"""轮询任务读通道需要一条 RLS 口子

Revision ID: 0014
Revises: 0013
Create Date: 2026-11-05

后台轮询是"从 channel_id 开始"的：它还没有工作区上下文，而 `bot_channel` 的策略要求
`workspace_id = app_ws_id()`，直接 SELECT 会一行都看不到（先有鸡还是先有蛋）。

和 0012 那条 `token_hash = app_bot_token_hash()` 同理，这里再放一条**只按主键命中自己**
的口子：任务在读任何东西之前先把 `app.bot_channel` 设成本次要处理的通道 id，
策略允许它看见那一行，其余行照旧不可见。读到 workspace_id 之后立刻 `bind_tenant`，
后面所有查询都回到正常的租户上下文里。

两条策略是 permissive 关系（PG 会 OR 起来），所以原来的隔离策略不用改。
"""

from __future__ import annotations

from collections.abc import Sequence

from alembic import op

from app.roles import APP_ROLE

revision: str = "0014"
down_revision: str = "0013"
branch_labels: Sequence[str] | None = None
depends_on: Sequence[str] | None = None

CREATE_POLICY = """
CREATE POLICY bot_channel_worker ON bot_channel
    FOR ALL
    USING (id = current_setting('app.bot_channel', true)::uuid)
    WITH CHECK (id = current_setting('app.bot_channel', true)::uuid)
"""


def upgrade() -> None:
    op.execute("DROP POLICY IF EXISTS bot_channel_worker ON bot_channel")
    op.execute(CREATE_POLICY)
    op.execute(f"GRANT SELECT, INSERT, UPDATE, DELETE ON bot_channel TO {APP_ROLE}")


def downgrade() -> None:
    op.execute("DROP POLICY IF EXISTS bot_channel_worker ON bot_channel")