feat: Add roots change notification support to MCP server

- Implement roots change notification handler in McpAsyncServer
- Add rootsChangeConsumer builder methods to support single and multiple consumers
- Rename info() builder method to serverInfo() for clarity
- Add comprehensive tests for roots change notification functionality
- Add default server info implementation in Builder

Resolves #39

Author: tzolov

mcp/src/main/java/org/springframework/ai/mcp/server/McpAsyncServer.java

@@ -23,6 +23,7 @@
 import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.function.Consumer;
 
 import com.fasterxml.jackson.core.type.TypeReference;
 import org.slf4j.Logger;
@@ -39,6 +40,7 @@
 import org.springframework.ai.mcp.spec.McpSchema;
 import org.springframework.ai.mcp.spec.McpSchema.CallToolResult;
 import org.springframework.ai.mcp.spec.McpSchema.ClientCapabilities;
+import org.springframework.ai.mcp.spec.McpSchema.ListRootsResult;
 import org.springframework.ai.mcp.spec.McpSchema.LoggingLevel;
 import org.springframework.ai.mcp.spec.McpSchema.LoggingMessageNotification;
 import org.springframework.ai.mcp.spec.McpSchema.Tool;
@@ -84,7 +86,6 @@ public class McpAsyncServer {
 
 	private LoggingLevel minLoggingLevel = LoggingLevel.DEBUG;
 
-	// TODO: Add support for roots list changed notification
 	/**
 	 * Create a new McpAsyncServer with the given transport and capabilities.
 	 * @param mcpTransport The transport layer implementation for MCP communication
@@ -94,11 +95,13 @@ public class McpAsyncServer {
 	 * @param resources The map of resource registrations
 	 * @param resourceTemplates The list of resource templates
 	 * @param prompts The map of prompt registrations
+	 * @param rootsChangeConsumers The list of consumers that will be notified when the
+	 * roots list changes
 	 */
 	public McpAsyncServer(McpTransport mcpTransport, McpSchema.Implementation serverInfo,
 			McpSchema.ServerCapabilities serverCapabilities, List<ToolRegistration> tools,
 			Map<String, ResourceRegistration> resources, List<McpSchema.ResourceTemplate> resourceTemplates,
-			Map<String, PromptRegistration> prompts) {
+			Map<String, PromptRegistration> prompts, List<Consumer<List<McpSchema.Root>>> rootsChangeConsumers) {
 
 		this.serverInfo = serverInfo;
 		this.tools = new CopyOnWriteArrayList<>(tools != null ? tools : List.of());
@@ -156,6 +159,13 @@ public McpAsyncServer(McpTransport mcpTransport, McpSchema.Implementation server
 
 		notificationHandlers.put(McpSchema.METHOD_NOTIFICATION_INITIALIZED, (params) -> Mono.empty());
 
+		if (Utils.isEmpty(rootsChangeConsumers)) {
+			rootsChangeConsumers = List.of((roots) -> logger
+				.warn("Roots list changed notification, but no consumers provided. Roots list changed: {}", roots));
+		}
+		notificationHandlers.put(McpSchema.METHOD_NOTIFICATION_ROOTS_LIST_CHANGED,
+				rootsListChnagedNotificationHandler(rootsChangeConsumers));
+
 		this.transport = mcpTransport;
 		this.mcpSession = new DefaultMcpSession(Duration.ofSeconds(10), mcpTransport, requestHandlers,
 				notificationHandlers);
@@ -238,6 +248,33 @@ public void close() {
 		this.mcpSession.close();
 	}
 
+	private static TypeReference<McpSchema.ListRootsResult> LIST_ROOTS_RESULT_TYPE_REF = new TypeReference<>() {
+	};
+
+	private NotificationHandler rootsListChnagedNotificationHandler(
+			List<Consumer<List<McpSchema.Root>>> rootsChangeConsumers) {
+
+		if (this.clientCapabilities != null && this.clientCapabilities.roots() != null) {
+
+			Mono<ListRootsResult> updatedRootsList = this.mcpSession.sendRequest(McpSchema.METHOD_ROOTS_LIST, null,
+					LIST_ROOTS_RESULT_TYPE_REF);
+
+			return params -> updatedRootsList // @formatter:off
+				.flatMap(listRootsResult -> 
+					Mono.fromRunnable(() -> 
+						rootsChangeConsumers.stream().forEach(consumer -> consumer.accept(listRootsResult.roots())))
+					.subscribeOn(Schedulers.boundedElastic())) // TODO: Check if this is needed
+				.onErrorResume(error -> {
+					logger.error("Error handling roots list change notification", error);
+					return Mono.empty();
+				})
+				.then(); // Convert to Mono<Void>
+				// @formatter:on
+		}
+
+		return params -> Mono.empty();
+	};
+
 	// ---------------------------------------
 	// Tool Management
 	// ---------------------------------------

mcp/src/main/java/org/springframework/ai/mcp/server/McpServer.java

@@ -20,6 +20,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.function.Consumer;
 import java.util.function.Function;
 
 import org.springframework.ai.mcp.spec.McpSchema;
@@ -206,9 +207,12 @@ public static Builder using(McpTransport transport) {
 	 */
 	public static class Builder {
 
+		private final static McpSchema.Implementation DEFAULT_SERVER_INFO = new McpSchema.Implementation("mcp-server",
+				"1.0.0");
+
 		private final McpTransport transport;
 
-		private McpSchema.Implementation serverInfo;
+		private McpSchema.Implementation serverInfo = DEFAULT_SERVER_INFO;
 
 		private McpSchema.ServerCapabilities serverCapabilities;
 
@@ -241,6 +245,8 @@ public static class Builder {
 		 */
 		private Map<String, PromptRegistration> prompts = new HashMap<>();
 
+		private List<Consumer<List<McpSchema.Root>>> rootsChangeConsumers = new ArrayList<>();
+
 		private Builder(McpTransport transport) {
 			Assert.notNull(transport, "Transport must not be null");
 			this.transport = transport;
@@ -255,22 +261,23 @@ private Builder(McpTransport transport) {
 		 * @return This builder instance for method chaining
 		 * @throws IllegalArgumentException if serverInfo is null
 		 */
-		public Builder info(McpSchema.Implementation serverInfo) {
+		public Builder serverInfo(McpSchema.Implementation serverInfo) {
 			Assert.notNull(serverInfo, "Server info must not be null");
 			this.serverInfo = serverInfo;
 			return this;
 		}
 
 		/**
 		 * Sets the server implementation information using name and version strings. This
-		 * is a convenience method alternative to {@link #info(McpSchema.Implementation)}.
+		 * is a convenience method alternative to
+		 * {@link #serverInfo(McpSchema.Implementation)}.
 		 * @param name The server name. Must not be null or empty.
 		 * @param version The server version. Must not be null or empty.
 		 * @return This builder instance for method chaining
 		 * @throws IllegalArgumentException if name or version is null or empty
-		 * @see #info(McpSchema.Implementation)
+		 * @see #serverInfo(McpSchema.Implementation)
 		 */
-		public Builder info(String name, String version) {
+		public Builder serverInfo(String name, String version) {
 			Assert.hasText(name, "Name must not be null or empty");
 			Assert.hasText(version, "Version must not be null or empty");
 			this.serverInfo = new McpSchema.Implementation(name, version);
@@ -518,6 +525,49 @@ public Builder prompts(PromptRegistration... prompts) {
 			return this;
 		}
 
+		/**
+		 * Registers a consumer that will be notified when the list of roots changes. This
+		 * is useful for updating resource availability dynamically, such as when new
+		 * files are added or removed.
+		 * @param consumer The consumer to register. Must not be null.
+		 * @return This builder instance for method chaining
+		 * @throws IllegalArgumentException if consumer is null
+		 */
+		public Builder rootsChangeConsumer(Consumer<List<McpSchema.Root>> consumer) {
+			Assert.notNull(consumer, "Consumer must not be null");
+			this.rootsChangeConsumers.add(consumer);
+			return this;
+		}
+
+		/**
+		 * Registers multiple consumers that will be notified when the list of roots
+		 * changes. This method is useful when multiple consumers need to be registered at
+		 * once.
+		 * @param consumers The list of consumers to register. Must not be null.
+		 * @return This builder instance for method chaining
+		 * @throws IllegalArgumentException if consumers is null
+		 */
+		public Builder rootsChangeConsumers(List<Consumer<List<McpSchema.Root>>> consumers) {
+			Assert.notNull(consumers, "Consumers list must not be null");
+			this.rootsChangeConsumers.addAll(consumers);
+			return this;
+		}
+
+		/**
+		 * Registers multiple consumers that will be notified when the list of roots
+		 * changes using varargs. This method provides a convenient way to register
+		 * multiple consumers inline.
+		 * @param consumers The consumers to register. Must not be null.
+		 * @return This builder instance for method chaining
+		 * @throws IllegalArgumentException if consumers is null
+		 */
+		public Builder rootsChangeConsumers(Consumer<List<McpSchema.Root>>... consumers) {
+			for (Consumer<List<McpSchema.Root>> consumer : consumers) {
+				this.rootsChangeConsumers.add(consumer);
+			}
+			return this;
+		}
+
 		/**
 		 * Builds a synchronous MCP server that provides blocking operations. Synchronous
 		 * servers process each request to completion before handling the next one, making
@@ -539,12 +589,9 @@ public McpSyncServer sync() {
 		 * settings
 		 */
 		public McpAsyncServer async() {
-			if (serverInfo == null) {
-				serverInfo = new McpSchema.Implementation("mcp-server", "1.0.0");
-			}
 
 			return new McpAsyncServer(transport, serverInfo, serverCapabilities, tools, resources, resourceTemplates,
-					prompts);
+					prompts, rootsChangeConsumers);
 		}
 
 	}

mcp/src/test/java/org/springframework/ai/mcp/attic/DemoServer.java

@@ -43,7 +43,7 @@ public static void main(String[] args) {
 		SseServerTransport transport = new SseServerTransport(new ObjectMapper(), "/mcp/message");
 
 		var mcpServer = McpServer.using(transport)
-			.info("Weather Forecast", "1.0.0")
+			.serverInfo("Weather Forecast", "1.0.0")
 			.tool(new McpSchema.Tool("weather", "Weather forecast tool by location", Map.of("city", "String")),
 					(arguments) -> {
 						String city = (String) arguments.get("city");