Serve MCP 2026-07-28 from McpServerAdapter, experimentally

changes.md

@@ -89,12 +89,22 @@ Changes log
           supporting helper class. Applications with multiple STDIO protocol helpers must
           select one explicitly.
     - Enhancements
-        - Added the MCP extension using the official Java SDK 2.1.0 on shared Restlet HTTP
+        - Added the MCP extension using the official Java SDK (2.2.0-M2) on shared Restlet HTTP
           connectors and explicitly configured STDIO helpers. The supported stateless profile
           uses revision 2025-11-25, native SDK tools/resources/prompts and in-JVM dispatch,
           bounded messages/calls, one-shot SSE responses, and request cancellation. Sessions,
           listening GET streams, replay and Ikanos revision compatibility are not supported.
           Borrowed HTTP connectors are not stopped by the MCP client.
+        - The MCP server adapter also serves MCP revision 2026-07-28, experimentally, on the same
+          endpoint: a request whose `MCP-Protocol-Version` header names it goes to the SDK's
+          modern stateless server, other requests to the 2025-11-25 one. The tools, resources,
+          templates and prompts registered on the adapter are served to both revisions;
+          `McpServerAdapter.getModernTools()` adds tools on the SDK's modern types, served to
+          2026-07-28 clients only, for `input_required` results and streamed progress. The
+          interceptors wrap each 2026-07-28 request and its final result, the tool filters and
+          the call limit apply to both revisions, and `setRequestStateKey()` shares the key
+          sealing `input_required` state between instances. Not yet supported for 2026-07-28:
+          stdio, `subscriptions/listen`, and the MCP client. The SDK's modern API is a preview.
         - Added experimental SDK-native gRPC hosting of unary, server-streaming,
           client-streaming and bidirectional methods on a borrowed Restlet/Netty HTTP/2 listener.
           Request messages are read as the application requests them, within the queue budget,

org.restlet.ext.mcp/src/main/java/org/restlet/ext/mcp/McpProtocol.java

@@ -13,6 +13,13 @@
  */
 public final class McpProtocol {
     public static final String VERSION = "2025-11-25";
+
+    /**
+     * The stateless revision also served, experimentally, by {@link McpServerAdapter}: requests
+     * whose {@link #VERSION_HEADER} names it go to the MCP SDK's modern server.
+     */
+    public static final String MODERN_VERSION = "2026-07-28";
+
     public static final String VERSION_HEADER = "MCP-Protocol-Version";
     public static final String CONTEXT_KEY = "org.restlet.ext.mcp.requestContext";
     public static final String STREAM_TRANSPORT_ATTRIBUTE = "org.restlet.ext.mcp.streamTransport";

org.restlet.ext.mcp/src/main/java/org/restlet/ext/mcp/McpRequestContext.java

@@ -16,18 +16,31 @@
 /** MCP-only transport metadata, also available in native SDK callbacks under CONTEXT_KEY. */
 public final class McpRequestContext {
     private final Request request;
+    private final String protocolVersion;
     private final Map<String, Object> attributes = new ConcurrentHashMap<>();
 
     public McpRequestContext(Request request) {
+        this(request, McpProtocol.VERSION);
+    }
+
+    /**
+     * Creates the context of a request using a given MCP revision.
+     *
+     * @param request The transport request, or null.
+     * @param protocolVersion The MCP revision of the request, such as {@link
+     *     McpProtocol#MODERN_VERSION}.
+     */
+    public McpRequestContext(Request request, String protocolVersion) {
         this.request = request;
+        this.protocolVersion = java.util.Objects.requireNonNull(protocolVersion, "protocolVersion");
     }
 
     public Optional<Request> transportRequest() {
         return Optional.ofNullable(request);
     }
 
     public String protocolVersion() {
-        return McpProtocol.VERSION;
+        return protocolVersion;
     }
 
     public Map<String, Object> attributes() {