feat(wechat): add Intent Transaction Layer with unified task schema

Introduce Draft → Confirm → Commit flow for WeChat schedule intents behind
feature flags, plus h5_tasks dual-write/read aggregation and rollout scripts
so reminders and automations get explicit user confirmation before persisting.

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

task-unified-sync.test.mjs

@@ -0,0 +1,102 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { attachUnifiedTaskSync } from './task-unified-sync.mjs';
+
+test('attachUnifiedTaskSync wraps scheduled task create when enabled', async () => {
+  const syncCalls = [];
+  const scheduledTaskService = {
+    async createTask(payload) {
+      return {
+        id: 'task-1',
+        userId: payload.userId,
+        title: payload.title,
+        taskSpec: payload.taskSpec,
+        recurrence: 'daily',
+        hour: 6,
+        minute: 0,
+        nextRunAt: 5000,
+        timezone: 'Asia/Shanghai',
+        notifyChannel: 'both',
+        sourceChannel: payload.sourceChannel,
+      };
+    },
+  };
+  const taskUnifiedService = {
+    async syncFromCommit(payload) {
+      syncCalls.push(payload);
+      return { id: 'unified-1' };
+    },
+  };
+
+  attachUnifiedTaskSync({
+    scheduleService: {},
+    scheduledTaskService,
+    taskUnifiedService,
+    pool: { async query() { return [[]]; } },
+    env: { H5_UNIFIED_TASKS_ENABLED: '1' },
+  });
+
+  await scheduledTaskService.createTask({
+    userId: 'user-1',
+    title: '每日新闻',
+    taskSpec: 'news',
+    sourceChannel: 'wechat',
+  });
+
+  assert.equal(syncCalls.length, 1);
+  assert.equal(syncCalls[0].kind, 'scheduled_task');
+});
+
+test('attachUnifiedTaskSync syncs lifecycle on markTaskSucceeded', async () => {
+  const lifecycleCalls = [];
+  const scheduledTaskService = {
+    async markTaskSucceeded(task) {
+      return {
+        ...task,
+        status: 'active',
+        nextRunAt: 9000,
+        lastRunAt: 8000,
+      };
+    },
+  };
+  attachUnifiedTaskSync({
+    scheduleService: {},
+    scheduledTaskService,
+    taskUnifiedService: {
+      async syncLegacyLifecycle(payload) {
+        lifecycleCalls.push(payload);
+      },
+    },
+    pool: { async query() { return [[]]; } },
+    env: { H5_UNIFIED_TASKS_ENABLED: '1' },
+  });
+  await scheduledTaskService.markTaskSucceeded({
+    id: 'task-1',
+    userId: 'user-1',
+    recurrence: 'daily',
+  });
+  assert.equal(lifecycleCalls.length, 1);
+  assert.equal(lifecycleCalls[0].status, 'active');
+});
+
+test('attachUnifiedTaskSync is noop when feature disabled', async () => {
+  const syncCalls = [];
+  const scheduledTaskService = {
+    async createTask() {
+      return { id: 'task-1' };
+    },
+  };
+  attachUnifiedTaskSync({
+    scheduleService: {},
+    scheduledTaskService,
+    taskUnifiedService: {
+      async syncFromCommit() {
+        syncCalls.push(true);
+      },
+    },
+    pool: { async query() { return [[]]; } },
+    env: { H5_UNIFIED_TASKS_ENABLED: '0' },
+  });
+  await scheduledTaskService.createTask({ userId: 'user-1' });
+  assert.equal(syncCalls.length, 0);
+});