House Calendar

The family calendar from the kitchen wall, on an Android tablet in the same spot and on the parents' phones.

• The display shows the family's week as a column for each person and a row for each day, like a paper family organiser.
• The phones carry the same calendar, with reminders for the things you're in or taking someone to.
• Lifts are first-class. Every event says who is taking them, or shows that it still needs someone.
• Term time. Repeating clubs skip the school holidays you've entered.

There's no account, no server and no internet. The devices sync with each other directly over the home Wi-Fi, or over Bluetooth. House Calendar is the sibling of House Points.

Status

Version 1 is complete and verified on emulators (phone and 10" tablet): events and activities, term time, lifts, reminders, sync, display mode, adding from other apps, and export. Sync over real Wi-Fi, the Bluetooth fallback, and running on the actual kitchen tablet still need physical devices. See REVIEW.md. Screens are in docs/screens/.

Download

House Calendar for Android (Android 9 or later), or see the website. Releases are signed with the key whose SHA-256 certificate fingerprint is:

FB:7E:99:E5:2A:0A:42:5D:67:A7:54:9E:01:1B:22:25:F6:4B:B3:D6:A2:34:DB:5E:95:32:E7:15:83:BC:F8:52

How it's built

Every calendar is a pure function of an append-only log of operations. Devices exchange the operations they're missing, and two devices holding the same operations always show the same calendar.

Module	What it is
contracts	The frozen vocabulary: IDs, calendar value types, the op envelope and payloads, and the codec (pure JVM)
schedule	Ops in, calendar out: repeat rules, term time, the agenda, instants across daylight saving, clashes, reminders, edit scopes (pure JVM)
intake	Untrusted input from other apps: .ics files, "Add to calendar" intents, shared text (pure JVM)
sync	Op factory, version vectors, the authenticated and encrypted sync protocol, and who dials whom (pure JVM, copied from House Points)
data	SQLite op log, Keystore-wrapped family key, device identity and settings, encrypted export (Android)
lan	Same-Wi-Fi discovery (mDNS) and TCP transport (Android)
nearby	Bluetooth fallback through Nearby Connections (Android)
app	Jetpack Compose UI: the phone screens and the kitchen display mode (Android)

Design documents

Document	Purpose
VISION.md	One paragraph
CONCEPT.md	The idea, for families
SPEC.md	Requirements, and the worked examples that are also the tests
SAD.md	Architecture
CONTRACTS.md	The contracts module
PLAN.md	Build order and acceptance
PRODUCT.md, DESIGN.md	Product context and the visual system ("Organiser")
REVIEW.md	Decisions taken while the owner was away, and what is verified where

Building

You need JDK 17 and an Android SDK with platform 35 (set sdk.dir in local.properties).

./gradlew test                    # contracts, schedule, intake, sync on the JVM
./gradlew testDebugUnitTest       # Android modules' JVM tests
./gradlew :schedule:benchmark     # the sizing benchmark (NFR-PERF-1), reported, not gating
./gradlew :app:installDebug       # installs "House Calendar (debug)" beside any release install
./gradlew :app:assembleRelease    # signed if housecalendar.signing.* are set in ~/.gradle/gradle.properties

Fonts

Bricolage Grotesque and Atkinson Hyperlegible (Next and Mono) are bundled under the SIL Open Font License. See licenses/.

Licence

MIT. See LICENSE. The bundled fonts keep their own SIL Open Font License.