Jean-Luc Makiola
b91c13030b
Delivery no longer waits to be told. The scan reads `Instances` and `Reminders`, plans every reminder, posts what has come due and arms one exact alarm for the next — replacing both halves of what the provider used to do for us. Reacting to `EVENT_REMINDER` could not be made reliable, only more hopeful. An app that reacts cannot distinguish "nothing was due" from "the broadcast never came", and AOSP's own unbundled calendar carries three workarounds for OEM providers that retarget it or write the alert row late. Etar's fallback was not the answer either: it replaces the alarm but still reads `CalendarAlerts` for what to show, and it disables itself the moment one real broadcast arrives — useless against a broadcast that arrives with no row behind it. Keeping the old receiver alongside was rejected for the same reason it looks attractive: on a healthy device both paths fire, and there is no honest way to suppress one without the latch we just ruled out. So the provider path goes — `EventReminderReceiver`, `ReminderAlertStore`, `ReminderRecovery` and the `CalendarAlerts` writes with it. Reminder delivery no longer needs WRITE_CALENDAR. One alarm exists at a time, re-planned on every firing, so an edit needs no alarm bookkeeping to stay in sync. Every trigger runs the same idempotent scan: the alarm, boot and package-replace (both wipe pending alarms), clock and timezone changes, a provider change while the app is up, launch, and a daily worker for a device that drops the alarm with nothing to announce it. RECEIVE_BOOT_COMPLETED is new and load-bearing — without it reminders stop dead after a restart. `ReminderAlert.alertId` becomes `key`, derived from the reminder rather than a row id that no longer exists, and the notification tag and PendingIntent request codes ride on it, so a re-posted reminder still replaces itself. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Calendula
A modern Material 3 Expressive calendar for Android.
Reads, writes, and reminds — on top of the system calendar, with zero network access.
Calendula is named after the flower whose name — like the word calendar —
comes from the Latin kalendae, the first day of the month. It lives
entirely on top of Android's CalendarContract: any calendar synced to your
device (CalDAV via DAVx5, Google, local, WebCal subscriptions, …) simply
appears, and everything you create or edit syncs back the same way. No own
database, no sync stack reinvented.
✨ Features
Calendar
- Month, week, and day views with a one-tap view switcher
- Full event details — attendees and their responses, reminders, recurrence (humanized), availability, visibility, foreign time zones
- Per-calendar visibility toggle, grouped by account
Editing
- Create, edit, and delete events — including recurring events with scoped writes: only this event, this and all following, or the whole series
- Recurrence picker with one-tap presets and custom rules (interval, weekday toggles, end conditions); rules it can't express are preserved verbatim
- Conflict-safe saves: if an event changed elsewhere while you were editing, Calendula asks instead of silently overwriting
- Read-only calendars (WebCal, birthdays) are detected and respected
Reminders
- Event reminders delivered by Calendula itself as notifications — essential when it's your only calendar app, since Android delegates reminder delivery to calendar apps
- Tap a reminder to land on the event
Design & privacy
- Real Material 3 Expressive throughout — dynamic color (Android 12+), expressive motion and shapes, light/dark theme
- German and English UI, per-app language setting — and open to community translations
- Zero telemetry, zero analytics, no internet permission — your data never leaves the device
📦 Install
F-Droid (recommended)
Calendula is on the official F-Droid repository — just search for Calendula in any F-Droid client, or install it from f-droid.org.
Self-hosted repo (latest builds)
New versions are built, signed, and published to a self-hosted repository the moment each tag lands — usually a few days ahead of the official repo, which rebuilds on F-Droid's own schedule. Add it for the freshest builds:
-
In your F-Droid client, open Settings → Repositories → Add (or open the link below on your phone):
https://apps.dev.jeanlucmakiola.de/dev/fdroid/repo?fingerprint=C2C0640402BF458FC0ED957AF0B37AA4C14022E72F89CE90B5965B458CF73425Repo:
https://apps.dev.jeanlucmakiola.de/dev/fdroid/repo· fingerprint (SHA-256):C2C0 6404 02BF 458F C0ED 957A F0B3 7AA4 C140 22E7 2F89 CE90 B596 5B45 8CF7 3425 -
Refresh, search for Calendula, install.
Both channels share the same signing key, so you can switch between them without reinstalling. Or build from source — see below.
📚 Documentation
- Building from source — requirements and Gradle tasks
- Architecture — the layered design and key pipelines
- Roadmap — what's shipped and what's next
🌍 Translations
Calendula ships in German and English, and you're warmly invited to add your language. Translations are managed on a self-hosted Weblate:
No coding needed — register on the Weblate server, pick (or request) a language, and translate the strings in your browser. You can also reach this link in the app from the top of Settings → App language.
📜 License
MIT — Jean-Luc Makiola, 2026