fix(tui/composer): restore Option+Enter newline and Cmd+Z undo

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

@@ -242,6 +242,10 @@ impl TextArea {
             KeyEvent { code: KeyCode::Char('\u{0006}'), modifiers: KeyModifiers::NONE, .. } /* ^F */ => {
                 self.move_cursor_right();
             }
+            KeyEvent {
+                code: KeyCode::Char(c),
+                ..
+            } if matches!(c, '\n' | '\r') => self.insert_str("\n"),
             KeyEvent {
                 code: KeyCode::Char(c),
                 // Insert plain characters (and Shift-modified). Do NOT insert when ALT is held,
@@ -321,6 +325,13 @@ impl TextArea {
             } => {
                 self.undo();
             }
+            KeyEvent {
+                code: KeyCode::Char('z'),
+                modifiers: KeyModifiers::SUPER,
+                ..
+            } => {
+                self.undo();
+            }
             // macOS-like shortcuts (when terminals report the Command key as SUPER):
             // Cmd+Left  -> move to beginning of line
             // Cmd+Right -> move to end of line
@@ -1275,6 +1286,17 @@ mod tests {
         assert_eq!(t.cursor(), 0);
     }
 
+    #[test]
+    fn alt_enter_inserts_newline() {
+        let mut t = TextArea::new();
+        t.input(KeyEvent::new(KeyCode::Enter, KeyModifiers::ALT));
+        assert_eq!(t.text(), "\n");
+
+        let mut t = TextArea::new();
+        t.input(KeyEvent::new(KeyCode::Char('\n'), KeyModifiers::ALT));
+        assert_eq!(t.text(), "\n");
+    }
+
     #[test]
     fn control_h_backspace() {
         // Test Ctrl+H as backspace