fix: Lifespan pr cleanup/Extending ASGI lifespan examples

README.md

@@ -1317,6 +1317,8 @@ Run from the repository root:
     uvicorn examples.snippets.servers.streamable_http_basic_mounting:app --reload
 """
 
+import contextlib
+
 from starlette.applications import Starlette
 from starlette.routing import Mount
 
@@ -1332,11 +1334,20 @@ def hello() -> str:
     return "Hello from MCP!"
 
 
+# Create lifespan context manager to initialize the session manager
+@contextlib.asynccontextmanager
+async def lifespan(app: Starlette):
+    """Context manager for managing MCP session manager lifecycle."""
+    async with mcp.session_manager.run():
+        yield
+
+
 # Mount the StreamableHTTP server to the existing ASGI server
 app = Starlette(
     routes=[
         Mount("/", app=mcp.streamable_http_app()),
-    ]
+    ],
+    lifespan=lifespan,
 )
 ```
 
@@ -1354,6 +1365,8 @@ Run from the repository root:
     uvicorn examples.snippets.servers.streamable_http_host_mounting:app --reload
 """
 
+import contextlib
+
 from starlette.applications import Starlette
 from starlette.routing import Host
 
@@ -1369,11 +1382,20 @@ def domain_info() -> str:
     return "This is served from mcp.acme.corp"
 
 
+# Create lifespan context manager to initialize the session manager
+@contextlib.asynccontextmanager
+async def lifespan(app: Starlette):
+    """Context manager for managing MCP session manager lifecycle."""
+    async with mcp.session_manager.run():
+        yield
+
+
 # Mount using Host-based routing
 app = Starlette(
     routes=[
         Host("mcp.acme.corp", app=mcp.streamable_http_app()),
-    ]
+    ],
+    lifespan=lifespan,
 )
 ```
 
@@ -1391,6 +1413,8 @@ Run from the repository root:
     uvicorn examples.snippets.servers.streamable_http_multiple_servers:app --reload
 """
 
+import contextlib
+
 from starlette.applications import Starlette
 from starlette.routing import Mount
 
@@ -1418,12 +1442,24 @@ def send_message(message: str) -> str:
 api_mcp.settings.streamable_http_path = "/"
 chat_mcp.settings.streamable_http_path = "/"
 
+
+# Create lifespan context manager to initialize both session managers
+@contextlib.asynccontextmanager
+async def lifespan(app: Starlette):
+    """Context manager for managing multiple MCP session managers."""
+    async with contextlib.AsyncExitStack() as stack:
+        await stack.enter_async_context(api_mcp.session_manager.run())
+        await stack.enter_async_context(chat_mcp.session_manager.run())
+        yield
+
+
 # Mount the servers
 app = Starlette(
     routes=[
         Mount("/api", app=api_mcp.streamable_http_app()),
         Mount("/chat", app=chat_mcp.streamable_http_app()),
-    ]
+    ],
+    lifespan=lifespan,
 )
 ```
 
@@ -1441,6 +1477,8 @@ Run from the repository root:
     uvicorn examples.snippets.servers.streamable_http_path_config:app --reload
 """
 
+import contextlib
+
 from starlette.applications import Starlette
 from starlette.routing import Mount
 
@@ -1457,11 +1495,20 @@ def process_data(data: str) -> str:
     return f"Processed: {data}"
 
 
+# Create lifespan context manager to initialize the session manager
+@contextlib.asynccontextmanager
+async def lifespan(app: Starlette):
+    """Context manager for managing MCP session manager lifecycle."""
+    async with mcp_at_root.session_manager.run():
+        yield
+
+
 # Mount at /process - endpoints will be at /process instead of /process/mcp
 app = Starlette(
     routes=[
         Mount("/process", app=mcp_at_root.streamable_http_app()),
-    ]
+    ],
+    lifespan=lifespan,
 )
 ```
 

examples/snippets/servers/streamable_http_basic_mounting.py

@@ -5,6 +5,8 @@
     uvicorn examples.snippets.servers.streamable_http_basic_mounting:app --reload
 """
 
+import contextlib
+
 from starlette.applications import Starlette
 from starlette.routing import Mount
 
@@ -20,9 +22,18 @@ def hello() -> str:
     return "Hello from MCP!"
 
 
+# Create lifespan context manager to initialize the session manager
+@contextlib.asynccontextmanager
+async def lifespan(app: Starlette):
+    """Context manager for managing MCP session manager lifecycle."""
+    async with mcp.session_manager.run():
+        yield
+
+
 # Mount the StreamableHTTP server to the existing ASGI server
 app = Starlette(
     routes=[
         Mount("/", app=mcp.streamable_http_app()),
-    ]
+    ],
+    lifespan=lifespan,
 )

examples/snippets/servers/streamable_http_host_mounting.py

@@ -5,6 +5,8 @@
     uvicorn examples.snippets.servers.streamable_http_host_mounting:app --reload
 """
 
+import contextlib
+
 from starlette.applications import Starlette
 from starlette.routing import Host
 
@@ -20,9 +22,18 @@ def domain_info() -> str:
     return "This is served from mcp.acme.corp"
 
 
+# Create lifespan context manager to initialize the session manager
+@contextlib.asynccontextmanager
+async def lifespan(app: Starlette):
+    """Context manager for managing MCP session manager lifecycle."""
+    async with mcp.session_manager.run():
+        yield
+
+
 # Mount using Host-based routing
 app = Starlette(
     routes=[
         Host("mcp.acme.corp", app=mcp.streamable_http_app()),
-    ]
+    ],
+    lifespan=lifespan,
 )

examples/snippets/servers/streamable_http_multiple_servers.py

@@ -5,6 +5,8 @@
     uvicorn examples.snippets.servers.streamable_http_multiple_servers:app --reload
 """
 
+import contextlib
+
 from starlette.applications import Starlette
 from starlette.routing import Mount
 
@@ -32,10 +34,22 @@ def send_message(message: str) -> str:
 api_mcp.settings.streamable_http_path = "/"
 chat_mcp.settings.streamable_http_path = "/"
 
+
+# Create lifespan context manager to initialize both session managers
+@contextlib.asynccontextmanager
+async def lifespan(app: Starlette):
+    """Context manager for managing multiple MCP session managers."""
+    async with contextlib.AsyncExitStack() as stack:
+        await stack.enter_async_context(api_mcp.session_manager.run())
+        await stack.enter_async_context(chat_mcp.session_manager.run())
+        yield
+
+
 # Mount the servers
 app = Starlette(
     routes=[
         Mount("/api", app=api_mcp.streamable_http_app()),
         Mount("/chat", app=chat_mcp.streamable_http_app()),
-    ]
+    ],
+    lifespan=lifespan,
 )

examples/snippets/servers/streamable_http_path_config.py

@@ -5,6 +5,8 @@
     uvicorn examples.snippets.servers.streamable_http_path_config:app --reload
 """
 
+import contextlib
+
 from starlette.applications import Starlette
 from starlette.routing import Mount
 
@@ -21,9 +23,18 @@ def process_data(data: str) -> str:
     return f"Processed: {data}"
 
 
+# Create lifespan context manager to initialize the session manager
+@contextlib.asynccontextmanager
+async def lifespan(app: Starlette):
+    """Context manager for managing MCP session manager lifecycle."""
+    async with mcp_at_root.session_manager.run():
+        yield
+
+
 # Mount at /process - endpoints will be at /process instead of /process/mcp
 app = Starlette(
     routes=[
         Mount("/process", app=mcp_at_root.streamable_http_app()),
-    ]
+    ],
+    lifespan=lifespan,
 )

examples/snippets/servers/streamable_simple_lifespan.py

@@ -0,0 +1,55 @@
+"""
+Example showing ASGI route mounting with lifespan context management.
+
+From the repository root:
+    cd examples/snippets/servers
+    uv run streamable_uvicorn_lifespan.py
+"""
+
+import contextlib
+
+from starlette.applications import Starlette
+from starlette.routing import Mount
+
+from mcp.server.fastmcp import FastMCP
+
+# Create MCP server
+mcp = FastMCP(name="My App", stateless_http=True)
+
+
+@mcp.tool()
+def ping() -> str:
+    """A simple ping tool"""
+    return "pong"
+
+
+# lifespan for managing the session manager
+@contextlib.asynccontextmanager
+async def lifespan(app: Starlette):
+    """Gather any session managers for startup/shutdown.
+    See streamable_starlette_mount.py for example of multiple mcp managers.
+    """
+    async with mcp.session_manager.run():
+        yield
+
+
+"""Create the Starlette app and mount the MCP server.
+lifespan ensures the session manager is started/stopped with the app.
+session_manager references must only be made after streamable_http_app()
+"""
+app = Starlette(
+    routes=[
+        # Mounted at /mcp
+        Mount("/", app=mcp.streamable_http_app()),
+    ],
+    lifespan=lifespan,
+)
+
+if __name__ == "__main__":
+    import uvicorn
+
+    """Attach to another ASGI server LIFO
+    ASGI chain: Uvicorn -> Starlette -> FastMCP
+    Route: http://0.0.0.0:8000/mcp
+    """
+    uvicorn.run(app, host="0.0.0.0", port=8000)