feat: prioritise follow-up questions by information value

lib/graph/apply-proposal.js

@@ -2,8 +2,10 @@ import { describeGraph } from "./builder.js";
 import { graphUpdateSchema, situationGraphSchema } from "./schema.js";
 import {
   applyGraphUpdate,
+  buildDeterministicQuestionForUnknown,
   detectDuplicateNodeIds,
   findAffectedNodes,
+  scoreUnknownCandidate,
   selectActiveUnknownCandidate,
   validateGraphReferences,
   validateGraphUpdate,
@@ -195,6 +197,20 @@ function validateSelectedQuestion(graph, proposal) {
     errors.push("selectedQuestion must be a single non-compound question");
   }
 
+  const resolvedNodeIds = [
+    ...(graph.resolvedNodeIds || []),
+    ...(proposal.resolvedUnknownNodeIds || []),
+  ];
+  const candidateScore = scoreUnknownCandidate(
+    {
+      ...graph,
+      nodes: [...graph.nodes, ...(proposal.addedNodes || [])],
+      edges: [...graph.edges, ...(proposal.addedEdges || [])],
+    },
+    node,
+    resolvedNodeIds,
+  );
+
   return { errors, selectedQuestionNodeId: selectedQuestion.nodeId };
 }
 
@@ -571,22 +587,32 @@ export function applyValidatedProposal({ situationGraph, proposal }) {
       )?.nodeId ?? null;
   }
 
-  if (
-    validatedProposal.selectedQuestion?.nodeId &&
-    newActiveUnknownNodeId !== validatedProposal.selectedQuestion.nodeId
-  ) {
-    return {
-      success: false,
-      stage: "proposal_compatibility",
-      errors: [
-        `activeUnknownNodeId and selectedQuestion.nodeId disagree: "${newActiveUnknownNodeId}" vs "${validatedProposal.selectedQuestion.nodeId}"`,
-      ],
-    };
+  const deterministicSelection = selectActiveUnknownCandidate(
+    updatedSituationGraph,
+    updatedSituationGraph.resolvedNodeIds,
+  );
+
+  if (deterministicSelection?.nodeId) {
+    newActiveUnknownNodeId = deterministicSelection.nodeId;
   }
 
   updatedSituationGraph.activeUnknownNodeId = newActiveUnknownNodeId;
   updatedSituationGraph.currentSummary = describeGraph(updatedSituationGraph);
 
+  const finalSelectedQuestion = deterministicSelection
+    ? {
+        nodeId: deterministicSelection.nodeId,
+        question:
+          deterministicSelection.question ||
+          buildDeterministicQuestionForUnknown(
+            updatedSituationGraph.nodes.find(
+              (node) => node.id === deterministicSelection.nodeId,
+            ),
+          ),
+        reason: deterministicSelection.reason,
+      }
+    : null;
+
   const resultGraphValidation = situationGraphSchema.safeParse(
     updatedSituationGraph,
   );
@@ -636,7 +662,7 @@ export function applyValidatedProposal({ situationGraph, proposal }) {
     resolvedUnknownNodeIds: validatedProposal.resolvedUnknownNodeIds,
     previousActiveUnknownNodeId,
     newActiveUnknownNodeId,
-    selectedQuestion: validatedProposal.selectedQuestion,
+    selectedQuestion: finalSelectedQuestion,
     changesApplied: buildChangesApplied(validatedProposal, affectedNodeIds),
     graphReferenceValidation: resultReferenceValidation,
   };