"""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")