diff --git a/tools/ai-cli-dispatch/src/cli.ts b/tools/ai-cli-dispatch/src/cli.ts
index 32ec4cd..5be1ef3 100644
--- a/tools/ai-cli-dispatch/src/cli.ts
+++ b/tools/ai-cli-dispatch/src/cli.ts
@@ -8,6 +8,7 @@ import {
   type ClientName,
   type ClientInfo,
   type ExecResult,
+  type DebugInfo,
   ClientNotFoundError,
 } from "./types.js";
 
@@ -15,13 +16,14 @@ export interface CliDeps {
   detectClients?: () => ClientInfo[];
   executePrompt?: (
     client: ClientName,
-    prompt: string
+    prompt: string,
+    options?: { timeoutMs?: number; debug?: boolean; onDebug?: (info: DebugInfo) => void }
   ) => Promise<ExecResult>;
   resolveClient?: (
     prompt: string,
     config?: { client?: ClientName; defaultClient?: ClientName }
   ) => ClientName | null;
-  resolveConfig?: () => { paths: Partial<Record<ClientName, string>>; defaultClient?: ClientName };
+  resolveConfig?: () => { paths: Partial<Record<ClientName, string>>; defaultClient?: ClientName; timeout?: number };
   stdoutWrite?: (chunk: string) => void;
   stderrWrite?: (chunk: string) => void;
 }
@@ -54,12 +56,13 @@ export async function main(
     rawArgs[0]?.includes("cli.ts") ? rawArgs.slice(1) : rawArgs;
 
   const args = minimist(parseArgs, {
-    string: ["client", "prompt"],
+    string: ["client", "prompt", "timeout"],
     boolean: ["json", "text", "help", "debug"],
     alias: { h: "help" },
   });
 
   const jsonMode = !args.text;
+  const debug = !!args.debug;
 
   if (args.help) {
     printHelp();
@@ -114,8 +117,18 @@ export async function main(
       return 1;
     }
 
+    const config = resolveConfig();
+    const parsedTimeout =
+      typeof args.timeout === "string" ? Number(args.timeout) : undefined;
+    const timeoutMs =
+      Number.isFinite(parsedTimeout) ? parsedTimeout : config.timeout;
+
     try {
-      const result = await executePrompt(client, prompt);
+      const result = await executePrompt(client, prompt, {
+        timeoutMs,
+        debug,
+        onDebug: debug ? (info) => stderrWrite(JSON.stringify(info) + "\n") : undefined,
+      });
       if (jsonMode) {
         console.log(JSON.stringify(result, null, 2));
       } else {
@@ -167,8 +180,17 @@ export async function main(
       return 1;
     }
 
+    const parsedTimeout =
+      typeof args.timeout === "string" ? Number(args.timeout) : undefined;
+    const timeoutMs =
+      Number.isFinite(parsedTimeout) ? parsedTimeout : config.timeout;
+
     try {
-      const result = await executePrompt(client, prompt);
+      const result = await executePrompt(client, prompt, {
+        timeoutMs,
+        debug,
+        onDebug: debug ? (info) => stderrWrite(JSON.stringify(info) + "\n") : undefined,
+      });
       if (jsonMode) {
         console.log(JSON.stringify(result, null, 2));
       } else {
diff --git a/tools/ai-cli-dispatch/src/config.ts b/tools/ai-cli-dispatch/src/config.ts
index 6fd1c15..8c0365c 100644
--- a/tools/ai-cli-dispatch/src/config.ts
+++ b/tools/ai-cli-dispatch/src/config.ts
@@ -10,6 +10,7 @@ import { CLIENT_NAMES, isWindows } from "./constants.js";
 export interface ResolvedConfig {
   paths: Partial<Record<ClientName, string>>;
   defaultClient?: ClientName;
+  timeout?: number;
 }
 
 export interface ResolveConfigOptions {
@@ -89,5 +90,22 @@ export function resolveConfig(
   ) {
     result.defaultClient = defaultClient as ClientName;
   }
+
+  const flagTimeout =
+    typeof flags.timeout === "string" ? Number(flags.timeout) : undefined;
+  const envTimeout =
+    typeof env.AI_CLI_TIMEOUT === "string"
+      ? Number(env.AI_CLI_TIMEOUT)
+      : undefined;
+  const fileTimeout =
+    typeof fileConfig.timeout === "number" ? fileConfig.timeout : undefined;
+
+  const resolvedTimeout =
+    (Number.isFinite(flagTimeout) ? flagTimeout : undefined) ??
+    (Number.isFinite(envTimeout) ? envTimeout : undefined) ??
+    (Number.isFinite(fileTimeout) ? fileTimeout : undefined) ??
+    600_000;
+
+  result.timeout = resolvedTimeout;
   return result;
 }
diff --git a/tools/ai-cli-dispatch/src/dispatch.ts b/tools/ai-cli-dispatch/src/dispatch.ts
index 9bc2a4c..3c2c6a2 100644
--- a/tools/ai-cli-dispatch/src/dispatch.ts
+++ b/tools/ai-cli-dispatch/src/dispatch.ts
@@ -1,3 +1,4 @@
+import { CLIENT_NAMES } from "./constants.js";
 import type { ClientName } from "./types.js";
 
 export interface DispatchConfig {
@@ -5,8 +6,6 @@ export interface DispatchConfig {
   client?: ClientName;
 }
 
-const CLIENT_NAMES: ClientName[] = ["codex", "claude", "opencode"];
-
 export function resolveClient(
   prompt: string,
   config?: DispatchConfig
diff --git a/tools/ai-cli-dispatch/src/execute.ts b/tools/ai-cli-dispatch/src/execute.ts
index 010fcf8..b443e6a 100644
--- a/tools/ai-cli-dispatch/src/execute.ts
+++ b/tools/ai-cli-dispatch/src/execute.ts
@@ -2,7 +2,7 @@ import type { ChildProcess } from "node:child_process";
 import { spawn as defaultSpawn } from "node:child_process";
 import type { PathLike } from "node:fs";
 import { existsSync as defaultExistsSync } from "node:fs";
-import type { ClientName, ExecResult } from "./types.js";
+import type { ClientName, ExecResult, DebugInfo } from "./types.js";
 import { ClientNotFoundError, ExecError } from "./types.js";
 
 const CLIENT_ARGS: Record<ClientName, (prompt: string) => string[]> = {
@@ -14,6 +14,8 @@ const CLIENT_ARGS: Record<ClientName, (prompt: string) => string[]> = {
 export interface ExecuteOptions {
   clientPath?: string;
   timeoutMs?: number;
+  debug?: boolean;
+  onDebug?: (info: DebugInfo) => void;
   spawn?: (command: string, args: string[], options?: { shell?: boolean }) => ChildProcess;
   existsSync?: (path: PathLike) => boolean;
 }
@@ -28,12 +30,14 @@ export async function executePrompt(
       stdout: "",
       stderr: "",
       exitCode: -1,
+      client,
+      durationMs: 0,
     });
   }
 
   const spawnImpl = options.spawn ?? defaultSpawn;
   const existsSyncImpl = options.existsSync ?? defaultExistsSync;
-  const timeoutMs = options.timeoutMs ?? 300_000;
+  const timeoutMs = options.timeoutMs ?? 600_000;
 
   const command = options.clientPath ?? client;
   if (options.clientPath && !existsSyncImpl(options.clientPath)) {
@@ -46,6 +50,8 @@ export async function executePrompt(
       stdout: "",
       stderr: "",
       exitCode: -1,
+      client,
+      durationMs: 0,
     });
   }
   const args = argBuilder(prompt);
@@ -55,6 +61,8 @@ export async function executePrompt(
     let timedOut = false;
     let stdout = "";
     let stderr = "";
+    let exitSignal: NodeJS.Signals | null = null;
+    const startMs = Date.now();
 
     const child = spawnImpl(command, args, {
       shell: false,
@@ -80,8 +88,31 @@ export async function executePrompt(
       if (settled) return;
       settled = true;
       clearTimeout(timeout);
-      if (err) reject(err);
-      else resolve(result!);
+      const durationMs = Date.now() - startMs;
+      if (options.debug || options.onDebug) {
+        const effectiveExitCode = result?.exitCode ?? (err instanceof ExecError ? err.result.exitCode : null);
+        const debugInfo: DebugInfo = {
+          command,
+          args,
+          pid: child.pid ?? undefined,
+          exitCode: effectiveExitCode,
+          exitSignal,
+          durationMs,
+          stderrLength: stderr.length,
+          stdoutLength: stdout.length,
+          noisySuccess: effectiveExitCode === 0 && stderr.length > 0,
+        };
+        options.onDebug?.(debugInfo);
+      }
+      if (err) {
+        if (err instanceof ExecError) {
+          err.result.client = client;
+          err.result.durationMs = durationMs;
+        }
+        reject(err);
+      } else {
+        resolve({ ...result!, client, durationMs });
+      }
     }
 
     child.on("error", (err: NodeJS.ErrnoException) => {
@@ -89,22 +120,25 @@ export async function executePrompt(
         settle(new ClientNotFoundError(client));
       } else {
         settle(
-          new ExecError(err.message, { stdout, stderr, exitCode: -1 })
+          new ExecError(err.message, { stdout, stderr, exitCode: -1, client, durationMs: 0 })
         );
       }
     });
 
-    child.on("close", (code: number | null) => {
+    child.on("close", (code: number | null, signal: NodeJS.Signals | null) => {
+      exitSignal = signal;
       if (timedOut) {
         settle(
           new ExecError(`Execution timed out after ${timeoutMs}ms`, {
             stdout,
             stderr,
             exitCode: -1,
+            client,
+            durationMs: 0,
           })
         );
       } else {
-        settle(undefined, { stdout, stderr, exitCode: code ?? -1 });
+        settle(undefined, { stdout, stderr, exitCode: code ?? -1, client, durationMs: 0 });
       }
     });
   });
diff --git a/tools/ai-cli-dispatch/src/types.ts b/tools/ai-cli-dispatch/src/types.ts
index 3338814..0bf167d 100644
--- a/tools/ai-cli-dispatch/src/types.ts
+++ b/tools/ai-cli-dispatch/src/types.ts
@@ -11,11 +11,20 @@ export interface ExecResult {
   stdout: string;
   stderr: string;
   exitCode: number;
+  client: ClientName;
+  durationMs: number;
 }
 
-export interface ToolConfig {
-  clients: ClientName[];
-  defaultClient?: ClientName;
+export interface DebugInfo {
+  command: string;
+  args: string[];
+  pid?: number;
+  exitCode: number | null;
+  exitSignal: NodeJS.Signals | null;
+  durationMs: number;
+  stderrLength: number;
+  stdoutLength: number;
+  noisySuccess: boolean;
 }
 
 export class ClientNotFoundError extends Error {
diff --git a/tools/ai-cli-dispatch/tests/cli.test.ts b/tools/ai-cli-dispatch/tests/cli.test.ts
index ec5c80d..5d0d846 100644
--- a/tools/ai-cli-dispatch/tests/cli.test.ts
+++ b/tools/ai-cli-dispatch/tests/cli.test.ts
@@ -39,6 +39,8 @@ describe("main", () => {
     stdout: "output",
     stderr: "",
     exitCode: 0,
+    client: "codex",
+    durationMs: 42,
   };
 
   it("returns 0 for --help and prints usage", async () => {
@@ -152,6 +154,8 @@ describe("main", () => {
             stdout: "hello-out",
             stderr: "hello-err",
             exitCode: 0,
+            client: "codex",
+            durationMs: 42,
           }),
           stdoutWrite: (chunk) => stdoutChunks.push(chunk),
           stderrWrite: (chunk) => stderrChunks.push(chunk),
@@ -259,7 +263,7 @@ describe("main", () => {
             return mockResult;
           },
           resolveClient: () => "claude",
-          resolveConfig: () => ({ paths: {} }),
+          resolveConfig: () => ({ paths: {}, timeout: 600_000 }),
         }
       );
       assert.strictEqual(code, 0);
@@ -286,7 +290,7 @@ describe("main", () => {
             return mockResult;
           },
           resolveClient: () => "codex",
-          resolveConfig: () => ({ paths: {} }),
+          resolveConfig: () => ({ paths: {}, timeout: 600_000 }),
         }
       );
       assert.strictEqual(code, 0);
@@ -310,7 +314,7 @@ describe("main", () => {
             return mockResult;
           },
           resolveClient: (_p, cfg) => cfg?.client ?? null,
-          resolveConfig: () => ({ paths: {}, defaultClient: "claude" }),
+          resolveConfig: () => ({ paths: {}, defaultClient: "claude", timeout: 600_000 }),
         }
       );
       assert.strictEqual(code, 0);
@@ -329,7 +333,7 @@ describe("main", () => {
           detectClients: () => mockClients,
           executePrompt: async () => mockResult,
           resolveClient: () => null,
-          resolveConfig: () => ({ paths: {} }),
+          resolveConfig: () => ({ paths: {}, timeout: 600_000 }),
         }
       );
       assert.strictEqual(code, 1);
@@ -351,7 +355,7 @@ describe("main", () => {
             throw new ClientNotFoundError("claude");
           },
           resolveClient: () => "claude",
-          resolveConfig: () => ({ paths: {} }),
+          resolveConfig: () => ({ paths: {}, timeout: 600_000 }),
         }
       );
       assert.strictEqual(code, 1);
@@ -388,9 +392,11 @@ describe("main", () => {
             stdout: "done",
             stderr: "",
             exitCode: 0,
+            client: "codex",
+            durationMs: 42,
           }),
           resolveClient: () => "codex",
-          resolveConfig: () => ({ paths: {} }),
+          resolveConfig: () => ({ paths: {}, timeout: 600_000 }),
           stdoutWrite: (chunk) => stdoutChunks.push(chunk),
         }
       );
@@ -400,4 +406,136 @@ describe("main", () => {
       out.restore();
     }
   });
+
+  it("run prints debug diagnostic JSON to stderr with --debug", async () => {
+    const out = captureOutput();
+    const stderrChunks: string[] = [];
+    try {
+      const code = await main(
+        ["node", "cli.ts", "run", "--client", "codex", "--prompt", "hello", "--debug"],
+        {
+          detectClients: () => mockClients,
+          executePrompt: async (_client, _prompt, options?) => {
+            options?.onDebug?.({
+              command: "codex",
+              args: ["exec", "--yolo", "hello"],
+              pid: 12345,
+              exitCode: 0,
+              exitSignal: null,
+              durationMs: 42,
+              stderrLength: 0,
+              stdoutLength: 6,
+            } as any);
+            return {
+              stdout: "output",
+              stderr: "",
+              exitCode: 0,
+              client: "codex",
+              durationMs: 42,
+            };
+          },
+          stderrWrite: (chunk) => stderrChunks.push(chunk),
+        }
+      );
+      assert.strictEqual(code, 0);
+      assert.strictEqual(stderrChunks.length, 1);
+      const diag = JSON.parse(stderrChunks[0]);
+      assert.strictEqual(diag.command, "codex");
+      assert.deepStrictEqual(diag.args, ["exec", "--yolo", "hello"]);
+      assert.strictEqual(diag.pid, 12345);
+      assert.strictEqual(diag.exitCode, 0);
+      assert.strictEqual(diag.exitSignal, null);
+      assert.strictEqual(diag.durationMs, 42);
+      assert.strictEqual(diag.stderrLength, 0);
+    } finally {
+      out.restore();
+    }
+  });
+
+  it("run ignores non-numeric --timeout and falls back to config timeout", async () => {
+    const out = captureOutput();
+    try {
+      let receivedTimeout: number | undefined;
+      const code = await main(
+        ["node", "cli.ts", "run", "--client", "codex", "--prompt", "hello", "--timeout", "not-a-number"],
+        {
+          detectClients: () => mockClients,
+          executePrompt: async (_client, _prompt, options?) => {
+            receivedTimeout = options?.timeoutMs;
+            return mockResult;
+          },
+          resolveConfig: () => ({ paths: {}, timeout: 600_000 }),
+        }
+      );
+      assert.strictEqual(code, 0);
+      assert.strictEqual(receivedTimeout, 600_000);
+    } finally {
+      out.restore();
+    }
+  });
+
+  it("dispatch ignores non-numeric --timeout and falls back to config timeout", async () => {
+    const out = captureOutput();
+    try {
+      let receivedTimeout: number | undefined;
+      const code = await main(
+        ["node", "cli.ts", "dispatch", "do something", "--timeout", "bad"],
+        {
+          detectClients: () => mockClients,
+          executePrompt: async (_client, _prompt, options?) => {
+            receivedTimeout = options?.timeoutMs;
+            return mockResult;
+          },
+          resolveClient: () => "codex",
+          resolveConfig: () => ({ paths: {}, timeout: 600_000 }),
+        }
+      );
+      assert.strictEqual(code, 0);
+      assert.strictEqual(receivedTimeout, 600_000);
+    } finally {
+      out.restore();
+    }
+  });
+
+  it("dispatch prints debug diagnostic JSON to stderr with --debug", async () => {
+    const out = captureOutput();
+    const stderrChunks: string[] = [];
+    try {
+      const code = await main(
+        ["node", "cli.ts", "dispatch", "do something", "--debug"],
+        {
+          detectClients: () => mockClients,
+          executePrompt: async (_client, _prompt, options?) => {
+            options?.onDebug?.({
+              command: "codex",
+              args: ["exec", "--yolo", "do something"],
+              pid: 12345,
+              exitCode: 0,
+              exitSignal: null,
+              durationMs: 42,
+              stderrLength: 0,
+              stdoutLength: 6,
+            } as any);
+            return {
+              stdout: "output",
+              stderr: "",
+              exitCode: 0,
+              client: "codex",
+              durationMs: 42,
+            };
+          },
+          resolveClient: () => "codex",
+          resolveConfig: () => ({ paths: {}, timeout: 600_000 }),
+          stderrWrite: (chunk) => stderrChunks.push(chunk),
+        }
+      );
+      assert.strictEqual(code, 0);
+      assert.strictEqual(stderrChunks.length, 1);
+      const diag = JSON.parse(stderrChunks[0]);
+      assert.strictEqual(diag.command, "codex");
+      assert.strictEqual(diag.durationMs, 42);
+    } finally {
+      out.restore();
+    }
+  });
 });
diff --git a/tools/ai-cli-dispatch/tests/config.test.ts b/tools/ai-cli-dispatch/tests/config.test.ts
index 99d505c..1598dd9 100644
--- a/tools/ai-cli-dispatch/tests/config.test.ts
+++ b/tools/ai-cli-dispatch/tests/config.test.ts
@@ -135,4 +135,71 @@ describe("resolveConfig", () => {
     });
     assert.strictEqual(config.defaultClient, undefined);
   });
+
+  it("returns default timeout of 600000 when no sources are present", () => {
+    const config = resolveConfig({
+      existsSync: () => false,
+      whichSync: () => undefined,
+    });
+    assert.strictEqual(config.timeout, 600_000);
+  });
+
+  it("loads timeout from file config", () => {
+    const config = resolveConfig({
+      existsSync: () => true,
+      readFileSync: () => JSON.stringify({ timeout: 120_000 }),
+      whichSync: () => undefined,
+    });
+    assert.strictEqual(config.timeout, 120_000);
+  });
+
+  it("overrides file timeout with env var", () => {
+    const config = resolveConfig({
+      env: { AI_CLI_TIMEOUT: "240000" },
+      existsSync: () => true,
+      readFileSync: () => JSON.stringify({ timeout: 120_000 }),
+      whichSync: () => undefined,
+    });
+    assert.strictEqual(config.timeout, 240_000);
+  });
+
+  it("overrides env timeout with CLI flag", () => {
+    const config = resolveConfig({
+      flags: { timeout: "480000" },
+      env: { AI_CLI_TIMEOUT: "240000" },
+      existsSync: () => true,
+      readFileSync: () => JSON.stringify({ timeout: 120_000 }),
+      whichSync: () => undefined,
+    });
+    assert.strictEqual(config.timeout, 480_000);
+  });
+
+  it("respects full priority ordering for timeout: flag > env > file > default", () => {
+    const config = resolveConfig({
+      flags: { timeout: "480000" },
+      env: { AI_CLI_TIMEOUT: "240000" },
+      existsSync: () => true,
+      readFileSync: () => JSON.stringify({ timeout: 120_000 }),
+      whichSync: () => undefined,
+    });
+    assert.strictEqual(config.timeout, 480_000);
+  });
+
+  it("ignores invalid timeout from env var and falls back to default", () => {
+    const config = resolveConfig({
+      env: { AI_CLI_TIMEOUT: "not-a-number" },
+      existsSync: () => false,
+      whichSync: () => undefined,
+    });
+    assert.strictEqual(config.timeout, 600_000);
+  });
+
+  it("ignores invalid timeout from file and falls back to default", () => {
+    const config = resolveConfig({
+      existsSync: () => true,
+      readFileSync: () => JSON.stringify({ timeout: "not-a-number" }),
+      whichSync: () => undefined,
+    });
+    assert.strictEqual(config.timeout, 600_000);
+  });
 });
diff --git a/tools/ai-cli-dispatch/tests/execute.test.ts b/tools/ai-cli-dispatch/tests/execute.test.ts
index f50225f..c2ea7df 100644
--- a/tools/ai-cli-dispatch/tests/execute.test.ts
+++ b/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] : []
   );
@@ -203,4 +204,162 @@ describe("executePrompt", () => {
         err instanceof ExecError && err.message.includes("Unknown client")
     );
   });
+
+  it("includes client and durationMs in result", async () => {
+    const scenarios = new Map<string, MockScenario>([
+      ["codex exec --yolo hello", { stdout: "ok", exitCode: 0 }],
+    ]);
+    const result = await executePrompt("codex", "hello", {
+      spawn: mockSpawn(scenarios),
+      existsSync: () => true,
+    });
+    assert.strictEqual(result.client, "codex");
+    assert.strictEqual(typeof result.durationMs, "number");
+    assert.ok(result.durationMs >= 0);
+  });
+
+  it("rejects with ExecError containing custom timeout value", async () => {
+    const scenarios = new Map<string, MockScenario>([
+      ["codex exec --yolo slow", { hang: true }],
+    ]);
+    await assert.rejects(
+      executePrompt("codex", "slow", {
+        spawn: mockSpawn(scenarios),
+        existsSync: () => true,
+        timeoutMs: 50,
+      }),
+      (err: unknown) =>
+        err instanceof ExecError &&
+        err.message === "Execution timed out after 50ms" &&
+        err.result.exitCode === -1 &&
+        err.result.client === "codex" &&
+        typeof err.result.durationMs === "number"
+    );
+  });
+
+  it("uses default timeout of 600000 when timeoutMs is not provided", async () => {
+    const delays: number[] = [];
+    const origSetTimeout = global.setTimeout;
+    (global as any).setTimeout = function(callback: any, delay: number) {
+      delays.push(delay);
+      return origSetTimeout(callback, delay);
+    };
+
+    const scenarios = new Map<string, MockScenario>([
+      ["codex exec --yolo hello", { stdout: "ok", exitCode: 0 }],
+    ]);
+    try {
+      await executePrompt("codex", "hello", {
+        spawn: mockSpawn(scenarios),
+        existsSync: () => true,
+      });
+      assert.strictEqual(delays[0], 600_000);
+    } finally {
+      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);
+  });
+
+  it("reports noisySuccess=true when stderr is non-empty and exitCode is 0", async () => {
+    const scenarios = new Map<string, MockScenario>([
+      ["codex exec --yolo hello", { stdout: "ok", stderr: "warn", exitCode: 0 }],
+    ]);
+    const debugInfos: any[] = [];
+    await executePrompt("codex", "hello", {
+      spawn: mockSpawn(scenarios),
+      existsSync: () => true,
+      debug: true,
+      onDebug: (info) => debugInfos.push(info),
+    });
+    assert.strictEqual(debugInfos[0].noisySuccess, true);
+  });
+
+  it("reports noisySuccess=false when stderr is empty and exitCode is 0", async () => {
+    const scenarios = new Map<string, MockScenario>([
+      ["codex exec --yolo hello", { stdout: "ok", stderr: "", exitCode: 0 }],
+    ]);
+    const debugInfos: any[] = [];
+    await executePrompt("codex", "hello", {
+      spawn: mockSpawn(scenarios),
+      existsSync: () => true,
+      debug: true,
+      onDebug: (info) => debugInfos.push(info),
+    });
+    assert.strictEqual(debugInfos[0].noisySuccess, false);
+  });
+
+  it("reports noisySuccess=false when exitCode is non-zero even if stderr is non-empty", async () => {
+    const scenarios = new Map<string, MockScenario>([
+      ["codex exec --yolo fail", { stdout: "", stderr: "error", exitCode: 1 }],
+    ]);
+    const debugInfos: any[] = [];
+    await executePrompt("codex", "fail", {
+      spawn: mockSpawn(scenarios),
+      existsSync: () => true,
+      debug: true,
+      onDebug: (info) => debugInfos.push(info),
+    });
+    assert.strictEqual(debugInfos[0].noisySuccess, false);
+  });
 });