Dates/times/numbers: `frontend/src/lib/i18n/format.ts` + `useLocale()`. **Form date fields:** `AppDateInput` only (no native `<input type="date">`); wire format `YYYY-MM-DD`. **Filter selects:** `FORM_SELECT_CLASS` from `components/shared/formSelectStyles.ts` (chevron via `globals.css`). **Tables:** `components/ui/shared/Table.tsx` — use `text-start`/`text-end`/`text-center`, never physical `text-left`/`text-right`. Appointments: `ScheduleDayPicker`. Skill: `.cursor/skills/i18n-formatting/SKILL.md`.