feat: 定时任务管理 + 会话只读分享

定时任务：
- 管理员可查看/编辑/删除/触发全部用户的定时任务（新增 /api/scheduled-tasks/admin/* 接口与管理页）
- 卡死任务恢复：单次执行超 30 分钟超时重试（最多 3 次），耗尽后标记 failed；看门狗回收服务重启遗留的「执行中」任务

会话分享：
- 新增「只读链接」分享模式，生成公开免登录的只读对话快照页（/share/:code）
- 公开接口 /api/public/shares/* 提供对话快照与图片附件

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

offline-backend-20260512/backend/CLAUDE.md

@@ -214,7 +214,7 @@ FastAPI application on port 8001 with health check at `GET /health`. Set `GATEWA
 |--------|-----------|
 | **Models** (`/api/models`) | `GET /` - list models; `GET /{name}` - model details |
 | **MCP** (`/api/mcp`) | `GET /config` - get config; `PUT /config` - update config (saves to extensions_config.json) |
-| **Skills** (`/api/skills`) | `GET /` - list skills (optional `search` fuzzy-name + `tag_id` filters; each item carries `tags` + owner-authored `detail`); `GET /{name}` - details; `PUT /{name}` - update enabled; `PUT /{name}/detail` - set the long-form `detail` text (custom skill: owner or admin; built-in/public: admin only — materializes a `skills` row on demand); `POST /install` - install from .skill archive (accepts standard optional frontmatter like `version`, `author`, `compatibility`) |
+| **Skills** (`/api/skills`) | `GET /` - list skills (optional `search` fuzzy-name + `tag_id` filters; each item carries `tags` + owner-authored `detail`); `GET /{name}` - details; `PUT /{name}` - update enabled; `PUT /{name}/detail` - set the long-form `detail` text (custom skill: owner or admin; built-in/public: admin only — materializes a `skills` row on demand); `GET /{name}/content` - raw SKILL.md source, restricted to an admin or the publisher (custom-skill owner); other users get 403 and see only description + detail; `POST /install` - install from .skill archive (accepts standard optional frontmatter like `version`, `author`, `compatibility`) |
 | **Memory** (`/api/memory`) | `GET /` - memory data; `POST /reload` - force reload; `GET /config` - config; `GET /status` - config + data |
 | **Agents** (`/api/agents`) | `GET /` - list built-in, owned, and published agents (optional `search` + `tag_id` filters; each item carries `tags`); `POST /` - create user-owned agent; `GET/PUT/DELETE /{id}` - read/update/delete by stable agent id; `GET /check` - validate non-empty display name (duplicates allowed) |
 | **Tags** (`/api/tags`) | `GET /` - list tags (optional `tag_type` filter; open to all); `POST /` - create tag (admin); `PUT /{id}` / `DELETE /{id}` - update/delete tag (admin); `GET /assignments/{target_type}/{target_id}` - tags on a resource; `PUT /assignments/{target_type}/{target_id}` - replace a resource's tags (admin). Tags are typed `agent`/`skill`/`scheduled_task` and may only tag resources of their own type. |
@@ -225,9 +225,18 @@ FastAPI application on port 8001 with health check at `GET /health`. Set `GATEWA
 | **Thread Runs** (`/api/threads/{id}/runs`) | `POST /` - create background run; `POST /stream` - create + SSE stream; `POST /wait` - create + block; `GET /` - list runs; `GET /{rid}` - run details; `POST /{rid}/cancel` - cancel; `GET /{rid}/join` - join SSE; `GET /{rid}/messages` - paginated messages `{data, has_more}`; `GET /{rid}/events` - full event stream; `GET /../messages` - thread messages with feedback; `GET /../token-usage` - aggregate tokens |
 | **Feedback** (`/api/threads/{id}/runs/{rid}/feedback`) | `PUT /` - upsert feedback; `DELETE /` - delete user feedback; `POST /` - create feedback; `GET /` - list feedback; `GET /stats` - aggregate stats; `DELETE /{fid}` - delete specific |
 | **Runs** (`/api/runs`) | `POST /stream` - stateless run + SSE; `POST /wait` - stateless run + block; `GET /{rid}/messages` - paginated messages by run_id `{data, has_more}` (cursor: `after_seq`/`before_seq`); `GET /{rid}/feedback` - list feedback by run_id |
+| **Thread Shares** (`/api/thread-shares`) | Per-conversation sharing with two modes (`thread_shares.mode`). **`import`**: `POST /` `{thread_id, mode}` - create (or reuse) a revocable share code; `GET /{code}/preview` + `POST /{code}/import` - copy that conversation into the caller's account (fresh `thread_id` via `app/gateway/thread_copy.py` + new `threads_meta` row + `user-data` copy; dedup on `metadata.shared_origin`). **`view`**: a public, read-only static page — see Public Shares below. Both modes: `GET /` - list my codes; `DELETE /{code}` - revoke. |
+| **Public Shares** (`/api/public/shares`) | **Unauthenticated** (the `/api/public/` prefix is whitelisted in `auth_middleware._PUBLIC_PATH_PREFIXES`). `GET /{code}` - read-only conversation snapshot (title + serialized messages + artifacts) for a `view`-mode share; messages are read straight from the latest checkpoint. `GET /{code}/files/{path}` - serves an **image** referenced by that conversation (images only — non-image paths 404; SVG forced to download). Missing/revoked/non-`view` codes all return 404. |
+| **Scheduled Tasks** (`/api/scheduled-tasks`) | Per-user cron-like agent tasks. `GET/POST /` - list/create owned tasks; `PATCH/DELETE /{id}` - update/delete (owner); `POST /{id}/{pause,resume,trigger}`; `GET /{id}/runs`, `GET/DELETE /runs/{rid}`, run-file preview/edit/download; publish/subscribe under `/{id}/{publish,unpublish,subscribe}` and `GET /published`. **Admin (cross-user):** `GET /admin/all` - every task; `PATCH/DELETE /admin/{id}` - edit/delete any task; `POST /admin/{id}/trigger`; `GET /admin/{id}/runs`. Admin routes require `system_role == "admin"`. |
 
 Proxied through nginx: `/api/langgraph/*` → LangGraph, all other `/api/*` → Gateway.
 
+### Scheduled Task Runtime
+
+`ScheduledTaskService` (`deerflow/runtime/scheduler/service.py`) polls due tasks every `poll_interval_seconds` and executes each in its own throwaway thread, serialized by a shared `_agent_run_lock`.
+
+**Stuck-run recovery**: each execution attempt is bounded by `_RUN_ATTEMPT_TIMEOUT_SECONDS` (30 min) via `asyncio.wait_for`. On timeout the run is retried up to `_MAX_RUN_RETRIES` (3) times, then marked `failed`. A watchdog (`_reconcile_stuck_runs`, run every poll) recovers runs left in `running` with no in-process owner — e.g. orphaned by a crash or restart — re-driving them through the same retry budget so a task can never stay perpetually "executing". The `scheduled_task_runs.retry_count` column tracks consumed retries.
+
 ### Custom Agent Persistence
 
 Custom agent metadata lives in the `agents` ORM table (`deerflow.persistence.agents`). `agents.id` is the stable runtime id and the filesystem directory name under `.deer-flow/agents/{id}/`; `agents.name` is display-only, can contain Chinese characters, and is not unique. `user_id IS NULL` marks built-in agents, user-owned agents are visible only to their owner unless `published = true`, and update/delete operations require ownership. The runtime accepts `agent_id` in context/configurable, and non-default `assistant_id` values are treated as agent ids after visibility checks.