fix(input): leave navigate mode on ctrl+[ (#2340)

refs #1431

src/client/shell/input.rs

@@ -10,6 +10,19 @@ fn is_retained_selection_copy_key(key: &crate::input::TerminalKey) -> bool {
         && matches!(key.modifiers, KeyModifiers::CONTROL | KeyModifiers::SUPER)
 }
 
+/// True for Ctrl+[, the terminal-level equivalent of Esc.
+///
+/// A legacy terminal sends Ctrl+[ as 0x1b, the same byte as Esc, so it already
+/// arrives as `KeyCode::Esc`. Under the kitty keyboard protocol the modified key
+/// is reported on its own and reaches navigate mode as `Char('[')` with CONTROL.
+/// Ctrl+Shift+[ stays distinct because it carries SHIFT.
+///
+/// Navigate mode checks this only after keybinding dispatch, so a configured
+/// Ctrl+[ binding keeps working and this stays a fallback cancel.
+fn is_ctrl_bracket_key(key: &crate::input::TerminalKey) -> bool {
+    key.code == KeyCode::Char('[') && key.modifiers == KeyModifiers::CONTROL
+}
+
 pub(super) fn is_modal_paste_shortcut_for_platform(
     key: &crate::input::TerminalKey,
     macos: bool,
@@ -650,9 +663,7 @@ impl ClientShellState {
 
         self.pending_workspace_highlight = None;
         if key.code == KeyCode::Esc || self.config.keybinds.matches_prefix(key) {
-            self.mode = self.copy_or_terminal_mode();
-            self.navigate_workspace_id = None;
-            outcome.repaint = true;
+            self.cancel_navigate(outcome);
             return;
         }
 
@@ -687,6 +698,12 @@ impl ClientShellState {
             return;
         }
         if self.workspace_preview_action_blocked() {
+            // Bindings cannot run against a foreign preview, so Ctrl+[ has
+            // nothing to lose to and cancels here the same way Esc does.
+            if is_ctrl_bracket_key(key) {
+                self.cancel_navigate(outcome);
+                return;
+            }
             self.push_endpoint_notice(
                 ClientEndpointNoticeKind::Rejected,
                 "navigate_endpoint_inactive",
@@ -816,9 +833,17 @@ impl ClientShellState {
         });
         if let Some(binding) = binding {
             self.record_navigate_binding(binding, false, outcome);
+        } else if is_ctrl_bracket_key(key) {
+            self.cancel_navigate(outcome);
         }
     }
 
+    fn cancel_navigate(&mut self, outcome: &mut ClientShellInput) {
+        self.mode = self.copy_or_terminal_mode();
+        self.navigate_workspace_id = None;
+        outcome.repaint = true;
+    }
+
     fn record_navigate_binding(
         &mut self,
         binding: crate::input::KeybindMatch,

src/client/shell/tests/workspace_navigation.rs

@@ -968,3 +968,61 @@ fn navigation_highlight_ends_for_noop_focus_and_focused_creation() {
         }
     }
 }
+
+// Kitty keyboard protocol (CSI u) encodings of `[` (codepoint 91).
+const KITTY_CTRL_BRACKET: &[u8] = b"\x1b[91;5u";
+const KITTY_CTRL_SHIFT_BRACKET: &[u8] = b"\x1b[91;6u";
+
+#[test]
+fn kitty_ctrl_bracket_leaves_navigation_like_esc() {
+    let mut state = local_navigation_state(false);
+    enter_navigation(&mut state);
+    preview_key(&mut state, b"\x1b[B");
+
+    preview_key(&mut state, KITTY_CTRL_BRACKET);
+
+    assert_eq!(state.mode, ClientShellMode::Terminal);
+    assert!(state.navigate_workspace_id.is_none());
+}
+
+#[test]
+fn configured_ctrl_bracket_navigate_binding_wins_over_cancel() {
+    let config: Config = toml::from_str("[keys]\nnavigate_workspace_down = \"ctrl+[\"\n").unwrap();
+    let mut state = ClientShellState::new(ClientShellConfig::from_config(&config));
+    state.set_snapshot(Box::new(workspaces(3)));
+    state.set_pane_surface(surface());
+    state.compose(100, 28).unwrap();
+    enter_navigation(&mut state);
+    assert_selected(&state, &ClientEndpointId::Local, "ws_1");
+
+    preview_key(&mut state, KITTY_CTRL_BRACKET);
+
+    assert_eq!(state.mode, ClientShellMode::Navigate);
+    assert_selected(&state, &ClientEndpointId::Local, "ws_2");
+}
+
+#[test]
+fn kitty_ctrl_shift_bracket_keeps_navigation_open() {
+    let mut state = local_navigation_state(false);
+    enter_navigation(&mut state);
+
+    state.handle_input_bytes(KITTY_CTRL_SHIFT_BRACKET);
+
+    assert_eq!(state.mode, ClientShellMode::Navigate);
+    assert_selected(&state, &ClientEndpointId::Local, "ws_1");
+}
+
+#[test]
+fn kitty_ctrl_bracket_cancels_a_blocked_foreign_preview() {
+    let (mut state, remote) = state_with_remote();
+    state.compose(100, 28).unwrap();
+    enter_navigation(&mut state);
+    preview_key(&mut state, b"\x1b[B");
+    assert_selected(&state, &remote, "ws_1");
+    assert!(state.workspace_preview_action_blocked());
+
+    preview_key(&mut state, KITTY_CTRL_BRACKET);
+
+    assert_ne!(state.mode, ClientShellMode::Navigate);
+    assert!(state.navigate_workspace_id.is_none());
+}