fix(confidence-engine): expose reconstruction validation issues

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 () => {