diff --git a/nodejs/test/e2e/session.e2e.test.ts b/nodejs/test/e2e/session.e2e.test.ts
index 900ca4e859..1337410386 100644
--- a/nodejs/test/e2e/session.e2e.test.ts
+++ b/nodejs/test/e2e/session.e2e.test.ts
@@ -639,19 +639,17 @@ describe("Sessions", () => {
         await using session = await client.createSession({ onPermissionRequest: approveAll });
 
         let disposed = false;
-        const disposedPromise = new Promise<void>((resolve) => {
-            session.on((event) => {
-                if (event.type === "user.message") {
-                    // Call disconnect from within a handler — must not deadlock.
-                    session.disconnect().then(() => {
-                        disposed = true;
-                        resolve();
-                    });
-                }
-            });
+        let disposedPromise: Promise<void> | undefined;
+        session.on((event) => {
+            if (event.type === "session.idle") {
+                // Isolate handler reentrancy from active-turn cancellation.
+                disposedPromise = session.disconnect().then(() => {
+                    disposed = true;
+                });
+            }
         });
 
-        await session.send({ prompt: "What is 1+1?" });
+        await session.sendAndWait({ prompt: "What is 1+1?" });
 
         // If this times out, we deadlocked.
         await vi.waitFor(() => expect(disposed).toBe(true), { timeout: 10_000 });
diff --git a/python/e2e/test_mcp_and_agents_e2e.py b/python/e2e/test_mcp_and_agents_e2e.py
index 6f443a970c..915928f1e3 100644
--- a/python/e2e/test_mcp_and_agents_e2e.py
+++ b/python/e2e/test_mcp_and_agents_e2e.py
@@ -183,6 +183,8 @@ async def test_should_accept_custom_agent_configuration_on_session_resume(
         )
         session_id = session1.session_id
         await session1.send_and_wait("What is 1+1?")
+        # End the first attachment before testing resume-time reconfiguration.
+        await session1.disconnect()
 
         # Resume with custom agents
         custom_agents: list[CustomAgentConfig] = [