feat(S-103): Test-drive and implement --debug diagnostic mode

tools/ai-cli-dispatch/tests/execute.test.ts

@@ -16,6 +16,7 @@ interface MockScenario {
 
 function createMockChildProcess(scenario: MockScenario): any {
   const child = new EventEmitter() as any;
+  child.pid = 12345;
   child.stdout = Readable.from(
     scenario.stdout !== undefined ? [scenario.stdout] : []
   );
@@ -257,4 +258,66 @@ describe("executePrompt", () => {
       global.setTimeout = origSetTimeout;
     }
   });
+
+  it("emits debug info via onDebug when debug is true for successful execution", async () => {
+    const scenarios = new Map<string, MockScenario>([
+      ["codex exec --yolo hello", { stdout: "ok", stderr: "warn", exitCode: 0 }],
+    ]);
+    const debugInfos: any[] = [];
+    const result = await executePrompt("codex", "hello", {
+      spawn: mockSpawn(scenarios),
+      existsSync: () => true,
+      debug: true,
+      onDebug: (info) => debugInfos.push(info),
+    });
+    assert.strictEqual(result.exitCode, 0);
+    assert.strictEqual(debugInfos.length, 1);
+    const info = debugInfos[0];
+    assert.strictEqual(info.command, "codex");
+    assert.deepStrictEqual(info.args, ["exec", "--yolo", "hello"]);
+    assert.strictEqual(info.pid, 12345);
+    assert.strictEqual(info.exitCode, 0);
+    assert.strictEqual(info.exitSignal, null);
+    assert.strictEqual(info.stderrLength, 4);
+    assert.strictEqual(info.stdoutLength, 2);
+    assert.strictEqual(typeof info.durationMs, "number");
+    assert.ok(info.durationMs >= 0);
+  });
+
+  it("emits debug info via onDebug when debug is true for failed execution", async () => {
+    const scenarios = new Map<string, MockScenario>([
+      ["codex exec --yolo fail", { stdout: "", stderr: "error", exitCode: 1 }],
+    ]);
+    const debugInfos: any[] = [];
+    const result = await executePrompt("codex", "fail", {
+      spawn: mockSpawn(scenarios),
+      existsSync: () => true,
+      debug: true,
+      onDebug: (info) => debugInfos.push(info),
+    });
+    assert.strictEqual(result.exitCode, 1);
+    assert.strictEqual(debugInfos.length, 1);
+    assert.strictEqual(debugInfos[0].exitCode, 1);
+    assert.strictEqual(debugInfos[0].stderrLength, 5);
+    assert.strictEqual(debugInfos[0].stdoutLength, 0);
+  });
+
+  it("emits debug info via onDebug for spawn errors", async () => {
+    const scenarios = new Map<string, MockScenario>();
+    const debugInfos: any[] = [];
+    await assert.rejects(
+      executePrompt("codex", "hello", {
+        spawn: mockSpawn(scenarios),
+        existsSync: () => true,
+        debug: true,
+        onDebug: (info) => debugInfos.push(info),
+      }),
+      (err: unknown) => err instanceof ClientNotFoundError
+    );
+    assert.strictEqual(debugInfos.length, 1);
+    assert.strictEqual(debugInfos[0].command, "codex");
+    assert.deepStrictEqual(debugInfos[0].args, ["exec", "--yolo", "hello"]);
+    assert.strictEqual(debugInfos[0].exitCode, null);
+    assert.strictEqual(debugInfos[0].exitSignal, null);
+  });
 });