refactor: single-source the connection-kind mapping off the providers

architecture/container-lifecycle.md

@@ -36,10 +36,14 @@ container instance.
 `build_di_container` is an async FastAPI dependency that yields a *child
 container* scoped to the current *connection*, then closes it:
 
-- It applies the *scope mapping*: a `fastapi.Request` → `Scope.REQUEST` with the
-  request placed in `context[fastapi.Request]`; a `fastapi.WebSocket` →
-  `Scope.SESSION` with the socket in `context[fastapi.WebSocket]`. Any other
-  `HTTPConnection` yields a child with `scope=None`.
+- It applies the *scope mapping* by walking the registered *context providers*
+  (`_CONNECTION_PROVIDERS`): the first whose `context_type` the connection is an
+  instance of supplies both the scope and the context key. So a `fastapi.Request`
+  → `Scope.REQUEST` with the request placed in `context[fastapi.Request]`; a
+  `fastapi.WebSocket` → `Scope.SESSION` with the socket in
+  `context[fastapi.WebSocket]`. Any other `HTTPConnection` matches no provider and
+  yields a child with `scope=None`. The providers are the single source — adding a
+  connection kind is adding a provider, with no change to this dispatch.
 - The child is built from the root container via
   `build_child_container(context=..., scope=...)`.
 - After the endpoint returns, the `finally` block calls

architecture/glossary.md

@@ -26,10 +26,12 @@ off of.
 _Avoid_: request (a request is only one kind of connection)
 
 **Scope mapping**:
-The fixed correspondence this integration imposes between a connection kind and
-a `modern_di.Scope`: a `Request` opens a `REQUEST`-scoped child container; a
-`WebSocket` opens a `SESSION`-scoped one. Any other `HTTPConnection` gets no
-scope (`None`).
+The correspondence between a connection kind and a `modern_di.Scope`, sourced
+from the registered *context providers* (each carries its `context_type` and
+`scope`): a `Request` opens a `REQUEST`-scoped child container; a `WebSocket`
+opens a `SESSION`-scoped one. Any other `HTTPConnection` matches no provider and
+gets no scope (`None`). The providers are the single source — there is no
+separate hardcoded table.
 _Avoid_: scope resolution
 
 **Context provider**:

modern_di_fastapi/main.py

@@ -14,6 +14,12 @@
 fastapi_request_provider = providers.ContextProvider(scope=Scope.REQUEST, context_type=fastapi.Request)
 fastapi_websocket_provider = providers.ContextProvider(scope=Scope.SESSION, context_type=fastapi.WebSocket)
 
+# The single source of the connection-kind mapping. Each provider pairs a connection
+# type (``context_type``) with the scope its child container opens at; ``setup_di``
+# registers them and ``build_di_container`` dispatches off them. Add a connection
+# kind by adding its provider here — nothing else changes.
+_CONNECTION_PROVIDERS = (fastapi_request_provider, fastapi_websocket_provider)
+
 
 def fetch_di_container(app_: fastapi.FastAPI) -> Container:
     return typing.cast(Container, app_.state.di_container)
@@ -30,7 +36,7 @@ async def _lifespan_manager(app_: fastapi.FastAPI) -> typing.AsyncIterator[None]
 
 def setup_di(app: fastapi.FastAPI, container: Container) -> Container:
     app.state.di_container = container
-    container.providers_registry.add_providers(fastapi_request_provider, fastapi_websocket_provider)
+    container.providers_registry.add_providers(*_CONNECTION_PROVIDERS)
     old_lifespan_manager = app.router.lifespan_context
     app.router.lifespan_context = _merge_lifespan_context(
         old_lifespan_manager,
@@ -42,12 +48,11 @@ def setup_di(app: fastapi.FastAPI, container: Container) -> Container:
 async def build_di_container(connection: HTTPConnection) -> typing.AsyncIterator[Container]:
     context: dict[type[typing.Any], typing.Any] = {}
     scope = None
-    if isinstance(connection, fastapi.Request):
-        scope = fastapi_request_provider.scope
-        context[fastapi.Request] = connection
-    elif isinstance(connection, fastapi.WebSocket):
-        context[fastapi.WebSocket] = connection
-        scope = fastapi_websocket_provider.scope
+    for provider in _CONNECTION_PROVIDERS:
+        if isinstance(connection, provider.context_type):
+            context[provider.context_type] = connection
+            scope = provider.scope
+            break
     container = fetch_di_container(connection.app).build_child_container(context=context, scope=scope)
     try:
         yield container

pyproject.toml

@@ -17,7 +17,7 @@ classifiers = [
     "Typing :: Typed",
     "Topic :: Software Development :: Libraries",
 ]
-dependencies = ["fastapi>=0.100,<1", "modern-di>=2.19.0,<3"]
+dependencies = ["fastapi>=0.100,<1", "modern-di>=2.21.0,<3"]
 version = "0"
 
 [project.urls]