feat: Home/End jump to line start/end in multiline composer

Plain Home and End now navigate within the current line instead of
jumping to the absolute start/end of the entire input.  Ctrl+A and
Ctrl+E remain as absolute start/end shortcuts.

- Add move_cursor_line_start() / move_cursor_line_end() to App
- Wire Home -> move_cursor_line_start(), End -> move_cursor_line_end()
- On single-line input the new methods behave identically to the
  absolute versions (no behaviour change)
- End on a newline character skips to the end of the next line
- 14 tests covering multiline, singleline, and edge cases

crates/tui/src/tui/app.rs

@@ -3218,6 +3218,38 @@ impl App {
         self.needs_redraw = true;
     }
 
+    /// In a multiline composer, jump to the start of the current line.
+    /// On single-line input this is equivalent to `move_cursor_start`.
+    pub fn move_cursor_line_start(&mut self) {
+        let byte_pos = byte_index_at_char(&self.input, self.cursor_position);
+        let before = &self.input[..byte_pos];
+        if let Some(last_nl_byte) = before.rfind('\n') {
+            // Position after the '\n' (start of the current line).
+            self.cursor_position = char_count(&self.input[..=last_nl_byte]);
+        } else {
+            self.cursor_position = 0;
+        }
+        self.needs_redraw = true;
+    }
+
+    /// In a multiline composer, jump to the end of the current line
+    /// (just before the next `\n` or at the end of input).
+    /// On single-line input this is equivalent to `move_cursor_end`.
+    pub fn move_cursor_line_end(&mut self) {
+        let mut search_start = byte_index_at_char(&self.input, self.cursor_position);
+        // If the cursor sits on a '\n', skip past it — the user
+        // wants the end of the *next* line.
+        if self.input.as_bytes().get(search_start) == Some(&b'\n') {
+            search_start += 1;
+        }
+        if let Some(offset) = self.input[search_start..].find('\n') {
+            self.cursor_position = char_count(&self.input[..search_start + offset]);
+        } else {
+            self.cursor_position = char_count(&self.input);
+        }
+        self.needs_redraw = true;
+    }
+
     /// Move forward one word. Skips over the current word then any trailing
     /// whitespace to land on the first character of the next word.
     pub fn move_cursor_word_forward(&mut self) {
@@ -4235,6 +4267,60 @@ mod tests {
         assert!(default_composer_arrows_scroll_for_platform(true, true));
     }
 
+    #[test]
+    fn move_cursor_line_start_multiline() {
+        let mut app = App::new(test_options(false), &Config::default());
+        app.input = "abc\ndef\nghi".to_string();
+        app.cursor_position = "abc\ndef\nghi".chars().count(); // absolute end
+        app.move_cursor_line_start();
+        assert_eq!(app.cursor_position, "abc\ndef\n".len()); // start of "ghi"
+    }
+
+    #[test]
+    fn move_cursor_line_start_singleline() {
+        let mut app = App::new(test_options(false), &Config::default());
+        app.input = "hello".to_string();
+        app.cursor_position = 3;
+        app.move_cursor_line_start();
+        assert_eq!(app.cursor_position, 0);
+    }
+
+    #[test]
+    fn move_cursor_line_end_multiline() {
+        let mut app = App::new(test_options(false), &Config::default());
+        app.input = "abc\ndef\nghi".to_string();
+        app.cursor_position = 0; // start of first line
+        app.move_cursor_line_end();
+        assert_eq!(app.cursor_position, "abc".len()); // before first '\n'
+    }
+
+    #[test]
+    fn move_cursor_line_end_at_newline_skips_to_next_line() {
+        let mut app = App::new(test_options(false), &Config::default());
+        app.input = "abc\ndef\nghi".to_string();
+        app.cursor_position = "abc".len(); // on the '\n'
+        app.move_cursor_line_end();
+        assert_eq!(app.cursor_position, "abc\ndef".len()); // end of second line
+    }
+
+    #[test]
+    fn move_cursor_line_end_last_line() {
+        let mut app = App::new(test_options(false), &Config::default());
+        app.input = "abc\ndef".to_string();
+        app.cursor_position = "abc\n".len(); // start of last line
+        app.move_cursor_line_end();
+        assert_eq!(app.cursor_position, "abc\ndef".chars().count()); // absolute end
+    }
+
+    #[test]
+    fn move_cursor_line_start_already_at_start() {
+        let mut app = App::new(test_options(false), &Config::default());
+        app.input = "abc\ndef".to_string();
+        app.cursor_position = "abc\n".len(); // start of second line
+        app.move_cursor_line_start();
+        assert_eq!(app.cursor_position, "abc\n".len()); // unchanged
+    }
+
     struct EnvVarGuard {
         key: &'static str,
         previous: Option<OsString>,

crates/tui/src/tui/ui.rs

@@ -3267,10 +3267,10 @@ async fn run_event_loop(
                     app.move_cursor_start();
                 }
                 KeyCode::Home => {
-                    app.move_cursor_start();
+                    app.move_cursor_line_start();
                 }
                 KeyCode::End => {
-                    app.move_cursor_end();
+                    app.move_cursor_line_end();
                 }
                 KeyCode::Char('e') if key.modifiers.contains(KeyModifiers::CONTROL) => {
                     app.move_cursor_end();

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

@@ -5524,6 +5524,78 @@ fn composer_arrows_scroll_config_overrides_default() {
     );
 }
 
+#[test]
+fn home_jumps_to_line_start_multiline() {
+    let mut app = create_test_app();
+    app.input = "line one\nline two\nline three".to_string();
+    app.cursor_position = app.input.chars().count();
+    app.move_cursor_line_start();
+    assert_eq!(app.cursor_position, "line one\nline two\n".len());
+}
+
+#[test]
+fn home_from_middle_of_line_jumps_to_line_start() {
+    let mut app = create_test_app();
+    app.input = "line one\nline two".to_string();
+    app.cursor_position = "line one\nli".len();
+    app.move_cursor_line_start();
+    assert_eq!(app.cursor_position, "line one\n".len());
+}
+
+#[test]
+fn home_on_singleline_jumps_to_zero() {
+    let mut app = create_test_app();
+    app.input = "hello world".to_string();
+    app.cursor_position = 6;
+    app.move_cursor_line_start();
+    assert_eq!(app.cursor_position, 0);
+}
+
+#[test]
+fn end_jumps_to_line_end_multiline() {
+    let mut app = create_test_app();
+    app.input = "line one\nline two\nline three".to_string();
+    app.cursor_position = 0;
+    app.move_cursor_line_end();
+    assert_eq!(app.cursor_position, "line one".len());
+}
+
+#[test]
+fn end_from_middle_of_line_jumps_to_line_end() {
+    let mut app = create_test_app();
+    app.input = "line one\nline two".to_string();
+    app.cursor_position = "line one\nli".len();
+    app.move_cursor_line_end();
+    assert_eq!(app.cursor_position, "line one\nline two".len());
+}
+
+#[test]
+fn end_on_singleline_jumps_to_absolute_end() {
+    let mut app = create_test_app();
+    app.input = "hello world".to_string();
+    app.cursor_position = 0;
+    app.move_cursor_line_end();
+    assert_eq!(app.cursor_position, app.input.chars().count());
+}
+
+#[test]
+fn home_at_line_start_stays_put() {
+    let mut app = create_test_app();
+    app.input = "line one\nline two".to_string();
+    app.cursor_position = "line one\n".len();
+    app.move_cursor_line_start();
+    assert_eq!(app.cursor_position, "line one\n".len());
+}
+
+#[test]
+fn end_at_newline_skips_to_next_line_end() {
+    let mut app = create_test_app();
+    app.input = "line one\nline two\nline three".to_string();
+    app.cursor_position = "line one".len();
+    app.move_cursor_line_end();
+    assert_eq!(app.cursor_position, "line one\nline two".len());
+}
+
 #[test]
 fn notification_settings_tui_always_keeps_configured_method_no_threshold() {
     let config = Config {