Plugin tier lacks a shared TUI toolkit: alternate-screen/menu-runner boilerplate copy-pasted across 10 menu files (and already drifted)

Start with the duplicated alternate-screen blocks in command_line/mcp/install_menu.py, command_line/model_settings_menu.py, plugins/agent_skills/skills_menu.py, plugins/agent_skills/skills_install_menu.py, plugins/hook_manager/hooks_menu.py, and plugins/plugin_list/plugins_menu.py; use the listed rg command to find the remaining copies. Extract the shared menu runner and quit-binding behavior described in the issue, then update the affected menus so terminal cleanup and input flushing are consistent across them.

Theme

Every interactive menu in the repo re-implements the same prompt_toolkit "run a fullscreen-ish menu" dance by copy-paste. Because there is no shared helper, plugin authors clone core menus from command_line/, which is exactly what jscpd caught:

• plugins/agent_skills/skills_menu.py:449-469 ↔ command_line/mcp/install_menu.py:634-654
• plugins/agent_skills/skills_menu.py:440-459 ↔ plugins/plugin_list/plugins_menu.py:267-286
• plugins/agent_skills/skills_install_menu.py:17-35 ↔ skills_menu.py:8-26 (import/page-size preamble)
• plugins/agent_skills/skills_install_menu.py:582-609 ↔ command_line/model_settings_menu.py:915-942
• plugins/hook_manager/hooks_menu.py:505-518 ↔ command_line/model_settings_menu.py:927-942

The cloned block is always the same ~30-line sequence:

layout = Layout(root_container)
app = Application(layout=layout, key_bindings=kb, full_screen=False, mouse_support=False)
set_awaiting_user_input(True)
sys.stdout.write("\033[?1049h")   # enter alternate buffer
sys.stdout.write("\033[2J\033[H")
sys.stdout.flush()
time.sleep(0.05)
try:
    self.update_display()
    sys.stdout.write("\033[2J\033[H"); sys.stdout.flush()
    app.run(in_thread=True)
finally:
    sys.stdout.write("\033[?1049l")
    sys.stdout.flush()
    # (sometimes) termios.tcflush(...)
    set_awaiting_user_input(False)

rg -l '1049h' code_puppy/ shows 20 files containing this escape-sequence dance; at least 9 of them pair it with the full Application(...) + app.run(in_thread=True) boilerplate:

• command_line/mcp/install_menu.py, command_line/mcp/custom_server_form.py, command_line/model_settings_menu.py, command_line/add_model_menu.py
• plugins/agent_skills/skills_menu.py, plugins/agent_skills/skills_install_menu.py, plugins/hook_manager/hooks_menu.py, plugins/plugin_list/plugins_menu.py, plugins/prune/prune_menu.py

Divergence evidence (the clones are already drifting)

• skills_menu.py / skills_install_menu.py / hooks_menu.py flush stale input via termios.tcflush(...) in finally; model_settings_menu.py and plugins_menu.py don't — they can replay buffered keypresses into the next prompt.
• hooks_menu.py:498-503 wraps set_awaiting_user_input(True) in try/except Exception: pass; everyone else calls it bare. One copy got defensive, eight didn't.
• Some copies time.sleep(0.1) after exit to "let the terminal settle", others don't.
• Quit keybindings differ subtly: some bind q+escape+c-c to exit, mcp/install_menu.py treats escape/backspace as "back" — fine, but the shared part (c-c exits, alternate-buffer restore) is re-typed each time, so any fix (e.g. issue #428-style terminal-state bugs) must be applied 9+ times.

Proposed shared abstraction

Add code_puppy/tui/ (or command_line/tui_toolkit.py) exporting a context manager + runner so menus can't diverge on terminal hygiene:

# code_puppy/tui/menu_runner.py
@contextmanager
def alternate_screen(flush_stale_input: bool = True):
    set_awaiting_user_input(True)
    sys.stdout.write("\x1b[?1049h\x1b[2J\x1b[H"); sys.stdout.flush()
    time.sleep(0.05)
    try:
        yield
    finally:
        sys.stdout.write("\x1b[?1049l"); sys.stdout.flush()
        if flush_stale_input:
            _tcflush_stdin_safe()
        set_awaiting_user_input(False)

def run_menu(root_container, kb, update_display) -> None:
    app = Application(layout=Layout(root_container), key_bindings=kb,
                      full_screen=False, mouse_support=False)
    with alternate_screen():
        update_display()
        sys.stdout.write("\x1b[2J\x1b[H"); sys.stdout.flush()
        app.run(in_thread=True)

Plus a small add_quit_bindings(kb, on_quit) helper for the q/escape/c-c trio. Each menu file then shrinks by ~40 lines and inherits future terminal-state fixes for free. Given the CONTRIBUTING.md golden rule pushes new functionality into plugins, a sanctioned TUI toolkit is the only way plugin menus stop being forks of command_line/ menus.

Filed by Zen Reviewer C (code-puppy-60635a) — DRY review round