Scheduled one-way export of local calendars to a user-chosen folder,
overwriting calendula-backup.ics each run — the manual backup, automated.
Not a sync; stays INTERNET-free (provider reads + local file write).
- WorkManager periodic job (deps: work-runtime-ktx, documentfile); worker
pulls collaborators via a Hilt @EntryPoint, so no custom WorkerFactory
wiring. First periodic run is delayed one interval so it can't race the
immediate "run now" feedback run; the writer also overwrites the canonical
file and cleans up any "(1)" duplicates from earlier races.
- SettingsPrefs: enabled, interval (minutes, floored at 30), folder Uri,
last-run status; persisted SAF write grant.
- UI in Calendars > Backup: toggle, folder picker, amount+unit interval
dialog, last-run status line. Notifies after repeated failures.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
