fix: 修复 SQLite 连接复用导致数据库不可用

app/db.py

@@ -5,6 +5,7 @@ from datetime import UTC, datetime
 
 from sqlalchemy import Engine, create_engine, event
 from sqlalchemy.orm import DeclarativeBase, Session, sessionmaker
+from sqlalchemy.pool import NullPool
 
 from app.config import get_settings
 
@@ -20,7 +21,10 @@ def create_sqlite_engine(database_url: str):
             db_path.parent.mkdir(parents=True, exist_ok=True)
 
     connect_args = {"check_same_thread": False, "timeout": 10}
-    engine = create_engine(database_url, connect_args=connect_args)
+    engine_kwargs = {"connect_args": connect_args}
+    if database_url.startswith("sqlite:///") and database_url != "sqlite:///:memory:":
+        engine_kwargs["poolclass"] = NullPool
+    engine = create_engine(database_url, **engine_kwargs)
     engine.dialect.connect_args = connect_args
 
     @event.listens_for(engine, "connect")

tests/unit/test_db_stability.py

@@ -1,4 +1,5 @@
 import pytest
+from sqlalchemy.pool import NullPool
 
 from app.db import check_database_integrity, checkpoint_sqlite_wal, create_sqlite_engine, ensure_sqlite_schema_compat
 
@@ -11,6 +12,14 @@ def test_check_database_integrity_returns_ok_for_valid_sqlite_database():
         engine.dispose()
 
 
+def test_file_sqlite_engine_does_not_reuse_connections_after_operational_errors(tmp_path):
+    engine = create_sqlite_engine(f"sqlite:///{tmp_path / 'app.db'}")
+    try:
+        assert isinstance(engine.pool, NullPool)
+    finally:
+        engine.dispose()
+
+
 def test_check_database_integrity_raises_when_sqlite_reports_problem(monkeypatch):
     class FakeCursor:
         def execute(self, _sql):