fix(tui): queued-message edit shortcut unreachable in some terminals (#12240)

## Problem

The TUI's "edit queued message" shortcut (Alt+Up) is either silently
swallowed or recognized as another key combination by Apple Terminal,
Warp, and VSCode's integrated terminal on macOS. Users in those
environments see the hint but pressing the keys does nothing.

## Mental model

When a model turn is in progress the user can still type follow-up
messages. These are queued and displayed below the composer with a hint
line showing how to pop the most recent one back into the editor. The
hint text and the actual key handler must agree on which shortcut is
used, and that shortcut must actually reach the TUI—i.e. it must not be
intercepted by the host terminal.

Three terminals are known to intercept Alt+Up: Apple Terminal (remaps it
to cursor movement), Warp (consumes it for its own command palette), and
VSCode (maps it to "move line up"). For these we use Shift+Left instead.

<p align="center">
<img width="283" height="182" alt="image"
src="https://github.com/user-attachments/assets/4a9c5d13-6e47-4157-bb41-28b4ce96a914"
/>
</p>

| macOS Native Terminal | Warp | VSCode Terminal |
|---|---|---|
| <img width="1557" height="1010" alt="SCR-20260219-kigi"
src="https://github.com/user-attachments/assets/f4ff52f8-119e-407b-a3f3-52f564c36d70"
/> | <img width="1479" height="1261" alt="SCR-20260219-krrf"
src="https://github.com/user-attachments/assets/5807d7c4-17ae-4a2b-aa27-238fd49d90fd"
/> | <img width="1612" height="1312" alt="SCR-20260219-ksbz"
src="https://github.com/user-attachments/assets/1cedb895-6966-4d63-ac5f-0eea0f7057e8"
/> |

## Non-goals

- Making the binding user-configurable at runtime (deferred to a broader
keybinding-config effort).
- Remapping any other shortcuts that might be terminal-specific.

## Tradeoffs

- **Exhaustive match instead of a wildcard default.** The
`queued_message_edit_binding_for_terminal` function explicitly lists
every `TerminalName` variant. This is intentional: adding a new terminal
to the enum will produce a compile error, forcing the author to decide
which binding that terminal should use.

- **Binding lives on `ChatWidget`, hint lives on `QueuedUserMessages`.**
The key event handler that actually acts on the press is in
`ChatWidget`, but the rendered hint text is inside `QueuedUserMessages`.
These are kept in sync by `ChatWidget` calling
`bottom_pane.set_queued_message_edit_binding(self.queued_message_edit_binding)`
during construction. A mismatch would show the wrong hint but would not
lose data.

## Architecture

```mermaid
  graph TD
      TI["terminal_info().name"] --> FN["queued_message_edit_binding_for_terminal(name)"]
      FN --> KB["KeyBinding"]
      KB --> CW["ChatWidget.queued_message_edit_binding<br/><i>key event matching</i>"]
      KB --> BP["BottomPane.set_queued_message_edit_binding()"]
      BP --> QUM["QueuedUserMessages.edit_binding<br/><i>rendered in hint line</i>"]

      subgraph "Special terminals (Shift+Left)"
          AT["Apple Terminal"]
          WT["Warp"]
          VS["VSCode"]
      end

      subgraph "Default (Alt+Up)"
          GH["Ghostty"]
          IT["iTerm2"]
          OT["Others…"]
      end

      AT --> FN
      WT --> FN
      VS --> FN
      GH --> FN
      IT --> FN
      OT --> FN
```

No new crates or public API surface. The only cross-crate dependency
added is `codex_core::terminal::{TerminalName, terminal_info}`, which
already existed for telemetry.

## Observability

No new logging. Terminal detection already emits a `tracing::debug!` log
line at startup with the detected terminal name, which is sufficient to
diagnose binding mismatches.

## Tests

- Existing `alt_up_edits_most_recent_queued_message` test is preserved
and explicitly sets the Alt+Up binding to isolate from the host
terminal.
- New parameterized async tests verify Shift+Left works for Apple
Terminal, Warp, and VSCode.
- A sync unit test asserts the mapping table covers the three special
terminals (Shift+Left) and that iTerm2 still gets Alt+Up.
  
Fixes #4490

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

@@ -67,6 +67,7 @@ use codex_core::protocol::UndoStartedEvent;
 use codex_core::protocol::ViewImageToolCallEvent;
 use codex_core::protocol::WarningEvent;
 use codex_core::skills::model::SkillMetadata;
+use codex_core::terminal::TerminalName;
 use codex_otel::OtelManager;
 use codex_otel::RuntimeMetricsSummary;
 use codex_protocol::ThreadId;
@@ -1640,6 +1641,7 @@ async fn make_chatwidget_manual(
         frame_requester: FrameRequester::test_dummy(),
         show_welcome_banner: true,
         queued_user_messages: VecDeque::new(),
+        queued_message_edit_binding: crate::key_hint::alt(KeyCode::Up),
         suppress_session_configured_redraw: false,
         pending_notification: None,
         quit_shortcut_expires_at: None,
@@ -2781,6 +2783,9 @@ async fn empty_enter_during_task_does_not_queue() {
 #[tokio::test]
 async fn alt_up_edits_most_recent_queued_message() {
     let (mut chat, _rx, _op_rx) = make_chatwidget_manual(None).await;
+    chat.queued_message_edit_binding = crate::key_hint::alt(KeyCode::Up);
+    chat.bottom_pane
+        .set_queued_message_edit_binding(crate::key_hint::alt(KeyCode::Up));
 
     // Simulate a running task so messages would normally be queued.
     chat.bottom_pane.set_task_running(true);
@@ -2808,6 +2813,77 @@ async fn alt_up_edits_most_recent_queued_message() {
     );
 }
 
+async fn assert_shift_left_edits_most_recent_queued_message_for_terminal(
+    terminal_name: TerminalName,
+) {
+    let (mut chat, _rx, _op_rx) = make_chatwidget_manual(None).await;
+    chat.queued_message_edit_binding = queued_message_edit_binding_for_terminal(terminal_name);
+    chat.bottom_pane
+        .set_queued_message_edit_binding(chat.queued_message_edit_binding);
+
+    // Simulate a running task so messages would normally be queued.
+    chat.bottom_pane.set_task_running(true);
+
+    // Seed two queued messages.
+    chat.queued_user_messages
+        .push_back(UserMessage::from("first queued".to_string()));
+    chat.queued_user_messages
+        .push_back(UserMessage::from("second queued".to_string()));
+    chat.refresh_queued_user_messages();
+
+    // Press Shift+Left to edit the most recent (last) queued message.
+    chat.handle_key_event(KeyEvent::new(KeyCode::Left, KeyModifiers::SHIFT));
+
+    // Composer should now contain the last queued message.
+    assert_eq!(
+        chat.bottom_pane.composer_text(),
+        "second queued".to_string()
+    );
+    // And the queue should now contain only the remaining (older) item.
+    assert_eq!(chat.queued_user_messages.len(), 1);
+    assert_eq!(
+        chat.queued_user_messages.front().unwrap().text,
+        "first queued"
+    );
+}
+
+#[tokio::test]
+async fn shift_left_edits_most_recent_queued_message_in_apple_terminal() {
+    assert_shift_left_edits_most_recent_queued_message_for_terminal(TerminalName::AppleTerminal)
+        .await;
+}
+
+#[tokio::test]
+async fn shift_left_edits_most_recent_queued_message_in_warp_terminal() {
+    assert_shift_left_edits_most_recent_queued_message_for_terminal(TerminalName::WarpTerminal)
+        .await;
+}
+
+#[tokio::test]
+async fn shift_left_edits_most_recent_queued_message_in_vscode_terminal() {
+    assert_shift_left_edits_most_recent_queued_message_for_terminal(TerminalName::VsCode).await;
+}
+
+#[test]
+fn queued_message_edit_binding_mapping_covers_special_terminals() {
+    assert_eq!(
+        queued_message_edit_binding_for_terminal(TerminalName::AppleTerminal),
+        crate::key_hint::shift(KeyCode::Left)
+    );
+    assert_eq!(
+        queued_message_edit_binding_for_terminal(TerminalName::WarpTerminal),
+        crate::key_hint::shift(KeyCode::Left)
+    );
+    assert_eq!(
+        queued_message_edit_binding_for_terminal(TerminalName::VsCode),
+        crate::key_hint::shift(KeyCode::Left)
+    );
+    assert_eq!(
+        queued_message_edit_binding_for_terminal(TerminalName::Iterm2),
+        crate::key_hint::alt(KeyCode::Up)
+    );
+}
+
 /// Pressing Up to recall the most recent history entry and immediately queuing
 /// it while a task is running should always enqueue the same text, even when it
 /// is queued repeatedly.