fix(scheduled-task): enable worker by default and add WeChat preflight

Scheduled automations were saved but never executed because the worker
required an explicit env flag. Follow H5_REMINDER_WORKER_ENABLED when unset,
add WeChat preflight to write tasks deterministically, and surface worker
warnings on create.

Co-authored-by: Cursor <cursoragent@cursor.com>

scheduled-task-intent.test.mjs

@@ -1,8 +1,11 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
 import {
+  buildScheduledTaskCreatePayload,
+  extractScheduledTaskSpec,
   isScheduledTaskIntent,
   parseScheduledTaskIntent,
+  resolveOnceRunAtLocal,
   shouldUseScheduledTaskAutomation,
 } from './scheduled-task-intent.mjs';
 import { shouldUseScheduleAssistant } from './schedule-intent.mjs';
@@ -12,6 +15,10 @@ test('detects daily news page automation intent', () => {
   const intent = parseScheduledTaskIntent('每天6点帮我做今日新闻页面');
   assert.equal(intent.action, 'create_scheduled_task');
   assert.equal(intent.recurrence, 'daily');
+  assert.equal(intent.hour, 6);
+  assert.equal(intent.minute, 0);
+  assert.match(intent.taskSpec, /今日新闻页面/u);
+  assert.equal(intent.needsClarification, undefined);
 });
 
 test('detects explicit scheduled task phrase', () => {
@@ -42,6 +49,43 @@ test('parses cancel and list intents', () => {
   assert.equal(parseScheduledTaskIntent('看看我的定时自动任务').action, 'list_scheduled_tasks');
 });
 
+test('parses one-shot tonight schedule with task spec', () => {
+  const intent = parseScheduledTaskIntent('我想创建一个定时执行任务，今晚 21:45 分执行做新闻页面');
+  assert.equal(intent.action, 'create_scheduled_task');
+  assert.equal(intent.recurrence, 'once');
+  assert.match(intent.runAtLocal, /^\d{4}-\d{2}-\d{2} 21:45$/);
+  assert.match(intent.taskSpec, /新闻页面/u);
+});
+
+test('buildScheduledTaskCreatePayload maps parsed intent', () => {
+  const intent = parseScheduledTaskIntent('每天6点帮我做今日新闻页面');
+  const payload = buildScheduledTaskCreatePayload(intent, {
+    userId: 'user-1',
+    sourceMessageId: 'msg-1',
+    sourceText: '每天6点帮我做今日新闻页面',
+  });
+  assert.equal(payload.userId, 'user-1');
+  assert.equal(payload.recurrence, 'daily');
+  assert.equal(payload.hour, 6);
+  assert.match(payload.taskSpec, /今日新闻页面/u);
+});
+
+test('extractScheduledTaskSpec keeps executable content', () => {
+  assert.match(
+    extractScheduledTaskSpec('每天6点帮我做今日新闻页面'),
+    /今日新闻页面/u,
+  );
+});
+
+test('resolveOnceRunAtLocal returns future local datetime', () => {
+  const now = Date.parse('2026-08-11T10:00:00+08:00');
+  const runAtLocal = resolveOnceRunAtLocal('今晚 21:45 做新闻页', '今晚21:45做新闻页', {
+    timezone: 'Asia/Shanghai',
+    now,
+  });
+  assert.match(runAtLocal, /^2026-08-11 21:45$/);
+});
+
 test('isScheduledTaskIntent excludes none', () => {
   assert.equal(isScheduledTaskIntent({ action: 'create_scheduled_task' }), true);
   assert.equal(isScheduledTaskIntent({ action: 'none' }), false);