feat(tui): support Shift+Enter to insert newline in composer (#801)

* feat(tui): support Shift+Enter to insert newline in composer

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* test(tui): cover shift-enter newline handling

---------

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
Co-authored-by: Hunter Bown <hmbown@gmail.com>

crates/tui/src/tui/keybindings.rs

@@ -145,7 +145,7 @@ pub const KEYBINDINGS: &[KeybindingEntry] = &[
         section: KeybindingSection::Editing,
     },
     KeybindingEntry {
-        chord: "Ctrl+J / Alt+Enter",
+        chord: "Ctrl+J / Alt+Enter / Shift+Enter",
         description_id: crate::localization::MessageId::KbInsertNewline,
         section: KeybindingSection::Editing,
     },

crates/tui/src/tui/ui.rs

@@ -2370,10 +2370,7 @@ async fn run_event_loop(
                     continue;
                 }
                 // Input handling
-                KeyCode::Char('j') if key.modifiers.contains(KeyModifiers::CONTROL) => {
-                    app.insert_char('\n');
-                }
-                KeyCode::Enter if key.modifiers.contains(KeyModifiers::ALT) => {
+                _ if is_composer_newline_key(key) => {
                     app.insert_char('\n');
                 }
                 KeyCode::Enter
@@ -3108,6 +3105,18 @@ fn next_escape_action(app: &App, slash_menu_open: bool) -> EscapeAction {
     }
 }
 
+fn is_composer_newline_key(key: KeyEvent) -> bool {
+    match key.code {
+        KeyCode::Char('j') => key.modifiers.contains(KeyModifiers::CONTROL),
+        KeyCode::Enter => {
+            key.modifiers.contains(KeyModifiers::ALT)
+                || (key.modifiers.contains(KeyModifiers::SHIFT)
+                    && !key.modifiers.contains(KeyModifiers::CONTROL))
+        }
+        _ => false,
+    }
+}
+
 fn handle_history_search_key(app: &mut App, key: KeyEvent) {
     match key.code {
         KeyCode::Enter => {

crates/tui/src/tui/ui/tests.rs

@@ -16,6 +16,34 @@ use std::process::Command;
 use std::time::{Duration, Instant};
 use tempfile::TempDir;
 
+#[test]
+fn composer_newline_shortcuts_do_not_steal_ctrl_enter() {
+    assert!(is_composer_newline_key(KeyEvent::new(
+        KeyCode::Char('j'),
+        KeyModifiers::CONTROL,
+    )));
+    assert!(is_composer_newline_key(KeyEvent::new(
+        KeyCode::Enter,
+        KeyModifiers::ALT,
+    )));
+    assert!(is_composer_newline_key(KeyEvent::new(
+        KeyCode::Enter,
+        KeyModifiers::SHIFT,
+    )));
+    assert!(!is_composer_newline_key(KeyEvent::new(
+        KeyCode::Enter,
+        KeyModifiers::NONE,
+    )));
+    assert!(!is_composer_newline_key(KeyEvent::new(
+        KeyCode::Enter,
+        KeyModifiers::CONTROL,
+    )));
+    assert!(!is_composer_newline_key(KeyEvent::new(
+        KeyCode::Enter,
+        KeyModifiers::CONTROL | KeyModifiers::SHIFT,
+    )));
+}
+
 #[test]
 fn selection_point_from_position_ignores_top_padding() {
     let area = Rect {