Workout Timer

A native Android workout-timer app built with Kotlin and Jetpack Compose. Track a training session with a dedicated timer per exercise, per rest period, and a global stopwatch — backed by a detailed history. The UI is a faithful recreation of the supplied Claude Design prototype (technical / data-focused, fitness-watch aesthetic, dark theme).

Features

• Default workout — "Full Body Calisthenics":
  • Superset 1: Tuck Planche + Abs, 6 alternating sets each
  • Superset 2: Pull-ups + Push-ups, 6 sets each
  • Plank Hold: 90 s, 1 set
  • Superset 3: Chin-ups + Dips, 6 sets each
  • Defaults: 30 s work, 60 s rest between sets, 120 s rest between blocks.
• Live engine — 5 s countdown, then auto-advancing work → rest → work timers alongside a global stopwatch.
  • Finish set ends the current exercise early and jumps to rest.
  • Skip rest ends a rest early and starts the next exercise.
  • Pause/Resume freezes both the dedicated timer and the global stopwatch.
• Always-visible context — current block (superset) name, the exercise just done, the one now, and the one next; plus sets done / remaining.
• Reps — optionally log reps during a set; entering a value auto-fills the following sets of the same exercise (still editable). At the end you can edit every set, with a "Set all" shortcut per exercise.
• Post-workout review — rate satisfaction and breathlessness (4 levels each).
• Detailed history — every session is saved automatically: date/time, real per-set durations vs planned, reps, ratings, planned-vs-actual delta.
• Sound & vibration — toggled live from always-visible buttons on the active screen; each timer end fires a ~2 s beep / vibration pattern when enabled.
• Workout library — create, edit (including the name), and duplicate workouts. A workout is one or more blocks; a block with several exercises is a superset (alternating each round). Per-exercise duration, rest-between-sets, and rest-after-block are all configurable. The library shows the estimated session duration if all timings are respected.
• Keeps the screen awake while a workout is running.

Project layout

app/src/main/java/io/shizen/workouttimer/
├── data/            Models, schedule builder, formatting, SharedPreferences repo
├── timer/           Feedback (sound/vibration) + ActiveController (timer engine)
├── ui/
│   ├── theme/       Colours (oklch→sRGB), fonts, Material theme
│   ├── components/  Icons, buttons, stepper, sheet, dialog, pill
│   └── screens/     Home, History, History detail, Editor, Active, Summary
├── AppViewModel.kt  State, navigation, persistence
└── MainActivity.kt

Build

Requires the Android SDK (compileSdk 35) and a JDK 17+. The first build downloads the Android Gradle Plugin and Compose dependencies from Google's Maven and Maven Central, so a network connection is needed.

If the Gradle wrapper jar (gradle/wrapper/gradle-wrapper.jar) is not present, generate it once with a locally installed Gradle (8.x):

gradle wrapper --gradle-version 8.11.1

Then build:

./gradlew assembleDebug

Opening the project in Android Studio also regenerates the wrapper automatically.

Notes

• Persistence uses SharedPreferences with JSON payloads (kotlinx.serialization), mirroring the prototype's localStorage model.
• Fonts: the design specifies Manrope + JetBrains Mono. To stay asset- and network-free, the app maps these to the platform's geometric sans and monospace families. Drop the real font files into res/font and point WtFonts at them to match pixel-for-pixel.
• Colours were converted from the design's oklch tokens to sRGB in ui/theme/Color.kt.