server ¶

MCP server implementation: Dispatcher, transports, middleware, subscriptions.

What belongs here ¶

• Server struct and options (NewServer, WithBearerToken, WithToolTimeout, etc.)
• Dispatcher — JSON-RPC routing, method handlers, session state
• Transports: SSE (transport.go), Streamable HTTP (streamable_transport.go)
• InProcessTransport — core.Transport implementation for testing/embedding
• Middleware chain (WithMiddleware, LoggingMiddleware)
• Server-to-client request infrastructure (sendServerRequest, routeServerResponse)
• Resource subscriptions (WithSubscriptions, NotifyResourceUpdated)
• Broadcast notifications (Broadcast) — fan out to all connected sessions
• Extension registration (WithExtension) — extensions declare capabilities in initialize response
• Startup validation (validateExtensionRefs) — calls RefValidator on registered extensions to warn about unresolvable resource references

Dependencies ¶

• core/ — protocol types (Request, Response, ToolDef, etc.)
• servicekit — SSE hub, graceful shutdown
• Does NOT import client/

In-process transport ¶

For testing, use NewInProcessTransport(srv) with client.WithTransport():

transport := server.NewInProcessTransport(srv,
    server.WithServerRequestHandler(func(ctx context.Context, req *core.Request) *core.Response {
        return client.HandleServerRequest(req) // for sampling/elicitation
    }),
    server.WithNotificationHandler(func(method string, params []byte) {
        // capture notifications in tests
    }),
)
c := client.NewClient("memory://", info, client.WithTransport(transport))

The in-process transport passes *core.Request/*core.Response directly — no JSON envelope serialization. This catches logic bugs; HTTP transport tests catch wire format bugs.