# Halkyon Train What holds for every app and package of this repository is in the [root AGENTS.md](../../AGENTS.md); it applies here in full, and Learn's patterns (`apps/learn/AGENTS.md`) wherever Train needs the same thing. - **A shell on the shared packages**, Todo's copied and renamed (decided 2026-10-28, ADR 0030, D12; what Train is to do: ADR 0030): signing in, the instances, the account and the look work, and since step 5a (28 Oct 2026) a person's workouts are kept and synced with `serverpod_offline_sync`, every row sealed (ADR 0030, D7, D14, D15), and on Android a workout is recorded (5b: ADR 0030, D13, D16, D18 to D21), and since 5c home lists them and each has its page with its map (D22 to D24). Packages: `halkyon_train_server`, `halkyon_train_client` (generated, never edited), `halkyon_train_flutter`; app ID `app.halkyon.train` on every platform; no web build. Licences as Learn's (server SSPL, client and app AGPL; `LICENSE.md`). - **The server** includes `halkyon_base` (ADR 0014) and configures it in `server.dart` (`trainBase()`, `lib/src/train_base.dart`): its basics say it serves `train` (never change it once apps use it), sign-in mails name Halkyon Train, the source is this repository, `minimumAppBuild` 1, and `deleteTrainData` (`lib/src/train_data.dart`) as its `deletePersonData` hook, which deletes the person's sync spaces and so, by the sync engine's cascades, every row of theirs (`test/integration/workout/person_deletion_test.dart`). Authentication through the module's builders: a password, SimpleLogin on the register, email codes proving an address, server-side sessions; no anonymous accounts (ADR 0020, D25), nor GitHub (D36). **Accounts** (ADR 0016): Train holds its own register when it runs alone, and is a member of the instance's register (Learn's server on learn.halkyon.eu) where the operator sets `ACCOUNT_REGISTER_URL` (`trainBase(accounts: AccountsMode.fromEnvironment())`) with the instance's shared `INSTANCE_SECRET` (`instanceSecret`); then sign-in, handles and profiles are the register's, the email settings are the register's alone, and an identified person's deletion goes to the register first. `addInstanceRoutes` serves the calls between the services on its web server, and the server doesn't start without the secret where it needs it. `schedulePruning` (`lib/src/pruning.dart`) keeps the module's pruning scheduled, one entry each however often the server starts (and cancels the one under the pruning's name before ADR 0020, D25): the anonymous accounts left from before daily, sign-up attempts and codes hourly, as the register the deletions its members haven't confirmed hourly, as a member the people the register no longer knows daily (each a no-op in the other mode). Session logs are never persisted, in any run mode. **The Loop's firmware relay** (ADR 0030, D10, D40, `lib/src/firmware/`): the `firmware` endpoint asks Polar's firmware service in the person's place and hands on the file, kept in memory a day per hardware and version (`FirmwareRelay`); on by default, off where the operator sets `LOOP_FIRMWARE_RELAY=off`, the app then offering the direct way alone; tested on a fake Polar (`test/integration/firmware/`). **Routes** (ADR 0030, D11, D44, `lib/src/routing/`): the `routing` endpoint plans a route through the instance's BRouter (`BROUTER_URL`; none: `offered` is false and plans are refused) for the people signed in, at most 50 waypoints and 30 plans a person a minute, nothing kept or logged; BRouter's GeoJSON read in `brouter.dart` (points, elevations, climbs above 3 m, turn hints, stretches by surface), tested on its format (`test/unit/routing/`) and on a fake BRouter (`test/integration/routing/`). Train's running profile is `apps/train/brouter/halkyon-run.brf`, which the sidecar's profiles hold beside BRouter's own. **Deployed** (D46) beside learn.halkyon.eu's server once `deploy/.env` names `deploy/compose.train.yaml`: at train.halkyon.eu (`config/production.yaml`, the image `Dockerfile` as Learn's), a member of Learn's register, its database `halkyon_train` in the instance's PostgreSQL, BRouter's image `deploy/brouter/` (its segments kept current by `segments.sh`); `redeploy.sh` and `backup.sh` take Train's server and database in only where it is switched on, and the operator's steps are `deploy/sidecars/README.md`, *Train*. Migrations (2026-10-28): an initial one with Serverpod's tables, its auth modules' and the module's as they stand (Todo's grew one by one with the module; Train starts where they ended), then `workouts`, purely additive: the sync engine's tables and Train's first three, then `profile`, `days` (Train's `day`, `day_series` and `night`) and `plans` (`plan`, D42), each purely additive. **Synced models** (`database: sync`, the module `offline_sync`, `experimental_features: databaseSync` in `config/generator.yaml`): `content_key` (the person's key sealed to the account), `workout` and `workout_series` (a workout's series in chunks of at most ten minutes, deleted with it), `profile` (the body's figures, one row a person), `day`, `day_series` (a day's 24/7 heart rate in chunks of three hours, deleted with it) and `night` (one row a person and date each, ADR 0030, D37) and `plan` (an interval plan, D42), each a sealed `payload` with its `keyId` and `nonce`, nothing else readable. Tests (`test/integration/train_server_test.dart`) call the module's endpoints through the server's own dispatch (`halkyon_base.`), since the generated test tools expose the project's endpoints alone. - **The app** is halkyon_app's `InstanceGate` and `SessionGate` with Train's frame (`trainFrame`: "Train" under "Halkyon", its icon, `train.example.org`, its own sentence) and `ServerpodInstanceChecker(app: 'train')`; `TrainDependencies` (`AppDependencies`) on one instance, `TrainPerson` per person: their own sync database in their folder (`sync.sqlite`, halkyon_app's `PersonFolders`, one person's at a time), halkyon_app's `SyncService` behind `AppCompatibility` (the module's basics' `minimumAppBuild`, against the build `package_info_plus` reads), their key (`TrainKeys`, `lib/src/core/privacy/`: one key per person, IDs `train1..`, the oldest-made writing, kept in `content_key` and opened only in Train's form, ADR 0030, D15) and their workouts (`WorkoutRepository`, `lib/src/feature/workout/`: halkyon_app's `PayloadEnvelope` seals a workout for its row and a series chunk for its row and its workout; payloads are versioned JSON, a series' columns delta-coded, gzipped before sealing; a deletion blanks every payload first); the gateways' tests run on a sync database opened without a server, the repository's on memory gateways and real libsodium; a person's app whose home lists their workouts (`WorkoutsCubit`, with `TrainPerson.deletions`, halkyon_app's `DelayedDeletions`) and opens each one's page (`WorkoutCubit`: `analyse` in `workout_analysis.dart` reads its series into the track's pieces, splits, elevation and charts, drawn by `workout_chart.dart`; the map with flutter_map on the instance's source, `MapSourceRepository` asking `map.source`, its tiles from `TrainPerson.mapTiles`, vector_map_tiles in the app and none in widget tests), and the account sheet: halkyon_app's `AccountTiles` (whose account on which instance, Switch account, Sign out, Delete account, which asks first) in Train's words, and halkyon_app's About (`showAppAbout`: the source of what the instance runs, from `TrainDependencies.sourceCodeUrl`, and the licence list). Texts through gen-l10n in British English (the template), German (informal du), an empty `en_US` and `en_GB` (`test/l10n/arb_files_test.dart` keeps them in step). The look follows the system's theme mode and language until Train has settings. Countries in where an instance keeps its data are named by halkyon_app's CLDR names (`AssetCountryNames`), its language picked by halkyon_app's `resolveAppLocale`. Widget tests start Train's whole tree with halkyon_app's fakes (`test/app/train_app_test.dart`). - **Recording** (ADR 0030, D13, D16, D18 to D21, D26 to D28) is Android's alone for now (iOS waits for a Mac, D25) (`TrainPerson.recording` null elsewhere): `RecorderService` (Kotlin, `android/app/src/main/kotlin/app/halkyon/train/`), a foreground service of the types `location` and `health` started from the open app, takes fixes from LocationManager's GPS (no Play services), steps from the step detector the heart rate from the strap and a row from the rower the person chose (ADR 0030, D26 to D28: `NotifyLink.kt` on Android's own Bluetooth API, no package, `HeartRateMeasurement.kt` parsing 0x2A37 and `RowerData.kt` FTMS's Rower Data 0x2AD1; `DeviceScanner.kt` finds them for the sheets over `…/recorder/straps` and `…/recorder/rowers`; each remembered in the person's `strap.json` and `rower.json`, `DeviceStore`), decides auto-pause (`AutoPause.kt`) and appends each sample as a line to the person's `recording.txt` (format in `recording_file.dart`), flushed every 5 s; `MainActivity` asks the permissions (never background location) and bridges `app.halkyon.train/recorder` (methods) and `…/recorder/lines` (the file so far, then each line). The app (`lib/src/feature/recording/`) follows those lines with `RecordingBloc`, works out what the screen and the notification show (`liveOf`, the saved totals' functions), and saves a recording as a workout and its series (`recordedWorkout`) or throws it away; one cut off, or stopped and not saved, is found as the person's app opens. Tests: the Dart side with `test/support/fake_recorder_platform.dart`; the Kotlin auto-pause and the strap's and the rower's parsers on the JVM, `JAVA_HOME= ./gradlew :app:testDebugUnitTest` in `android/` after a first `flutter build apk` (which writes `gradlew`), not part of `tool/check.dart`, as CI's runner has no Android SDK. - **Health Connect** (ADR 0030, D30, D31) is Android's (`TrainPerson.health` null elsewhere): `HealthConnectBridge.kt` on AndroidX's `connect-client` 1.1.0 over `app.halkyon.train/health` (its records' mapping in `HealthRecords.kt`, tested on the JVM; the rationale's links from Health Connect in the manifest, `…/health/rationale` to the app), `HealthPlatform` in Dart (`lib/src/feature/health/`), `HealthConnect` per person: with writing on, every workout written as `healthRecordsOf` makes it (client IDs from the workout's ID, a version counted up as it changes, a fingerprint deciding whether it did), written again or deleted as the workouts change and as the app opens, what was written kept in the person's `health_connect.json` (`HealthStore`, never synced); with reading on, the sessions of the apps the person turned on brought in as workouts through the changes token (`importedWorkout` in `health_import.dart`, the workout's `origin` in its payload; a double of one Train has brings at most its heart rate, `isDouble`; one deleted in Train is remembered so it stays out; a track only when asked for on its page, `bringInTrack`), as the app opens and comes to the front (`HealthConnectListener`, which opens the rationale too); the screen from the account sheet (`HealthScreen`, `HealthCubit`). Tests on `test/support/fake_health_platform.dart`. Train needs Android 8 (API 26) for it. - **The Polar Loop** (ADR 0030, D32 to D36) is Android's (`TrainPerson.loop` null elsewhere): `LoopBridge.kt` on Polar's BLE SDK 8.3.0 (from JitPack, a repository asked for Polar's group alone, its files pinned by SHA-256 in `android/gradle/verification-metadata.xml`; a new version needs its checksums there) over `app.halkyon.train/loop`, `…/loop/state` and `…/loop/search`, the first-time use's figures mapped and checked in `LoopSetup.kt` (tested on the JVM); `LoopPlatform` in Dart (`lib/src/feature/loop/`), `PolarLoop` per person: the band remembered in the person's `loop.json` (`LoopStore`, never synced) with what it was set up with and what it told, connected while the app is open, its clock set as each connection is ready, a changed profile offered on the band's screen and sent only when the person says (D35), *Let the band go* a factory reset after asking; its days and nights (D37, D38, `lib/src/feature/day/`) read as each connection is ready (every half hour at most, or when the person pulls *Days*) and by a WorkManager job every four hours while the app is closed (`LoopWorker.kt`, into the person's `loop_days.txt`, which the app takes in as it opens, `LoopLines`), `LoopDays.kt` turning the SDK's answers into lines of JSON (tested on the JVM), `DayRepository` sealing them as `day`, `night` and `day_series` rows (payloads in `day_payload.dart`), and what is sealed, up to yesterday, deleted on the band by the next read (`KnownLoop.keptUntil`), never today; its training sessions (D39) read with the days and kept as workouts of origin *Polar Loop* (`loop_workouts.dart`: `takeLoopSessions`, Polar's sport 1 and 2 as running and cycling, the rest as `Activity.other`, which the edit sheet changes; a double of a recorded workout gives it its heart rate), remembered in `loop.json` (`takenSessions`), written to Health Connect as Train's own; its firmware (D10, D40) asked for on the day's first connection and on the band's screen, from Polar directly (the SDK) or through the instance as the person chose (`KnownLoop.firmwareVia`, `FirmwareRelayGateway` on the server's `firmware` endpoint), updated only after asking, the band read and kept first and set up again after (`PolarLoop.updateFirmware`, `LoopFirmware.kt`); its live heart rate (D41) read by the recording service through the same SDK (`PolarSdk.kt`, one for the process, held by the bridge and by a recording; `LoopHeart.kt`) while no strap sends, the file's `loop` lines its state; home's *Days* tab and a day's page (`DaysCubit`, `DayCubit`); `loopFiguresOf` fills Polar's defaults for the band alone (`loop_figures.dart`), the setup sheet asks for what the profile lacks with `ProfileForm(only: …)`. **Interval plans** (D42, `lib/src/feature/plan/`): home's *Plans* tab (`PlansCubit`, deletions undone for a moment as workouts' are), a plan's editor (`PlanEditorCubit`, `PlanScreen`, a step on `showStepSheet`) and three templates (`plan_templates.dart`); `PlanRepository` seals each as a `plan` row (payload in `plan_payload.dart`, the step's JSON shared with the recorder). A recording runs the plan chosen on the Record sheet in its service: `recorderPlanOf` (`plan_speech.dart`) spells out its run with zones as heart rates and the spoken lines, `PlanRunner.kt` runs it (tested on the JVM), `PlanCues.kt` gives the tone, vibration and voice; the file's `plan` and `step` lines bring it back (`Recording.plan`, `planSteps`), `LivePlan` is the step on the recording screen, and *Lap* ends a step (`RecorderPlatform.lap`). Saved, the steps are the workout's laps (D43, `WorkoutPlan` in its payload, worked out in `recordedWorkout`), and its page lists them with their figures and whether each held its target (`LapFigures` in `workout_analysis.dart`), the charts shading the work steps. The person's body's figures are the synced, sealed `profile` (D33, *Your body*, `lib/src/feature/profile/`). Polar's SDK isn't free software (D36): the app's AGPL carries a section 7 permission for it (`halkyon_train_flutter/LICENSE-polar-exception.md`), its notices are in the licence list (`registerPolarLicense`, on Android), and an F-Droid listing of Train declares `NonFreeDep`. Never ask the SDK for `FEATURE_TELEMETRY`. Tests on `test/support/fake_loop_platform.dart`. - **The icon** is Lucide's `bike` fading from cobalt through violet and strawberry into carrot (ADR 0031), drawn with the other apps' by the repository's `tool/app_icons.py` (`python3 -I tool/app_icons.py train` from the root): `assets/icon/halkyon_train_icon.png`, Lucide's ISC licence beside it, and every platform's launcher icon through flutter_launcher_icons. `registerLucideLicense` puts Lucide's notice in the licence list. - **`serverpod start`** runs in `apps/train/halkyon_train_server` (it launches the app from `lib/driver.dart`); `.mcp.json`'s `--server-dir` names it when a session works on Train. Its tests need throwaway passwords in its git-ignored `config/passwords.yaml` (`database`, `serviceSecret`, `serverSideSessionKeyHashPepper`, `emailSignInPepper`) or from the environment, as CI gives them. Train's development server has ports of its own (API 8180, Insights 8181, web 8182, PostgreSQL 8190; the app's `assets/config.json`), so it runs beside Learn's, as a member of Learn's register; its tests use `config/test.yaml`'s ports, as Learn's and Todo's do, which Melos runs one package at a time.