Jean-Luc Makiola
27a48b9eb4
Dropping a single occurrence on a calendar with no _sync_id records it in the master row's EXDATE (the #47 fix; synced calendars use a cancelled exception instead and are unaffected). An EXDATE stamp is an absolute instant — it excludes an occurrence only while the series keeps generating one at exactly that instant — and nothing ever rewrote it when the anchor moved. buildEventUpdateValues shifts DTSTART on any time change and rewrites RRULE/DURATION/zone/all-day, so every occurrence regenerates elsewhere while the stamps stay behind matching nothing: the occurrence the user deleted comes back. updateEventFromOccurrence is worse — it splits the series by inserting a fresh event built from the form, which carries no EXDATE at all, so every exclusion in the tail is lost. Shift each stamp by the same wall-clock delta the anchor takes, re-resolved in the event's (possibly new) zone. Reusing the anchor's rule is what keeps an exclusion pinned to its occurrence when a DST boundary sits between the two, or the zone itself changed; a millisecond delta would bake in the offset that happened to apply at the edited occurrence. Parsing reads all-day-ness from the old form and writing takes it from the new one, so the VALUE=DATE and date-time forms convert into each other when the event switches — the wrong form matches no occurrence and loses the exclusion just as surely as the wrong instant. Stamps in a shape Calendula never writes (a TZID-parameterised or floating one from a sync adapter) are left exactly as they are, whole list included: a stale stamp excludes nothing, but a mangled one could exclude the wrong occurrence. For the split, the parent's stamps past the cutoff are re-timed onto the new series. The one *at* the split point is dropped: it names the occurrence being edited, which exists by definition, and honouring a stale exclusion for it would swallow the edit whole. The parent keeps its full list — stamps past the truncation are inert once it stops generating those occurrences. The write repeats the whole time/recurrence set for the reason #47 documents (an EXDATE-only update is not read as a recurrence change), and a failure rolls the new series back before the parent is truncated, so the split fails whole rather than landing with the exclusions dropped. Dropping the recurrence now clears EXDATE with the RRULE. Dormant rather than harmless: adding a recurrence back later would punch the old holes into the new one. This reaches every calendar type through the "all events" path, including synced ones, where an upstream EXDATE must move with the series for the same reason — and reaches a calendar move too, which copies EXDATE verbatim and then applies the field edits as a normal series update. Co-Authored-By: Claude Opus 5 <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
- English and German UI plus community translations (Spanish, French, Italian, Polish, and more in progress), per-app language setting — and open to more languages
- Zero telemetry, zero analytics, no internet permission — your data never leaves the device
📦 Install
Pick whichever channel you already use — they all install the same app:
| Channel | Updates | Notes |
|---|---|---|
| Official F-Droid | On F-Droid's build schedule | Recommended; no extra setup |
| Self-hosted F-Droid repo | Minutes after a release | Fastest; needs the repo added once |
| Codeberg release / Obtainium | Per release | Plain APK download, or automated by Obtainium |
| Google Play | Per release | Signed with Google's key — see below |
| Build from source | Whenever you build | Full control |
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.
F-Droid rebuilds from source on its own schedule, so a new version usually shows up there a few days after release.
Self-hosted F-Droid repo (fastest updates)
Every release is built, signed, and published to a self-hosted F-Droid repository as part of the release pipeline, so it lands there first. Add it once and your F-Droid client handles updates from then on:
-
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.
Codeberg release / Obtainium
If you'd rather not use F-Droid at all, every release is also published on
Codeberg with the
signed APK (calendula_vX.Y.Z.apk) and a .sha256 checksum attached — download
and install it directly.
For automatic updates from that channel, use
Obtainium — on the phone,
add Calendula in one tap,
or do it by hand: Add App → paste https://codeberg.org/jlmakiola/calendula
→ Add. Either way, Obtainium tracks the releases and prompts you when a new
one appears.
Google Play
Calendula is live on Google Play: play.google.com/store/apps/details?id=de.jeanlucmakiola.calendula.
Play builds are signed with Google's key rather than mine, so switching between Play and any other channel requires an uninstall (and with it, a fresh start for app settings — your events live in the system calendar and are unaffected).
Build from source
The build is a plain Gradle build with no proprietary dependencies — see
docs/BUILDING.md (note the floret-kit submodule).
Official F-Droid, the self-hosted repo, and the Codeberg releases all share the same signing key, so you can switch freely between them without reinstalling. Google Play is the exception — see above.
📚 Documentation
- Contributing — how to report, propose, and patch
- Building from source — requirements and Gradle tasks
- Architecture — the layered design and key pipelines
- Milestones — what's shipped and what's next
🤝 Contributing
Bug reports, ideas, and patches are all welcome on Codeberg.
The short version: start with an issue. Features get a yes-or-no before they
get code, and both features and bugs are assigned a milestone whose
release/vX.Y.Z branch your pull request then targets. Typo and docs fixes can
skip straight to a pull request. Translations don't go through pull requests at
all — Weblate owns them.
Read CONTRIBUTING.md before writing code: it covers the
workflow, the build (note the floret-kit submodule), and the architectural
rules a change is reviewed against.
🌍 Translations
Calendula ships in English and German, with community translations in Arabic, Chinese, French, Italian, Polish, Portuguese, Russian, and Spanish at varying degrees of completeness — partial is fine, untranslated strings simply fall back to English. You're warmly invited to add or finish 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