fix: add sqlite wal mode and timeout

src/blacki/adk_runtime.py

@@ -83,6 +83,11 @@ def build_session_db_kwargs(env: ServerEnv) -> dict[str, Any]:
     Note: Pool settings are only relevant for PostgreSQL. SQLite uses
     a single connection and ignores pool settings.
     """
+    session_uri = build_session_service_uri(env)
+    is_sqlite = session_uri is None or session_uri.startswith("sqlite")
+
+    if is_sqlite:
+        return {"connect_args": {"timeout": 15}}
     return {}
 
 
@@ -102,7 +107,21 @@ def create_session_service(
         )
 
     if session_service_uri.startswith(("postgresql+asyncpg://", "sqlite+aiosqlite://")):
-        return DatabaseSessionService(session_service_uri, **session_db_kwargs)
+        service = DatabaseSessionService(session_service_uri, **session_db_kwargs)
+
+        if session_service_uri.startswith("sqlite"):
+            from sqlalchemy import event
+
+            @event.listens_for(service.db_engine.sync_engine, "connect")
+            def set_sqlite_pragma(
+                dbapi_connection: Any, connection_record: Any
+            ) -> None:
+                cursor = dbapi_connection.cursor()
+                cursor.execute("PRAGMA journal_mode=WAL")
+                cursor.execute("PRAGMA synchronous=NORMAL")
+                cursor.close()
+
+        return service
 
     msg = (
         "Shared ADK runtime does not support the configured session URI: "

tests/test_adk_runtime.py

@@ -3,7 +3,7 @@
 
 from collections.abc import AsyncIterator
 from pathlib import Path
-from unittest.mock import AsyncMock, patch
+from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
 from google.adk.events import Event
@@ -70,10 +70,17 @@ def test_build_session_service_uri_converts_postgresql_to_asyncpg() -> None:
         )
 
 
-def test_build_session_db_kwargs_returns_empty_dict() -> None:
-    """Test that session DB kwargs returns empty dict for SQLite."""
+def test_build_session_db_kwargs_returns_timeout_for_sqlite() -> None:
+    """Test that session DB kwargs returns timeout config for SQLite."""
     env = _build_server_env()
 
+    assert build_session_db_kwargs(env) == {"connect_args": {"timeout": 15}}
+
+
+def test_build_session_db_kwargs_returns_empty_for_postgres() -> None:
+    """Test that session DB kwargs returns empty dict for PostgreSQL."""
+    env = _build_server_env(agent_engine="postgresql://localhost:5432/db")
+
     assert build_session_db_kwargs(env) == {}
 
 
@@ -95,6 +102,44 @@ def test_create_session_service_with_sqlite_uri(tmp_path: Path) -> None:
     assert isinstance(session_service, DatabaseSessionService)
 
 
+def test_create_session_service_sqlite_event_listener(tmp_path: Path) -> None:
+    """Test that SQLite session services execute PRAGMAs on connect."""
+    db_path = tmp_path / "sessions.db"
+
+    with patch("sqlalchemy.event.listens_for") as mock_listens_for:
+        create_session_service(
+            f"sqlite+aiosqlite:///{db_path}",
+            {},
+        )
+
+        # Get the decorator returned by event.listens_for and the function it wrapped
+        decorator = mock_listens_for.return_value
+        set_sqlite_pragma = decorator.call_args[0][0]
+
+        # Call the wrapped function with a mock connection
+        mock_conn = MagicMock()
+        set_sqlite_pragma(mock_conn, None)
+
+        # Verify it executed the pragmas
+        cursor = mock_conn.cursor.return_value
+        assert cursor.execute.call_count == 2
+        cursor.execute.assert_any_call("PRAGMA journal_mode=WAL")
+        cursor.execute.assert_any_call("PRAGMA synchronous=NORMAL")
+        cursor.close.assert_called_once()
+
+
+@patch("blacki.adk_runtime.DatabaseSessionService")
+def test_create_session_service_with_postgres_uri(mock_db_service: AsyncMock) -> None:
+    """Test that PostgreSQL session services skip SQLite PRAGMAs."""
+    session_service = create_session_service(
+        "postgresql+asyncpg://user:pass@localhost/db",
+        {},
+    )
+
+    # Since we mocked it, it returns the mock object
+    assert session_service == mock_db_service.return_value
+
+
 def test_create_session_service_rejects_unsupported_uri() -> None:
     """Test that unsupported session URIs fail fast."""
     with pytest.raises(ValueError, match="does not support"):