mcp: handle list changed notifications

crates/mcp/tests/fixtures/mock_server.rs

@@ -16,6 +16,7 @@ fn main() {
         "tools-call-forbidden" => tools_call_forbidden(),
         "fail-init" => fail_init(),
         "sampling" => sampling_request(),
+        "list-changed-all" => list_changed_all(),
         "shutdown-hang" => shutdown_hang(),
         other => panic!("unknown mock mode: {other}"),
     }
@@ -223,6 +224,36 @@ fn sampling_request() {
     assert_eq!(response["error"]["code"], -32601);
 }
 
+fn list_changed_all() {
+    let init = read_json();
+    write_json(json!({
+        "jsonrpc": "2.0",
+        "id": init["id"],
+        "result": initialize_result(),
+    }));
+    let initialized = read_json();
+    assert_eq!(initialized["method"], "notifications/initialized");
+    for method in [
+        "notifications/tools/list_changed",
+        "notifications/resources/list_changed",
+        "notifications/prompts/list_changed",
+    ] {
+        write_json(json!({
+            "jsonrpc": "2.0",
+            "method": method,
+            "params": {
+                "malicious_instruction": "INJECT_ME_FROM_LIST_CHANGED_PARAMS"
+            }
+        }));
+    }
+
+    let shutdown = read_json();
+    assert_eq!(shutdown["method"], "shutdown");
+    write_json(json!({"jsonrpc":"2.0", "id": shutdown["id"], "result": {}}));
+    let notification = read_json();
+    assert_eq!(notification["method"], "exit");
+}
+
 fn shutdown_hang() {
     let init = read_json();
     write_json(json!({

crates/mcp/tests/stdio_lifecycle.rs

@@ -1,8 +1,8 @@
 use std::time::Duration;
 
 use mcp::stdio::{
-    CallToolRequest, McpErrorKind, McpPhase, McpStdioClient, McpStdioLimits, McpStdioServerSpec,
-    McpToolListLimits,
+    CallToolRequest, McpErrorKind, McpListChangedKind, McpPhase, McpStdioClient, McpStdioLimits,
+    McpStdioServerSpec, McpToolListLimits,
 };
 
 fn mock_server(mode: &str) -> McpStdioServerSpec {
@@ -239,6 +239,36 @@ async fn shutdown_terminates_or_kills_uncooperative_server() {
     assert!(shutdown.terminated || shutdown.killed);
 }
 
+#[tokio::test]
+async fn list_changed_notifications_record_bounded_kind_only_state() {
+    let mut client = McpStdioClient::connect(mock_server("list-changed-all"), tight_limits())
+        .await
+        .expect("initialize succeeds");
+    tokio::time::sleep(Duration::from_millis(50)).await;
+
+    let snapshot = client.snapshot_list_changes().await;
+    assert_eq!(snapshot.server_name, "mock");
+    assert!(snapshot.contains(McpListChangedKind::Tools));
+    assert!(snapshot.contains(McpListChangedKind::Resources));
+    assert!(snapshot.contains(McpListChangedKind::Prompts));
+    let methods: Vec<&'static str> = snapshot
+        .kinds()
+        .map(McpListChangedKind::notification_method)
+        .collect();
+    assert_eq!(
+        methods,
+        vec![
+            "notifications/tools/list_changed",
+            "notifications/resources/list_changed",
+            "notifications/prompts/list_changed"
+        ]
+    );
+
+    client.clear_list_changes().await;
+    assert!(client.snapshot_list_changes().await.is_empty());
+    client.shutdown().await.expect("shutdown succeeds");
+}
+
 #[tokio::test]
 async fn sampling_requests_fail_closed_and_are_not_advertised() {
     let mut client = McpStdioClient::connect(mock_server("sampling"), tight_limits())