A simplified Kotlin Multiplatform (KMP) contacts management app designed for technical interviews. This app mirrors GART architecture patterns and contains intentional bugs for candidates to identify and fix.

Project Overview

This is an Android-focused KMP app that displays contacts and groups with the following features:

Bottom navigation with Groups and Contacts tabs
Status badges for contacts (Active, Pending, Inactive)
Nostr-style npub identifiers for contacts
Avatar images loaded from network
Room database with reactive Flow-based queries
Clean Architecture with domain, data, and presentation layers
ViewObjects (VOs) separating domain from presentation
Dependency injection with Koin

Getting Started

Prerequisites

Android Studio Ladybug (2024.2.1) or newer
Android SDK 26+
JDK 17 is auto-provisioned by the Gradle toolchain — no manual install needed

Build & Run

# Build debug APK
./gradlew assembleDebug

# On Windows, use:
gradlew.bat assembleDebug

# Install on connected device
adb install -r composeApp/build/outputs/apk/debug/composeApp-debug.apk

# Or run directly from Android Studio

Troubleshooting

Problem	Fix
`Unsupported class file major version`	The toolchain should handle this automatically. If not, ensure JDK 17+ is installed.
Out of memory during build	Increase heap in `gradle.properties`: `org.gradle.jvmargs=-Xmx3072M`
`SDK location not found`	Create a `local.properties` file with `sdk.dir=/path/to/your/Android/Sdk`
Gradle sync fails in Android Studio	File -> Invalidate Caches -> Restart, then re-sync.

Architecture

composeApp/src/
├── androidMain/kotlin/io/assessment/contacts/
│   ├── ContactsApplication.kt
│   ├── MainActivity.kt
│   └── di/DatabaseModule.kt        # Android-specific Room setup
└── commonMain/kotlin/io/assessment/contacts/
    ├── App.kt
    ├── MainViewModel.kt
    ├── core/
    │   ├── data/
    │   │   ├── database/           # Room entities, DAOs, DatabaseSeeder
    │   │   ├── datasource/         # Data sources
    │   │   └── repository/         # Repository implementations
    │   ├── domain/
    │   │   ├── contact/            # Contact, ContactStatus, ContactError
    │   │   ├── group/              # Group, GroupError
    │   │   ├── result/             # Result type utilities
    │   │   └── usecase/            # Use case interfaces
    │   └── presentation/           # Shared presentation utilities
    ├── contacts/
    │   ├── data/                   # ContactMapper
    │   ├── domain/                 # ObserveContactsUseCase
    │   ├── di/                     # ContactsModule
    │   └── presentation/           # ViewModel, Screen, State, ContactVO
    ├── groups/
    │   ├── data/                   # GroupMapper
    │   ├── domain/                 # ObserveGroupsUseCase
    │   ├── di/                     # GroupsModule
    │   └── presentation/           # ViewModel, Screen, State, GroupVO
    ├── designsystem/               # Theme, Colors, Typography
    ├── navigation/                 # NavigationRoot, BottomNavDestItem
    └── di/                         # App-level DI modules