Keep backtrack Esc hint gated on empty composer (#5076)

## Summary
- only prime backtrack and show the ESC hint when the composer is empty
- keep the composer-side ESC hint unchanged when drafts or attachments
exist and cover it with a regression test

Fixes #5030

------
https://chatgpt.com/codex/tasks/task_i_68e95ba59cd8832caec8e72ae2efeb55

codex-rs/tui/src/bottom_pane/chat_composer.rs

@@ -857,10 +857,12 @@ impl ChatComposer {
             return (InputResult::None, true);
         }
         if key_event.code == KeyCode::Esc {
-            let next_mode = esc_hint_mode(self.footer_mode, self.is_task_running);
-            if next_mode != self.footer_mode {
-                self.footer_mode = next_mode;
-                return (InputResult::None, true);
+            if self.is_empty() {
+                let next_mode = esc_hint_mode(self.footer_mode, self.is_task_running);
+                if next_mode != self.footer_mode {
+                    self.footer_mode = next_mode;
+                    return (InputResult::None, true);
+                }
             }
         } else {
             self.footer_mode = reset_mode_after_activity(self.footer_mode);
@@ -1797,6 +1799,35 @@ mod tests {
         });
     }
 
+    #[test]
+    fn esc_hint_stays_hidden_with_draft_content() {
+        use crossterm::event::KeyCode;
+        use crossterm::event::KeyEvent;
+        use crossterm::event::KeyModifiers;
+
+        let (tx, _rx) = unbounded_channel::<AppEvent>();
+        let sender = AppEventSender::new(tx);
+        let mut composer = ChatComposer::new(
+            true,
+            sender,
+            true,
+            "Ask Codex to do anything".to_string(),
+            false,
+        );
+
+        type_chars_humanlike(&mut composer, &['d']);
+
+        assert!(!composer.is_empty());
+        assert_eq!(composer.current_text(), "d");
+        assert_eq!(composer.footer_mode, FooterMode::ShortcutSummary);
+        assert!(matches!(composer.active_popup, ActivePopup::None));
+
+        let _ = composer.handle_key_event(KeyEvent::new(KeyCode::Esc, KeyModifiers::NONE));
+
+        assert_eq!(composer.footer_mode, FooterMode::ShortcutSummary);
+        assert!(!composer.esc_backtrack_hint);
+    }
+
     #[test]
     fn question_mark_only_toggles_on_first_char() {
         use crossterm::event::KeyCode;