- y/p use pbcopy/pbpaste (xsel is X11, absent on macOS); xsel kept as the Linux variant in a comment
- bind C-a send-prefix: C-a C-a sends a literal C-a to the shell
- is_vim reads #{pane_current_command}; the @tmux_vim_<pane> variable was never set, so C-h/j/k/l never reached vim