engine/session updates

docs/skills/pydantic-settings/SKILL.md

@@ -270,36 +270,32 @@ After settings validation, select an async SQLAlchemy driver URL. This is a pure
 from functools import cache
 
 from sqlalchemy import URL
-from sqlalchemy.ext.asyncio import AsyncEngine, create_async_engine
+from sqlalchemy.ext.asyncio import AsyncEngine
+from sqlalchemy.ext.asyncio import create_async_engine
 
 
-def get_database_url(
-  settings: Settings,
-) -> str:
-  match settings.database:
-    case SqliteSettings(path=path):
-      url = URL.create(
-        drivername="sqlite+aiosqlite",
-        database=path,
-      )
-    case PostgresSettings() as database:
-      url = URL.create(
-        drivername="postgresql+asyncpg",
-        host=database.host,
-        port=database.port,
-        database=database.database,
-        user=database.user,
-        password=database.password.get_secret_value(),
-      )
-  return url.render_as_string(hide_password=False)
+def get_database_url(settings: Settings) -> str:
+    match settings.database:
+        case SqliteSettings(path=path):
+            url = URL.create(
+                drivername="sqlite+aiosqlite",
+                database=path,
+            )
+        case PostgresSettings() as database:
+            url = URL.create(
+                drivername="postgresql+asyncpg",
+                host=database.host,
+                port=database.port,
+                database=database.database,
+                username=database.user,
+                password=database.password.get_secret_value(),
+            )
+    return url.render_as_string(hide_password=False)
 
 
 @cache
 def get_engine(database_url: str) -> AsyncEngine:
-  return create_async_engine(
-    database_url,
-    pool_pre_ping=True,
-  )
+    return create_async_engine(database_url, pool_pre_ping=True)
 
 
 async def dispose_engine(database_url: str) -> None:
@@ -308,6 +304,11 @@ async def dispose_engine(database_url: str) -> None:
     await engine.dispose()
   finally:
     get_engine.cache_clear()
+
+
+async def refresh_engine(database_url: str) -> AsyncEngine:
+    await dispose_engine(database_url)
+    return get_engine(database_url)
 ```
 
 At the composition boundary, resolve the URL once with `get_database_url(settings)` and use it to retrieve the cached engine. In FastAPI, expose that engine through lifespan and build one `async_sessionmaker` from it; each request or unit of work then creates its own `AsyncSession`. Do not call `aiosqlite.connect()` or `asyncpg.create_pool()` directly: `aiosqlite` and `asyncpg` are selected as SQLAlchemy drivers by the URL, while SQLAlchemy owns pooling, disposal, and session integration.