diff --git a/src/cli.ts b/src/cli.ts
index 9d8e34272..3bd68c5ac 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -25,6 +25,7 @@ import { execSync, execFileSync, spawnSync, spawn } from 'node:child_process';
 import { existsSync, mkdirSync, copyFileSync, readFileSync, writeFileSync, renameSync, readdirSync, readlinkSync, symlinkSync, appendFileSync, statSync, unlinkSync, rmSync, realpathSync, chmodSync } from 'node:fs';
 import { underReadIsolation, sendCredFilePath } from './adapters/cli/read-isolation.js';
 import { atomicWriteFileSync } from './utils/atomic-write.js';
+import { writeAndFlush } from './cli/stdout-flush.js';
 import { join, dirname, basename, resolve } from 'node:path';
 import { homedir, userInfo } from 'node:os';
 import { fileURLToPath } from 'node:url';
@@ -7111,8 +7112,19 @@ async function relaySend(
         try { unlinkSync(cfile); } catch { /* */ }
         if (preparedContentOutfile) { try { unlinkSync(preparedContentOutfile); } catch { /* */ } }
         if (cardOutfile) { try { unlinkSync(cardOutfile); } catch { /* */ } }
-        if (res.stdout) process.stdout.write(res.stdout);
-        if (res.stderr) process.stderr.write(res.stderr);
+        // The host child normally returns a short success JSON, but either
+        // stream can contain an upstream error body.  This relay exits
+        // explicitly, so wait for both writes or a large response is silently
+        // truncated at the sandbox boundary.
+        try {
+          await Promise.all([
+            res.stdout ? writeAndFlush(process.stdout, res.stdout) : Promise.resolve(),
+            res.stderr ? writeAndFlush(process.stderr, res.stderr) : Promise.resolve(),
+          ]);
+        } catch (writeError) {
+          console.error(`relay: 无法完整输出 host 响应：${writeError instanceof Error ? writeError.message : String(writeError)}`);
+          process.exit(1);
+        }
         process.exit(res.code ?? 0);
       } catch { /* partial write — retry next tick */ }
     }
@@ -10737,6 +10749,7 @@ async function cmdAsk(sub: string, rest: string[]): Promise<void> {
   // result.kind==='answered' 时用 toLegacySelected 取回旧的 string（单问单选）
   const selected = toLegacySelected(result);
 
+  let stdoutPayload: string | undefined;
   if (useJson) {
     const out: AskJsonOutput = {
       // `selected` 是「单问单选」的向后兼容值（= toLegacySelected 的形状判据：
@@ -10749,7 +10762,7 @@ async function cmdAsk(sub: string, rest: string[]): Promise<void> {
       comment: result.kind === 'answered' ? result.comment : null,
       timedOut: result.kind === 'timedOut',
     };
-    process.stdout.write(JSON.stringify(out) + '\n');
+    stdoutPayload = JSON.stringify(out) + '\n';
   } else if (result.kind === 'answered') {
     // 非 JSON 模式：单选输出 key，多选输出逗号分隔的 keys。
     //
@@ -10766,7 +10779,19 @@ async function cmdAsk(sub: string, rest: string[]): Promise<void> {
     // N 项→逗号分隔，全程 exit 0。文字作答时 answers[0] 为空数组同样落空行（上面已在
     // stderr 提示改读 --json 的 comment）。
     const value = multiSelect ? (result.answers[0]?.join(',') ?? '') : (selected ?? '');
-    process.stdout.write(value + '\n');
+    stdoutPayload = value + '\n';
+  }
+
+  // `ask --json` includes the user's free-form comment, whose size is not
+  // bounded by this CLI.  stdout is asynchronous for pipes; an immediate
+  // process.exit() can otherwise lose everything after the pipe buffer.
+  if (stdoutPayload !== undefined) {
+    try {
+      await writeAndFlush(process.stdout, stdoutPayload);
+    } catch (writeError) {
+      console.error(`botmux ask: stdout 输出失败：${writeError instanceof Error ? writeError.message : String(writeError)}`);
+      process.exit(1);
+    }
   }
 
   switch (result.kind) {
diff --git a/src/cli/pm2-readonly-client.ts b/src/cli/pm2-readonly-client.ts
index 0cc6947f1..da60175a5 100644
--- a/src/cli/pm2-readonly-client.ts
+++ b/src/cli/pm2-readonly-client.ts
@@ -13,6 +13,7 @@ import {
   revalidateLinuxPm2GodProcess,
   type LinuxPm2GodProcess,
 } from '../core/pm2-lifecycle-owner.js';
+import { writeAndFlush } from './stdout-flush.js';
 
 const require = createRequire(import.meta.url);
 const pm2 = require('pm2') as any;
@@ -81,8 +82,15 @@ pm2.Client.pingDaemon((alive: boolean) => {
     if (mode === 'jlist') {
       pm2.list((error: Error | null | undefined, list: unknown[]) => {
         if (error) fail(`PM2 read-only jlist failed: ${error.message}`);
-        process.stdout.write(JSON.stringify(Array.isArray(list) ? list : []));
-        pm2.disconnect(() => process.exit(0));
+        // A PM2 registry can exceed the pipe's high-water mark. Calling
+        // process.exit() immediately after write() truncates its tail, making
+        // the parent reject a valid registry as malformed. Wait for stdout's
+        // completion callback before disconnecting and exiting.
+        void writeAndFlush(process.stdout, JSON.stringify(Array.isArray(list) ? list : []))
+          .then(
+            () => pm2.disconnect(() => process.exit(0)),
+            writeError => fail(`PM2 read-only jlist stdout write failed: ${writeError instanceof Error ? writeError.message : String(writeError)}`),
+          );
       });
       return;
     }
diff --git a/src/cli/stdout-flush.ts b/src/cli/stdout-flush.ts
new file mode 100644
index 000000000..7574aff87
--- /dev/null
+++ b/src/cli/stdout-flush.ts
@@ -0,0 +1,16 @@
+/** A minimal writable surface whose completion callback means the chunk has
+ * reached the underlying stream.  `write()` returning false is only a
+ * backpressure signal; callers that must not exit early must await callback. */
+export interface CompletionWritable {
+  write(chunk: string, callback: (error?: Error | null) => void): boolean;
+}
+
+/** Write one complete payload before allowing a child process to exit. */
+export function writeAndFlush(stream: CompletionWritable, chunk: string): Promise<void> {
+  return new Promise((resolve, reject) => {
+    stream.write(chunk, error => {
+      if (error) reject(error);
+      else resolve();
+    });
+  });
+}
diff --git a/test/ask-cli.test.ts b/test/ask-cli.test.ts
index aa104f0a8..a7fb09bdc 100644
--- a/test/ask-cli.test.ts
+++ b/test/ask-cli.test.ts
@@ -193,4 +193,50 @@ describe('botmux ask — CLI boundary', () => {
       });
     }
   });
+
+  it('--json 完整输出超出 pipe 容量的文字作答', async () => {
+    const dataDir = mkdtempSync(join(tmpdir(), 'botmux-ask-cli-'));
+    tempDirs.push(dataDir);
+    const comment = 'x'.repeat(500_000);
+
+    const server = createServer((req, res) => {
+      req.resume();
+      res.writeHead(200, { 'content-type': 'application/json' });
+      res.end(JSON.stringify({
+        kind: 'answered',
+        answers: [[]],
+        by: 'ou_test',
+        comment,
+        timedOut: false,
+      }));
+    });
+    await new Promise<void>((resolve) => server.listen(0, '127.0.0.1', resolve));
+
+    try {
+      const port = (server.address() as AddressInfo).port;
+      const registryDir = join(dataDir, 'dashboard-daemons');
+      mkdirSync(registryDir, { recursive: true });
+      writeFileSync(
+        join(registryDir, 'cli_test.json'),
+        JSON.stringify({ larkAppId: 'cli_test', ipcPort: port, lastHeartbeat: Date.now() }),
+      );
+
+      const result = await runAsk(dataDir, [
+        'ask', 'buttons', '--json', '--options', 'yes,no', '请作答',
+      ]);
+      expect(result.status).toBe(0);
+      expect(Buffer.byteLength(result.stdout)).toBeGreaterThan(400_000);
+      expect(JSON.parse(result.stdout)).toMatchObject({
+        selected: null,
+        answers: [[]],
+        by: 'ou_test',
+        comment,
+        timedOut: false,
+      });
+    } finally {
+      await new Promise<void>((resolve, reject) => {
+        server.close((err) => err ? reject(err) : resolve());
+      });
+    }
+  }, 30_000);
 });
diff --git a/test/pm2-readonly-jlist.test.ts b/test/pm2-readonly-jlist.test.ts
new file mode 100644
index 000000000..ad0b107d2
--- /dev/null
+++ b/test/pm2-readonly-jlist.test.ts
@@ -0,0 +1,58 @@
+import { spawnSync } from 'node:child_process';
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { afterEach, describe, expect, it } from 'vitest';
+import { captureReadonlyPm2Jlist } from '../src/cli/pm2-readonly.js';
+
+const PKG_ROOT = dirname(dirname(fileURLToPath(import.meta.url)));
+const PM2_PATH = join(PKG_ROOT, 'node_modules', 'pm2', 'bin', 'pm2');
+const homes: string[] = [];
+
+function tempHome(): string {
+  const home = mkdtempSync(join(tmpdir(), 'botmux-pm2-readonly-'));
+  homes.push(home);
+  return home;
+}
+
+afterEach(() => {
+  for (const home of homes.splice(0)) {
+    const pm2Home = join(home, '.botmux', 'pm2');
+    spawnSync(process.execPath, [PM2_PATH, 'kill'], {
+      env: { ...process.env, PM2_HOME: pm2Home },
+      stdio: 'ignore',
+      timeout: 10_000,
+    });
+    rmSync(home, { recursive: true, force: true });
+  }
+});
+
+describe('PM2 read-only jlist stdout integrity', () => {
+  it('returns a large jlist without truncation', () => {
+    const home = tempHome();
+    const pm2Home = join(home, '.botmux', 'pm2');
+    mkdirSync(pm2Home, { recursive: true });
+    expect(spawnSync(process.execPath, [PM2_PATH, 'status'], {
+      env: { ...process.env, PM2_HOME: pm2Home },
+      stdio: 'ignore',
+      timeout: 10_000,
+    }).status).toBe(0);
+
+    const idleScript = join(home, 'idle.js');
+    writeFileSync(idleScript, 'setInterval(() => {}, 1000);\n');
+    for (let i = 0; i < 6; i++) {
+      const started = spawnSync(process.execPath, [PM2_PATH, 'start', idleScript, '--name', `flush-probe-${i}`], {
+        env: { ...process.env, PM2_HOME: pm2Home, BOTMUX_FLUSH_PROBE: 'x'.repeat(30_000) },
+        stdio: 'ignore',
+        timeout: 20_000,
+      });
+      expect(started.status).toBe(0);
+    }
+
+    const stdout = captureReadonlyPm2Jlist({ pkgRoot: PKG_ROOT, home: pm2Home });
+    // Keep the fixture well past the partial-flush range observed with a pipe.
+    expect(Buffer.byteLength(stdout)).toBeGreaterThan(200_000);
+    expect(JSON.parse(stdout)).toHaveLength(6);
+  }, 90_000);
+});