fix(confidence-engine): log case-start failures

app/api/cases/start/route.js

@@ -16,10 +16,25 @@ export async function POST(request) {
           ? result.statusCode
           : 500;
 
+    const diagnostics = {
+      status,
+      error: result.error ?? "Start case failed",
+      validationErrors: result.validationErrors,
+      analysisErrors: result.analysisErrors,
+      validationIssues: result.validationIssues,
+      rawResponse: result.rawResponse ?? undefined,
+    };
+
+    if (status >= 500) {
+      console.error("[api/cases/start] error response", diagnostics);
+    } else {
+      console.warn("[api/cases/start] error response", diagnostics);
+    }
+
     return Response.json(
       {
         success: false,
-        error: result.error ?? "Start case failed",
+        error: diagnostics.error,
         validationErrors: result.validationErrors,
         diagnostics: result.diagnostics,
         analysisErrors: result.analysisErrors,
@@ -28,7 +43,12 @@ export async function POST(request) {
       },
       { status },
     );
-  } catch {
+  } catch (error) {
+    console.error("[api/cases/start] unhandled exception", {
+      message: error instanceof Error ? error.message : String(error),
+      stack: error instanceof Error ? error.stack : undefined,
+      error,
+    });
     return Response.json(
       {
         success: false,

docs/current-handoff.md

@@ -57,6 +57,12 @@
 - This is a generation-time relationship-reference integrity defect. v0.5 now requires semantic units before relationships and exact reuse of emitted endpoint IDs; legitimate missing endpoint concepts must be materialised first under existing provenance rules.
 - The builder remains unchanged. Live compliance remains untested; next restart point is one production-default relationship-reference-integrity validation.
 
+## Case-start error logging
+
+- The latest live validation was blocked by an HTTP 500 route-level exception with generic client output. `/api/cases/start` now writes structured Next.js server-console diagnostics for every route-owned error response: 4xx at warning level and 5xx/502 at error level.
+- Caught exceptions log their actual exception, message, and stack while the client response remains generic; successful responses are not logged. No reasoning, status, or response semantics changed.
+- Next restart point: one production-default manufacturing call while observing the Next.js dev-server terminal.
+
 ## Current product architecture
 
 Three distinct routes, not a single page:

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

@@ -1,6 +1,8 @@
-import { beforeEach, describe, expect, it, vi } from "vitest";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 
 const mockStartCase = vi.fn();
+let warnSpy;
+let errorSpy;
 
 vi.mock("@/lib/graph/orchestrator.js", () => ({
   startCase: (...args) => mockStartCase(...args),
@@ -10,6 +12,13 @@ describe("app/api/cases/start route", () => {
   beforeEach(() => {
     vi.resetModules();
     vi.clearAllMocks();
+    warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
+    errorSpy = vi.spyOn(console, "error").mockImplementation(() => {});
+  });
+
+  afterEach(() => {
+    warnSpy.mockRestore();
+    errorSpy.mockRestore();
   });
 
   it("delegates request body to the orchestrator", async () => {
@@ -78,6 +87,8 @@ describe("app/api/cases/start route", () => {
       success: true,
       reconstruction,
     });
+    expect(warnSpy).not.toHaveBeenCalled();
+    expect(errorSpy).not.toHaveBeenCalled();
   });
 
   it("returns 400 for invalid request input", async () => {
@@ -102,6 +113,12 @@ describe("app/api/cases/start route", () => {
       success: false,
       error: "Invalid start-case request",
     });
+    expect(warnSpy).toHaveBeenCalledTimes(1);
+    expect(warnSpy).toHaveBeenCalledWith(
+      "[api/cases/start] error response",
+      expect.objectContaining({ status: 400, error: "Invalid start-case request" }),
+    );
+    expect(errorSpy).not.toHaveBeenCalled();
   });
 
   it("returns provider/internal failures as 5xx without stack traces", async () => {
@@ -148,6 +165,18 @@ describe("app/api/cases/start route", () => {
         received: "undefined",
       }),
     ]);
+    expect(errorSpy).toHaveBeenCalledTimes(1);
+    expect(errorSpy).toHaveBeenCalledWith(
+      "[api/cases/start] error response",
+      expect.objectContaining({
+        status: 502,
+        error: "Provider unavailable",
+        analysisErrors: ["reconstruction: Required"],
+        validationIssues: expect.any(Array),
+        rawResponse,
+      }),
+    );
+    expect(warnSpy).not.toHaveBeenCalled();
   });
 
   it("returns structured 500 on malformed JSON", async () => {
@@ -163,5 +192,13 @@ describe("app/api/cases/start route", () => {
       success: false,
       error: "Internal server error",
     });
+    expect(errorSpy).toHaveBeenCalledWith(
+      "[api/cases/start] unhandled exception",
+      expect.objectContaining({
+        message: "Unexpected token",
+        stack: expect.any(String),
+        error: expect.any(Error),
+      }),
+    );
   });
 });