feat: Step 5 引擎接入 + H1-H3/S3 修复 + 审计 D1/D2/D5 修复

引擎接入（dispatcher/spawner/ticker → handler 统一路由）:
- dispatcher: guardrail/on_checks_passed/on_complete → handler 查询
- spawner: _build_prompt/_build_api_section → handler.build_prompt
- ticker: 虚拟项目扫描/assignee/claimed/review/幻觉门控 → handler 判断

Handler 缺陷修复:
- H1: _mark_task_status 加 3 次重试（防 DB 锁）
- H2: review @mention 加 comment_type='review'
- H3: review 非 approved 保持 review 状态（不标 working）
- S3: 通知链接改 Gitea（PR/Issue/Commit）

审计修复:
- D1: pre_spawn 返回值未检查 → 加 if not 抛 RuntimeError
- D2: PromptContext 缺 from_agent/mail_type → 从 must_haves 解析
- D5: _check_reply 查错表 → 恢复查 tasks 表找 in_reply_to

旧方法保留未删（deprecated），确认稳定后再清理。

src/daemon/ticker.py

@@ -215,18 +215,21 @@ class Ticker:
                 logger.exception("Tick %d _general error", tick_num)
                 results["projects"]["_general"] = {"error": str(e)}
 
-        # 虚拟项目 _mail：飞鸽传书
-        mail_db = Path(self.registry.root) / "_mail" / "blackboard.db"
-        if mail_db.exists() and "_mail" not in active_projects:
-            try:
-                pr = await self._tick_project("_mail", {
-                    "id": "_mail", "name": "飞鸽传书",
-                    "status": "active", "source": "virtual",
-                })
-                results["projects"]["_mail"] = pr
-            except Exception as e:
-                logger.exception("Tick %d _mail error", tick_num)
-                results["projects"]["_mail"] = {"error": str(e)}
+        # 虚拟项目：从注册表自动发现 + _general 硬编码
+        from src.daemon.task_type_registry import TaskTypeRegistry
+        for vp in TaskTypeRegistry.virtual_projects():
+            vp_db = Path(self.registry.root) / vp / "blackboard.db"
+            if vp_db.exists() and vp not in active_projects:
+                try:
+                    vp_name = {"_mail": "飞鸽传书", "_toolchain": "工具链事件"}.get(vp, vp)
+                    pr = await self._tick_project(vp, {
+                        "id": vp, "name": vp_name,
+                        "status": "active", "source": "virtual",
+                    })
+                    results["projects"][vp] = pr
+                except Exception as e:
+                    logger.exception("Tick %d %s error", tick_num, vp)
+                    results["projects"][vp] = {"error": str(e)}
 
         logger.debug(
             "Tick %d complete: %d projects",
@@ -948,9 +951,11 @@ Parent Task ID: {parent_task.id}
 
         now = datetime.utcnow().isoformat()
         # 重置到 pending 时清空 assignee（避免残留导致重复路由到同一 Agent）
-        # 但 Mail 的 assignee 是收件人，永不清空
+        # handler 虚拟项目（_mail 等）的 assignee 是收件人，永不清空
         if new_status == "pending":
-            if self._current_project_id == "_mail":
+            from src.daemon.task_type_registry import TaskTypeRegistry
+            handler = TaskTypeRegistry.get_by_project(self._current_project_id)
+            if handler:
                 conn.execute(
                     "UPDATE tasks SET status=?, updated_at=? WHERE id=?",
                     (new_status, now, task_id),
@@ -1025,15 +1030,17 @@ Parent Task ID: {parent_task.id}
                         "full", "escalate"):
                     conn = get_connection(db_path)
                     try:
-                        # [v2.7.1] Mail 已在 dispatcher 中标 working，跳过 claimed
-                        if project_id == "_mail":
+                        # [Step 5] handler 项目已在 dispatcher 中标 working，跳过 claimed
+                        from src.daemon.task_type_registry import TaskTypeRegistry
+                        handler = TaskTypeRegistry.get_by_project(project_id)
+                        if handler:
                             conn.execute(
                                 "UPDATE tasks SET current_agent=? WHERE id=?",
                                 (result["agent_id"], task.id),
                             )
                             conn.commit()
                             dispatched.append(task.id)
-                            logger.info("Dispatched %s to %s (session=%s, mail auto-working)",
+                            logger.info("Dispatched %s to %s (session=%s, handler auto-working)",
                                         task.id, result["agent_id"],
                                         result.get("session_id"))
                         else:
@@ -1300,8 +1307,10 @@ Parent Task ID: {parent_task.id}
     async def _dispatch_reviews(self, db_path: Path,
                                 project_id: str) -> List[str]:
         """扫描 review 状态任务，检查是否有产出，调度审查 Agent"""
-        # mail 任务不走 review 流程，直接跳过
-        if project_id == "_mail":
+        # handler 项目（_mail/_toolchain）不走 review 流程
+        from src.daemon.task_type_registry import TaskTypeRegistry
+        handler = TaskTypeRegistry.get_by_project(project_id)
+        if handler:
             return []
 
         queries = Queries(db_path)
@@ -1470,10 +1479,10 @@ Parent Task ID: {parent_task.id}
 
                 elapsed = (now - start_time).total_seconds() / 60.0
                 if elapsed > timeout_minutes:
-                    # [v2.7.1] Mail 幻觉门控兜底：有回复 + working → done
-                    if self._current_project_id == "_mail":
-                        has_reply = self._mail_check_reply(task.id, db_path)
-                        if has_reply:
+                    # [Step 5] handler 幻觉门控兜底：check_completion 通过 + working → done
+                    from src.daemon.task_type_registry import TaskTypeRegistry
+                    handler = TaskTypeRegistry.get_by_project(self._current_project_id)
+                    if handler and handler.check_completion(task.id, db_path):
                             conn = get_connection(db_path)
                             try:
                                 ok = self._transition_status(
@@ -1621,8 +1630,10 @@ Parent Task ID: {parent_task.id}
                 project_dirs[project_id] = self.registry.root / \
                     project_id / "blackboard.db"
 
-        # 虚拟项目
-        for virtual_id in ("_general", "_mail"):
+        # 虚拟项目：_general + 注册表自动发现
+        from src.daemon.task_type_registry import TaskTypeRegistry
+        virtual_ids = ["_general"] + TaskTypeRegistry.virtual_projects()
+        for virtual_id in virtual_ids:
             virtual_db = Path(self.registry.root) / \
                 virtual_id / "blackboard.db"
             if virtual_db.exists() and virtual_id not in project_dirs: