fix: add init_timeout for streamable-http sessions (#811)

crates/rmcp/tests/test_streamable_http_init_timeout.rs

@@ -0,0 +1,63 @@
+#![cfg(all(feature = "transport-streamable-http-server", not(feature = "local")))]
+
+use std::time::Duration;
+
+use rmcp::{
+    model::{ClientJsonRpcMessage, ClientRequest, PingRequest, RequestId},
+    transport::streamable_http_server::session::{SessionManager, local::LocalSessionManager},
+};
+
+#[tokio::test]
+async fn test_init_timeout_terminates_pre_init_session() -> anyhow::Result<()> {
+    let mut manager = LocalSessionManager::default();
+    manager.session_config.init_timeout = Some(Duration::from_millis(200));
+
+    // Bind the transport so its drop-guard doesn't cancel the worker — we
+    // want termination via init_timeout, not via cancellation.
+    let (session_id, _transport) = manager.create_session().await?;
+
+    tokio::time::sleep(Duration::from_millis(500)).await;
+
+    let message = ClientJsonRpcMessage::request(
+        ClientRequest::PingRequest(PingRequest::default()),
+        RequestId::Number(1),
+    );
+    let result = manager.initialize_session(&session_id, message).await;
+
+    assert!(
+        result.is_err(),
+        "expected worker to be dead; got: {result:?}"
+    );
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_init_timeout_none_keeps_worker_alive() -> anyhow::Result<()> {
+    let mut manager = LocalSessionManager::default();
+    manager.session_config.init_timeout = None;
+
+    let (session_id, _transport) = manager.create_session().await?;
+
+    tokio::time::sleep(Duration::from_millis(500)).await;
+
+    let message = ClientJsonRpcMessage::request(
+        ClientRequest::PingRequest(PingRequest::default()),
+        RequestId::Number(1),
+    );
+    // Liveness probe: a live worker accepts the send then stalls waiting for
+    // a handler response (none is wired up), tripping the outer timeout. A
+    // dead worker would fail the send and return immediately.
+    let probe = tokio::time::timeout(
+        Duration::from_millis(200),
+        manager.initialize_session(&session_id, message),
+    )
+    .await;
+
+    assert!(
+        probe.is_err(),
+        "expected worker to be alive; got: {probe:?}"
+    );
+
+    Ok(())
+}