Hide ephemeral system threads from TUI routing (#40494)

## What changed

- Ignore `thread/started` notifications for ephemeral threads whose feature source is `system`, preventing hidden helper threads from entering TUI thread routing or refreshing the agents overview.
- Continue routing persisted system threads normally.

## Testing

- Add coverage for hidden and persisted system-thread notifications in the agents overview.
- Add generated-title normalization cases for wrapping quotes, trailing punctuation, and meaningful leading punctuation.

GitOrigin-RevId: e1ea48502b4f9aa7d5a187c7407df69c55abe2a9

codex-rs/tui/src/app/agents_overview_tests.rs

@@ -11,6 +11,8 @@ use codex_app_server_protocol::CurrentTimeReadParams;
 use codex_app_server_protocol::ServerRequest;
 use codex_app_server_protocol::SessionSource;
 use codex_app_server_protocol::ThreadActiveFlag;
+use codex_app_server_protocol::ThreadSource;
+use codex_app_server_protocol::ThreadStartedNotification;
 use codex_app_server_protocol::ThreadUnsubscribeParams;
 use codex_app_server_protocol::ThreadUnsubscribeResponse;
 use codex_app_server_protocol::ThreadUnsubscribeStatus;
@@ -67,6 +69,92 @@ fn overview_thread(
     }
 }
 
+#[tokio::test]
+async fn hidden_system_thread_does_not_refresh_shared_overview() {
+    let mut app = make_test_app().await;
+    let app_server = crate::start_embedded_app_server_for_picker(app.chat_widget.config_ref())
+        .await
+        .expect("embedded app server");
+    let view = app.agents_overview_view(Vec::new(), /*selected_thread_id*/ None);
+    app.chat_widget.show_bottom_pane_view(Box::new(view));
+
+    let request_id = uuid::Uuid::new_v4();
+    app.agents_overview.request_id = Some(request_id);
+
+    let parent_thread_id = ThreadId::new();
+    app.primary_thread_id = Some(parent_thread_id);
+    app.active_thread_id = Some(parent_thread_id);
+    app.ensure_thread_channel(parent_thread_id);
+    app.agents_overview
+        .dispatched_requests
+        .insert(parent_thread_id, Vec::new());
+
+    let hidden_thread_id = ThreadId::new();
+    let mut thread = overview_thread(
+        hidden_thread_id,
+        Some(parent_thread_id),
+        "Generate thread title",
+        ThreadStatus::Idle,
+    );
+    thread.ephemeral = true;
+    thread.thread_source = Some(ThreadSource::Feature("system".to_string()));
+
+    app.handle_app_server_event(
+        &app_server,
+        AppServerEvent::ServerNotification(Box::new(ServerNotification::ThreadStarted(
+            ThreadStartedNotification { thread },
+        ))),
+    )
+    .await;
+
+    assert_eq!(
+        (
+            app.agents_overview.request_id,
+            app.agents_overview.refresh_pending,
+        ),
+        (Some(request_id), false)
+    );
+    assert!(!app.thread_event_channels.contains_key(&hidden_thread_id));
+    assert!(
+        !app.agents_overview
+            .dispatched_requests
+            .contains_key(&hidden_thread_id)
+    );
+
+    let visible_thread_id = ThreadId::new();
+    let mut thread = overview_thread(
+        visible_thread_id,
+        Some(parent_thread_id),
+        "Persisted system thread",
+        ThreadStatus::Idle,
+    );
+    thread.thread_source = Some(ThreadSource::Feature("system".to_string()));
+
+    app.handle_app_server_event(
+        &app_server,
+        AppServerEvent::ServerNotification(Box::new(ServerNotification::ThreadStarted(
+            ThreadStartedNotification { thread },
+        ))),
+    )
+    .await;
+
+    assert_eq!(
+        (
+            app.agents_overview.request_id,
+            app.agents_overview.refresh_pending,
+        ),
+        (Some(request_id), true)
+    );
+    assert!(app.thread_event_channels.contains_key(&visible_thread_id));
+    assert!(
+        app.agents_overview
+            .dispatched_requests
+            .contains_key(&visible_thread_id)
+    );
+
+    app_server.shutdown().await.expect("shutdown app server");
+}
+
 #[tokio::test]
 async fn shared_overview_shows_only_root_sessions() {
     assert_eq!(

codex-rs/tui/src/app/app_server_events.rs

@@ -20,6 +20,7 @@ use codex_app_server_protocol::ServerRequest;
 use codex_app_server_protocol::SessionSource;
 use codex_app_server_protocol::ThreadReadParams;
 use codex_app_server_protocol::ThreadReadResponse;
+use codex_app_server_protocol::ThreadSource;
 use codex_protocol::ThreadId;
 use codex_protocol::protocol::SubAgentSource;
 
@@ -92,6 +93,15 @@ impl App {
             let _ = self.dynamic_tool_status_updates.send(status.clone());
         }
 
+        if let ServerNotification::ThreadStarted(started) = &notification
+            && started.thread.ephemeral
+            && matches!(
+                started.thread.thread_source.as_ref(),
+                Some(ThreadSource::Feature(feature)) if feature == "system"
+            )
+        {
+            return;
+        }
         // Hidden helper threads must not enter visible thread routing or overview refreshes.
         if let ServerNotificationThreadTarget::Thread(thread_id) =
             server_notification_thread_target(&notification)

codex-rs/tui/src/app/thread_title_tests.rs

@@ -99,6 +99,40 @@ fn normalizes_generated_title_whitespace() {
     );
 }
 
+#[test]
+fn removes_wrapping_quotes_and_trailing_punctuation_from_generated_titles() {
+    for title in [
+        r#""Fix login errors!""#,
+        "'Fix login errors?'",
+        "`Fix login errors.`",
+        "“Fix login errors!”",
+    ] {
+        let response = serde_json::json!({ "title": title }).to_string();
+
+        assert_eq!(
+            parse_thread_title(&response),
+            Some("Fix login errors".to_string()),
+            "response: {response}"
+        );
+    }
+}
+
+#[test]
+fn preserves_meaningful_leading_punctuation_in_generated_titles() {
+    for (title, expected) in [
+        (".NET migration.", ".NET migration"),
+        ("!important styling!", "!important styling"),
+    ] {
+        let response = serde_json::json!({ "title": title }).to_string();
+
+        assert_eq!(
+            parse_thread_title(&response),
+            Some(expected.to_string()),
+            "response: {response}"
+        );
+    }
+}
+
 #[test]
 fn rejects_invalid_or_empty_generated_titles() {
     for response in [