diff --git a/back/schedule/addCron.ts b/back/schedule/addCron.ts
index bdb29da0..5ebdf7a5 100644
--- a/back/schedule/addCron.ts
+++ b/back/schedule/addCron.ts
@@ -68,7 +68,11 @@ const addCron = (
             schedule,
             async () => {
               Logger.info('[schedule][准备运行任务] 命令: %s', item.command);
-              await runCron(item.command, item);
+              await runCron(
+                item.command,
+                item,
+                () => scheduleStacks.get(item.id) === jobs,
+              );
             },
             {
               name: `${item.id}: ${item.name || ''}`,
diff --git a/back/shared/interface.ts b/back/shared/interface.ts
index 01fd6cb7..2ea99f04 100644
--- a/back/shared/interface.ts
+++ b/back/shared/interface.ts
@@ -18,6 +18,7 @@ export interface IDependencyFn<T> {
 export interface ICronFn<T> {
   (): Promise<T>;
   cron?: TCron;
+  isCurrent?: () => boolean;
 }
 
 export interface ISchedule {
diff --git a/back/shared/pLimit.ts b/back/shared/pLimit.ts
index 47f8b6c8..969a6d58 100644
--- a/back/shared/pLimit.ts
+++ b/back/shared/pLimit.ts
@@ -50,11 +50,9 @@ class TaskLimit {
             Buffer.from(tlsConfig.clientCert),
           )
         : credentials.createInsecure();
-      this._client = new ApiClient(
-        `localhost:${config.grpcPort}`,
-        creds,
-        { 'grpc.enable_http_proxy': 0 },
-      );
+      this._client = new ApiClient(`localhost:${config.grpcPort}`, creds, {
+        'grpc.enable_http_proxy': 0,
+      });
     }
     return this._client;
   }
@@ -113,12 +111,15 @@ class TaskLimit {
     }
   }
 
-  public removeQueuedCron(id: string) {
+  public removeQueuedCron(id: string, completed?: ICronFn<any>) {
     if (this.queuedCrons.has(id)) {
       const runs = this.queuedCrons.get(id);
       if (runs && runs.length > 0) {
-        runs.pop();
-        this.queuedCrons.set(id, runs);
+        const remaining = completed
+          ? runs.filter((run) => run !== completed)
+          : runs.slice(0, -1);
+        if (remaining.length) this.queuedCrons.set(id, remaining);
+        else this.queuedCrons.delete(id);
       }
     }
   }
@@ -143,9 +144,15 @@ class TaskLimit {
     cron: TCron,
     fn: ICronFn<T>,
     options?: Partial<QueueAddOptions>,
+    isCurrent: () => boolean = () => true,
   ): Promise<T | void> {
+    if (!isCurrent()) return;
     fn.cron = cron;
-    let runs = this.queuedCrons.get(cron.id);
+    fn.isCurrent = isCurrent;
+    // Invalidated snapshots must not consume the new revision's repeat budget.
+    const runs = this.queuedCrons
+      .get(cron.id)
+      ?.filter((run) => run.isCurrent?.() !== false);
     const result = runs?.length ? [...runs, fn] : [fn];
     const repeatTimes = this.repeatCronNotifyMap.get(cron.id) || 0;
     if (result?.length > 5) {
diff --git a/back/shared/runCron.ts b/back/shared/runCron.ts
index ab5511a8..8a862681 100644
--- a/back/shared/runCron.ts
+++ b/back/shared/runCron.ts
@@ -8,15 +8,23 @@ import { RunningInstanceModel, InstanceStatus } from '../data/runningInstance';
 import dayjs from 'dayjs';
 import { observeChildProcess, asError } from './childProcess';
 
-export function runCron(cmd: string, cron: ICron): Promise<number | void> {
-  return taskLimit.runWithCronLimit(cron, async () => {
+export function runCron(
+  cmd: string,
+  cron: ICron,
+  isCurrent: () => boolean = () => true,
+): Promise<number | void> {
+  const execute = async () => {
     try {
+      if (!isCurrent()) return;
       // Check if the cron is already running and stop it (only if multiple instances are not allowed)
       try {
         const existingCron = await CrontabModel.findOne({
           where: { id: Number(cron.id) },
         });
 
+        // A mutation may commit while this queued run is reading the database.
+        if (!isCurrent() || !existingCron || existingCron.isDisabled) return;
+
         // Default to single instance mode (0) for backward compatibility
         const allowSingleInstances =
           existingCron?.allow_multiple_instances === 0;
@@ -56,6 +64,8 @@ export function runCron(cmd: string, cron: ICron): Promise<number | void> {
         throw error;
       }
 
+      // In particular, invalidation can happen while stopping a previous run.
+      if (!isCurrent()) return;
       Logger.info(
         `[schedule][开始执行任务] 参数 ${JSON.stringify({
           ...cron,
@@ -94,7 +104,8 @@ export function runCron(cmd: string, cron: ICron): Promise<number | void> {
         asError(error).message,
       );
     } finally {
-      taskLimit.removeQueuedCron(cron.id);
+      taskLimit.removeQueuedCron(cron.id, execute);
     }
-  });
+  };
+  return taskLimit.runWithCronLimit(cron, execute, undefined, isCurrent);
 }
diff --git a/cli/test/integration/differential.test.cjs b/cli/test/integration/differential.test.cjs
index e6bb8b50..76a0e348 100644
--- a/cli/test/integration/differential.test.cjs
+++ b/cli/test/integration/differential.test.cjs
@@ -31,7 +31,7 @@ test('Shell and CLI agree on isolated script state and account modes', async (t)
     path.join(root, 'static/build'),
   ])
     await fs.mkdir(directory, { recursive: true });
-  for (const name of ['task.sh', 'otask.sh', 'share.sh', 'api.sh', 'env.sh'])
+  for (const name of ['task.sh', 'task-timeout.sh', 'otask.sh', 'share.sh', 'api.sh', 'env.sh'])
     await fs.copyFile(
       path.resolve(__dirname, '../../../shell', name),
       path.join(context.paths.dir_shell, name),
@@ -355,6 +355,7 @@ t() { :; }
 sleep() { printf DELAYED; }
 enter_script_workdir() { :; }
 run_else() { :; }
+run_task_command() { "$@"; }
 which_program=true
 main "$@"
 `,
diff --git a/cli/test/integration/executablePaths.test.cjs b/cli/test/integration/executablePaths.test.cjs
index 41ed5319..8cbf8013 100644
--- a/cli/test/integration/executablePaths.test.cjs
+++ b/cli/test/integration/executablePaths.test.cjs
@@ -10,7 +10,7 @@ test('legacy Shell and TS resolve executable paths after selecting the working d
   t.after(() => fs.rmSync(root, { recursive: true, force: true }));
   for (const dir of ['shell/preload', 'shell/lang', 'data/config', 'data/scripts/bin', 'data/scripts/custom', 'data/log', 'static/build', 'bin'])
     fs.mkdirSync(path.join(root, dir), { recursive: true });
-  for (const name of ['task.sh', 'otask.sh', 'share.sh', 'api.sh', 'env.sh'])
+  for (const name of ['task.sh', 'task-timeout.sh', 'otask.sh', 'share.sh', 'api.sh', 'env.sh'])
     fs.copyFileSync(path.resolve(__dirname, '../../../shell', name), path.join(root, 'shell', name));
   for (const name of ['zh.sh', 'en.sh'])
     fs.copyFileSync(path.resolve(__dirname, '../../../shell/lang', name), path.join(root, 'shell/lang', name));
diff --git a/cli/test/integration/stdin.test.cjs b/cli/test/integration/stdin.test.cjs
index 6c4100dc..aac8b5a7 100644
--- a/cli/test/integration/stdin.test.cjs
+++ b/cli/test/integration/stdin.test.cjs
@@ -10,7 +10,7 @@ test('legacy Shell and TS preserve task stdin in each execution mode', t => {
   t.after(() => fs.rmSync(root, { recursive: true, force: true }));
   for (const dir of ['shell/preload', 'shell/lang', 'data/config', 'data/scripts', 'data/log', 'static/build', 'bin'])
     fs.mkdirSync(path.join(root, dir), { recursive: true });
-  for (const name of ['task.sh', 'otask.sh', 'share.sh', 'api.sh', 'env.sh'])
+  for (const name of ['task.sh', 'task-timeout.sh', 'otask.sh', 'share.sh', 'api.sh', 'env.sh'])
     fs.copyFileSync(path.resolve(__dirname, '../../../shell', name), path.join(root, 'shell', name));
   for (const name of ['zh.sh', 'en.sh'])
     fs.copyFileSync(path.resolve(__dirname, '../../../shell/lang', name), path.join(root, 'shell/lang', name));
diff --git a/docs/development/task-startup.md b/docs/development/task-startup.md
index fffc9c74..7546f1c9 100644
--- a/docs/development/task-startup.md
+++ b/docs/development/task-startup.md
@@ -59,3 +59,20 @@ resolved.
 Provider initialization, including provider configuration reads, now happens at
 first use. A script's explicit `import __ql_notify__`, `require(...)`, or independent
 notification helper still loads that module immediately.
+
+## Task timeouts
+
+`task -m DURATION ...` also applies to sourced Shell scripts. The timeout worker
+inherits before-hook variables, arrays and functions without serializing them.
+At the deadline, the worker's process group receives TERM, followed by KILL after
+0.5 seconds, so ordinary child processes cannot continue after the timeout.
+Explicit interpreters and other commands use the same mechanism. Processes that
+intentionally create a separate session/process group are outside this boundary.
+The wrapper records status 124 and runs its after hook; concurrent account mode
+retains its existing aggregate status behavior. Zero disables the timeout.
+
+Cron executions waiting for a concurrency slot retain their schedule revision.
+Disabling, deleting or replacing that revision prevents its queued executions
+from starting when a slot becomes available. Already running executions retain
+the existing stop behavior. Invalidated callbacks do not count against a new
+revision's limit of five pending/running executions.
diff --git a/shell/otask.sh b/shell/otask.sh
index c11041f3..f826bfa5 100755
--- a/shell/otask.sh
+++ b/shell/otask.sh
@@ -164,7 +164,7 @@ run_normal() {
   if [[ $isJsOrPythonFile == 'false' ]]; then
     clear_non_sh_env
   fi
-  $timeoutCmd $which_program $file_param "${script_params[@]}"
+  run_task_command $which_program $file_param "${script_params[@]}"
 }
 
 handle_env_split() {
@@ -203,7 +203,7 @@ run_concurrent() {
       export "${env_param}=${array[$i - 1]}"
       clear_non_sh_env
     fi
-    eval envParam="${env_param}" numParam="${i}" $timeoutCmd $which_program $file_param "${script_params[@]}" &>$single_log_path &
+    eval envParam="${env_param}" numParam="${i}" run_task_command $which_program $file_param "${script_params[@]}" &>$single_log_path &
   done
 
   wait
@@ -243,7 +243,7 @@ run_designated() {
 
   enter_script_workdir
 
-  envParam="${env_param}" numParam="${num_param}" $timeoutCmd $which_program $file_param "${script_params[@]}"
+  envParam="${env_param}" numParam="${num_param}" run_task_command $which_program $file_param "${script_params[@]}"
 }
 
 ## 运行其他命令
@@ -299,7 +299,7 @@ run_else() {
   fi
 
   clear_non_sh_env
-  $timeoutCmd $which_program $file_param "$@"
+  run_task_command $which_program $file_param "$@"
 }
 
 check_file() {
@@ -336,10 +336,6 @@ check_nounset() {
 
 main() {
   if [[ $1 == *.js ]] || [[ $1 == *.mjs ]] || [[ $1 == *.py ]] || [[ $1 == *.pyc ]] || [[ $1 == *.sh ]] || [[ $1 == *.ts ]]; then
-    if [[ $1 == *.sh ]]; then
-      timeoutCmd=""
-    fi
-
     case $# in
     1)
       run_normal "$1"
diff --git a/shell/task-timeout.sh b/shell/task-timeout.sh
new file mode 100644
index 00000000..a4448d97
--- /dev/null
+++ b/shell/task-timeout.sh
@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+
+# Fork from the current Bash state: an external `bash -c` would lose private
+# before-hook variables, arrays and functions used by sourced Shell scripts.
+run_task_command() {
+  local timeout_seconds
+  if [[ -z ${command_timeout_time:-} ]]; then
+    "$@"
+    return $?
+  fi
+  timeout_seconds=$(awk -v value="$command_timeout_time" 'BEGIN {
+    if (value !~ /^([0-9]+([.][0-9]*)?|[.][0-9]+)([eE][+-]?[0-9]+)?[smhd]?$/) exit 1
+    unit = substr(value, length(value), 1)
+    factor = unit == "d" ? 86400 : unit == "h" ? 3600 : unit == "m" ? 60 : 1
+    printf "%.9f", (value + 0) * factor
+  }') || { printf 'Invalid task timeout: %s\n' "$command_timeout_time" >&2; return 125; }
+  if [[ $timeout_seconds == '0.000000000' ]]; then
+    "$@"
+    return $?
+  fi
+  (
+    timeout_dir=$(mktemp -d "${TMPDIR:-/tmp}/ql-task-timeout.XXXXXXXX") || exit 125
+    # Both children get private process groups. The timer and the wrapper must
+    # survive terminating the task, and descendants must not outlive a timeout.
+    set -m
+    ( set +m; "$@" ) <&0 &
+    timeout_worker=$!
+    (
+      set +m
+      : > "$timeout_dir/ready"
+      sleep "$timeout_seconds" || exit 125
+      : > "$timeout_dir/expired"
+      kill -TERM -- "-$timeout_worker" 2>/dev/null || :
+      sleep 0.5
+      kill -KILL -- "-$timeout_worker" 2>/dev/null || :
+    ) &
+    timeout_watcher=$!
+    set +m
+    trap 'kill -KILL -- "-$timeout_watcher" 2>/dev/null || :
+      if kill -TERM -- "-$timeout_worker" 2>/dev/null; then sleep 0.1; fi
+      kill -KILL -- "-$timeout_worker" 2>/dev/null || :
+      wait "$timeout_worker" 2>/dev/null || :
+      wait "$timeout_watcher" 2>/dev/null || :
+      rm -rf -- "$timeout_dir"' EXIT
+    trap 'exit 130' INT
+    trap 'exit 143' TERM
+    trap 'exit 129' HUP
+    trap 'exit 131' QUIT
+    # Do not clean up a timer whose process group has not initialized yet.
+    while [[ ! -f "$timeout_dir/ready" ]]; do
+      kill -0 "$timeout_watcher" 2>/dev/null || exit 125
+      sleep 0.001
+    done
+    wait "$timeout_worker"
+    timeout_code=$?
+    if [[ -f "$timeout_dir/expired" ]]; then
+      # Let the timer finish escalation even if the task leader exited first.
+      wait "$timeout_watcher" 2>/dev/null || :
+      exit 124
+    fi
+    exit "$timeout_code"
+  )
+}
diff --git a/shell/task.sh b/shell/task.sh
index a4fe900c..92bd620f 100755
--- a/shell/task.sh
+++ b/shell/task.sh
@@ -3,6 +3,7 @@
 dir_shell=$QL_DIR/shell
 . $dir_shell/share.sh
 . $dir_shell/api.sh
+. $dir_shell/task-timeout.sh
 
 trap 'single_hanle SIGINT'  INT
 trap 'single_hanle SIGTERM' TERM
@@ -112,11 +113,6 @@ format_params() {
     mtime_format="%Y-%m-%d %H:%M:%S.%3N"
   fi
   timeoutCmd=""
-  if [[ $command_timeout_time ]]; then
-    if type timeout &>/dev/null; then
-      timeoutCmd="timeout --foreground -s 2 -k 10s $command_timeout_time "
-    fi
-  fi
   # params=$(echo "$@" | sed -E 's/([^ ])&([^ ])/\1\\\&\2/g')
 
   # 分割 task 内置参数和脚本参数
diff --git a/test/back/execution-lifecycle.test.cjs b/test/back/execution-lifecycle.test.cjs
index 3e0b9e91..afa945e6 100644
--- a/test/back/execution-lifecycle.test.cjs
+++ b/test/back/execution-lifecycle.test.cjs
@@ -36,7 +36,7 @@ test(
       },
       '../loaders/logger': logger,
       '../data/cron': {
-        CrontabModel: { findOne: async () => null },
+        CrontabModel: { findOne: async () => ({ isDisabled: 0 }) },
         CrontabStatus: {},
       },
       '../data/runningInstance': {
diff --git a/test/back/queued-cron-invalidation.test.cjs b/test/back/queued-cron-invalidation.test.cjs
new file mode 100644
index 00000000..a08417e4
--- /dev/null
+++ b/test/back/queued-cron-invalidation.test.cjs
@@ -0,0 +1,98 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const load = require('../helpers/load-security-module.cjs');
+const tick = () => new Promise(setImmediate);
+function gate() { let release; const promise = new Promise(r => release = r); return { promise, release }; }
+
+async function fixture() {
+  const logger = { info() {}, error() {}, warn() {} }, notices = [];
+  const limit = load('back/shared/pLimit.ts', {
+    '../data/system': { AuthDataType: { systemConfig: 'systemConfig' }, SystemModel: { sync: async () => {}, findOne: async () => ({ info: { cronConcurrency: 1 } }) } },
+    '../loaders/logger': logger,
+    '../services/notify': class {},
+    '../shared/i18n': { t: s => s, tf: s => s },
+    '../config': { grpcPort: 1 },
+    '../protos/api': { ApiClient: class { systemNotify(value, cb) { notices.push(value); cb(); } } },
+    '../config/grpcCerts': { getGrpcCerts: () => null },
+  }).default;
+  await tick();
+  const spawned = [], records = new Map(), jobs = new Map();
+  let readGate, killGate;
+  const { runCron } = load('back/shared/runCron.ts', {
+    'cross-spawn': { spawn: command => { spawned.push(command); return {}; } },
+    './pLimit': limit,
+    '../loaders/logger': logger,
+    '../data/cron': { CrontabModel: { findOne: async ({ where }) => { const row = records.get(String(where.id)); if (readGate) await readGate.promise; return row; }, update: async () => {} }, CrontabStatus: { running: 0, queued: 3, idle: 1 } },
+    '../data/runningInstance': { RunningInstanceModel: { update: async () => {} }, InstanceStatus: { running: 0, stopped: 2 } },
+    '../config/util': { killTask: async () => { if (killGate) await killGate.promise; } },
+    './childProcess': { observeChildProcess: () => ({ completed: Promise.resolve({ code: 0 }) }), asError: e => e },
+  });
+  const { addCron } = load('back/schedule/addCron.ts', {
+    '../shared/cronScheduler': { createCronJob: (schedule, callback) => ({ start() {}, cancel() {}, fire: callback }) },
+    '../shared/cronSchedule': { isValidCronSchedule: x => x !== 'invalid' },
+    './data': { scheduleStacks: jobs }, '../shared/runCron': { runCron }, '../loaders/logger': logger,
+    '../shared/i18n': { tf: s => s },
+  });
+  const { delCron } = load('back/schedule/delCron.ts', { './data': { scheduleStacks: jobs }, '../loaders/logger': logger });
+  function add(id = '1', command = 'old', replace = false) {
+    records.set(id, { isDisabled: 0, allow_multiple_instances: 1 });
+    addCron({ request: { crons: [{ id, command, schedule: '* * * * * *' }], replace } }, err => assert.ifError(err));
+    return jobs.get(id)[0];
+  }
+  function remove(id = '1') { delCron({ request: { ids: [id] } }, err => assert.ifError(err)); }
+  async function block() { const g = gate(); const done = limit.runWithCronLimit({ id: 'blocker' }, async () => { await g.promise; }); await tick(); return { release: async () => { g.release(); await done; } }; }
+  return { limit, spawned, records, jobs, add, remove, block, notices, setReadGate: g => readGate = g, setKillGate: g => killGate = g };
+}
+
+for (const operation of ['disable', 'delete', 'update', 'replace', 'disable-enable']) {
+  test(`queued scheduled execution is invalidated by ${operation}`, async () => {
+    const f = await fixture(), old = f.add(), blocker = await f.block();
+    const queued = old.fire();
+    if (operation === 'disable' || operation === 'disable-enable') { f.records.get('1').isDisabled = 1; f.remove(); }
+    if (operation === 'delete') { f.records.delete('1'); f.remove(); }
+    if (operation === 'update') f.add('1', 'new');
+    if (operation === 'replace') f.add('1', 'new', true);
+    if (operation === 'disable-enable') f.add('1', 'old');
+    const next = f.jobs.get('1')?.[0].fire();
+    await blocker.release(); await queued; await next;
+    assert.deepEqual(f.spawned, ['update', 'replace'].includes(operation) ? ['new'] : operation === 'disable-enable' ? ['old'] : []);
+    assert.equal(f.limit.cronLimitPendingCount, 0);
+    assert.equal(f.limit.cronLimitActiveCount, 0);
+  });
+}
+
+test('stale callbacks cannot re-enqueue after cancellation', async () => {
+  const f = await fixture(), old = f.add(); f.remove(); await old.fire();
+  assert.deepEqual(f.spawned, []);
+});
+
+test('invalidation during an asynchronous database read prevents spawning', async () => {
+  const f = await fixture(), old = f.add(), pending = gate(); f.setReadGate(pending);
+  const run = old.fire(); await tick(); f.remove(); pending.release(); await run;
+  assert.deepEqual(f.spawned, []);
+});
+
+test('invalidation while replacing a running instance prevents the old spawn', async () => {
+  const f = await fixture(), old = f.add(), pending = gate();
+  f.records.set('1', { isDisabled: 0, allow_multiple_instances: 0, pid: 10, status: 0 }); f.setKillGate(pending);
+  const run = old.fire(); await tick(); f.remove(); pending.release(); await run;
+  assert.deepEqual(f.spawned, []);
+});
+
+test('database removal or disable is respected before scheduler RPC arrives', async () => {
+  for (const disabled of [true, false]) {
+    const f = await fixture(), old = f.add(), blocker = await f.block(); const run = old.fire();
+    if (disabled) f.records.get('1').isDisabled = 1; else f.records.delete('1');
+    await blocker.release(); await run; assert.deepEqual(f.spawned, []);
+  }
+});
+
+test('five stale runs do not suppress the new revision or erase its repeat accounting', async () => {
+  const f = await fixture(), old = f.add(), blocker = await f.block();
+  const pending = Array.from({ length: 5 }, () => old.fire());
+  const current = f.add('1', 'new'); pending.push(...Array.from({ length: 5 }, () => current.fire()));
+  assert.equal(f.notices.length, 0);
+  await blocker.release(); await Promise.all(pending);
+  assert.deepEqual(f.spawned, Array(5).fill('new'));
+  await current.fire(); assert.equal(f.spawned.length, 6);
+});
diff --git a/test/back/task-shell-lifecycle.test.cjs b/test/back/task-shell-lifecycle.test.cjs
index 9aefe072..6f8ddf2a 100644
--- a/test/back/task-shell-lifecycle.test.cjs
+++ b/test/back/task-shell-lifecycle.test.cjs
@@ -12,6 +12,7 @@ function extract(file, name) {
   return text.slice(start, text.indexOf('\n}', start) + 2);
 }
 const helpers = [
+  fs.readFileSync('shell/task-timeout.sh', 'utf8'),
   ...['handle_task_start', 'handle_task_end', 'run_task_before', 'run_task_after', 'get_env_array', 'clear_env'].map(n => extract('shell/share.sh', n)),
   ...['run_shell_script', 'define_program', 'format_params'].map(n => extract('shell/task.sh', n)),
 ].join('\n');
@@ -24,7 +25,7 @@ function fixture(t) {
   write('env.sh', 'export QA_PANEL="alpha&beta&gamma"\n');
   write('before.sh', 'export QA_BEFORE=ready\nqa_function() { printf "HOOK_FUNCTION\\n"; }\n');
   write('after.sh', 'printf "AFTER:%s:%s\\n" "$QA_PANEL" "$QA_BEFORE" >> "$QA_ROOT/events"\n');
-  const run = (args) => {
+  const run = (args, timeout = '') => {
     const r = spawnSync('/bin/bash', ['-c', helpers + `
       dir_scripts=$QA_ROOT; dir_shell=$QA_ROOT; dir_dep=$QA_ROOT
       file_env=$QA_ROOT/env.sh; file_task_before=$QA_ROOT/before.sh; file_task_after=$QA_ROOT/after.sh
@@ -40,7 +41,7 @@ function fixture(t) {
       format_params "$@"; define_program "${'${task_shell_params[@]}'}"
       . "$QA_TASK_SOURCE"
       printf 'WRAPPER_FINISHED\\n' >> "$QA_ROOT/events"
-    `, 'fixture', ...args], { cwd: root, env: { ...process.env, QA_ROOT: root, QA_TASK_SOURCE: taskSource }, encoding: 'utf8', timeout: 10000 });
+    `, 'fixture', ...args], { cwd: root, env: { ...process.env, command_timeout_time: timeout, QA_ROOT: root, QA_TASK_SOURCE: taskSource }, encoding: 'utf8', timeout: 10000 });
     assert.equal(r.status, 0, r.stdout + r.stderr);
     return { stdout: r.stdout, events: fs.readFileSync(path.join(root, 'events'), 'utf8').trim().split('\n') };
   };
@@ -117,3 +118,77 @@ for (const mode of ['desi', 'conc']) {
     assert.equal(r.events.filter(x => x.startsWith('AFTER:')).length, 1);
   });
 }
+
+for (const [label, args] of [
+  ['sourced shell', ['probe.sh', '--', 'space value']],
+  ['explicit bash', ['bash', 'probe.sh', 'space value']],
+]) {
+  test(`${label} timeout stops descendants and finalizes once with 124`, t => {
+    const f = fixture(t);
+    f.write('before.sh', 'export QA_BEFORE=ready\nprivate_value=private\nprivate_array=(one "two words")\nqa_function() { printf "HOOK_FUNCTION\\n"; }\n');
+    f.write('probe.sh', `[[ "$QA_PANEL" == 'alpha&beta&gamma' && "$QA_BEFORE" == ready && "$1" == 'space value' ]] || exit 91\n${label === 'sourced shell' ? '[[ "$private_value" = private && "${private_array[1]}" = "two words" ]] || exit 92\nqa_function\n' : ''}trap 'echo EXIT_TRAP' EXIT\nsleep 3\necho SHOULD_NOT_RUN\n`);
+    const before = Date.now();
+    const r = f.run(args, '0.2s');
+    assert.ok(Date.now() - before < 2500, r.stdout);
+    assert.doesNotMatch(r.stdout, /SHOULD_NOT_RUN/);
+    assert.match(r.stdout, /EXIT_TRAP/);
+    assert.deepEqual(r.events, ['STATUS:0:', 'AFTER:alpha&beta&gamma:ready', 'STATUS:1:124', 'STAT:124', 'WRAPPER_FINISHED']);
+  });
+}
+
+test('timeout escalates when a shell and its children ignore TERM', t => {
+  const f = fixture(t);
+  f.write('probe.sh', 'trap "" TERM\nsleep 3\necho SHOULD_NOT_RUN\n');
+  const before = Date.now();
+  const r = f.run(['probe.sh'], '0.1');
+  assert.ok(Date.now() - before < 2500);
+  assert.doesNotMatch(r.stdout, /SHOULD_NOT_RUN/);
+  assert.ok(r.events.includes('STATUS:1:124'));
+});
+
+test('completed timed tasks keep their exit code and do not wait for the timer', t => {
+  const f = fixture(t);
+  f.write('probe.sh', 'exit 7\n');
+  const before = Date.now();
+  const r = f.run(['probe.sh'], '1h');
+  assert.ok(Date.now() - before < 1500);
+  assert.ok(r.events.includes('STATUS:1:7'));
+});
+
+test('zero disables the deadline and invalid durations never start the script', t => {
+  const f = fixture(t);
+  f.write('probe.sh', 'echo DID_RUN\n');
+  assert.match(f.run(['probe.sh'], '0s').stdout, /DID_RUN/);
+  f.write('events', '');
+  const r = f.run(['probe.sh'], 'wrong');
+  assert.doesNotMatch(r.stdout, /DID_RUN/);
+  assert.ok(r.events.includes('STATUS:1:125'));
+});
+
+for (const [runtime, filename, body] of [
+  ['python3', 'timed.py', 'import time\nprint("STARTED", flush=True)\ntime.sleep(3)\nprint("SHOULD_NOT_RUN", flush=True)\n'],
+  ['node', 'timed.cjs', 'console.log("STARTED"); setTimeout(() => console.log("SHOULD_NOT_RUN"), 3000);\n'],
+]) {
+  test(`${runtime} timeout stops execution and reports 124`, t => {
+    const f = fixture(t);
+    f.write(filename, body);
+    const r = f.run([runtime, filename], '0.5s');
+    assert.match(r.stdout, /STARTED/);
+    assert.doesNotMatch(r.stdout, /SHOULD_NOT_RUN/);
+    assert.ok(r.events.includes('STATUS:1:124'));
+    assert.equal(r.events.filter(x => x.startsWith('AFTER:')).length, 1);
+  });
+}
+
+for (const mode of ['desi', 'conc']) {
+  test(`timed shell ${mode} preserves selected accounts and terminates every worker`, t => {
+    const f = fixture(t);
+    f.write('probe.sh', 'echo "ACCOUNT=$QA_PANEL"\nsleep 3\necho SHOULD_NOT_RUN\n');
+    const r = f.run(['probe.sh', mode, 'QA_PANEL', '2-3'], '0.2s');
+    assert.match(r.stdout, mode === 'desi' ? /ACCOUNT=beta&gamma/ : /ACCOUNT=beta\nACCOUNT=gamma/);
+    assert.doesNotMatch(r.stdout, /SHOULD_NOT_RUN/);
+    assert.equal(r.events.filter(x => x.startsWith('AFTER:')).length, 1);
+    // Concurrent mode retains its existing aggregate wait status behavior.
+    assert.ok(r.events.includes(`STATUS:1:${mode === 'desi' ? 124 : 0}`));
+  });
+}