Replace the picker with an accessible combobox (role=combobox + role=listbox):
focusing shows the full zone list (no typing/erasing needed), typing filters it
case-insensitively (underscores ignored, so "york" matches America/New_York),
with arrow-key navigation, Enter/click to select, and Escape to close. Fixes the
datalist limitation where a pre-filled value collapsed the dropdown to one match.
e2e updated to type+click options and a type-to-search case added.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The IANA picker was an <input list=datalist>, which filters the dropdown by
whatever text is already in the field — so with the stored zone pre-filled a
user only saw a single option and had to erase the value (undiscoverable) to
browse. datalist is also unreliable in iOS Safari.
Replace it with a native <select> grouped by region (<optgroup>): tapping
shows the whole list with no typing/erasing, and it renders as the native
wheel picker on iOS. The "Use detected" one-tap shortcut still covers the
common case. Option labels are shortened (region stripped, underscores → spaces)
while values remain full IANA ids. e2e updated from fill() to selectOption().
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
- Derive isExplicit from timezoneQuery.data?.isExplicitlySet
- Apply the input===stored no-op guard only when isExplicit is true
- Keep pending and empty-input guards unconditional
- Add unit tests (AdminPage.timezone.test.ts) verifying first-run Save is
enabled when isExplicitlySet:false and input matches stored fallback value
- Import fetchAdminTimezone + setAdminTimezone from api/client.js
- timezoneQuery: useQuery(['admin','timezone'], fetchAdminTimezone, retry:false, staleTime:60s)
- timezoneMutation: useMutation(setAdminTimezone) with invalidateQueries on success
- Timezone <section aria-label="Timezone"> after Shared Calendar (with marginBottom on preceding section)
- Searchable <input type=text list=iana-zones> + <datalist> from Intl.supportedValuesOf (guarded)
- 'Use detected: <zone>' affordance for D-02 one-tap seed
- 'Using system default' note when isExplicitlySet === false (D-06)
- Save button disabled while pending or when input equals stored value
- No touch to eventDateTime.ts / hydrateEvents.ts / other sections (D-07)
