Standard last-event-id request header name

Author: CrazyHZM

mcp-spring/mcp-spring-webflux/src/main/java/io/modelcontextprotocol/client/transport/WebClientStreamableHttpTransport.java

@@ -35,6 +35,7 @@
 import java.util.function.Function;
 import java.util.function.Supplier;
 
+import static io.modelcontextprotocol.spec.McpSchema.Headers.LAST_EVENT_ID;
 import static io.modelcontextprotocol.spec.McpSchema.Headers.MCP_SESSION_ID;
 
 /**
@@ -190,7 +191,7 @@ private Mono<Disposable> reconnect(McpTransportStream<Disposable> stream) {
 				.headers(httpHeaders -> {
 					transportSession.sessionId().ifPresent(id -> httpHeaders.add(MCP_SESSION_ID, id));
 					if (stream != null) {
-						stream.lastId().ifPresent(id -> httpHeaders.add("last-event-id", id));
+						stream.lastId().ifPresent(id -> httpHeaders.add(LAST_EVENT_ID, id));
 					}
 				})
 				.exchangeToFlux(response -> {

mcp/src/main/java/io/modelcontextprotocol/spec/McpSchema.java

@@ -142,8 +142,18 @@ public static final class ErrorCodes {
 	 */
 	public static final class Headers {
 
+		/**
+		 * The Model Context Protocol (MCP) session ID header name.
+		 */
 		public static final String MCP_SESSION_ID = "Mcp-Session-Id";
 
+		/**
+		 * The Last-Event-ID HTTP request header reports an EventSource object's last
+		 * event ID string to the server when the user agent is to reestablish the
+		 * connection.
+		 */
+		public static final String LAST_EVENT_ID = "Last-Event-ID";
+
 	}
 
 	public sealed interface Request permits InitializeRequest, CallToolRequest, CreateMessageRequest, ElicitRequest,