fix(terminal): advertise kitty keyboard protocol for Shift+Enter (#1247)

Orca's terminal already encodes Shift+Enter as the kitty CSI-u sequence
`\x1b[13;2u`, but without `vtExtensions.kittyKeyboard` xterm.js never
answers the `CSI ? u` probe. CLIs that gate enhanced input on that
handshake (Claude Code, Codex, etc.) therefore drop the extended bytes
and treat Shift+Enter as a plain Enter — most visibly when running
inside tmux, which strips extended-key encodings by default.

- Enable `vtExtensions.kittyKeyboard` in the default terminal options
  (matches VS Code's xtermTerminal).
- Lock in the flag with a regression test in pane-lifecycle.test.ts.
- Add docs/terminal-extended-keys.md explaining the Orca side and the
  tmux-side `set -s extended-keys on` + `terminal-features xterm*:extkeys`
  users need for nested Shift+Enter to reach a CLI.

Verified end-to-end in Electron: `cat -v` + Shift+Enter now prints
`^[[13;2u`, and `printf '\e[?u'` elicits the expected `CSI ? 0 u` reply
from xterm.js.

Co-authored-by: Orca <help@stably.ai>

docs/terminal-extended-keys.md

@@ -0,0 +1,66 @@
+# Extended Key Chords in the Terminal (Shift+Enter, etc.)
+
+## What Orca sends
+
+Orca's built‑in terminal already encodes extended key chords using the
+[kitty keyboard protocol][kitty] (CSI‑u). For example, **Shift+Enter** is sent
+as the byte sequence:
+
+```
+ESC [ 1 3 ; 2 u      (i.e. \x1b[13;2u)
+```
+
+See `src/renderer/src/components/terminal-pane/terminal-shortcut-policy.ts`
+for the full table.
+
+Orca also advertises kitty‑protocol support to the running program via
+`vtExtensions.kittyKeyboard` on xterm.js (see
+`src/renderer/src/lib/pane-manager/pane-terminal-options.ts`), so CLIs that
+probe with `CSI ? u` learn that the terminal speaks CSI‑u and enable their
+enhanced input handlers.
+
+## Why Shift+Enter may not reach your CLI inside tmux
+
+tmux, by default, strips both extended‑key encodings (modifyOtherKeys
+`CSI 27 ; 2 ; 13 ~` *and* kitty‑style `CSI 13 ; 2 u`). If you run Claude
+Code, Codex, or any other CLI under tmux, Shift+Enter will look like a
+plain `Enter` unless tmux is told to pass those bytes through.
+
+Add this to `~/.tmux.conf` (tmux 3.2+):
+
+```tmux
+set -s extended-keys on
+set -as terminal-features 'xterm*:extkeys'
+```
+
+Then reload: `tmux source-file ~/.tmux.conf` (or restart the tmux server).
+
+- `extended-keys on` — tell tmux to accept and forward the extended
+  encodings instead of collapsing them to the unshifted key.
+- `terminal-features 'xterm*:extkeys'` — tell tmux that the surrounding
+  terminal (Orca, in this case) understands those encodings, so tmux is
+  willing to emit them.
+
+## Verifying end‑to‑end
+
+Inside an Orca terminal (no tmux), run:
+
+```
+cat -v
+```
+
+Press **Shift+Enter**. You should see:
+
+```
+^[[13;2u
+```
+
+That's caret notation for `\x1b[13;2u` — the expected CSI‑u encoding. If
+you see `^M` (or a blank newline) instead, either the chord isn't reaching
+the terminal (check `keyboard-handlers.ts` / `terminal-shortcut-policy.ts`)
+or you're inside tmux without the config above.
+
+Inside tmux after the config, the same `cat -v` test should print the same
+`^[[13;2u`.
+
+[kitty]: https://sw.kovidgoyal.net/kitty/keyboard-protocol/

src/renderer/src/lib/pane-manager/pane-lifecycle.test.ts

@@ -53,6 +53,16 @@ describe('buildDefaultTerminalOptions', () => {
   it('leaves macOS Option available for keyboard layout characters', () => {
     expect(buildDefaultTerminalOptions().macOptionIsMeta).toBe(false)
   })
+
+  it('advertises kitty keyboard protocol so CLIs enable enhanced key reporting', () => {
+    // Why: Orca already writes CSI-u bytes for extended key chords like
+    // Shift+Enter (see terminal-shortcut-policy.ts). CLIs that gate
+    // enhanced input on a CSI ? u handshake only read those bytes once the
+    // terminal advertises support. Regressing this flag silently breaks
+    // Shift+Enter (and other extended chords) in apps like Claude Code and
+    // Codex, especially when running inside tmux.
+    expect(buildDefaultTerminalOptions().vtExtensions?.kittyKeyboard).toBe(true)
+  })
 })
 
 describe('attachWebgl', () => {

src/renderer/src/lib/pane-manager/pane-terminal-options.ts

@@ -16,6 +16,16 @@ export function buildDefaultTerminalOptions(): ITerminalOptions {
     // Why: on macOS, non-US layouts rely on Option to compose characters like @ and €.
     macOptionIsMeta: false,
     macOptionClickForcesSelection: true,
-    drawBoldTextInBrightColors: true
+    drawBoldTextInBrightColors: true,
+    // Why: advertise kitty keyboard protocol support so CLIs that probe
+    // (CSI ? u) know Orca accepts enhanced key reporting. Without this,
+    // Orca already writes \x1b[13;2u for Shift+Enter (see
+    // terminal-shortcut-policy.ts), but programs that respect the protocol
+    // handshake fall back to legacy encodings and ignore the CSI-u byte,
+    // making chords like Shift+Enter invisible to the app — especially
+    // noticeable inside tmux. Matches VS Code's xtermTerminal.ts.
+    vtExtensions: {
+      kittyKeyboard: true
+    }
   }
 }