TimerMeet UI Designer

Overview

Keep TimerMeet's interface simple, clear, and fast, built entirely in plain tkinter/ttk. This skill governs how to change the GUI; business logic and validation belong in app.py, never in main_window.py/alarm_ui.py.

Hard rules

1. No CustomTkinter or any themed widget toolkit, ever. Tried and reverted once already (v2.0.0 → v2.0.1) for adding 20+ seconds to startup with a real-sized meeting list.
2. Never call root.update()/root.update_idletasks() synchronously, for any reason. This caused the v2.1.0 startup freeze. Let mainloop() process pending work on its own.
3. Mind the per-meeting widget budget. Each meeting card is rendered once per visible meeting; every extra widget in _render_card is a real, multiplying cost with a real-sized list (dozens of meetings), not a rounding error.
4. Reuse, don't reinvent. Use the existing color constants and _button()/_entry()/_make_option_menu()/_ScrollablePanel helpers in main_window.py.
5. Every string goes through i18n. Add new keys to both translations["es"] and translations["en"] in i18n.py -- tests/test_i18n.py enforces they never drift apart.

Workflow

1. Read SDD.md's "Arquitectura: backend y frontend sí están separados" section and .claude/skills/timermeet-python-builder/references/module-map.md first.
2. Prefer merging/removing over adding (see references/design-notes.md for the widget-count budget and the project's track record of fixing real bugs by simplifying, not adding).
3. Implement the smallest widget-tree diff that satisfies the request.
4. Run python -m py_compile timermeet_app/*.py and python -m unittest discover -s tests -- the i18n parity test catches a missed translation key immediately.
5. Smoke-test with python timermeet.py (see .claude/skills/timermeet-python-builder/references/validation.md): confirm it opens fast, stays responsive, and the changed screen behaves as expected. You cannot see the rendered window -- if a layout/spacing request is ambiguous, describe what you changed and ask for confirmation rather than iterating blindly.
6. Update SDD.md if the change affects user-visible behavior (not just styling).

References

• references/design-notes.md -- color palette, spacing conventions, and the widget-count budget.