modelcontextprotocol
diff --git a/‎mcp-core/src/main/java/io/modelcontextprotocol/server/transport/StdioServerTransportProvider.java‎
Lines changed: 1 addition & 1 deletion b/‎mcp-core/src/main/java/io/modelcontextprotocol/server/transport/StdioServerTransportProvider.java‎
Lines changed: 1 addition & 1 deletion
@@ -160,7 +160,7 @@ public StdioMcpSessionTransport() {
 		@Override
 		public Mono<Void> sendMessage(McpSchema.JSONRPCMessage message) {
 
-			return Mono.zip(inboundReady.asMono(), outboundReady.asMono()).then(Mono.defer(() -> {
+			return Mono.when(inboundReady.asMono(), outboundReady.asMono()).then(Mono.defer(() -> {
 				if (outboundSink.tryEmitNext(message).isSuccess()) {
 					return Mono.empty();
 				}
Original file line number	Diff line number	Diff line change
`@@ -160,7 +160,7 @@ public StdioMcpSessionTransport() {`
`160`	`160`	`@Override`
`161`	`161`	`public Mono<Void> sendMessage(McpSchema.JSONRPCMessage message) {`
`162`	`162`
`163`		`- return Mono.zip(inboundReady.asMono(), outboundReady.asMono()).then(Mono.defer(() -> {`
	`163`	`+ return Mono.when(inboundReady.asMono(), outboundReady.asMono()).then(Mono.defer(() -> {`
`164`	`164`	`if (outboundSink.tryEmitNext(message).isSuccess()) {`
`165`	`165`	`return Mono.empty();`
`166`	`166`	`}`