fix(persistence): repair missing mcp readme column

tests/integration/persistence/test_migrations.py

@@ -11,6 +11,7 @@ from __future__ import annotations
 
 import pytest
 from alembic.script import ScriptDirectory
+from sqlalchemy import inspect, text
 from sqlalchemy.ext.asyncio import create_async_engine
 
 from langbot.pkg.entity.persistence.base import Base
@@ -147,6 +148,41 @@ class TestSQLiteMigrationUpgrade:
         rev2 = await get_alembic_current(sqlite_engine)
         assert rev2 == rev1, f"Expected {rev1}, got {rev2}"
 
+    @pytest.mark.asyncio
+    async def test_upgrade_repairs_head_stamped_mcp_readme_column(self, sqlite_engine):
+        """
+        A database may already be stamped at the previous head while missing a
+        column added by an earlier guarded migration. Upgrade should still
+        repair mcp_servers.readme so startup ORM queries do not fail.
+        """
+        async with sqlite_engine.begin() as conn:
+            await conn.execute(
+                text(
+                    """
+                    CREATE TABLE mcp_servers (
+                        uuid VARCHAR(255) NOT NULL PRIMARY KEY,
+                        name VARCHAR(255) NOT NULL,
+                        enable BOOLEAN NOT NULL,
+                        mode VARCHAR(255) NOT NULL,
+                        extra_args JSON NOT NULL,
+                        created_at DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL,
+                        updated_at DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL
+                    )
+                    """
+                )
+            )
+
+        await run_alembic_stamp(sqlite_engine, '7b2c1d9e4f30')
+        await run_alembic_upgrade(sqlite_engine, 'head')
+
+        async with sqlite_engine.connect() as conn:
+            columns = await conn.run_sync(
+                lambda sync_conn: {column['name'] for column in inspect(sync_conn).get_columns('mcp_servers')}
+            )
+
+        assert 'readme' in columns
+        assert await get_alembic_current(sqlite_engine) == alembic_head_revision()
+
 
 class TestSQLiteMigrationFreshDatabase:
     """Tests for fresh database workflow."""