docs: document support for resumability and redelivery (#606)

Add missing documentation on resumability and redelivery in the
streamable transport.

Indirectly, also update stale transcluded examples. Example changes
weren't causing CI failure as we only trigger the docs check on changes
to the raw docs.

Author: findleyr

docs/client.md

@@ -53,9 +53,11 @@ func Example_roots() {
 
 	// Connect the server and client...
 	t1, t2 := mcp.NewInMemoryTransports()
-	if _, err := s.Connect(ctx, t1, nil); err != nil {
+	serverSession, err := s.Connect(ctx, t1, nil)
+	if err != nil {
 		log.Fatal(err)
 	}
+	defer serverSession.Close()
 
 	clientSession, err := c.Connect(ctx, t2, nil)
 	if err != nil {

docs/protocol.md

@@ -148,6 +148,7 @@ To create a streamable MCP server, you create a `StreamableHTTPHandler` and
 pass it an `mcp.Server`:
 
 ```go
+// TODO: Until we have a way to clean up abandoned sessions, this test will leak goroutines (see #499)
 func ExampleStreamableHTTPHandler() {
 	// Create a new streamable handler, using the same MCP server for every request.
 	//
@@ -185,6 +186,19 @@ client, err := mcp.Connect(ctx, transport, &mcp.ClientOptions{...})
 The `StreamableClientTransport` handles the HTTP requests and communicates with
 the server using the streamable transport protocol.
 
+#### Resumability and Redelivery
+
+By default, the streamable server does not support [resumability or
+redelivery](https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#resumability-and-redelivery)
+of messages, because doing so requires either a persistent storage solution or
+unbounded memory usage (see also
+[#580](https://github.com/modelcontextprotocol/go-sdk/issues/580)).
+
+To enable resumability, set `StreamableHTTPOptions.EventStore` to a non-nil
+value. The SDK provides a `MemoryEventStore` for testing or simple use cases;
+for production use it is generally advisable to use a more sophisticated
+implementation.
+
 #### Stateless Mode
 
 The streamable server supports a _stateless mode_ by setting

docs/troubleshooting.md

@@ -33,7 +33,7 @@ func ExampleLoggingTransport() {
 	if err != nil {
 		log.Fatal(err)
 	}
-	defer serverSession.Wait()
+	defer serverSession.Close()
 
 	client := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
 	var b bytes.Buffer
@@ -71,7 +71,7 @@ func ExampleStreamableHTTPHandler_middleware() {
 	server := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.1.0"}, nil)
 	handler := mcp.NewStreamableHTTPHandler(func(r *http.Request) *mcp.Server {
 		return server
-	}, nil)
+	}, &mcp.StreamableHTTPOptions{Stateless: true})
 	loggingHandler := http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
 		// Example debugging; you could also capture the response.
 		body, err := io.ReadAll(req.Body)

internal/docs/protocol.src.md

@@ -112,6 +112,19 @@ client, err := mcp.Connect(ctx, transport, &mcp.ClientOptions{...})
 The `StreamableClientTransport` handles the HTTP requests and communicates with
 the server using the streamable transport protocol.
 
+#### Resumability and Redelivery
+
+By default, the streamable server does not support [resumability or
+redelivery](https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#resumability-and-redelivery)
+of messages, because doing so requires either a persistent storage solution or
+unbounded memory usage (see also
+[#580](https://github.com/modelcontextprotocol/go-sdk/issues/580)).
+
+To enable resumability, set `StreamableHTTPOptions.EventStore` to a non-nil
+value. The SDK provides a `MemoryEventStore` for testing or simple use cases;
+for production use it is generally advisable to use a more sophisticated
+implementation.
+
 #### Stateless Mode
 
 The streamable server supports a _stateless mode_ by setting