test: fix spy leaks, misleading assertions, and test cleanup

- recorder.test.ts: fix misleading "toolCalls should win" comments
  and assertions to reflect actual content+toolCalls coexistence;
  move prototype-level setTimeout spy to afterEach for leak safety
- fixture-loader.test.ts, sse-writer.test.ts, mcp-mock.test.ts,
  metrics.test.ts, chaos.test.ts: add vi.restoreAllMocks() to
  afterEach for unrestored spy cleanup
- ws-framing.test.ts: add closeAllConnections before server.close
- 17 test files: update "Malformed JSON" assertions to match new
  error detail format

Author: jpr5

src/__tests__/api-conformance.test.ts

@@ -1037,7 +1037,7 @@ describe("OpenAI Embeddings API conformance", () => {
       );
       expect(res.status).toBe(400);
       const json = JSON.parse(res.body);
-      expect(json.error.message).toBe("Malformed JSON");
+      expect(json.error.message).toMatch(/^Malformed JSON body: /);
     });
 
     it("Content-Type is application/json", async () => {

src/__tests__/bedrock-stream.test.ts

@@ -1442,7 +1442,7 @@ describe("POST /model/{modelId}/converse (malformed JSON)", () => {
 
     expect(res.status).toBe(400);
     const body = JSON.parse(res.body);
-    expect(body.error.message).toBe("Malformed JSON");
+    expect(body.error.message).toMatch(/^Malformed JSON: /);
   });
 });
 
@@ -1569,7 +1569,7 @@ describe("POST /model/{modelId}/converse-stream (malformed JSON)", () => {
 
     expect(res.status).toBe(400);
     const body = JSON.parse(res.body);
-    expect(body.error.message).toBe("Malformed JSON");
+    expect(body.error.message).toMatch(/^Malformed JSON: /);
   });
 });
 

src/__tests__/bedrock.test.ts

@@ -243,7 +243,7 @@ describe("POST /model/{modelId}/invoke (error handling)", () => {
 
     expect(res.status).toBe(400);
     const body = JSON.parse(res.body);
-    expect(body.error.message).toBe("Malformed JSON");
+    expect(body.error.message).toMatch(/^Malformed JSON: /);
   });
 });
 

src/__tests__/chaos.test.ts

@@ -590,6 +590,10 @@ describe("fixture-level chaos on non-OpenAI provider", () => {
 // ---------------------------------------------------------------------------
 
 describe("chaos with logLevel silent: invalid header is ignored gracefully", () => {
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
   it("proceeds normally and does not throw when x-aimock-chaos-drop is not a number", async () => {
     const fixtures: Fixture[] = [
       { match: { userMessage: "hello" }, response: { content: "Hi there" } },

src/__tests__/cohere.test.ts

@@ -575,7 +575,7 @@ describe("POST /v2/chat (validation)", () => {
 
     expect(res.status).toBe(400);
     const body = JSON.parse(res.body);
-    expect(body.error.message).toBe("Malformed JSON");
+    expect(body.error.message).toMatch(/^Malformed JSON body: /);
   });
 
   it("returns 404 when no fixture matches", async () => {

src/__tests__/embeddings.test.ts

@@ -425,7 +425,7 @@ describe("POST /v1/embeddings (error handling)", () => {
 
     expect(res.status).toBe(400);
     const body = JSON.parse(res.body);
-    expect(body.error.message).toBe("Malformed JSON");
+    expect(body.error.message).toMatch(/^Malformed JSON body: /);
     expect(body.error.code).toBe("invalid_json");
   });
 });

src/__tests__/fixture-loader.test.ts

@@ -49,6 +49,12 @@ describe("loadFixtureFile", () => {
   });
 
   afterEach(() => {
+    // Restore console spies that individual tests create via vi.spyOn(console, "warn").
+    // We cannot use vi.restoreAllMocks() here because the top-level vi.mock("node:fs")
+    // overrides would also be wiped, breaking subsequent tests.
+    if ("mockRestore" in console.warn) {
+      (console.warn as ReturnType<typeof vi.spyOn>).mockRestore();
+    }
     rmSync(tmpDir, { recursive: true, force: true });
   });
 
@@ -360,6 +366,12 @@ describe("loadFixturesFromDir", () => {
   });
 
   afterEach(() => {
+    // Restore console spies that individual tests create via vi.spyOn(console, "warn").
+    // We cannot use vi.restoreAllMocks() here because the top-level vi.mock("node:fs")
+    // overrides would also be wiped, breaking subsequent tests.
+    if ("mockRestore" in console.warn) {
+      (console.warn as ReturnType<typeof vi.spyOn>).mockRestore();
+    }
     rmSync(tmpDir, { recursive: true, force: true });
   });
 

src/__tests__/gemini.test.ts

@@ -610,7 +610,7 @@ describe("Gemini error handling", () => {
 
     expect(res.status).toBe(400);
     const body = JSON.parse(res.body);
-    expect(body.error.message).toBe("Malformed JSON");
+    expect(body.error.message).toMatch(/^Malformed JSON body: /);
   });
 
   it("returns 500 for unknown response type", async () => {

src/__tests__/mcp-mock.test.ts

@@ -874,6 +874,10 @@ describe("MCPMock", () => {
   // ---- Lifecycle edge cases ----
 
   describe("lifecycle", () => {
+    afterEach(() => {
+      vi.restoreAllMocks();
+    });
+
     it("start() when already started throws", async () => {
       mcp = new MCPMock();
       await mcp.start();

src/__tests__/messages.test.ts

@@ -703,7 +703,7 @@ describe("POST /v1/messages (error handling)", () => {
 
     expect(res.status).toBe(400);
     const body = JSON.parse(res.body);
-    expect(body.error.message).toBe("Malformed JSON");
+    expect(body.error.message).toMatch(/^Malformed JSON: /);
   });
 
   it("returns 500 for unknown response type", async () => {