the same scale?",
+    );
+    expect(diagnosticRecord.tieQuestion.toLowerCase()).not.toMatch(
+      /accounts receivable|capex|debt repayments|working capital/,
+    );
+    expect(diagnosticRecord.fallbackQuestion.strategy).toBeNull();
+    expect(diagnosticRecord.fallbackQuestion.question).toBe(
+      "What would clarify magnitude and nature of cash outflows (operating expenses, debt repayments, capex, or working capital shifts) in this situation?",
+    );
+  });
+});

tests/graph/update-proposal.test.js

@@ -0,0 +1,152 @@
+import { describe, expect, it } from "vitest";
+import { parseGraphUpdateProposal } from "@/lib/graph/update-proposal.js";
+
+function makeValidProposal(overrides = {}) {
+  return {
+    addedNodes: [],
+    updatedNodes: [
+      {
+        nodeId: "n-unknown",
+        previousStatus: "unknown",
+        newStatus: "resolved",
+        previousValue: null,
+        newValue: "1.9 complaints per 100 units",
+        reason: "The answer directly provides the normalized complaint rate.",
+      },
+    ],
+    addedEdges: [],
+    removedEdgeIds: [],
+    resolvedUnknownNodeIds: ["n-unknown"],
+    affectedNodeIds: [],
+    selectedQuestion: null,
+    ...overrides,
+  };
+}
+
+describe("parseGraphUpdateProposal", () => {
+  it("parses a valid proposal", () => {
+    const result = parseGraphUpdateProposal(makeValidProposal());
+    expect(result.success).toBe(true);
+    expect(result.proposal.updatedNodes).toHaveLength(1);
+  });
+
+  it("fails on malformed JSON", () => {
+    const result = parseGraphUpdateProposal("{not json");
+    expect(result.success).toBe(false);
+  });
+
+  it("fails when required update content is invalid", () => {
+    const result = parseGraphUpdateProposal({
+      updatedNodes: [{ nodeId: "n-unknown" }],
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it("removes null array entries and logs them", () => {
+    const result = parseGraphUpdateProposal(
+      JSON.stringify({
+        ...makeValidProposal(),
+        addedNodes: [null],
+      }),
+    );
+    expect(result.success).toBe(true);
+    expect(result.proposal.addedNodes).toEqual([]);
+    expect(result.normalisationsApplied).toEqual(
+      expect.arrayContaining([
+        expect.objectContaining({ change: "Removed null array entry" }),
+      ]),
+    );
+  });
+
+  it("fills missing optional arrays with empty arrays", () => {
+    const result = parseGraphUpdateProposal({
+      updatedNodes: [],
+    });
+    expect(result.success).toBe(true);
+    expect(result.proposal.addedNodes).toEqual([]);
+    expect(result.proposal.addedEdges).toEqual([]);
+    expect(result.normalisationsApplied.length).toBeGreaterThan(0);
+  });
+
+  it("normalises confirmed enum alias and preserves IDs", () => {
+    const result = parseGraphUpdateProposal({
+      ...makeValidProposal(),
+      addedNodes: [
+        {
+          id: "n-new",
+          label: "Reported update",
+          description: "A new reported claim",
+          kind: "reported_statement",
+          status: "supported",
+          confidence: "medium",
+          value: null,
+          unit: null,
+          evidenceIds: [],
+          dependsOn: [],
+          affects: [],
+          parentId: null,
+          childIds: [],
+        },
+      ],
+    });
+    expect(result.success).toBe(true);
+    expect(result.proposal.addedNodes[0].kind).toBe("reported_claim");
+    expect(result.proposal.addedNodes[0].id).toBe("n-new");
+  });
+
+  it("unknown enum values still fail", () => {
+    const result = parseGraphUpdateProposal({
+      ...makeValidProposal(),
+      addedNodes: [
+        {
+          id: "n-new",
+          label: "Bad node",
+          description: "Bad node",
+          kind: "unsupported_kind",
+          status: "supported",
+          confidence: "medium",
+          value: null,
+          unit: null,
+          evidenceIds: [],
+          dependsOn: [],
+          affects: [],
+          parentId: null,
+          childIds: [],
+        },
+      ],
+    });
+    expect(result.success).toBe(false);
+  });
+
+  it("defaults missing selectedQuestion to null", () => {
+    const result = parseGraphUpdateProposal({
+      addedNodes: [],
+      updatedNodes: [],
+      addedEdges: [],
+      removedEdgeIds: [],
+      resolvedUnknownNodeIds: [],
+      affectedNodeIds: [],
+    });
+    expect(result.success).toBe(true);
+    expect(result.proposal.selectedQuestion).toBeNull();
+  });
+
+  it("parses a valid selectedQuestion", () => {
+    const result = parseGraphUpdateProposal(
+      makeValidProposal({
+        selectedQuestion: {
+          nodeId: "n-follow-up",
+          question: "How should commercial value be defined for this decision?",
+          reason: "A consequential unknown remains unresolved.",
+        },
+      }),
+    );
+    expect(result.success).toBe(true);
+    expect(result.proposal.selectedQuestion?.nodeId).toBe("n-follow-up");
+  });
+
+  it("does not invent a next question field outside the contract", () => {
+    const result = parseGraphUpdateProposal(makeValidProposal());
+    expect(result.proposal.nextQuestion).toBeUndefined();
+  });
+});

tests/graph/upward-propagation.test.js

@@ -0,0 +1,419 @@
+import { describe, expect, it } from "vitest";
+import { applyValidatedProposal } from "@/lib/graph/apply-proposal.js";
+import { makeEdge, makeGraph, makeNode } from "@/lib/graph/schema.js";
+
+function makePropagationFixture({
+  key,
+  centralStatement,
+  firstObservationLabel,
+  secondObservationLabel,
+}) {
+  const parent = makeNode({
+    id: `${key}-parent`,
+    label: `Explanation for why ${centralStatement}`,
+    description:
+      "Need to understand what change or event could explain why these observations differ, because that is needed to investigate their relationship.",
+    kind: "unknown",
+    status: "unknown",
+    confidence: "medium",
+  });
+  const measurementChild = makeNode({
+    id: `${key}-child-measurement`,
+    label: "How the two observations were measured",
+    description: `Need evidence about the measure used for each observation, because that could help explain ${centralStatement}.`,
+    kind: "unknown",
+    status: "unknown",
+    confidence: "medium",
+    parentId: parent.id,
+  });
+  const timingChild = makeNode({
+    id: `${key}-child-timing`,
+    label: "Whether the two observations reflect different timing",
+    description: `Need to know whether the two observations reflect different timing, because that could help explain ${centralStatement}.`,
+    kind: "unknown",
+    status: "unknown",
+    confidence: "medium",
+    parentId: parent.id,
+  });
+  const cashMovementChild = makeNode({
+    id: `${key}-child-cash-movement`,
+    label: `Possible change mainly affecting ${secondObservationLabel}`,
+    description: `Need to know whether a possible change mainly affected ${secondObservationLabel}, because that could help explain ${centralStatement}.`,
+    kind: "unknown",
+    status: "unknown",
+    confidence: "medium",
+    parentId: parent.id,
+  });
+  const oneOffChild = makeNode({
+    id: `${key}-child-one-off`,
+    label: "Possible one-off event during the period",
+    description: `Need to know whether a possible one-off event happened during the period, because that could help explain ${centralStatement}.`,
+    kind: "unknown",
+    status: "unknown",
+    confidence: "medium",
+    parentId: parent.id,
+  });
+  const ancestor = makeNode({
+    id: `${key}-ancestor`,
+    label: `Reasoning for ${centralStatement}`,
+    description:
+      "Higher-level reasoning node depending on the parent explanation.",
+    kind: "unknown",
+    status: "unknown",
+    confidence: "medium",
+    childIds: [parent.id],
+  });
+  const unrelated = makeNode({
+    id: `${key}-unrelated`,
+    label: "Unrelated branch",
+    description: "Should remain unchanged.",
+    kind: "unknown",
+    status: "unknown",
+    confidence: "low",
+  });
+  const firstObservation = makeNode({
+    id: `${key}-obs-1`,
+    label: firstObservationLabel,
+    description: firstObservationLabel,
+    kind: "observation",
+    status: "supported",
+    confidence: "high",
+  });
+  const secondObservation = makeNode({
+    id: `${key}-obs-2`,
+    label: secondObservationLabel,
+    description: secondObservationLabel,
+    kind: "observation",
+    status: "supported",
+    confidence: "high",
+  });
+
+  const graph = makeGraph({
+    centralStatement,
+    nodes: [
+      ancestor,
+      parent,
+      measurementChild,
+      timingChild,
+      cashMovementChild,
+      oneOffChild,
+      unrelated,
+      firstObservation,
+      secondObservation,
+    ],
+    edges: [
+      makeEdge({
+        id: `${key}-e-parent-ancestor`,
+        fromNodeId: parent.id,
+        toNodeId: ancestor.id,
+        relationship: "depends_on",
+        description: "Ancestor depends on the parent explanation.",
+      }),
+      makeEdge({
+        id: `${key}-e-child-measurement-parent`,
+        fromNodeId: measurementChild.id,
+        toNodeId: parent.id,
+        relationship: "depends_on",
+        description: "Measurement child depends into the parent explanation.",
+      }),
+      makeEdge({
+        id: `${key}-e-child-timing-parent`,
+        fromNodeId: timingChild.id,
+        toNodeId: parent.id,
+        relationship: "depends_on",
+        description: "Timing child depends into the parent explanation.",
+      }),
+      makeEdge({
+        id: `${key}-e-child-cash-parent`,
+        fromNodeId: cashMovementChild.id,
+        toNodeId: parent.id,
+        relationship: "depends_on",
+        description: "Cash-movement child depends into the parent explanation.",
+      }),
+      makeEdge({
+        id: `${key}-e-child-one-off-parent`,
+        fromNodeId: oneOffChild.id,
+        toNodeId: parent.id,
+        relationship: "depends_on",
+        description: "One-off child depends into the parent explanation.",
+      }),
+    ],
+    activeUnknownNodeId: measurementChild.id,
+    resolvedNodeIds: [],
+    currentSummary: `Propagation fixture for ${key}`,
+  });
+
+  return {
+    graph,
+    ids: {
+      ancestor: ancestor.id,
+      parent: parent.id,
+      measurementChild: measurementChild.id,
+      timingChild: timingChild.id,
+      cashMovementChild: cashMovementChild.id,
+      oneOffChild: oneOffChild.id,
+      unrelated: unrelated.id,
+    },
+  };
+}
+
+const scenarios = [
+  {
+    key: "revenue-cash",
+    centralStatement: "revenue increased while cash fell",
+    firstObservationLabel: "Revenue increased by 18%.",
+    secondObservationLabel: "Cash in the bank fell over the same period.",
+  },
+  {
+    key: "satisfaction-complaints",
+    centralStatement:
+      "customer satisfaction increased while complaints increased",
+    firstObservationLabel: "Customer satisfaction increased.",
+    secondObservationLabel: "Complaints increased.",
+  },
+  {
+    key: "traffic-sales",
+    centralStatement: "traffic increased while sales stayed flat",
+    firstObservationLabel: "Website traffic increased.",
+    secondObservationLabel: "Sales stayed flat.",
+  },
+  {
+    key: "delivery-cancellations",
+    centralStatement: "delivery time fell while cancellations increased",
+    firstObservationLabel: "Average delivery time decreased.",
+    secondObservationLabel: "Cancellations increased.",
+  },
+  {
+    key: "production-defects",
+    centralStatement: "production increased while defects increased",
+    firstObservationLabel: "Production increased.",
+    secondObservationLabel: "Defects increased.",
+  },
+];
+
+describe("upward propagation", () => {
+  it.each(scenarios)(
+    "propagates resolved measurement child upward for $key",
+    ({
+      key,
+      centralStatement,
+      firstObservationLabel,
+      secondObservationLabel,
+    }) => {
+      const { graph, ids } = makePropagationFixture({
+        key,
+        centralStatement,
+        firstObservationLabel,
+        secondObservationLabel,
+      });
+      const unrelatedBefore = JSON.stringify(
+        graph.nodes.find((node) => node.id === ids.unrelated),
+      );
+
+      const result = applyValidatedProposal({
+        situationGraph: graph,
+        proposal: {
+          addedNodes: [
+            makeNode({
+              id: `${key}-anchor`,
+              label: "Update anchor",
+              description:
+                "Anchor state introduced by the answer because the update must contain a meaningful change.",
+              kind: "state",
+              status: "known",
+              confidence: "low",
+            }),
+          ],
+          updatedNodes: [
+            {
+              nodeId: ids.measurementChild,
+              previousStatus: "unknown",
+              newStatus: "resolved",
+              previousValue: null,
+              newValue:
+                "The figures were measured over the same accounting period using the same management accounts.",
+              reason: "The answer resolves the measurement child.",
+            },
+          ],
+          addedEdges: [],
+          removedEdgeIds: [],
+          resolvedUnknownNodeIds: [ids.measurementChild],
+          affectedNodeIds: [],
+          selectedQuestion: null,
+        },
+        previousQuestion:
+          "What evidence would clarify how the two observations were measured?",
+        answer:
+          "The figures were measured over the same accounting period using the same management accounts.",
+      });
+
+      expect(result.success).toBe(true);
+      expect(result.resolvedUnknownNodeIds).toContain(ids.measurementChild);
+      expect(result.propagationPerformed).toBe(true);
+      expect(result.resolvedChildNodeId).toBe(ids.measurementChild);
+      expect(result.parentNodeId).toBe(ids.parent);
+      expect(result.parentStatusBefore).toBe("unknown");
+      expect(result.parentStatusAfter).toBe("provisional");
+      expect(result.parentConfidenceBefore).toBe("medium");
+      expect(result.parentConfidenceAfter).toBe("medium");
+      expect(result.evidenceConfidenceBefore).toBe("medium");
+      expect(result.evidenceConfidenceAfter).toBe("medium");
+      expect(result.completenessBefore).toBe("empty");
+      expect(result.completenessAfter).toBe("partial");
+      expect(result.conclusionConfidenceBefore).toBe("low");
+      expect(result.conclusionConfidenceAfter).toBe("medium");
+      expect(result.confidenceCapReason).toBe(
+        "unresolved_direct_children_cap_conclusion",
+      );
+      expect(result.parentResolved).toBe(false);
+      expect(result.affectedAncestorIds).toContain(ids.parent);
+      expect(result.affectedAncestorIds).toContain(ids.ancestor);
+      expect(result.nextSelectedSibling).toBe(result.newActiveUnknownNodeId);
+      expect(result.nextSelectedSibling).toBe(result.selectedQuestion?.nodeId);
+      expect(result.nextSelectedSibling).not.toBe(ids.measurementChild);
+      expect([
+        ids.timingChild,
+        ids.cashMovementChild,
+        ids.oneOffChild,
+      ]).toContain(result.nextSelectedSibling);
+      expect(result.selectedQuestion?.question.toLowerCase()).not.toContain(
+        "measured",
+      );
+
+      const parentNode = result.updatedSituationGraph.nodes.find(
+        (node) => node.id === ids.parent,
+      );
+      expect(parentNode).toMatchObject({
+        status: "provisional",
+        confidence: "medium",
+        confidenceAssessment: {
+          evidenceConfidence: "medium",
+          completenessStatus: "partial",
+          conclusionConfidence: "medium",
+        },
+      });
+
+      const ancestorNode = result.updatedSituationGraph.nodes.find(
+        (node) => node.id === ids.ancestor,
+      );
+      expect(ancestorNode).toMatchObject({
+        status: "provisional",
+        confidence: "low",
+        confidenceAssessment: {
+          evidenceConfidence: "low",
+          completenessStatus: "empty",
+          conclusionConfidence: "low",
+        },
+      });
+
+      const resolvedChild = result.updatedSituationGraph.nodes.find(
+        (node) => node.id === ids.measurementChild,
+      );
+      expect(resolvedChild.status).toBe("resolved");
+      expect(resolvedChild.evidenceIds).toContain(
+        `answer:${ids.measurementChild}`,
+      );
+
+      expect(
+        result.updatedSituationGraph.nodes.filter(
+          (node) => node.id === ids.measurementChild,
+        ),
+      ).toHaveLength(1);
+      expect(
+        JSON.stringify(
+          result.updatedSituationGraph.nodes.find(
+            (node) => node.id === ids.unrelated,
+          ),
+        ),
+      ).toBe(unrelatedBefore);
+    },
+  );
+
+  it("resolves the parent only after all direct children are resolved", () => {
+    const { graph, ids } = makePropagationFixture({
+      key: "completion-rule",
+      centralStatement: "revenue increased while cash fell",
+      firstObservationLabel: "Revenue increased by 18%.",
+      secondObservationLabel: "Cash in the bank fell over the same period.",
+    });
+
+    const result = applyValidatedProposal({
+      situationGraph: graph,
+      proposal: {
+        addedNodes: [
+          makeNode({
+            id: "completion-rule-anchor",
+            label: "Update anchor",
+            description:
+              "Anchor state introduced by the answer because the update must contain a meaningful change.",
+            kind: "state",
+            status: "known",
+            confidence: "low",
+          }),
+        ],
+        updatedNodes: [
+          {
+            nodeId: ids.measurementChild,
+            previousStatus: "unknown",
+            newStatus: "resolved",
+            previousValue: null,
+            newValue: "same management accounts",
+            reason: "resolved measurement child",
+          },
+          {
+            nodeId: ids.timingChild,
+            previousStatus: "unknown",
+            newStatus: "resolved",
+            previousValue: null,
+            newValue: "timing aligned",
+            reason: "resolved timing child",
+          },
+          {
+            nodeId: ids.cashMovementChild,
+            previousStatus: "unknown",
+            newStatus: "resolved",
+            previousValue: null,
+            newValue: "cash left through operations",
+            reason: "resolved movement child",
+          },
+          {
+            nodeId: ids.oneOffChild,
+            previousStatus: "unknown",
+            newStatus: "resolved",
+            previousValue: null,
+            newValue: "no exceptional movement",
+            reason: "resolved one-off child",
+          },
+        ],
+        addedEdges: [],
+        removedEdgeIds: [],
+        resolvedUnknownNodeIds: [
+          ids.measurementChild,
+          ids.timingChild,
+          ids.cashMovementChild,
+          ids.oneOffChild,
+        ],
+        affectedNodeIds: [],
+        selectedQuestion: null,
+      },
+      previousQuestion:
+        "What evidence would clarify how the two observations were measured?",
+      answer: "All direct child questions are now answered.",
+    });
+
+    expect(result.success).toBe(true);
+    expect(result.parentResolved).toBe(true);
+    expect(result.resolvedUnknownNodeIds).toContain(ids.parent);
+    expect(
+      result.updatedSituationGraph.nodes.find((node) => node.id === ids.parent),
+    ).toMatchObject({
+      status: "resolved",
+      confidence: "high",
+      confidenceAssessment: {
+        evidenceConfidence: "high",
+        completenessStatus: "complete",
+        conclusionConfidence: "high",
+      },
+    });
+  });
+});

tests/reconstruction/compatibility.test.js

@@ -0,0 +1,179 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { normaliseAnalysisResponse } from "@/lib/reconstruction/compatibility.js";
+
+const mockGenerateReconstruction = vi.fn();
+
+vi.mock("@/lib/config.js", () => ({
+  getConfig: () => ({
+    ok: true,
+    config: {
+      OLLAMA_BASE_URL: "http://example.test",
+      OLLAMA_MODEL: "test-model",
+    },
+  }),
+}));
+
+vi.mock("@/lib/llm/provider.js", () => ({
+  getProvider: () => ({
+    generateReconstruction: (...args) => mockGenerateReconstruction(...args),
+  }),
+}));
+
+vi.mock("@/lib/reconstruction/prompt.js", () => ({
+  buildPrompt: async () => ({ prompt: "prompt", version: "v0.3" }),
+  PROMPT_VERSIONS: ["v0.1", "v0.2", "v0.3"],
+  DEFAULT_PROMPT_VERSION: "v0.3",
+}));
+
+describe("normaliseAnalysisResponse", () => {
+  beforeEach(() => {
+    vi.resetModules();
+    vi.clearAllMocks();
+  });
+
+  it("leaves already-valid responses unchanged", () => {
+    const input = {
+      evidence: [
+        {
+          id: "ev1",
+          description: "x",
+          evidenceType: "reported_statement",
+          confidence: "medium",
+          importance: "important",
+          source: "report",
+        },
+      ],
+    };
+
+    const result = normaliseAnalysisResponse(input);
+
+    expect(result.normalised).toEqual(input);
+    expect(result.changesApplied).toEqual([]);
+  });
+
+  it("normalises null evidence source deterministically", () => {
+    const input = {
+      evidence: [
+        {
+          id: "ev1",
+          description: "x",
+          evidenceType: "reported_statement",
+          confidence: "medium",
+          importance: "important",
+          source: null,
+        },
+      ],
+    };
+
+    const result = normaliseAnalysisResponse(input);
+
+    expect(result.normalised.evidence[0]).not.toHaveProperty("source");
+    expect(result.changesApplied).toHaveLength(1);
+  });
+
+  it("does not invent a next question", () => {
+    const input = { evidence: [] };
+    const result = normaliseAnalysisResponse(input);
+    expect(result.normalised.nextQuestion).toBeUndefined();
+  });
+
+  it("does not repair missing reasoning content", () => {
+    const input = { evidence: [{ source: null }] };
+    const result = normaliseAnalysisResponse(input);
+    expect(result.normalised.reconstruction).toBeUndefined();
+  });
+});
+
+describe("analyseScenario compatibility", () => {
+  it("succeeds when the only mismatch is null evidence source", async () => {
+    mockGenerateReconstruction.mockResolvedValue({
+      inputClassification: {
+        primaryType: "unexplained_change",
+        secondaryTypes: [],
+        reasoningModes: ["validate_measurement"],
+        classificationReason: "reason",
+        confidence: "medium",
+      },
+      reconstruction: {
+        summary: "summary",
+        actors: [],
+        systemsOrObjects: [],
+        expectedStates: [],
+        observedStates: [],
+        differences: [],
+        knownTransitions: [],
+        unexplainedTransitions: [],
+        contradictions: [],
+        importantUnknowns: [],
+        plausibleInterpretations: [],
+      },
+      evidence: [
+        {
+          id: "ev1",
+          description: "desc",
+          evidenceType: "reported_statement",
+          source: null,
+          attribution: null,
+          confidence: "medium",
+          importance: "important",
+        },
+      ],
+      nextQuestion: {
+        id: "q1",
+        question: "What denominator?",
+        targets: ["observedStates"],
+        reason: "reason",
+        expectedInformationValue: "high",
+        reasoningMode: "validate_measurement",
+      },
+    });
+
+    const { analyseScenario } = await import("@/lib/analysis.js");
+    const result = await analyseScenario("Scenario text", {
+      promptVersion: "v0.3",
+    });
+
+    expect(result.success).toBe(true);
+    expect(result.compatibilityApplied).toBe(true);
+    expect(result.compatibilityChanges).toHaveLength(1);
+    expect(result.evidence[0]).not.toHaveProperty("source");
+    expect(result.nextQuestion.question).toBe("What denominator?");
+  });
+
+  it("still fails when required reasoning content is missing", async () => {
+    mockGenerateReconstruction.mockResolvedValue({
+      evidence: [
+        {
+          id: "ev1",
+          description: "desc",
+          evidenceType: "reported_statement",
+          source: null,
+          attribution: null,
+          confidence: "medium",
+          importance: "important",
+        },
+      ],
+    });
+
+    const { analyseScenario } = await import("@/lib/analysis.js");
+    const result = await analyseScenario("Scenario text", {
+      promptVersion: "v0.3",
+    });
+
+    expect(result.success).toBe(false);
+    expect(result.compatibilityApplied).toBe(true);
+    expect(result.nextQuestion).toBeUndefined();
+  });
+
+  it("malformed JSON still fails", async () => {
+    mockGenerateReconstruction.mockResolvedValue("{not valid json");
+
+    const { analyseScenario } = await import("@/lib/analysis.js");
+    const result = await analyseScenario("Scenario text", {
+      promptVersion: "v0.3",
+    });
+
+    expect(result.success).toBe(false);
+    expect(result.compatibilityApplied).toBe(false);
+  });
+});

tests/smoke.test.js

@@ -0,0 +1,107 @@
+import { test, expect } from "@playwright/test";
+
+const BASE_URL = process.env.PLAYWRIGHT_BASE_URL || "http://localhost:3000";
+
+test.setTimeout(300000);
+
+test("graph-backed one-turn update smoke test", async ({ page }) => {
+  await page.goto(BASE_URL);
+
+  // Page should load without error
+  await expect(page.getByText(/Confidence Engine/i)).toBeVisible();
+
+  // Type the scenario
+  const textarea = page.locator("textarea[placeholder*='Describe']");
+  await textarea.fill(
+    "Complaints increased by 35% while production increased by 40%.",
+  );
+  await expect(textarea).toHaveValue(
+    "Complaints increased by 35% while production increased by 40%.",
+  );
+
+  // Button should be enabled
+  await expect(page.getByRole("button", { name: /Analyse/i })).toBeEnabled();
+
+  // Click Analyse and wait for graph-backed result
+  await page.getByRole("button", { name: /Analyse/i }).click();
+
+  await expect(
+    page
+      .locator("section")
+      .filter({ hasText: /Selected Question/i })
+      .last()
+      .getByRole("heading", { name: /Selected Question/i }),
+  ).toBeVisible({ timeout: 180000 });
+  await expect(
+    page.getByRole("heading", { name: /Situation Graph/i }),
+  ).toBeVisible({ timeout: 180000 });
+  await expect(page.getByText(/Central statement/i)).toBeVisible();
+  await expect(page.getByText(/Active unknown/i)).toBeVisible();
+  await expect(page.getByText(/Error:/i)).toHaveCount(0);
+
+  const rawJsonToggle = page.getByText(/Raw graph JSON/i);
+  await expect(rawJsonToggle).toBeVisible();
+  await rawJsonToggle.click();
+  await expect(page.getByText(/centralStatement/i)).toBeVisible();
+
+  const selectedQuestionSections = page
+    .locator("section")
+    .filter({ hasText: "Selected Question" });
+  await expect(selectedQuestionSections).toHaveCount(1);
+  const questionText = await selectedQuestionSections.first().innerText();
+  expect(questionText.length).toBeGreaterThan(25);
+
+  const answerTextarea = page.locator(
+    "textarea[placeholder*='Enter the answer']",
+  );
+  await expect(answerTextarea).toBeVisible();
+  await answerTextarea.fill(
+    "The complaint rate fell from 2.0 complaints per 100 units to 1.9 complaints per 100 units.",
+  );
+  await page.getByRole("button", { name: /Update situation/i }).click();
+
+  await expect(page.getByText(/Graph update applied/i)).toBeVisible({
+    timeout: 240000,
+  });
+  await expect(page.getByText(/Resolved unknowns/i)).toBeVisible();
+  await expect(page.getByText(/Newly surfaced unknowns/i)).toBeVisible();
+  await expect(page.getByText(/Affected nodes/i)).toBeVisible();
+  await expect(
+    page.getByText(/Selected Question|Next question:/i),
+  ).toBeVisible();
+  await expect(
+    page.getByText(
+      /Additional submission is disabled in this one-update prototype\./i,
+    ),
+  ).toBeVisible();
+  await expect(page.getByText(/Error:/i)).toHaveCount(0);
+  await expect(page.getByText(/Update error:/i)).toHaveCount(0);
+  await expect(answerTextarea).toHaveValue("");
+
+  const proposalToggle = page.getByText(/Proposal details/i);
+  await expect(proposalToggle).toBeVisible();
+
+  await rawJsonToggle.click();
+  await expect(page.getByText(/resolvedNodeIds/i)).toBeVisible();
+
+  // Get full body text for verification
+  const bodyText = await page.locator("body").innerText();
+
+  // Check key content indicators
+  const hasSelectedQuestion = bodyText.includes("Selected Question");
+  const hasComplaints =
+    bodyText.includes("Complaint") || bodyText.includes("complaint");
+  const hasProduction =
+    bodyText.includes("production") || bodyText.includes("Production");
+  const hasRateContext =
+    bodyText.toLowerCase().includes("rate") ||
+    bodyText.toLowerCase().includes("unit") ||
+    bodyText.toLowerCase().includes("denominator") ||
+    bodyText.toLowerCase().includes("per-unit");
+
+  // Basic structural checks
+  expect(bodyText.length).toBeGreaterThan(400);
+  expect(hasSelectedQuestion).toBe(true);
+  expect(bodyText.includes("Resolved unknowns")).toBe(true);
+  expect(bodyText.includes("Affected nodes")).toBe(true);
+});

tests/ui/scenario-form.test.jsx

@@ -0,0 +1,703 @@
+import React from "react";
+import { describe, expect, it, vi } from "vitest";
+import { renderToStaticMarkup } from "react-dom/server";
+import DiagnosticsView from "@/components/diagnostics-view.jsx";
+import GraphUpdateView from "@/components/graph-update-view.jsx";
+import SituationGraphView from "@/components/situation-graph-view.jsx";
+import {
+  ScenarioResultPanels,
+  UpdateErrorPanel,
+  submitAnswerForUpdateCase,
+  submitScenarioForStartCase,
+} from "@/components/scenario-form.jsx";
+
+function makeGraphResult(overrides = {}) {
+  return {
+    success: true,
+    situationGraph: {
+      centralStatement: "Complaints increased while production increased.",
+      currentSummary:
+        "Nodes: 2 observation, 1 unknown | Edges: 2 total | Unknowns: 1 unresolved",
+      activeUnknownNodeId: "n-unknown",
+      resolvedNodeIds: [],
+      nodes: [
+        {
+          id: "n-1",
+          label: "Complaints up 35%",
+          description: "Complaints increased by 35%",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+          value: 35,
+          unit: "%",
+        },
+        {
+          id: "n-2",
+          label: "Production up 40%",
+          description: "Production increased by 40%",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+          value: 40,
+          unit: "%",
+        },
+        {
+          id: "n-unknown",
+          label: "Complaint rate denominator",
+          description: "Need the denominator for complaint rate",
+          kind: "unknown",
+          status: "unknown",
+          confidence: "medium",
+          value: null,
+          unit: null,
+        },
+      ],
+      edges: [
+        { id: "e1", fromNodeId: "n-1", toNodeId: "n-unknown" },
+        { id: "e2", fromNodeId: "n-2", toNodeId: "n-unknown" },
+      ],
+    },
+    selectedQuestion: {
+      question: "What denominator is being used for the complaint rate?",
+    },
+    diagnostics: {
+      modelName: "test",
+      responseDurationMs: 1234,
+      validationStatus: "valid",
+      promptVersion: "test-prompt",
+      nodeCount: 3,
+      edgeCount: 2,
+      graphReferenceValidation: { valid: true, errors: [] },
+    },
+    ...overrides,
+  };
+}
+
+function makeUpdateSuccess(overrides = {}) {
+  return {
+    success: true,
+    stage: "update_applied",
+    updatedSituationGraph: {
+      centralStatement: "Complaints increased while production increased.",
+      currentSummary: "Updated summary",
+      activeUnknownNodeId: "n-child-1",
+      resolvedNodeIds: ["n-unknown"],
+      nodes: [
+        {
+          id: "n-1",
+          label: "Complaints up 35%",
+          description: "Complaints increased by 35%",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+          value: 35,
+          unit: "%",
+        },
+        {
+          id: "n-conclusion",
+          label: "Quality deterioration",
+          description: "Quality deterioration conclusion",
+          kind: "conclusion",
+          status: "weakened",
+          confidence: "medium",
+          value: null,
+          unit: null,
+        },
+        {
+          id: "n-unknown",
+          label: "Complaint rate denominator",
+          description: "Need the denominator for complaint rate",
+          kind: "unknown",
+          status: "resolved",
+          confidence: "medium",
+          value: "1.9 complaints per 100 units",
+          unit: null,
+        },
+        {
+          id: "n-next-unknown",
+          label:
+            "Explanation for why revenue increased by 18%, but cash in the bank fell over the same period",
+          description:
+            "Need to understand what change or event could explain why these observations differ, because that is needed to investigate their relationship.",
+          kind: "unknown",
+          status: "unknown",
+          confidence: "medium",
+          value: null,
+          unit: null,
+        },
+        {
+          id: "n-child-1",
+          label: "How the two observations were measured",
+          description:
+            "Need evidence about the measure used for each observation, because that could help explain revenue increased by 18%, but cash in the bank fell over the same period.",
+          kind: "unknown",
+          status: "unknown",
+          confidence: "medium",
+          value: null,
+          unit: null,
+          parentId: "n-next-unknown",
+        },
+      ],
+      edges: [
+        {
+          id: "e-rel-next",
+          fromNodeId: "n-conclusion",
+          toNodeId: "n-next-unknown",
+          relationship: "depends_on",
+          confidence: "medium",
+          description:
+            "This unresolved explanation arises from the now-assessed relationship between the observations.",
+        },
+        {
+          id: "e-child-next",
+          fromNodeId: "n-child-1",
+          toNodeId: "n-next-unknown",
+          relationship: "depends_on",
+          confidence: "medium",
+          description:
+            "This child unknown must be investigated before the broader parent explanation can be resolved.",
+        },
+      ],
+    },
+    proposal: {
+      addedNodes: [
+        {
+          id: "n-next-unknown",
+          label:
+            "Explanation for why revenue increased by 18%, but cash in the bank fell over the same period",
+          description:
+            "Need to understand what change or event could explain why these observations differ, because that is needed to investigate their relationship.",
+          kind: "unknown",
+          status: "unknown",
+          confidence: "medium",
+          value: null,
+          unit: null,
+          evidenceIds: [],
+          dependsOn: ["n-conclusion"],
+          affects: [],
+          parentId: "n-conclusion",
+          childIds: [],
+        },
+        {
+          id: "n-child-1",
+          label: "How the two observations were measured",
+          description:
+            "Need evidence about the measure used for each observation, because that could help explain revenue increased by 18%, but cash in the bank fell over the same period.",
+          kind: "unknown",
+          status: "unknown",
+          confidence: "medium",
+          value: null,
+          unit: null,
+          evidenceIds: [],
+          dependsOn: [],
+          affects: [],
+          parentId: "n-next-unknown",
+          childIds: [],
+        },
+      ],
+      updatedNodes: [
+        { nodeId: "n-unknown", newStatus: "resolved", reason: "answered" },
+      ],
+      addedEdges: [],
+      removedEdgeIds: [],
+      resolvedUnknownNodeIds: ["n-unknown"],
+      affectedNodeIds: ["n-conclusion"],
+      selectedQuestion: {
+        nodeId: "n-child-1",
+        question:
+          "What evidence would clarify how the two observations were measured?",
+        reason:
+          "Formulated from graph context using the evidence_gathering investigation strategy.",
+      },
+    },
+    selectedQuestion: {
+      nodeId: "n-child-1",
+      question:
+        "What evidence would clarify how the two observations were measured?",
+      reason:
+        "Formulated from graph context using the evidence_gathering investigation strategy.",
+    },
+    affectedNodeIds: ["n-conclusion"],
+    resolvedUnknownNodeIds: ["n-unknown"],
+    previousActiveUnknownNodeId: "n-unknown",
+    newActiveUnknownNodeId: "n-child-1",
+    emergentReasoningNodeCreated: true,
+    emergentReasoningNodeId: "n-next-unknown",
+    emergentReasoningNodeReason:
+      "Created a new unresolved reasoning unknown so the next justified question is backed by the graph.",
+    atomicityAssessment: "composite",
+    decompositionPerformed: true,
+    childUnknownCount: 1,
+    childNodeIds: ["n-child-1"],
+    atomicityReason:
+      "Decomposed a composite unknown into smaller broad candidate dimensions before asking the next question.",
+    previousReasoningState: {
+      comparabilityStatus: "uncertain",
+      reasoningStages: [
+        {
+          stage: "comparability",
+          status: "uncertain",
+          outcome:
+            "Comparability between the observations is not yet established across period, scale, or measurement basis.",
+        },
+        {
+          stage: "relationship",
+          status: "insufficient_information",
+          outcome: "not assessed until comparability is established",
+        },
+      ],
+    },
+    reasoningState: {
+      comparabilityStatus: "confirmed",
+      relationshipStatus: "insufficient_information",
+      reasoningStages: [
+        {
+          stage: "comparability",
+          status: "confirmed",
+          outcome:
+            "Comparability was confirmed by the user answer covering the same period and source basis.",
+        },
+        {
+          stage: "relationship",
+          status: "insufficient_information",
+          outcome:
+            "There is not enough structure to classify the relationship safely.",
+        },
+      ],
+    },
+    changesApplied: {
+      updatedNodeCount: 2,
+      resolvedUnknownCount: 1,
+      affectedNodeCount: 1,
+    },
+    diagnostics: { responseDurationMs: 100 },
+    ...overrides,
+  };
+}
+
+describe("scenario-form UI helpers", () => {
+  it("submits to /api/cases/start", async () => {
+    const fetchImpl = vi.fn().mockResolvedValue({ ok: true });
+
+    await submitScenarioForStartCase(fetchImpl, "Scenario text");
+
+    expect(fetchImpl).toHaveBeenCalledWith(
+      "/api/cases/start",
+      expect.objectContaining({
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+      }),
+    );
+  });
+
+  it("empty answer is rejected without fetch", async () => {
+    const fetchImpl = vi.fn();
+
+    const result = await submitAnswerForUpdateCase(fetchImpl, {
+      situationGraph: { nodes: [] },
+      previousQuestion: "What changed?",
+      answer: "   ",
+    });
+
+    expect(result.skipped).toBe(true);
+    expect(fetchImpl).not.toHaveBeenCalled();
+  });
+
+  it("update request body contains graph, previousQuestion and answer", async () => {
+    const fetchImpl = vi.fn().mockResolvedValue({
+      ok: true,
+      json: async () => ({ success: true }),
+    });
+    const graph = { nodes: [{ id: "n1" }], edges: [] };
+
+    await submitAnswerForUpdateCase(fetchImpl, {
+      situationGraph: graph,
+      previousQuestion: "What changed?",
+      answer: "The rate fell.",
+    });
+
+    expect(fetchImpl).toHaveBeenCalledWith(
+      "/api/cases/update",
+      expect.objectContaining({
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({
+          situationGraph: graph,
+          previousQuestion: "What changed?",
+          answer: "The rate fell.",
+        }),
+      }),
+    );
+  });
+});
+
+describe("graph-backed UI rendering", () => {
+  it("renders central statement from successful graph response", () => {
+    const data = makeGraphResult();
+    const html = renderToStaticMarkup(
+      <SituationGraphView
+        situationGraph={data.situationGraph}
+        selectedQuestion={data.selectedQuestion}
+      />,
+    );
+
+    expect(html).toContain("Central statement");
+    expect(html).toContain("Complaints increased while production increased.");
+  });
+
+  it("renders active unknown", () => {
+    const data = makeGraphResult();
+    const html = renderToStaticMarkup(
+      <SituationGraphView
+        situationGraph={data.situationGraph}
+        selectedQuestion={data.selectedQuestion}
+      />,
+    );
+
+    expect(html).toContain("Active unknown");
+    expect(html).toContain("Complaint rate denominator");
+  });
+
+  it("renders selected question exactly once", () => {
+    const data = makeGraphResult();
+    const html = renderToStaticMarkup(
+      <SituationGraphView
+        situationGraph={data.situationGraph}
+        selectedQuestion={data.selectedQuestion}
+      />,
+    );
+
+    expect(
+      html.match(/What denominator is being used for the complaint rate\?/g) ||
+        [],
+    ).toHaveLength(1);
+  });
+
+  it("no answer form appears when selectedQuestion is null", () => {
+    const html = renderToStaticMarkup(
+      <SituationGraphView
+        situationGraph={makeGraphResult().situationGraph}
+        selectedQuestion={null}
+      />,
+    );
+
+    expect(html).not.toContain("Update situation");
+  });
+
+  it("renders diagnostics", () => {
+    const html = renderToStaticMarkup(
+      <DiagnosticsView result={makeGraphResult()} />,
+    );
+
+    expect(html).toContain("Diagnostics");
+    expect(html).toContain("test");
+    expect(html).toContain("1234ms");
+    expect(html).toContain("Node count");
+    expect(html).toContain("Edge count");
+    expect(html).toContain("Graph references");
+  });
+
+  it("hides empty sections", () => {
+    const base = makeGraphResult();
+    const result = makeGraphResult({
+      selectedQuestion: null,
+      situationGraph: {
+        ...base.situationGraph,
+        activeUnknownNodeId: null,
+        nodes: [base.situationGraph.nodes[0]],
+        edges: [],
+      },
+    });
+
+    const html = renderToStaticMarkup(
+      <SituationGraphView
+        situationGraph={result.situationGraph}
+        selectedQuestion={result.selectedQuestion}
+      />,
+    );
+
+    expect(html).not.toContain("Selected Question");
+    expect(html).not.toContain("Active unknown");
+  });
+
+  it("displays API error clearly", () => {
+    const html = renderToStaticMarkup(
+      <ScenarioResultPanels
+        status="error"
+        result={{ error: "Invalid start-case request" }}
+      />,
+    );
+
+    expect(html).toContain("Error: Invalid start-case request");
+  });
+
+  it("renders expandable raw graph JSON", () => {
+    const data = makeGraphResult();
+    const html = renderToStaticMarkup(
+      <SituationGraphView
+        situationGraph={data.situationGraph}
+        selectedQuestion={data.selectedQuestion}
+      />,
+    );
+
+    expect(html).toContain("Raw graph JSON");
+    expect(html).toContain("&quot;centralStatement&quot;");
+  });
+
+  it("resolved unknowns render", () => {
+    const html = renderToStaticMarkup(
+      <GraphUpdateView
+        updateResult={{
+          ...makeUpdateSuccess(),
+          previousSituationGraph: makeGraphResult().situationGraph,
+        }}
+      />,
+    );
+
+    expect(html).toContain("Resolved unknowns");
+    expect(html).toContain("Complaint rate denominator");
+  });
+
+  it("newly surfaced unknowns render", () => {
+    const html = renderToStaticMarkup(
+      <GraphUpdateView
+        updateResult={{
+          ...makeUpdateSuccess(),
+          previousSituationGraph: makeGraphResult().situationGraph,
+        }}
+      />,
+    );
+
+    expect(html).toContain("Newly surfaced unknowns");
+    expect(html).toContain(
+      "Explanation for why revenue increased by 18%, but cash in the bank fell over the same period",
+    );
+  });
+
+  it("affected nodes render", () => {
+    const html = renderToStaticMarkup(
+      <GraphUpdateView
+        updateResult={{
+          ...makeUpdateSuccess(),
+          previousSituationGraph: makeGraphResult().situationGraph,
+        }}
+      />,
+    );
+
+    expect(html).toContain("Affected nodes");
+    expect(html).toContain("Quality deterioration");
+  });
+
+  it("renders validated next question when present", () => {
+    const html = renderToStaticMarkup(
+      <GraphUpdateView
+        updateResult={{
+          ...makeUpdateSuccess(),
+          previousSituationGraph: makeGraphResult().situationGraph,
+        }}
+      />,
+    );
+
+    expect(html).toContain(
+      "What evidence would clarify how the two observations were measured?",
+    );
+  });
+
+  it("no fake next question appears when there is none", () => {
+    const html = renderToStaticMarkup(
+      <GraphUpdateView
+        updateResult={{
+          ...makeUpdateSuccess({
+            newActiveUnknownNodeId: null,
+            selectedQuestion: null,
+            proposal: {
+              ...makeUpdateSuccess().proposal,
+              selectedQuestion: null,
+            },
+          }),
+          previousSituationGraph: makeGraphResult().situationGraph,
+        }}
+      />,
+    );
+
+    expect(html).toContain("No next question selected yet.");
+  });
+
+  it("previous and new active unknowns render labels", () => {
+    const html = renderToStaticMarkup(
+      <GraphUpdateView
+        updateResult={{
+          ...makeUpdateSuccess(),
+          previousSituationGraph: makeGraphResult().situationGraph,
+        }}
+      />,
+    );
+
+    expect(html).toContain("Previous active unknown");
+    expect(html).toContain("Complaint rate denominator");
+    expect(html).toContain("New active unknown");
+    expect(html).toContain(
+      "Explanation for why revenue increased by 18%, but cash in the bank fell over the same period",
+    );
+  });
+
+  it("successful update renders prior and new state together", () => {
+    const html = renderToStaticMarkup(
+      <GraphUpdateView
+        updateResult={{
+          ...makeUpdateSuccess(),
+          previousSituationGraph: makeGraphResult().situationGraph,
+        }}
+      />,
+    );
+
+    expect(html).toContain("Previous active unknown");
+    expect(html).toContain("Resolved unknowns");
+    expect(html).toContain("Newly surfaced unknowns");
+    expect(html).toContain("New active unknown");
+    expect(html).toContain("Next question");
+    expect(html).toContain(
+      "What evidence would clarify how the two observations were measured?",
+    );
+  });
+
+  it("update view shows comparability progression without raw ids in the normal view", () => {
+    const html = renderToStaticMarkup(
+      <GraphUpdateView
+        updateResult={{
+          ...makeUpdateSuccess({
+            selectedQuestion: {
+              nodeId: "n-next-unknown",
+              question:
+                "What evidence would clarify timing or measurement basis?",
+              reason: "A broad follow-up is now justified.",
+            },
+          }),
+          previousSituationGraph: makeGraphResult().situationGraph,
+        }}
+      />,
+    );
+
+    expect(html).toContain("Comparability:");
+    expect(html).toContain("uncertain → confirmed");
+    expect(html).toContain("Relationship status:");
+    expect(html).toContain("insufficient_information");
+    expect(html).toContain("Reasoning stages:");
+    expect(html).toContain("comparability: confirmed");
+    expect(html).toContain("relationship: insufficient_information");
+    expect(html).toContain(
+      "What evidence would clarify how the two observations were measured?",
+    );
+    expect(html).not.toContain("reasoning:comparability");
+  });
+
+  it("situation graph marks newly surfaced and active unknowns", () => {
+    const html = renderToStaticMarkup(
+      <SituationGraphView
+        situationGraph={makeUpdateSuccess().updatedSituationGraph}
+        selectedQuestion={makeUpdateSuccess().selectedQuestion}
+        newlySurfacedNodeIds={["n-next-unknown"]}
+      />,
+    );
+
+    expect(html).toContain("newly surfaced unknown");
+    expect(html).toContain("active unknown");
+    expect(html).toContain("resolved unknown");
+  });
+
+  it("disabled follow-up form is shown only as prototype limitation", () => {
+    const html = renderToStaticMarkup(
+      <GraphUpdateView
+        updateResult={makeUpdateSuccess()}
+      />,
+    );
+
+    expect(html).toContain(
+      "What evidence would clarify how the two observations were measured?",
+    );
+  });
+
+  it("raw ids remain only in collapsed proposal details", () => {
+    const html = renderToStaticMarkup(
+      <GraphUpdateView
+        updateResult={{
+          ...makeUpdateSuccess(),
+          previousSituationGraph: makeGraphResult().situationGraph,
+        }}
+      />,
+    );
+
+    expect(html).toContain("Proposal details");
+    expect(html).toContain("&quot;resolvedUnknownNodeIds&quot;");
+  });
+
+  it("update diagnostics render valid values", () => {
+    const html = renderToStaticMarkup(
+      <DiagnosticsView
+        result={{
+          diagnostics: {
+            promptVersion: "v0.4",
+            modelName: "configured-model",
+            responseDurationMs: 456,
+            validationStatus: "valid",
+            nodeCount: 7,
+            edgeCount: 3,
+            graphReferenceValidation: { valid: true, errors: [] },
+          },
+        }}
+      />,
+    );
+
+    expect(html).toContain("v0.4");
+    expect(html).toContain("456ms");
+    expect(html).toContain("7");
+    expect(html).toContain("3");
+    expect(html).toContain("✅ valid");
+  });
+
+  it("structured update error renders", () => {
+    const html = renderToStaticMarkup(
+      <UpdateErrorPanel
+        updateError={{
+          error: "Invalid graph update proposal",
+          proposalErrors: [{ message: "bad proposal" }],
+        }}
+      />,
+    );
+
+    expect(html).toContain("Update error: Invalid graph update proposal");
+    expect(html).toContain("bad proposal");
+  });
+
+  it("failed update does not fabricate history", () => {
+    const html = renderToStaticMarkup(
+      <>
+        <UpdateErrorPanel
+          updateError={{
+            error: "Update case failed",
+            errors: [
+              'New unknown must be explicitly related to an answer-derived node: "nu_commercial_val"',
+            ],
+          }}
+        />
+        <GraphUpdateView updateResult={null} />
+      </>,
+    );
+
+    expect(html).toContain("Update error: Update case failed");
+    expect(html).toContain("nu_commercial_val");
+    expect(html).not.toContain("Previous active unknown");
+    expect(html).not.toContain("Resolved unknowns");
+    expect(html).not.toContain("Newly surfaced unknowns");
+    expect(html).not.toContain("New active unknown");
+    expect(html).not.toContain("Proposal details");
+  });
+
+  it("proposal details remain collapsible", () => {
+    const html = renderToStaticMarkup(
+      <GraphUpdateView updateResult={makeUpdateSuccess()} />,
+    );
+
+    expect(html).toContain("Proposal details");
+  });
+});

tests/v03-reasoning.test.js

@@ -0,0 +1,598 @@
+import { describe, it, expect } from "vitest";
+import { promises as fs } from "node:fs";
+import { fileURLToPath } from "node:url";
+import { dirname, join } from "node:path";
+import {
+  PROMPT_VERSIONS,
+  buildPrompt,
+  DEFAULT_PROMPT_VERSION,
+} from "@/lib/reconstruction/prompt.js";
+import {
+  reconstructionV2Schema,
+  parseReconstructionV2,
+} from "@/lib/reconstruction/schema.js";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+const PROMPTS_DIR = join(__dirname, "../prompts");
+
+// ──────────────────────────────────────────────
+// v0.3 prompt loading tests
+// ──────────────────────────────────────────────
+
+describe("v0.3 prompt", () => {
+  it("v0.3 is in PROMPT_VERSIONS", () => {
+    expect(PROMPT_VERSIONS).toContain("v0.3");
+  });
+
+  it("DEFAULT_PROMPT_VERSION is v0.3 on this branch", () => {
+    expect(DEFAULT_PROMPT_VERSION).toBe("v0.3");
+  });
+
+  it("v0.2 remains available in PROMPT_VERSIONS", () => {
+    expect(PROMPT_VERSIONS).toContain("v0.2");
+  });
+
+  it("v0.3 prompt file loads from disk", async () => {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.3.md"),
+      "utf-8",
+    );
+    expect(typeof content).toBe("string");
+    expect(content.length).toBeGreaterThan(500);
+  });
+
+  it("v0.3 prompt contains normalisation guidance", async () => {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.3.md"),
+      "utf-8",
+    );
+    expect(content.toLowerCase()).toContain("normalise");
+    expect(content.toLowerCase()).toContain("rate");
+    expect(content.toLowerCase()).toContain("denominator") ||
+      expect(content.toLowerCase()).toContain("exposure");
+  });
+
+  it("v0.3 prompt contains discipline guidance", async () => {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.3.md"),
+      "utf-8",
+    );
+    // Should mention not generating speculative interpretations
+    expect(content).toMatch(/interpretation/i);
+    // Should mention one question discipline
+    expect(content).toMatch(/exactly.*one.*question|one.*only.*question|single.*question/i) ||
+      expect(content).toMatch(/Do NOT combine/i);
+  });
+
+  it("buildPrompt returns v0.3 prompt with scenario substituted", async () => {
+    const result = await buildPrompt("Test scenario text", "v0.3");
+    expect(result.version).toBe("v0.3");
+    expect(result.prompt).toContain("Test scenario text");
+    // Should contain the normalisation section guidance
+    expect(result.prompt.toLowerCase()).toContain("normalise");
+  });
+
+  it("buildPrompt returns v0.2 prompt when requested", async () => {
+    const result = await buildPrompt("Test scenario text", "v0.2");
+    expect(result.version).toBe("v0.2");
+    expect(result.prompt).toContain("Test scenario text");
+  });
+
+  it("buildPrompt default is v0.3", async () => {
+    const result = await buildPrompt("Test scenario text");
+    expect(result.version).toBe("v0.3");
+  });
+});
+
+// ──────────────────────────────────────────────
+// v0.2 prompt still works
+// ──────────────────────────────────────────────
+
+describe("v0.2 backward compatibility", () => {
+  it("v0.2 prompt file exists and loads", async () => {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.2.md"),
+      "utf-8",
+    );
+    expect(typeof content).toBe("string");
+    expect(content.length).toBeGreaterThan(500);
+  });
+
+  it("buildPrompt returns v0.2 version string", async () => {
+    const result = await buildPrompt("test", "v0.2");
+    expect(result.version).toBe("v0.2");
+  });
+});
+
+// ──────────────────────────────────────────────
+// Schema validation tests for v0.3-shaped output
+// ──────────────────────────────────────────────
+
+describe("v0.3 schema validation", () => {
+  it("validates a complete valid reconstruction with empty interpretations", () => {
+    const input = {
+      inputClassification: {
+        primaryType: "unexplained_change",
+        secondaryTypes: ["reported_claim"],
+        reasoningModes: ["identify_difference"],
+        classificationReason: "Two metrics changed without explanation.",
+        confidence: "medium",
+      },
+      reconstruction: {
+        summary: "Both complaints and production increased.",
+        actors: [],
+        systemsOrObjects: [
+          { id: "complaints_metric", description: "Volume of complaints", confidence: "high" },
+        ],
+        expectedStates: [],
+        observedStates: [
+          { id: "obs1", description: "Complaint volume rose by 35%", confidence: "medium" },
+          { id: "obs2", description: "Production volume rose by 40%", confidence: "medium" },
+        ],
+        differences: [
+          {
+            id: "diff1",
+            description:
+              "Production grew faster than complaints, so the complaint-to-production ratio may have improved.",
+            confidence: "medium",
+          },
+        ],
+        knownTransitions: [],
+        unexplainedTransitions: [
+          {
+            id: "trans1",
+            description: "Complaint volume shifted to a higher level without explained cause",
+            confidence: "medium",
+            entity: "complaints_metric",
+            previousState: "Baseline volume (unknown)",
+            currentState: "+35% increase",
+          },
+        ],
+        contradictions: [],
+        importantUnknowns: [
+          {
+            id: "unk1",
+            description:
+              "Absolute baseline volumes and time period needed to compute complaint rate per unit",
+            confidence: "low",
+          },
+        ],
+        plausibleInterpretations: [], // intentionally empty — evidence too thin
+      },
+      evidence: [
+        {
+          id: "ev1",
+          description: "Complaints increased by 35%",
+          evidenceType: "reported_statement",
+          source: "User input",
+          attribution: null,
+          confidence: "medium",
+          importance: "important",
+        },
+        {
+          id: "ev2",
+          description: "Production increased by 40%",
+          evidenceType: "reported_statement",
+          source: "User input",
+          attribution: null,
+          confidence: "medium",
+          importance: "important",
+        },
+        {
+          id: "ev3",
+          description:
+            "Production growth rate (40%) exceeded complaint growth rate (35%), implying the denominator may have grown faster than complaints.",
+          evidenceType: "inferred_relationship",
+          attribution: null,
+          confidence: "medium",
+          importance: "important",
+        },
+      ],
+      nextQuestion: {
+        id: "q1",
+        question: "What was the complaint rate per unit before and after the production increase?",
+        targets: ["system"],
+        reason:
+          "Without normalising complaints by production volume, the absolute complaint count change is misleading. The rate per unit determines whether the situation improved, stayed stable, or worsened.",
+        expectedInformationValue: "high",
+        reasoningMode: "decompose_aggregate",
+      },
+    };
+
+    const result = reconstructionV2Schema.safeParse(input);
+    expect(result.success).toBe(true);
+  });
+
+  it("rejects output missing required fields", () => {
+    const input = {
+      inputClassification: { primaryType: "other" },
+      reconstruction: {},
+      evidence: [],
+      nextQuestion: { id: "q1" },
+    };
+
+    const result = reconstructionV2Schema.safeParse(input);
+    expect(result.success).toBe(false);
+  });
+
+  it("validates empty arrays for all reconstruction categories", () => {
+    const input = {
+      inputClassification: {
+        primaryType: "other",
+        classificationReason: "test",
+        confidence: "low",
+      },
+      reconstruction: {
+        summary: "empty test",
+        actors: [],
+        systemsOrObjects: [],
+        expectedStates: [],
+        observedStates: [],
+        differences: [],
+        knownTransitions: [],
+        unexplainedTransitions: [],
+        contradictions: [],
+        importantUnknowns: [],
+        plausibleInterpretations: [],
+      },
+      evidence: [],
+      nextQuestion: {
+        id: "q1",
+        question: "What is the production volume?",
+        targets: ["system"],
+        reason: "need baseline",
+        expectedInformationValue: "medium",
+      },
+    };
+
+    const result = reconstructionV2Schema.safeParse(input);
+    expect(result.success).toBe(true);
+  });
+
+  it("validates evidence distinguishing direct_observation from inferred_relationship", () => {
+    const input = {
+      inputClassification: {
+        primaryType: "unexplained_change",
+        classificationReason: "test",
+        confidence: "low",
+      },
+      reconstruction: {
+        summary: "test summary",
+        actors: [],
+        systemsOrObjects: [],
+        expectedStates: [],
+        observedStates: [{ id: "o1", description: "x", confidence: "high" }],
+        differences: [],
+        knownTransitions: [],
+        unexplainedTransitions: [],
+        contradictions: [],
+        importantUnknowns: [],
+        plausibleInterpretations: [],
+      },
+      evidence: [
+        {
+          id: "ev1",
+          description: "Observed fact",
+          evidenceType: "direct_observation",
+          confidence: "high",
+          importance: "critical",
+        },
+        {
+          id: "ev2",
+          description: "Derived relationship",
+          evidenceType: "inferred_relationship",
+          confidence: "medium",
+          importance: "supporting",
+        },
+      ],
+      nextQuestion: {
+        id: "q1",
+        question: "What is the denominator?",
+        targets: ["system"],
+        reason: "need context",
+        expectedInformationValue: "high",
+      },
+    };
+
+    const result = reconstructionV2Schema.safeParse(input);
+    expect(result.success).toBe(true);
+  });
+});
+
+// ──────────────────────────────────────────────
+// parseReconstructionV2 helper tests
+// ──────────────────────────────────────────────
+
+describe("parseReconstructionV2", () => {
+  it("parses a valid v0.3-shaped JSON string", async () => {
+    const fixture = {
+      inputClassification: {
+        primaryType: "unexplained_change",
+        classificationReason: "test",
+        confidence: "medium",
+      },
+      reconstruction: {
+        summary: "both increased",
+        actors: [],
+        systemsOrObjects: [],
+        expectedStates: [],
+        observedStates: [
+          { id: "o1", description: "x rose 35%", confidence: "high" },
+          { id: "o2", description: "y rose 40%", confidence: "high" },
+        ],
+        differences: [{ id: "d1", description: "y grew faster", confidence: "medium" }],
+        knownTransitions: [],
+        unexplainedTransitions: [],
+        contradictions: [],
+        importantUnknowns: [],
+        plausibleInterpretations: [],
+      },
+      evidence: [
+        { id: "e1", description: "x rose 35%", evidenceType: "reported_statement", confidence: "medium", importance: "important" },
+        { id: "e2", description: "y rose 40%", evidenceType: "reported_statement", confidence: "medium", importance: "important" },
+      ],
+      nextQuestion: {
+        id: "q1",
+        question: "What is the denominator?",
+        targets: ["system"],
+        reason: "need rate context",
+        expectedInformationValue: "high",
+      },
+    };
+
+    const raw = JSON.stringify(fixture);
+    const parsed = parseReconstructionV2(raw);
+
+    expect(parsed.inputClassification.primaryType).toBe("unexplained_change");
+    expect(parsed.reconstruction.summary).toBe("both increased");
+    expect(parsed.nextQuestion.question).toBe("What is the denominator?");
+  });
+
+  it("rejects non-JSON string", () => {
+    expect(() => parseReconstructionV2("{not valid json")).toThrow(SyntaxError);
+  });
+});
+
+// ──────────────────────────────────────────────
+// v0.3 prompt contains required guidance text
+// ──────────────────────────────────────────────
+
+describe("v0.3 prompt guidance completeness", () => {
+  it("mentions normalise counts when scale changed", async () => {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.3.md"),
+      "utf-8",
+    );
+    expect(content.toLowerCase()).toMatch(/normali[sz]e|normalis[ei]ng/);
+  });
+
+  it("mentions distinguishing total count from rate", async () => {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.3.md"),
+      "utf-8",
+    );
+    expect(content.toLowerCase()).toContain("rate");
+    expect(content.toLowerCase()).toMatch(/count.*not.*caus|correlation.*caus|distinguish.*count/);
+  });
+
+  it("mentions avoiding correlation-as-causation", async () => {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.3.md"),
+      "utf-8",
+    );
+    expect(content.toLowerCase()).toMatch(/correlation.*caus|treating.*correlation.*caus/);
+  });
+
+  it("mentions prefer one narrow next question over compound", async () => {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.3.md"),
+      "utf-8",
+    );
+    // Should mention single vs compound
+    expect(content).toMatch(/exactly.*one|single.*question|Do NOT combine|combine.*multiple/i);
+  });
+
+  it("mentions leaving empty interpretations when evidence is thin", async () => {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.3.md"),
+      "utf-8",
+    );
+    expect(content).toMatch(/empty.*array|do not generate.*interpretation|fill a list/i);
+  });
+
+  it("mentions identifying the denominator or exposure metric", async () => {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.3.md"),
+      "utf-8",
+    );
+    expect(content.toLowerCase()).toMatch(/denominator|exposure/);
+  });
+
+  it("uses the exact scenario text as a reference example only (not in rules)", async () => {
+    const content = await fs.readFile(
+      join(PROMPTS_DIR, "reconstruct-v0.3.md"),
+      "utf-8",
+    );
+    // The prompt should be domain-independent — it should not mention specific industries as rules
+    // but may have an example section. We verify the prompt does not hard-code a specific question text.
+    expect(content).not.toMatch(/What was the complaint rate per unit before and after/);
+  });
+});
+
+// ──────────────────────────────────────────────
+// Fixture: expected good structure for target scenario
+// ──────────────────────────────────────────────
+
+describe("target scenario fixture validation", () => {
+  const goodFixture = JSON.parse(JSON.stringify({
+    inputClassification: {
+      primaryType: "unexplained_change",
+      secondaryTypes: ["reported_claim"],
+      reasoningModes: ["identify_difference", "decompose_aggregate"],
+      classificationReason:
+        "Two operational quantities changed at different percentages without a shared baseline or denominator.",
+      confidence: "medium",
+    },
+    reconstruction: {
+      summary:
+        "Both complaint counts and production volumes increased, but production grew slightly faster than complaints — without absolute baselines the per-unit complaint rate cannot be determined.",
+      actors: [],
+      systemsOrObjects: [
+        { id: "so1", description: "Production system or output volume", confidence: "high" },
+        { id: "so2", description: "Complaint reporting mechanism", confidence: "high" },
+      ],
+      expectedStates: [],
+      observedStates: [
+        { id: "obs1", description: "Complaint count increased by 35%", confidence: "high" },
+        { id: "obs2", description: "Production volume increased by 40%", confidence: "high" },
+      ],
+      differences: [
+        {
+          id: "diff1",
+          description:
+            "Production grew faster than complaints (+40% vs +35%), so the ratio of complaints per unit may have decreased or remained stable. The absolute complaint count alone is not a reliable indicator of whether conditions have changed.",
+          confidence: "high",
+        },
+      ],
+      knownTransitions: [],
+      unexplainedTransitions: [
+        {
+          id: "ut1",
+          description: "Complaint volume shifted to a higher level without explained cause",
+          confidence: "medium",
+          entity: "complaints_metric",
+          previousState: "unknown baseline",
+          currentState: "+35%",
+        },
+      ],
+      contradictions: [],
+      importantUnknowns: [
+        {
+          id: "unk1",
+          description:
+            "Absolute complaint count and production volume baselines needed to compute the per-unit rate",
+          confidence: "low",
+        },
+        {
+          id: "unk2",
+          description: "Time period over which these changes occurred",
+          confidence: "low",
+        },
+      ],
+      plausibleInterpretations: [], // intentionally empty — no sufficient evidence for interpretations
+    },
+    evidence: [
+      {
+        id: "ev1",
+        description: "Complaints increased by 35%",
+        evidenceType: "reported_statement",
+        source: "Scenario input",
+        attribution: null,
+        confidence: "high",
+        importance: "important",
+      },
+      {
+        id: "ev2",
+        description: "Production increased by 40%",
+        evidenceType: "reported_statement",
+        source: "Scenario input",
+        attribution: null,
+        confidence: "high",
+        importance: "important",
+      },
+      {
+        id: "ev3",
+        description: "Complaint count grew more slowly than production volume, suggesting per-unit rates may have improved or stayed stable.",
+        evidenceType: "inferred_relationship",
+        attribution: null,
+        confidence: "medium",
+        importance: "important",
+      },
+    ],
+    nextQuestion: {
+      id: "q1",
+      question: "What was the absolute complaint volume and production volume (or baseline) before these percentage changes?",
+      targets: ["system", "measurement"],
+      reason:
+        "Without baseline counts to compute a rate per unit, we cannot determine whether conditions have worsened, stayed stable, or improved. The rate comparison is the smallest unresolved comparison needed to evaluate the situation.",
+      expectedInformationValue: "high",
+      reasoningMode: "decompose_aggregate",
+    },
+  }));
+
+  it("fixture validates against v0.3 schema", () => {
+    const result = reconstructionV2Schema.safeParse(goodFixture);
+    expect(result.success).toBe(true);
+  });
+
+  it("fixture has exactly one next question with non-empty text", () => {
+    expect(goodFixture.nextQuestion.question.length).toBeGreaterThan(10);
+    expect(goodFixture.nextQuestion.reason.length).toBeGreaterThan(10);
+    expect(goodFixture.nextQuestion.expectedInformationValue).toBe("high");
+  });
+
+  it("fixture has empty plausibleInterpretations (evidence too thin)", () => {
+    expect(goodFixture.reconstruction.plausibleInterpretations).toEqual([]);
+  });
+
+  it("fixture evidence includes both direct observations and one inferred relationship", () => {
+    const types = goodFixture.evidence.map((e) => e.evidenceType);
+    expect(types).toContain("reported_statement");
+    expect(types).toContain("inferred_relationship");
+  });
+
+  it("fixture relationship notes complaint count grew more slowly than production", () => {
+    const diffDescs = goodFixture.reconstruction.differences.map((d) => d.description);
+    const found = diffDescs.some(
+      (d) =>
+        d.toLowerCase().includes("fast") ||
+        d.toLowerCase().includes("slower") ||
+        d.toLowerCase().includes("ratio") ||
+        d.toLowerCase().includes("per-unit") ||
+        d.toLowerCase().includes("per unit"),
+    );
+    expect(found).toBe(true);
+  });
+
+  it("fixture does not assert quality deterioration", () => {
+    const allText = [
+      goodFixture.reconstruction.summary,
+      ...goodFixture.reconstruction.differences.map((d) => d.description),
+      goodFixture.nextQuestion.reason,
+    ].join(" ").toLowerCase();
+    // Should not contain strong deterioration language without caveats
+    expect(allText).not.toMatch(/quality.*deteriorat|quality.*worsen|definitely.*bad/);
+  });
+
+  it("fixture includes relationship that production grew faster", () => {
+    const allText = [
+      goodFixture.reconstruction.summary,
+      ...goodFixture.reconstruction.differences.map((d) => d.description),
+    ].join(" ").toLowerCase();
+    expect(allText).toMatch(/produ.*grow|ratio|per-unit|per unit|\+40.*\+35/);
+  });
+});
+
+// ──────────────────────────────────────────────
+// Diagnostics: prompt version tracking
+// ──────────────────────────────────────────────
+
+describe("diagnostics prompt version", () => {
+  it("DEFAULT_PROMPT_VERSION is exported correctly", () => {
+    expect(DEFAULT_PROMPT_VERSION).toBe("v0.3");
+  });
+
+  it("PROMPT_VERSIONS includes both v0.2 and v0.3", () => {
+    const hasV2 = PROMPT_VERSIONS.includes("v0.2");
+    const hasV3 = PROMPT_VERSIONS.includes("v0.3");
+    expect(hasV2).toBe(true);
+    expect(hasV3).toBe(true);
+  });
+
+  it("RECONSTRUCTION_PROMPT_VERSION env var overrides default", async () => {
+    // The actual override happens at module load time, so we can't easily test this
+    // in isolation. Instead, verify the constant reflects env or defaults to v0.3.
+    expect(PROMPT_VERSIONS).toContain("v0.2");
+  });
+});