From 2170a0664de90a7d1e4ee5f543f3e16361f8a0bb Mon Sep 17 00:00:00 2001
From: Steven <wenw@foxmail.com>
Date: Thu, 5 Nov 2026 23:33:44 +0800
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上一版把双进程抢会话修了，但生产重启后仍然不收消息：`start_all()` 是进程启动时的
查询，那一刻没有工作区上下文，`bot_channel` 的 RLS 把行全藏起来，一行都查不到，
于是"页面上显示已连接，实际上没人在拉消息"。

- 迁移 0016 补一条只读策略：`current_setting('app.bot_list') = 'on'` 时允许 SELECT
  （只开 SELECT，防止顺手拿它改别人的通道）；
- `start_all()` 走 `active_channel_ids()`，先设这个 GUC 再列通道；
- 补测试 `test_startup_sees_logged_in_channels`。
---
 2.Design/ROADMAP-M0-M1.md                     |  7 +++
 .../0016_bot_channel_startup_policy.py        | 43 +++++++++++++++++++
 backend/app/services/wechat_bot.py            | 26 +++++++----
 backend/tests/test_wechat_bot.py              | 23 ++++++++++
 4 files changed, 91 insertions(+), 8 deletions(-)
 create mode 100644 backend/alembic/versions/0016_bot_channel_startup_policy.py

diff --git a/2.Design/ROADMAP-M0-M1.md b/2.Design/ROADMAP-M0-M1.md
index 1148200..87ce332 100644
--- a/2.Design/ROADMAP-M0-M1.md
+++ b/2.Design/ROADMAP-M0-M1.md
@@ -824,6 +824,13 @@
 2. **回话别再带站点链接**：`PUBLIC_BASE_URL` 是内网地址，手机上打不开；
    现在只回「已保存任务：…」／「已保存知识草稿：…」。
 3. **栏目名从「接入」改成「机器人」**：用户要的是「我和这个机器人说话」，不是「配置接入」。
+4. **重启之后机器人静默不收消息**：生产是 `gunicorn -w 2`，两个进程各跑一遍 lifespan，
+   同一个通道会被起两条长轮询（消息被一个消费、回复从另一个发出，游标互相覆盖）；
+   而且 `start_all()` 是"没有工作区上下文"的查询，被 RLS 全藏起来，一行都查不到。
+   - 租约：会话级 `pg_try_advisory_lock`，抢到的进程收，另一个每 10 秒重试；进程挂了连接断、
+     锁自动释放，备用进程接上。页面「接收中」只认抢到租约的那个。
+   - 迁移 `0016` 补一条只读策略：`current_setting('app.bot_list') = 'on'` 时允许 SELECT，
+     `start_all()` 先设这个 GUC 再列通道。
 
 ### 13.7 教训：第一版是猜的
 
diff --git a/backend/alembic/versions/0016_bot_channel_startup_policy.py b/backend/alembic/versions/0016_bot_channel_startup_policy.py
new file mode 100644
index 0000000..6249129
--- /dev/null
+++ b/backend/alembic/versions/0016_bot_channel_startup_policy.py
@@ -0,0 +1,43 @@
+"""启动时列出要接管的通道，也需要一条 RLS 口子
+
+Revision ID: 0016
+Revises: 0015
+Create Date: 2026-11-05
+
+`BotManager.start_all()` 要在进程启动时问一句"现在有哪些通道已登录、该接着收消息"，
+但 `bot_channel` 的隔离策略要求 `workspace_id = app_ws_id()`，启动那一刻**没有工作区**，
+结果一行都查不到——表现是"重启之后机器人静默不收消息，页面上还显示已连接"。
+
+0014 那条口子是"知道 id、只看自己那一行"，这里补的是"允许列出还没开始干的活"：
+只有当次事务显式设了 `app.bot_list = 'on'` 时才放行，而且只开 **SELECT**，
+防止有人顺手拿它改别人的通道。
+"""
+
+from __future__ import annotations
+
+from collections.abc import Sequence
+
+from alembic import op
+
+from app.roles import APP_ROLE
+
+revision: str = "0016"
+down_revision: str = "0015"
+branch_labels: Sequence[str] | None = None
+depends_on: Sequence[str] | None = None
+
+CREATE_POLICY = """
+CREATE POLICY bot_channel_startup ON bot_channel
+    FOR SELECT
+    USING (current_setting('app.bot_list', true) = 'on')
+"""
+
+
+def upgrade() -> None:
+    op.execute("DROP POLICY IF EXISTS bot_channel_startup ON bot_channel")
+    op.execute(CREATE_POLICY)
+    op.execute(f"GRANT SELECT ON bot_channel TO {APP_ROLE}")
+
+
+def downgrade() -> None:
+    op.execute("DROP POLICY IF EXISTS bot_channel_startup ON bot_channel")
diff --git a/backend/app/services/wechat_bot.py b/backend/app/services/wechat_bot.py
index 5a15277..1e3b7dd 100644
--- a/backend/app/services/wechat_bot.py
+++ b/backend/app/services/wechat_bot.py
@@ -54,6 +54,23 @@ def site_base() -> str:
     return ""
 
 
+async def active_channel_ids() -> list[uuid.UUID]:
+    """列出"已扫码登录、该收消息"的通道。
+
+    启动时还没有工作区上下文，`bot_channel` 的 RLS 会把行全藏起来，所以先设
+    `app.bot_list='on'` 走迁移 0016 那条只读口子——不设的话重启后机器人会静默失联。
+    """
+    async with SessionFactory() as session, session.begin():
+        await session.execute(sa_text("SELECT set_config('app.bot_list', 'on', true)"))
+        rows = await session.execute(
+            select(BotChannel.id).where(
+                BotChannel.status == "active",
+                BotChannel.bot_token_enc.is_not(None),
+            )
+        )
+        return [row[0] for row in rows]
+
+
 async def acquire_lease(channel_id: uuid.UUID):
     """抢"这个通道由我收消息"的租约；抢到返回连接（关掉就是释放），抢不到返回 None。
 
@@ -103,14 +120,7 @@ class BotManager:
 
     async def start_all(self) -> None:
         """进程启动时把已登录的通道都拉起来，不然重启就静默不收消息了。"""
-        async with SessionFactory() as session:
-            rows = await session.execute(
-                select(BotChannel.id).where(
-                    BotChannel.status == "active",
-                    BotChannel.bot_token_enc.is_not(None),
-                )
-            )
-            ids = [row[0] for row in rows]
+        ids = await active_channel_ids()
         for channel_id in ids:
             await self.start(channel_id)
         if ids:
diff --git a/backend/tests/test_wechat_bot.py b/backend/tests/test_wechat_bot.py
index a616a99..9016c62 100644
--- a/backend/tests/test_wechat_bot.py
+++ b/backend/tests/test_wechat_bot.py
@@ -354,3 +354,26 @@ async def test_only_one_process_holds_the_polling_lease() -> None:
     third = await wechat_bot.acquire_lease(channel_id)
     assert third is not None, "前一个进程放手后，备用进程要能接上"
     await third.close()
+
+
+async def test_startup_sees_logged_in_channels(client: AsyncClient) -> None:
+    """重启后要能把已登录的通道接回来：没有工作区上下文时也得看得见（迁移 0016）。"""
+    user = await login(client)
+    ws = await create_workspace(client, user, "重启接管")
+    ws_id = uuid.UUID(ws["id"])
+
+    async with SessionFactory() as session:
+        await bind_tenant(session, ws_id, uuid.UUID(user["user_id"]))
+        channel = BotChannel(
+            workspace_id=ws_id,
+            kind="wechat_clawbot",
+            name="微信",
+            status="active",
+            bot_token_enc=wechat_ilink.encrypt_token("bot-token-x"),
+        )
+        session.add(channel)
+        await session.commit()
+        channel_id = channel.id
+
+    ids = await wechat_bot.active_channel_ids()
+    assert channel_id in ids, "启动时看不见已登录通道，重启后机器人就静默失联了"