diff --git a/app/api/cases/start/route.js b/app/api/cases/start/route.js
index 278dbed..eccc915 100644
--- a/app/api/cases/start/route.js
+++ b/app/api/cases/start/route.js
@@ -23,6 +23,7 @@ export async function POST(request) {
         validationErrors: result.validationErrors,
         diagnostics: result.diagnostics,
         analysisErrors: result.analysisErrors,
+        validationIssues: result.validationIssues,
         rawResponse: result.rawResponse ?? undefined,
       },
       { status },
diff --git a/docs/current-handoff.md b/docs/current-handoff.md
index ea087de..69f8af9 100644
--- a/docs/current-handoff.md
+++ b/docs/current-handoff.md
@@ -45,6 +45,12 @@
 - The remaining semantic weakness was substitution: narrower decision prerequisites were preserved, but the full supplied intervention-fit dependency was not. v0.5 now requires preservation of the user's actual dependency level; narrower evidence prerequisites may coexist but may not replace that higher-order contingency.
 - No schema, builder, or orchestrator change was required. Deterministic tests prove this instruction exists only; live compliance remains untested. Next restart point: one live intervention-fit validation, followed by bounded repeatability if it passes.
 
+## Reconstruction validation failure observability
+
+- The latest one-call intervention-fit validation returned HTTP 502: a real structured-output product failure, so intervention-fit semantic compliance was not evaluable.
+- Previous diagnostics flattened the failure to `reconstruction: Required` and truncated raw evidence. Failure responses now retain exact validation issue paths, codes, messages, available native metadata, and complete diagnostic raw response at the existing validation boundary.
+- Reasoning prompt, schema acceptance, and provider behaviour remain unchanged; no live calls occurred in this increment. Next restart point: one production-default manufacturing call—evaluate E if it succeeds, or use the new evidence to diagnose the exact structured-output defect if it fails.
+
 ## Current product architecture
 
 Three distinct routes, not a single page:
diff --git a/lib/analysis.js b/lib/analysis.js
index 91cb295..945054d 100644
--- a/lib/analysis.js
+++ b/lib/analysis.js
@@ -91,7 +91,7 @@ export async function analyseScenario(scenario, opts = {}) {
   try {
     rawResponseStr = JSON.stringify(rawResponse);
   } catch {
-    rawResponseStr = String(rawResponse).slice(0, 2000);
+    rawResponseStr = String(rawResponse);
   }
 
   const compatibility = normaliseAnalysisResponse(rawResponse);
@@ -129,7 +129,7 @@ export async function analyseScenario(scenario, opts = {}) {
 
   // ── Neither schema matched — partial failure ───────
   return buildPartialResult(
-    rawResponseStr?.slice(0, 2000),
+    rawResponseStr,
     resultV2.error ?? resultV1.error,
     OLLAMA_MODEL,
     duration,
@@ -218,6 +218,7 @@ function buildPartialResult(
   compatibility,
 ) {
   let errors = [];
+  const validationIssues = error?.issues ?? [];
   if (error && typeof error.flatten === "function") {
     errors = error.flatten().fieldErrors
       ? Object.entries(error.flatten().fieldErrors).flatMap(([k, v]) => [
@@ -233,13 +234,14 @@ function buildPartialResult(
     validationStatus: "invalid",
     modelName: model,
     responseDurationMs: duration,
-    rawResponse: rawResp?.slice(0, 2000),
+    rawResponse: rawResp,
     promptVersion: version,
     inputClassification: null,
     reconstruction: null,
     evidence: undefined,
     nextQuestion: undefined,
     errors,
+    validationIssues,
     ...buildCompatibilityDiagnostics(compatibility),
   };
 }
diff --git a/lib/graph/orchestrator.js b/lib/graph/orchestrator.js
index 054a214..cf2eabc 100644
--- a/lib/graph/orchestrator.js
+++ b/lib/graph/orchestrator.js
@@ -371,6 +371,7 @@ export async function startCase(body, dependencies = {}) {
         graphReferenceValidation: null,
       }),
       analysisErrors: analysis.errors ?? undefined,
+      validationIssues: analysis.validationIssues ?? undefined,
       rawResponse: analysis.rawResponse ?? undefined,
       statusCode: Number(analysis.statusCode) || 502,
     };
diff --git a/tests/app/api/cases-start-route.test.js b/tests/app/api/cases-start-route.test.js
index 3d4b202..76d8651 100644
--- a/tests/app/api/cases-start-route.test.js
+++ b/tests/app/api/cases-start-route.test.js
@@ -105,12 +105,23 @@ describe("app/api/cases/start route", () => {
   });
 
   it("returns provider/internal failures as 5xx without stack traces", async () => {
+    const rawResponse = `{"reconstruction":{"observedStates":[{"id":"obs-1"${"x".repeat(2500)}}]}}`;
     mockStartCase.mockResolvedValue({
       success: false,
       error: "Provider unavailable",
       diagnostics: { modelName: "llama3" },
       statusCode: 502,
-      rawResponse: '{"reconstruction":{"summary":""}}',
+      analysisErrors: ["reconstruction: Required"],
+      validationIssues: [
+        {
+          path: ["reconstruction", "observedStates", 2, "description"],
+          code: "invalid_type",
+          message: "Required",
+          expected: "string",
+          received: "undefined",
+        },
+      ],
+      rawResponse,
     });
 
     const { POST } = await import("@/app/api/cases/start/route.js");
@@ -125,7 +136,18 @@ describe("app/api/cases/start route", () => {
     expect(response.status).toBe(502);
     const body = await response.json();
     expect(body).toHaveProperty("rawResponse");
-    expect(body.rawResponse).toBe('{"reconstruction":{"summary":""}}');
+    expect(body.rawResponse).toBe(rawResponse);
+    expect(body.rawResponse.length).toBeGreaterThan(2000);
+    expect(body.analysisErrors).toEqual(["reconstruction: Required"]);
+    expect(body.validationIssues).toEqual([
+      expect.objectContaining({
+        path: ["reconstruction", "observedStates", 2, "description"],
+        code: "invalid_type",
+        message: "Required",
+        expected: "string",
+        received: "undefined",
+      }),
+    ]);
   });
 
   it("returns structured 500 on malformed JSON", async () => {
diff --git a/tests/graph/orchestrator.test.js b/tests/graph/orchestrator.test.js
index 202d562..ce68038 100644
--- a/tests/graph/orchestrator.test.js
+++ b/tests/graph/orchestrator.test.js
@@ -536,6 +536,36 @@ describe("lib/graph/orchestrator startCase", () => {
     expect(result).toHaveProperty("rawResponse");
   });
 
+  it("preserves structured reconstruction validation issues on analysis failure", async () => {
+    const validationIssues = [
+      {
+        path: ["reconstruction", "observedStates", 2, "description"],
+        code: "invalid_type",
+        message: "Required",
+        expected: "string",
+        received: "undefined",
+      },
+    ];
+    mockAnalyseScenario.mockResolvedValue({
+      success: false,
+      error: "Scenario analysis failed",
+      errors: ["reconstruction: Required"],
+      validationIssues,
+      rawResponse: "x".repeat(2501),
+    });
+    const { startCase } = await import("@/lib/graph/orchestrator.js");
+
+    const result = await startCase({ scenario: "Scenario text" });
+
+    expect(result).toMatchObject({
+      success: false,
+      statusCode: 502,
+      analysisErrors: ["reconstruction: Required"],
+      validationIssues,
+    });
+    expect(result.rawResponse).toHaveLength(2501);
+  });
+
   it("returns null selectedQuestion when neither analysis nor graph path yields a question", async () => {
     mockAnalyseScenario.mockResolvedValue(
       makeAnalysisResult({
diff --git a/tests/reconstruction/compatibility.test.js b/tests/reconstruction/compatibility.test.js
index 36f1c80..1c59490 100644
--- a/tests/reconstruction/compatibility.test.js
+++ b/tests/reconstruction/compatibility.test.js
@@ -192,6 +192,54 @@ describe("analyseScenario compatibility", () => {
     expect(result.nextQuestion).toBeUndefined();
   });
 
+  it("preserves nested validation issues and complete raw output on reconstruction failure", async () => {
+    mockGenerateReconstruction.mockResolvedValue({
+      inputClassification: {
+        primaryType: "unexplained_change",
+        secondaryTypes: [],
+        reasoningModes: [],
+        classificationReason: "reason",
+        confidence: "medium",
+      },
+      reconstruction: {
+        summary: "summary",
+        actors: [],
+        systemsOrObjects: [],
+        expectedStates: [],
+        observedStates: [{ id: "obs-1", confidence: "high" }],
+        differences: [],
+        knownTransitions: [],
+        unexplainedTransitions: [],
+        contradictions: [],
+        importantUnknowns: [],
+        plausibleInterpretations: [],
+        padding: "x".repeat(2500),
+      },
+      evidence: [],
+      nextQuestion: {
+        id: "q1",
+        question: "What changed?",
+        targets: [],
+        reason: "reason",
+        expectedInformationValue: "high",
+      },
+    });
+
+    const { analyseScenario } = await import("@/lib/analysis.js");
+    const result = await analyseScenario("Scenario text", {
+      promptVersion: "v0.3",
+    });
+
+    expect(result.success).toBe(false);
+    expect(result.rawResponse.length).toBeGreaterThan(2000);
+    expect(result.validationIssues).toContainEqual(expect.objectContaining({
+      path: ["reconstruction", "observedStates", 0, "description"],
+      code: "invalid_type",
+      message: "Required",
+    }));
+    expect(result.errors).toContain("reconstruction: Required");
+  });
+
   it("succeeds when reported_claim is the only evidenceType mismatch", async () => {
     mockGenerateReconstruction.mockResolvedValue({
       inputClassification: {