feat(tui): add /statusline command for interactive status line configuration (#10546)

## Summary
- Adds a new `/statusline` command to configure TUI footer status line
- Introduces reusable `MultiSelectPicker` component with keyboard
navigation, optional ordering and toggle support
- Implement status line setup modal that persist configuration to
config.toml

  ## Status Line Items
  The following items can be displayed in the status line:
  - **Model**: Current model name (with optional reasoning level)
  - **Context**: Remaining/used context window percentage
  - **Rate Limits**: 5-day and weekly usage limits
  - **Git**: Current branch (with optimized lookups)
  - **Tokens**: Used tokens, input/output token counts
  - **Session**: Session ID (full or shortened prefix)
  - **Paths**: Current directory, project root
  - **Version**: Codex version

  ## Features
  - Live preview while configuring status line items
  - Fuzzy search filtering in the picker
  - Intelligent truncation when items don't fit
  - Items gracefully omit when data is unavailable
  - Configuration persists to `config.toml`
  - Validates and warns about invalid status line items

  ## Test plan
  - [x] Run `/statusline` and verify picker UI appears
  - [x] Toggle items on/off and verify live preview updates
  - [x] Confirm selection persists after restart
  - [x] Verify truncation behavior with many items selected
  - [x] Test git branch detection in and out of git repos

---------

Co-authored-by: Josh McKinney <joshka@openai.com>

codex-rs/tui/src/chatwidget/tests.rs

@@ -830,6 +830,7 @@ async fn helpers_are_available_and_do_not_panic() {
         is_first_run: true,
         feedback_audience: FeedbackAudience::External,
         model: Some(resolved_model),
+        status_line_invalid_items_warned: Arc::new(AtomicBool::new(false)),
         otel_manager,
     };
     let mut w = ChatWidget::new(init, thread_manager);
@@ -958,6 +959,12 @@ async fn make_chatwidget_manual(
         feedback: codex_feedback::CodexFeedback::new(),
         feedback_audience: FeedbackAudience::External,
         current_rollout_path: None,
+        current_cwd: None,
+        status_line_invalid_items_warned: Arc::new(AtomicBool::new(false)),
+        status_line_branch: None,
+        status_line_branch_cwd: None,
+        status_line_branch_pending: false,
+        status_line_branch_lookup_complete: false,
         external_editor_state: ExternalEditorState::Closed,
     };
     widget.set_model(&resolved_model);
@@ -2637,6 +2644,7 @@ async fn collaboration_modes_defaults_to_code_on_startup() {
         is_first_run: true,
         feedback_audience: FeedbackAudience::External,
         model: Some(resolved_model.clone()),
+        status_line_invalid_items_warned: Arc::new(AtomicBool::new(false)),
         otel_manager,
     };
 
@@ -2682,6 +2690,7 @@ async fn experimental_mode_plan_applies_on_startup() {
         is_first_run: true,
         feedback_audience: FeedbackAudience::External,
         model: Some(resolved_model.clone()),
+        status_line_invalid_items_warned: Arc::new(AtomicBool::new(false)),
         otel_manager,
     };
 
@@ -4907,6 +4916,83 @@ async fn warning_event_adds_warning_history_cell() {
     );
 }
 
+#[tokio::test]
+async fn status_line_invalid_items_warn_once() {
+    let (mut chat, mut rx, _op_rx) = make_chatwidget_manual(None).await;
+    chat.config.tui_status_line = Some(vec![
+        "model_name".to_string(),
+        "bogus_item".to_string(),
+        "lines_changed".to_string(),
+        "bogus_item".to_string(),
+    ]);
+    chat.thread_id = Some(ThreadId::new());
+
+    chat.refresh_status_line();
+    let cells = drain_insert_history(&mut rx);
+    assert_eq!(cells.len(), 1, "expected one warning history cell");
+    let rendered = lines_to_single_string(&cells[0]);
+    assert!(
+        rendered.contains("bogus_item"),
+        "warning cell missing invalid item content: {rendered}"
+    );
+
+    chat.refresh_status_line();
+    let cells = drain_insert_history(&mut rx);
+    assert!(
+        cells.is_empty(),
+        "expected invalid status line warning to emit only once"
+    );
+}
+
+#[tokio::test]
+async fn status_line_branch_state_resets_when_git_branch_disabled() {
+    let (mut chat, _rx, _op_rx) = make_chatwidget_manual(None).await;
+    chat.status_line_branch = Some("main".to_string());
+    chat.status_line_branch_pending = true;
+    chat.status_line_branch_lookup_complete = true;
+    chat.config.tui_status_line = Some(vec!["model_name".to_string()]);
+
+    chat.refresh_status_line();
+
+    assert_eq!(chat.status_line_branch, None);
+    assert!(!chat.status_line_branch_pending);
+    assert!(!chat.status_line_branch_lookup_complete);
+}
+
+#[tokio::test]
+async fn status_line_branch_refreshes_after_turn_complete() {
+    let (mut chat, _rx, _op_rx) = make_chatwidget_manual(None).await;
+    chat.config.tui_status_line = Some(vec!["git-branch".to_string()]);
+    chat.status_line_branch_lookup_complete = true;
+    chat.status_line_branch_pending = false;
+
+    chat.handle_codex_event(Event {
+        id: "turn-1".into(),
+        msg: EventMsg::TurnComplete(TurnCompleteEvent {
+            last_agent_message: None,
+        }),
+    });
+
+    assert!(chat.status_line_branch_pending);
+}
+
+#[tokio::test]
+async fn status_line_branch_refreshes_after_interrupt() {
+    let (mut chat, _rx, _op_rx) = make_chatwidget_manual(None).await;
+    chat.config.tui_status_line = Some(vec!["git-branch".to_string()]);
+    chat.status_line_branch_lookup_complete = true;
+    chat.status_line_branch_pending = false;
+
+    chat.handle_codex_event(Event {
+        id: "turn-1".into(),
+        msg: EventMsg::TurnAborted(codex_core::protocol::TurnAbortedEvent {
+            reason: TurnAbortReason::Interrupted,
+        }),
+    });
+
+    assert!(chat.status_line_branch_pending);
+}
+
 #[tokio::test]
 async fn stream_recovery_restores_previous_status_header() {
     let (mut chat, mut rx, _op_rx) = make_chatwidget_manual(None).await;