fix: reopen root container across lifespan cycles

modern_di_fastapi/main.py

@@ -21,11 +21,11 @@ def fetch_di_container(app_: fastapi.FastAPI) -> Container:
 
 @contextlib.asynccontextmanager
 async def _lifespan_manager(app_: fastapi.FastAPI) -> typing.AsyncIterator[None]:
-    container = fetch_di_container(app_)
-    try:
+    # ``async with`` reopens the root container on each startup (``__aenter__``)
+    # and closes it on shutdown, so a second lifespan cycle against the same
+    # container works instead of raising ContainerClosedError.
+    async with fetch_di_container(app_):
         yield
-    finally:
-        await container.close_async()
 
 
 def setup_di(app: fastapi.FastAPI, container: Container) -> Container:

pyproject.toml

@@ -15,7 +15,7 @@ classifiers = [
     "Typing :: Typed",
     "Topic :: Software Development :: Libraries",
 ]
-dependencies = ["fastapi>=0.100,<1", "modern-di>=2.16.1,<3"]
+dependencies = ["fastapi>=0.100,<1", "modern-di>=2.19.0,<3"]
 version = "0"
 
 [project.urls]

tests/test_lifespan.py

@@ -0,0 +1,25 @@
+import typing
+
+import fastapi
+from starlette import status
+from starlette.testclient import TestClient
+
+from modern_di_fastapi import FromDI, fetch_di_container
+from tests.dependencies import Dependencies, SimpleCreator
+
+
+def test_lifespan_reopens_container_across_cycles(app: fastapi.FastAPI) -> None:
+    @app.get("/")
+    async def read_root(instance: typing.Annotated[SimpleCreator, FromDI(Dependencies.app_factory)]) -> None:
+        assert isinstance(instance, SimpleCreator)
+
+    container = fetch_di_container(app)
+
+    # First lifespan cycle: shutdown closes the root container.
+    with TestClient(app=app) as client:
+        assert client.get("/").status_code == status.HTTP_200_OK
+    assert container.closed
+
+    # Second cycle must reopen the same container instead of raising ContainerClosedError.
+    with TestClient(app=app) as client:
+        assert client.get("/").status_code == status.HTTP_200_OK