Function probeTmuxControlModeSync

src/utils/fullscreen.ts:56–86

* Sync one-shot probe: asks tmux directly whether this client is in control * mode via `#{client_control_mode}`. Runs on first isTmuxControlMode() call * when the env heuristic can't decide; result is cached. * * Sync (spawnSync) because the answer gates whether we enter fullscreen — an * async

()

 * query whatever tmux server happens to be running rather than our client.
 */
function probeTmuxControlModeSync(): void {
  // Seed cache with heuristic result so early returns below don't leave it
  // undefined — isTmuxControlMode() is called 15+ times per render, and an
  // undefined cache would re-enter this function (re-spawning tmux in the
  // failure case) on every call.
  tmuxControlModeProbed = isTmuxControlModeEnvHeuristic()
  if (tmuxControlModeProbed) return
  if (!process.env.TMUX) return
  // Only probe when iTerm might be involved: TERM_PROGRAM is iTerm.app
  // (covered above) or not set (SSH often doesn't propagate it). When
  // TERM_PROGRAM is explicitly a non-iTerm terminal, skip — tmux -CC is
  // an iTerm-only feature, so the subprocess would be wasted.
  if (process.env.TERM_PROGRAM) return
  let result
  try {
    result = spawnSync(
      'tmux',
      ['display-message', '-p', '#{client_control_mode}'],
      { encoding: 'utf8', timeout: 2000 },
    )
  } catch {
    // spawnSync can throw on some platforms (e.g. ENOENT on Windows if tmux
    // is absent and the runtime surfaces it as an exception rather than in
    // result.error). Treat the same as a non-zero exit.
    return
  }
  // Non-zero exit / spawn error: tmux too old (format var added in 2.4) or
  // unavailable. Keep the heuristic result cached.
  if (result.status !== 0) return
  tmuxControlModeProbed = result.stdout.trim() === '1'
}

/**
 * True when running under `tmux -CC` (iTerm2 integration mode).