Initial commit: GeoZoner Android app scaffolding

- Full Android project with Gradle wrapper
- Hilt DI, Room DB, Retrofit networking
- Auth flow with JWT token management
- Bottom navigation with 4 tabs
- Material 3 theme (light/dark)
- Stub screens ready for implementation
- Ready for Mapbox integration

app/build.gradle.kts

@@ -0,0 +1,148 @@
+import java.util.Properties
+
+plugins {
+    alias(libs.plugins.android.application)
+    alias(libs.plugins.kotlin.android)
+    alias(libs.plugins.kotlin.serialization)
+    alias(libs.plugins.compose.compiler)
+    alias(libs.plugins.ksp)
+    alias(libs.plugins.hilt)
+}
+
+// Load local.properties for Mapbox token
+val localProperties = Properties().apply {
+    val localPropsFile = rootProject.file("local.properties")
+    if (localPropsFile.exists()) {
+        load(localPropsFile.inputStream())
+    }
+}
+
+android {
+    namespace = "com.geozoner.app"
+    compileSdk = 35
+
+    defaultConfig {
+        applicationId = "com.geozoner.app"
+        minSdk = 29
+        targetSdk = 35
+        versionCode = 1
+        versionName = "0.1.0"
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+
+        // Inject Mapbox public token as a BuildConfig field
+        buildConfigField(
+            "String",
+            "MAPBOX_PUBLIC_TOKEN",
+            "\"${localProperties.getProperty("MAPBOX_PUBLIC_TOKEN", "")}\""
+        )
+
+        // Backend base URL
+        buildConfigField(
+            "String",
+            "BASE_URL",
+            "\"http://10.0.2.2:8000\""
+        )
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = true
+            isShrinkResources = true
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+            buildConfigField(
+                "String",
+                "BASE_URL",
+                "\"https://api.geozoner.com\""
+            )
+        }
+        debug {
+            isMinifyEnabled = false
+            applicationIdSuffix = ".debug"
+        }
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+    kotlinOptions {
+        jvmTarget = "17"
+    }
+
+    buildFeatures {
+        compose = true
+        buildConfig = true
+    }
+}
+
+dependencies {
+    // AndroidX Core
+    implementation(libs.androidx.core.ktx)
+    implementation(libs.androidx.lifecycle.runtime.ktx)
+    implementation(libs.androidx.lifecycle.runtime.compose)
+    implementation(libs.androidx.lifecycle.viewmodel.compose)
+    implementation(libs.androidx.activity.compose)
+    implementation(libs.androidx.navigation.compose)
+    implementation(libs.androidx.datastore.preferences)
+    implementation(libs.androidx.work.runtime.ktx)
+    implementation(libs.androidx.security.crypto)
+
+    // Compose
+    implementation(platform(libs.compose.bom))
+    implementation(libs.compose.ui)
+    implementation(libs.compose.ui.graphics)
+    implementation(libs.compose.ui.tooling.preview)
+    implementation(libs.compose.material3)
+    implementation(libs.compose.material.icons.extended)
+    debugImplementation(libs.compose.ui.tooling)
+    debugImplementation(libs.compose.ui.test.manifest)
+
+    // Room
+    implementation(libs.room.runtime)
+    implementation(libs.room.ktx)
+    ksp(libs.room.compiler)
+
+    // Hilt
+    implementation(libs.hilt.android)
+    ksp(libs.hilt.android.compiler)
+    implementation(libs.hilt.navigation.compose)
+    implementation(libs.hilt.work)
+    ksp(libs.hilt.work.compiler)
+
+    // Networking
+    implementation(libs.retrofit)
+    implementation(libs.okhttp)
+    implementation(libs.okhttp.logging)
+    implementation(libs.kotlinx.serialization.json)
+    implementation(libs.retrofit.kotlinx.serialization)
+
+    // Mapbox (uncomment after setting MAPBOX_DOWNLOADS_TOKEN in local.properties)
+    // implementation(libs.mapbox.maps)
+
+    // Firebase (uncomment when google-services.json is added)
+    // implementation(platform(libs.firebase.bom))
+    // implementation(libs.firebase.messaging)
+    // implementation(libs.firebase.analytics)
+
+    // Coroutines
+    implementation(libs.kotlinx.coroutines.android)
+    implementation(libs.kotlinx.coroutines.core)
+
+    // Image loading
+    implementation(libs.coil.compose)
+
+    // Health Connect (Phase 2)
+    // implementation(libs.androidx.health.connect)
+
+    // Testing
+    testImplementation(libs.junit)
+    androidTestImplementation(libs.junit.ext)
+    androidTestImplementation(libs.espresso.core)
+    androidTestImplementation(platform(libs.compose.bom))
+    androidTestImplementation(libs.compose.ui.test.junit4)
+}

app/proguard-rules.pro

@@ -0,0 +1,34 @@
+# Add project specific ProGuard rules here.
+
+# Retrofit
+-keepattributes Signature
+-keepattributes *Annotation*
+-keep class retrofit2.** { *; }
+-keepclasseswithmembers class * {
+    @retrofit2.http.* <methods>;
+}
+
+# Kotlinx Serialization
+-keepattributes *Annotation*, InnerClasses
+-dontnote kotlinx.serialization.AnnotationsKt
+-keepclassmembers class kotlinx.serialization.json.** {
+    *** Companion;
+}
+-keepclasseswithmembers class kotlinx.serialization.json.** {
+    kotlinx.serialization.KSerializer serializer(...);
+}
+-keep,includedescriptorclasses class com.geozoner.app.**$$serializer { *; }
+-keepclassmembers class com.geozoner.app.** {
+    *** Companion;
+}
+-keepclasseswithmembers class com.geozoner.app.** {
+    kotlinx.serialization.KSerializer serializer(...);
+}
+
+# OkHttp
+-dontwarn okhttp3.**
+-dontwarn okio.**
+
+# Room
+-keep class * extends androidx.room.RoomDatabase
+-keep @androidx.room.Entity class *

app/src/main/AndroidManifest.xml

@@ -0,0 +1,67 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <!-- Network -->
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+
+    <!-- Location -->
+    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
+    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
+    <uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
+
+    <!-- Foreground Service -->
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_LOCATION" />
+
+    <!-- Notifications (Android 13+) -->
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
+
+    <!-- Activity Recognition (for Health Connect) -->
+    <uses-permission android:name="android.permission.ACTIVITY_RECOGNITION" />
+
+    <!-- Boot receiver for WorkManager -->
+    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
+
+    <application
+        android:name=".GeoZonerApp"
+        android:allowBackup="true"
+        android:icon="@android:drawable/sym_def_app_icon"
+        android:label="@string/app_name"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.GeoZoner"
+        android:usesCleartextTraffic="true"
+        tools:targetApi="35">
+
+        <activity
+            android:name=".ui.MainActivity"
+            android:exported="true"
+            android:theme="@style/Theme.GeoZoner">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+        <!-- GPS Tracking Foreground Service -->
+        <service
+            android:name=".service.LocationTrackingService"
+            android:exported="false"
+            android:foregroundServiceType="location" />
+
+        <!-- WorkManager initializer (for Hilt) -->
+        <provider
+            android:name="androidx.startup.InitializationProvider"
+            android:authorities="${applicationId}.androidx-startup"
+            android:exported="false"
+            tools:node="merge">
+            <meta-data
+                android:name="androidx.work.WorkManagerInitializer"
+                android:value="androidx.startup"
+                tools:node="remove" />
+        </provider>
+
+    </application>
+
+</manifest>

app/src/main/java/com/geozoner/app/GeoZonerApp.kt

@@ -0,0 +1,43 @@
+package com.geozoner.app
+
+import android.app.Application
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import dagger.hilt.android.HiltAndroidApp
+
+@HiltAndroidApp
+class GeoZonerApp : Application() {
+
+    override fun onCreate() {
+        super.onCreate()
+        createNotificationChannels()
+    }
+
+    private fun createNotificationChannels() {
+        val manager = getSystemService(NotificationManager::class.java)
+
+        val trackingChannel = NotificationChannel(
+            CHANNEL_TRACKING,
+            getString(R.string.tracking_notification_channel),
+            NotificationManager.IMPORTANCE_LOW
+        ).apply {
+            description = "Shows notification while tracking activity"
+            setShowBadge(false)
+        }
+
+        val socialChannel = NotificationChannel(
+            CHANNEL_SOCIAL,
+            "Social",
+            NotificationManager.IMPORTANCE_DEFAULT
+        ).apply {
+            description = "Zone captures, friend updates, leaderboard changes"
+        }
+
+        manager.createNotificationChannels(listOf(trackingChannel, socialChannel))
+    }
+
+    companion object {
+        const val CHANNEL_TRACKING = "tracking"
+        const val CHANNEL_SOCIAL = "social"
+    }
+}

app/src/main/java/com/geozoner/app/data/local/TokenStorage.kt

@@ -0,0 +1,52 @@
+package com.geozoner.app.data.local
+
+import android.content.Context
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.stringPreferencesKey
+import androidx.datastore.preferences.preferencesDataStore
+import dagger.hilt.android.qualifiers.ApplicationContext
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.flow.map
+import javax.inject.Inject
+import javax.inject.Singleton
+
+private val Context.dataStore: DataStore<Preferences> by preferencesDataStore(name = "auth_prefs")
+
+@Singleton
+class TokenStorage @Inject constructor(
+    @ApplicationContext private val context: Context,
+) {
+    private val accessTokenKey = stringPreferencesKey("access_token")
+    private val refreshTokenKey = stringPreferencesKey("refresh_token")
+    private val userIdKey = stringPreferencesKey("user_id")
+
+    val accessToken: Flow<String?> = context.dataStore.data.map { it[accessTokenKey] }
+    val refreshToken: Flow<String?> = context.dataStore.data.map { it[refreshTokenKey] }
+    val userId: Flow<String?> = context.dataStore.data.map { it[userIdKey] }
+
+    val isLoggedIn: Flow<Boolean> = accessToken.map { it != null }
+
+    suspend fun saveTokens(accessToken: String, refreshToken: String) {
+        context.dataStore.edit { prefs ->
+            prefs[accessTokenKey] = accessToken
+            prefs[refreshTokenKey] = refreshToken
+        }
+    }
+
+    suspend fun saveUserId(userId: String) {
+        context.dataStore.edit { prefs ->
+            prefs[userIdKey] = userId
+        }
+    }
+
+    suspend fun getAccessTokenOnce(): String? = accessToken.first()
+
+    suspend fun getRefreshTokenOnce(): String? = refreshToken.first()
+
+    suspend fun clear() {
+        context.dataStore.edit { it.clear() }
+    }
+}

app/src/main/java/com/geozoner/app/data/local/dao/CachedZoneDao.kt

@@ -0,0 +1,30 @@
+package com.geozoner.app.data.local.dao
+
+import androidx.room.Dao
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
+import androidx.room.Query
+import com.geozoner.app.data.local.entity.CachedZoneEntity
+import kotlinx.coroutines.flow.Flow
+
+@Dao
+interface CachedZoneDao {
+
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insertAll(zones: List<CachedZoneEntity>)
+
+    @Query("SELECT * FROM cached_zones WHERE isOwn = 1")
+    fun getOwnZones(): Flow<List<CachedZoneEntity>>
+
+    @Query("SELECT * FROM cached_zones WHERE isOwn = 0")
+    fun getFriendZones(): Flow<List<CachedZoneEntity>>
+
+    @Query("SELECT * FROM cached_zones")
+    fun getAllZones(): Flow<List<CachedZoneEntity>>
+
+    @Query("DELETE FROM cached_zones WHERE isOwn = :isOwn")
+    suspend fun deleteByOwnership(isOwn: Boolean)
+
+    @Query("DELETE FROM cached_zones")
+    suspend fun deleteAll()
+}

app/src/main/java/com/geozoner/app/data/local/dao/PendingActivityDao.kt

@@ -0,0 +1,27 @@
+package com.geozoner.app.data.local.dao
+
+import androidx.room.Dao
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
+import androidx.room.Query
+import com.geozoner.app.data.local.entity.PendingActivityEntity
+import kotlinx.coroutines.flow.Flow
+
+@Dao
+interface PendingActivityDao {
+
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insert(activity: PendingActivityEntity): Long
+
+    @Query("SELECT * FROM pending_activities ORDER BY createdAt ASC")
+    fun getAll(): Flow<List<PendingActivityEntity>>
+
+    @Query("SELECT * FROM pending_activities ORDER BY createdAt ASC")
+    suspend fun getAllOnce(): List<PendingActivityEntity>
+
+    @Query("DELETE FROM pending_activities WHERE id = :id")
+    suspend fun deleteById(id: Long)
+
+    @Query("SELECT COUNT(*) FROM pending_activities")
+    fun count(): Flow<Int>
+}

app/src/main/java/com/geozoner/app/data/local/db/GeoZonerDatabase.kt

@@ -0,0 +1,21 @@
+package com.geozoner.app.data.local.db
+
+import androidx.room.Database
+import androidx.room.RoomDatabase
+import com.geozoner.app.data.local.dao.CachedZoneDao
+import com.geozoner.app.data.local.dao.PendingActivityDao
+import com.geozoner.app.data.local.entity.CachedZoneEntity
+import com.geozoner.app.data.local.entity.PendingActivityEntity
+
+@Database(
+    entities = [
+        PendingActivityEntity::class,
+        CachedZoneEntity::class,
+    ],
+    version = 1,
+    exportSchema = false,
+)
+abstract class GeoZonerDatabase : RoomDatabase() {
+    abstract fun pendingActivityDao(): PendingActivityDao
+    abstract fun cachedZoneDao(): CachedZoneDao
+}

app/src/main/java/com/geozoner/app/data/local/entity/CachedZoneEntity.kt

@@ -0,0 +1,18 @@
+package com.geozoner.app.data.local.entity
+
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+
+/**
+ * Local cache of zone data for offline map rendering.
+ */
+@Entity(tableName = "cached_zones")
+data class CachedZoneEntity(
+    @PrimaryKey val id: String,
+    val ownerId: String,
+    val polygonGeojson: String, // JSON string of GeoJSON polygon
+    val areaM2: Double,
+    val defenseLevel: Int,
+    val isOwn: Boolean, // true = current user's zone, false = friend's zone
+    val lastUpdated: Long = System.currentTimeMillis(),
+)

app/src/main/java/com/geozoner/app/data/local/entity/PendingActivityEntity.kt

@@ -0,0 +1,18 @@
+package com.geozoner.app.data.local.entity
+
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+
+/**
+ * Stores activity data locally when offline.
+ * Will be uploaded to server when connectivity is restored.
+ */
+@Entity(tableName = "pending_activities")
+data class PendingActivityEntity(
+    @PrimaryKey(autoGenerate = true) val id: Long = 0,
+    val type: String,
+    val startedAt: String,
+    val endedAt: String,
+    val gpsTrackJson: String, // JSON array of GpsPoints
+    val createdAt: Long = System.currentTimeMillis(),
+)

app/src/main/java/com/geozoner/app/data/remote/AuthInterceptor.kt

@@ -0,0 +1,40 @@
+package com.geozoner.app.data.remote
+
+import com.geozoner.app.data.local.TokenStorage
+import kotlinx.coroutines.runBlocking
+import okhttp3.Interceptor
+import okhttp3.Response
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/**
+ * Adds Authorization header with Bearer token to all requests
+ * except auth endpoints (login, register, refresh).
+ */
+@Singleton
+class AuthInterceptor @Inject constructor(
+    private val tokenStorage: TokenStorage,
+) : Interceptor {
+
+    override fun intercept(chain: Interceptor.Chain): Response {
+        val request = chain.request()
+
+        // Skip auth endpoints
+        val path = request.url.encodedPath
+        if (path.contains("/auth/")) {
+            return chain.proceed(request)
+        }
+
+        val token = runBlocking { tokenStorage.getAccessTokenOnce() }
+
+        val authenticatedRequest = if (token != null) {
+            request.newBuilder()
+                .header("Authorization", "Bearer $token")
+                .build()
+        } else {
+            request
+        }
+
+        return chain.proceed(authenticatedRequest)
+    }
+}

app/src/main/java/com/geozoner/app/data/remote/TokenAuthenticator.kt

@@ -0,0 +1,54 @@
+package com.geozoner.app.data.remote
+
+import com.geozoner.app.data.local.TokenStorage
+import com.geozoner.app.data.remote.api.AuthApi
+import com.geozoner.app.data.remote.dto.RefreshRequest
+import kotlinx.coroutines.runBlocking
+import okhttp3.Authenticator
+import okhttp3.Request
+import okhttp3.Response
+import okhttp3.Route
+import javax.inject.Inject
+import javax.inject.Singleton
+
+/**
+ * Handles 401 responses by refreshing the JWT token.
+ * If refresh fails, clears tokens (forcing re-login).
+ */
+@Singleton
+class TokenAuthenticator @Inject constructor(
+    private val tokenStorage: TokenStorage,
+    private val authApiProvider: dagger.Lazy<AuthApi>,
+) : Authenticator {
+
+    override fun authenticate(route: Route?, response: Response): Request? {
+        // Prevent infinite refresh loops
+        if (response.request.header("X-Retry-Auth") != null) {
+            runBlocking { tokenStorage.clear() }
+            return null
+        }
+
+        val refreshToken = runBlocking { tokenStorage.getRefreshTokenOnce() } ?: return null
+
+        return try {
+            val tokenResponse = runBlocking {
+                authApiProvider.get().refresh(RefreshRequest(refreshToken))
+            }
+
+            runBlocking {
+                tokenStorage.saveTokens(
+                    accessToken = tokenResponse.accessToken,
+                    refreshToken = tokenResponse.refreshToken,
+                )
+            }
+
+            response.request.newBuilder()
+                .header("Authorization", "Bearer ${tokenResponse.accessToken}")
+                .header("X-Retry-Auth", "true")
+                .build()
+        } catch (e: Exception) {
+            runBlocking { tokenStorage.clear() }
+            null
+        }
+    }
+}

app/src/main/java/com/geozoner/app/data/remote/api/ActivityApi.kt

@@ -0,0 +1,25 @@
+package com.geozoner.app.data.remote.api
+
+import com.geozoner.app.data.remote.dto.ActivityCreateRequest
+import com.geozoner.app.data.remote.dto.ActivityDetailResponse
+import com.geozoner.app.data.remote.dto.ActivityResponse
+import retrofit2.http.Body
+import retrofit2.http.GET
+import retrofit2.http.POST
+import retrofit2.http.Path
+import retrofit2.http.Query
+
+interface ActivityApi {
+
+    @POST("activities")
+    suspend fun createActivity(@Body request: ActivityCreateRequest): ActivityDetailResponse
+
+    @GET("activities")
+    suspend fun getActivities(
+        @Query("limit") limit: Int = 50,
+        @Query("offset") offset: Int = 0,
+    ): List<ActivityResponse>
+
+    @GET("activities/{activityId}")
+    suspend fun getActivity(@Path("activityId") activityId: String): ActivityDetailResponse
+}

app/src/main/java/com/geozoner/app/data/remote/api/AuthApi.kt

@@ -0,0 +1,21 @@
+package com.geozoner.app.data.remote.api
+
+import com.geozoner.app.data.remote.dto.LoginRequest
+import com.geozoner.app.data.remote.dto.RefreshRequest
+import com.geozoner.app.data.remote.dto.RegisterRequest
+import com.geozoner.app.data.remote.dto.TokenResponse
+import com.geozoner.app.data.remote.dto.UserResponse
+import retrofit2.http.Body
+import retrofit2.http.POST
+
+interface AuthApi {
+
+    @POST("auth/register")
+    suspend fun register(@Body request: RegisterRequest): UserResponse
+
+    @POST("auth/login")
+    suspend fun login(@Body request: LoginRequest): TokenResponse
+
+    @POST("auth/refresh")
+    suspend fun refresh(@Body request: RefreshRequest): TokenResponse
+}

app/src/main/java/com/geozoner/app/data/remote/api/FriendApi.kt

@@ -0,0 +1,21 @@
+package com.geozoner.app.data.remote.api
+
+import com.geozoner.app.data.remote.dto.MessageResponse
+import com.geozoner.app.data.remote.dto.UserResponse
+import retrofit2.http.DELETE
+import retrofit2.http.GET
+import retrofit2.http.POST
+import retrofit2.http.Path
+import retrofit2.http.Query
+
+interface FriendApi {
+
+    @POST("friends")
+    suspend fun addFriend(@Query("username") username: String): MessageResponse
+
+    @GET("friends")
+    suspend fun getFriends(): List<UserResponse>
+
+    @DELETE("friends/{friendId}")
+    suspend fun removeFriend(@Path("friendId") friendId: String)
+}

app/src/main/java/com/geozoner/app/data/remote/api/LeaderboardApi.kt

@@ -0,0 +1,10 @@
+package com.geozoner.app.data.remote.api
+
+import com.geozoner.app.data.remote.dto.LeaderboardEntryResponse
+import retrofit2.http.GET
+
+interface LeaderboardApi {
+
+    @GET("leaderboard")
+    suspend fun getLeaderboard(): List<LeaderboardEntryResponse>
+}

app/src/main/java/com/geozoner/app/data/remote/api/UserApi.kt

@@ -0,0 +1,21 @@
+package com.geozoner.app.data.remote.api
+
+import com.geozoner.app.data.remote.dto.UserResponse
+import com.geozoner.app.data.remote.dto.UserStatsResponse
+import com.geozoner.app.data.remote.dto.UserUpdateRequest
+import retrofit2.http.Body
+import retrofit2.http.GET
+import retrofit2.http.PATCH
+import retrofit2.http.Path
+
+interface UserApi {
+
+    @GET("users/me")
+    suspend fun getMe(): UserResponse
+
+    @PATCH("users/me")
+    suspend fun updateMe(@Body request: UserUpdateRequest): UserResponse
+
+    @GET("users/{userId}/stats")
+    suspend fun getUserStats(@Path("userId") userId: String): UserStatsResponse
+}

app/src/main/java/com/geozoner/app/data/remote/api/ZoneApi.kt

@@ -0,0 +1,18 @@
+package com.geozoner.app.data.remote.api
+
+import com.geozoner.app.data.remote.dto.ZoneBriefResponse
+import com.geozoner.app.data.remote.dto.ZoneDetailResponse
+import retrofit2.http.GET
+import retrofit2.http.Path
+
+interface ZoneApi {
+
+    @GET("zones")
+    suspend fun getMyZones(): List<ZoneBriefResponse>
+
+    @GET("zones/friends")
+    suspend fun getFriendZones(): List<ZoneBriefResponse>
+
+    @GET("zones/{zoneId}")
+    suspend fun getZone(@Path("zoneId") zoneId: String): ZoneDetailResponse
+}

app/src/main/java/com/geozoner/app/data/remote/dto/ActivityDto.kt

@@ -0,0 +1,47 @@
+package com.geozoner.app.data.remote.dto
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class GpsPointDto(
+    val lat: Double,
+    val lon: Double,
+    val timestamp: String? = null,
+    val altitude: Double? = null,
+    val hdop: Double? = null,
+)
+
+@Serializable
+data class ActivityCreateRequest(
+    val type: String,
+    @SerialName("started_at") val startedAt: String,
+    @SerialName("ended_at") val endedAt: String,
+    @SerialName("gps_track") val gpsTrack: List<GpsPointDto>,
+)
+
+@Serializable
+data class ActivityResponse(
+    val id: String,
+    @SerialName("user_id") val userId: String,
+    val type: String,
+    @SerialName("started_at") val startedAt: String? = null,
+    @SerialName("ended_at") val endedAt: String? = null,
+    @SerialName("distance_m") val distanceM: Double? = null,
+    val status: String,
+    @SerialName("created_at") val createdAt: String,
+)
+
+@Serializable
+data class ActivityDetailResponse(
+    val id: String,
+    @SerialName("user_id") val userId: String,
+    val type: String,
+    @SerialName("started_at") val startedAt: String? = null,
+    @SerialName("ended_at") val endedAt: String? = null,
+    @SerialName("distance_m") val distanceM: Double? = null,
+    val status: String,
+    @SerialName("created_at") val createdAt: String,
+    @SerialName("zone_id") val zoneId: String? = null,
+    @SerialName("area_m2") val areaM2: Double? = null,
+)

app/src/main/java/com/geozoner/app/data/remote/dto/AuthDto.kt

@@ -0,0 +1,29 @@
+package com.geozoner.app.data.remote.dto
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class RegisterRequest(
+    val username: String,
+    val email: String,
+    val password: String,
+)
+
+@Serializable
+data class LoginRequest(
+    val username: String,
+    val password: String,
+)
+
+@Serializable
+data class RefreshRequest(
+    @SerialName("refresh_token") val refreshToken: String,
+)
+
+@Serializable
+data class TokenResponse(
+    @SerialName("access_token") val accessToken: String,
+    @SerialName("refresh_token") val refreshToken: String,
+    @SerialName("token_type") val tokenType: String,
+)

app/src/main/java/com/geozoner/app/data/remote/dto/FriendDto.kt

@@ -0,0 +1,8 @@
+package com.geozoner.app.data.remote.dto
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class MessageResponse(
+    val detail: String,
+)

app/src/main/java/com/geozoner/app/data/remote/dto/LeaderboardDto.kt

@@ -0,0 +1,15 @@
+package com.geozoner.app.data.remote.dto
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class LeaderboardEntryResponse(
+    @SerialName("user_id") val userId: String,
+    val username: String,
+    @SerialName("avatar_url") val avatarUrl: String? = null,
+    @SerialName("total_pts") val totalPts: Int,
+    @SerialName("total_area_m2") val totalAreaM2: Double,
+    @SerialName("zone_count") val zoneCount: Int,
+    val rank: Int,
+)

app/src/main/java/com/geozoner/app/data/remote/dto/UserDto.kt

@@ -0,0 +1,31 @@
+package com.geozoner.app.data.remote.dto
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class UserResponse(
+    val id: String,
+    val username: String,
+    val email: String,
+    @SerialName("avatar_url") val avatarUrl: String? = null,
+    @SerialName("created_at") val createdAt: String,
+)
+
+@Serializable
+data class UserUpdateRequest(
+    val username: String? = null,
+    @SerialName("avatar_url") val avatarUrl: String? = null,
+    @SerialName("fcm_token") val fcmToken: String? = null,
+)
+
+@Serializable
+data class UserStatsResponse(
+    val id: String,
+    val username: String,
+    @SerialName("avatar_url") val avatarUrl: String? = null,
+    @SerialName("total_area_m2") val totalAreaM2: Double,
+    @SerialName("total_points") val totalPoints: Int,
+    @SerialName("zone_count") val zoneCount: Int,
+    @SerialName("activity_count") val activityCount: Int,
+)

app/src/main/java/com/geozoner/app/data/remote/dto/ZoneDto.kt

@@ -0,0 +1,27 @@
+package com.geozoner.app.data.remote.dto
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.JsonObject
+
+@Serializable
+data class ZoneBriefResponse(
+    val id: String,
+    @SerialName("owner_id") val ownerId: String,
+    @SerialName("polygon_geojson") val polygonGeojson: JsonObject,
+    @SerialName("area_m2") val areaM2: Double,
+    @SerialName("defense_level") val defenseLevel: Int,
+)
+
+@Serializable
+data class ZoneDetailResponse(
+    val id: String,
+    @SerialName("owner_id") val ownerId: String,
+    @SerialName("activity_id") val activityId: String,
+    @SerialName("polygon_geojson") val polygonGeojson: JsonObject,
+    @SerialName("area_m2") val areaM2: Double,
+    @SerialName("defense_level") val defenseLevel: Int,
+    @SerialName("defense_runs") val defenseRuns: Int,
+    @SerialName("created_at") val createdAt: String,
+    @SerialName("last_reinforced_at") val lastReinforcedAt: String? = null,
+)

app/src/main/java/com/geozoner/app/di/DatabaseModule.kt

@@ -0,0 +1,38 @@
+package com.geozoner.app.di
+
+import android.content.Context
+import androidx.room.Room
+import com.geozoner.app.data.local.dao.CachedZoneDao
+import com.geozoner.app.data.local.dao.PendingActivityDao
+import com.geozoner.app.data.local.db.GeoZonerDatabase
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.android.qualifiers.ApplicationContext
+import dagger.hilt.components.SingletonComponent
+import javax.inject.Singleton
+
+@Module
+@InstallIn(SingletonComponent::class)
+object DatabaseModule {
+
+    @Provides
+    @Singleton
+    fun provideDatabase(@ApplicationContext context: Context): GeoZonerDatabase {
+        return Room.databaseBuilder(
+            context,
+            GeoZonerDatabase::class.java,
+            "geozoner.db",
+        )
+            .fallbackToDestructiveMigration()
+            .build()
+    }
+
+    @Provides
+    fun providePendingActivityDao(db: GeoZonerDatabase): PendingActivityDao =
+        db.pendingActivityDao()
+
+    @Provides
+    fun provideCachedZoneDao(db: GeoZonerDatabase): CachedZoneDao =
+        db.cachedZoneDao()
+}

app/src/main/java/com/geozoner/app/di/NetworkModule.kt

@@ -0,0 +1,101 @@
+package com.geozoner.app.di
+
+import com.geozoner.app.BuildConfig
+import com.geozoner.app.data.remote.AuthInterceptor
+import com.geozoner.app.data.remote.TokenAuthenticator
+import com.geozoner.app.data.remote.api.ActivityApi
+import com.geozoner.app.data.remote.api.AuthApi
+import com.geozoner.app.data.remote.api.FriendApi
+import com.geozoner.app.data.remote.api.LeaderboardApi
+import com.geozoner.app.data.remote.api.UserApi
+import com.geozoner.app.data.remote.api.ZoneApi
+import com.jakewharton.retrofit2.converter.kotlinx.serialization.asConverterFactory
+import dagger.Module
+import dagger.Provides
+import dagger.hilt.InstallIn
+import dagger.hilt.components.SingletonComponent
+import kotlinx.serialization.json.Json
+import okhttp3.MediaType.Companion.toMediaType
+import okhttp3.OkHttpClient
+import okhttp3.logging.HttpLoggingInterceptor
+import retrofit2.Retrofit
+import java.util.concurrent.TimeUnit
+import javax.inject.Singleton
+
+@Module
+@InstallIn(SingletonComponent::class)
+object NetworkModule {
+
+    @Provides
+    @Singleton
+    fun provideJson(): Json = Json {
+        ignoreUnknownKeys = true
+        coerceInputValues = true
+        encodeDefaults = true
+    }
+
+    @Provides
+    @Singleton
+    fun provideOkHttpClient(
+        authInterceptor: AuthInterceptor,
+        tokenAuthenticator: TokenAuthenticator,
+    ): OkHttpClient {
+        val builder = OkHttpClient.Builder()
+            .addInterceptor(authInterceptor)
+            .authenticator(tokenAuthenticator)
+            .connectTimeout(30, TimeUnit.SECONDS)
+            .readTimeout(30, TimeUnit.SECONDS)
+            .writeTimeout(60, TimeUnit.SECONDS)
+
+        if (BuildConfig.DEBUG) {
+            builder.addInterceptor(
+                HttpLoggingInterceptor().apply {
+                    level = HttpLoggingInterceptor.Level.BODY
+                }
+            )
+        }
+
+        return builder.build()
+    }
+
+    @Provides
+    @Singleton
+    fun provideRetrofit(okHttpClient: OkHttpClient, json: Json): Retrofit {
+        val contentType = "application/json".toMediaType()
+        return Retrofit.Builder()
+            .baseUrl(BuildConfig.BASE_URL.trimEnd('/') + "/")
+            .client(okHttpClient)
+            .addConverterFactory(json.asConverterFactory(contentType))
+            .build()
+    }
+
+    @Provides
+    @Singleton
+    fun provideAuthApi(retrofit: Retrofit): AuthApi =
+        retrofit.create(AuthApi::class.java)
+
+    @Provides
+    @Singleton
+    fun provideUserApi(retrofit: Retrofit): UserApi =
+        retrofit.create(UserApi::class.java)
+
+    @Provides
+    @Singleton
+    fun provideActivityApi(retrofit: Retrofit): ActivityApi =
+        retrofit.create(ActivityApi::class.java)
+
+    @Provides
+    @Singleton
+    fun provideZoneApi(retrofit: Retrofit): ZoneApi =
+        retrofit.create(ZoneApi::class.java)
+
+    @Provides
+    @Singleton
+    fun provideFriendApi(retrofit: Retrofit): FriendApi =
+        retrofit.create(FriendApi::class.java)
+
+    @Provides
+    @Singleton
+    fun provideLeaderboardApi(retrofit: Retrofit): LeaderboardApi =
+        retrofit.create(LeaderboardApi::class.java)
+}

app/src/main/java/com/geozoner/app/service/LocationTrackingService.kt

@@ -0,0 +1,66 @@
+package com.geozoner.app.service
+
+import android.app.Notification
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Intent
+import android.os.IBinder
+import androidx.core.app.NotificationCompat
+import com.geozoner.app.GeoZonerApp
+import com.geozoner.app.R
+import com.geozoner.app.ui.MainActivity
+import dagger.hilt.android.AndroidEntryPoint
+
+/**
+ * Foreground service for GPS tracking during activity recording.
+ * TODO: Implement FusedLocationProviderClient, GPS point collection,
+ * loop detection, and broadcasting location updates to UI.
+ */
+@AndroidEntryPoint
+class LocationTrackingService : Service() {
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        when (intent?.action) {
+            ACTION_START -> startTracking()
+            ACTION_STOP -> stopTracking()
+        }
+        return START_STICKY
+    }
+
+    private fun startTracking() {
+        val notification = createNotification()
+        startForeground(NOTIFICATION_ID, notification)
+        // TODO: Start GPS location updates via FusedLocationProviderClient
+    }
+
+    private fun stopTracking() {
+        // TODO: Stop GPS location updates, collect final track
+        stopForeground(STOP_FOREGROUND_REMOVE)
+        stopSelf()
+    }
+
+    private fun createNotification(): Notification {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            0,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_IMMUTABLE or PendingIntent.FLAG_UPDATE_CURRENT,
+        )
+
+        return NotificationCompat.Builder(this, GeoZonerApp.CHANNEL_TRACKING)
+            .setContentTitle(getString(R.string.tracking_notification_title))
+            .setContentText(getString(R.string.tracking_notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+    }
+
+    companion object {
+        const val ACTION_START = "ACTION_START_TRACKING"
+        const val ACTION_STOP = "ACTION_STOP_TRACKING"
+        private const val NOTIFICATION_ID = 1001
+    }
+}

app/src/main/java/com/geozoner/app/ui/MainActivity.kt

@@ -0,0 +1,92 @@
+package com.geozoner.app.ui
+
+import android.os.Bundle
+import androidx.activity.ComponentActivity
+import androidx.activity.compose.setContent
+import androidx.activity.enableEdgeToEdge
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Icon
+import androidx.compose.material3.NavigationBar
+import androidx.compose.material3.NavigationBarItem
+import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Modifier
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.navigation.NavDestination.Companion.hierarchy
+import androidx.navigation.compose.currentBackStackEntryAsState
+import androidx.navigation.compose.rememberNavController
+import com.geozoner.app.data.local.TokenStorage
+import com.geozoner.app.ui.navigation.BottomNavItem
+import com.geozoner.app.ui.navigation.NavGraph
+import com.geozoner.app.ui.navigation.Screen
+import com.geozoner.app.ui.theme.GeoZonerTheme
+import dagger.hilt.android.AndroidEntryPoint
+import javax.inject.Inject
+
+@AndroidEntryPoint
+class MainActivity : ComponentActivity() {
+
+    @Inject
+    lateinit var tokenStorage: TokenStorage
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        enableEdgeToEdge()
+        setContent {
+            GeoZonerTheme {
+                val isLoggedIn by tokenStorage.isLoggedIn.collectAsState(initial = false)
+                GeoZonerApp(isLoggedIn = isLoggedIn)
+            }
+        }
+    }
+}
+
+@Composable
+fun GeoZonerApp(isLoggedIn: Boolean) {
+    val navController = rememberNavController()
+    val startDestination = if (isLoggedIn) Screen.Map.route else Screen.Login.route
+
+    val navBackStackEntry by navController.currentBackStackEntryAsState()
+    val currentDestination = navBackStackEntry?.destination
+
+    // Show bottom nav only on main screens
+    val showBottomBar = currentDestination?.hierarchy?.any { dest ->
+        BottomNavItem.entries.any { it.screen.route == dest.route }
+    } == true
+
+    Scaffold(
+        bottomBar = {
+            if (showBottomBar) {
+                NavigationBar {
+                    BottomNavItem.entries.forEach { item ->
+                        val selected = currentDestination?.hierarchy?.any {
+                            it.route == item.screen.route
+                        } == true
+
+                        NavigationBarItem(
+                            icon = { Icon(item.icon, contentDescription = item.label) },
+                            label = { Text(item.label) },
+                            selected = selected,
+                            onClick = {
+                                navController.navigate(item.screen.route) {
+                                    popUpTo(Screen.Map.route) { saveState = true }
+                                    launchSingleTop = true
+                                    restoreState = true
+                                }
+                            },
+                        )
+                    }
+                }
+            }
+        },
+    ) { innerPadding ->
+        NavGraph(
+            navController = navController,
+            startDestination = startDestination,
+            modifier = Modifier.padding(innerPadding),
+        )
+    }
+}

app/src/main/java/com/geozoner/app/ui/activity/TrackActivityScreen.kt

@@ -0,0 +1,53 @@
+package com.geozoner.app.ui.activity
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Button
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+import com.geozoner.app.R
+
+/**
+ * Activity tracking screen — will show real-time GPS track on map,
+ * distance/time counters, and start/stop controls.
+ * TODO: GPS foreground service, live map polyline, loop detection.
+ */
+@Composable
+fun TrackActivityScreen(
+    onActivityFinished: () -> Unit,
+) {
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(24.dp),
+        verticalArrangement = Arrangement.Center,
+        horizontalAlignment = Alignment.CenterHorizontally,
+    ) {
+        Text(
+            text = "Track Activity",
+            style = MaterialTheme.typography.headlineMedium,
+        )
+
+        Spacer(modifier = Modifier.height(16.dp))
+
+        Text(
+            text = "GPS tracking will be implemented here.\nSelect activity type, start recording, see live route.",
+            style = MaterialTheme.typography.bodyLarge,
+        )
+
+        Spacer(modifier = Modifier.height(32.dp))
+
+        Button(onClick = onActivityFinished) {
+            Text(stringResource(R.string.start_activity))
+        }
+    }
+}

app/src/main/java/com/geozoner/app/ui/auth/AuthViewModel.kt

@@ -0,0 +1,77 @@
+package com.geozoner.app.ui.auth
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.geozoner.app.data.local.TokenStorage
+import com.geozoner.app.data.remote.api.AuthApi
+import com.geozoner.app.data.remote.api.UserApi
+import com.geozoner.app.data.remote.dto.LoginRequest
+import com.geozoner.app.data.remote.dto.RegisterRequest
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.launch
+import javax.inject.Inject
+
+data class AuthUiState(
+    val isLoading: Boolean = false,
+    val error: String? = null,
+    val isSuccess: Boolean = false,
+)
+
+@HiltViewModel
+class AuthViewModel @Inject constructor(
+    private val authApi: AuthApi,
+    private val userApi: UserApi,
+    private val tokenStorage: TokenStorage,
+) : ViewModel() {
+
+    private val _loginState = MutableStateFlow(AuthUiState())
+    val loginState: StateFlow<AuthUiState> = _loginState.asStateFlow()
+
+    private val _registerState = MutableStateFlow(AuthUiState())
+    val registerState: StateFlow<AuthUiState> = _registerState.asStateFlow()
+
+    fun login(username: String, password: String) {
+        viewModelScope.launch {
+            _loginState.value = AuthUiState(isLoading = true)
+            try {
+                val tokens = authApi.login(LoginRequest(username, password))
+                tokenStorage.saveTokens(tokens.accessToken, tokens.refreshToken)
+
+                // Fetch user info to store user ID
+                val user = userApi.getMe()
+                tokenStorage.saveUserId(user.id)
+
+                _loginState.value = AuthUiState(isSuccess = true)
+            } catch (e: Exception) {
+                _loginState.value = AuthUiState(
+                    error = e.message ?: "Login failed"
+                )
+            }
+        }
+    }
+
+    fun register(username: String, email: String, password: String) {
+        viewModelScope.launch {
+            _registerState.value = AuthUiState(isLoading = true)
+            try {
+                authApi.register(RegisterRequest(username, email, password))
+                _registerState.value = AuthUiState(isSuccess = true)
+            } catch (e: Exception) {
+                _registerState.value = AuthUiState(
+                    error = e.message ?: "Registration failed"
+                )
+            }
+        }
+    }
+
+    fun clearLoginError() {
+        _loginState.value = _loginState.value.copy(error = null)
+    }
+
+    fun clearRegisterError() {
+        _registerState.value = _registerState.value.copy(error = null)
+    }
+}

app/src/main/java/com/geozoner/app/ui/auth/LoginScreen.kt

@@ -0,0 +1,115 @@
+package com.geozoner.app.ui.auth
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.text.KeyboardOptions
+import androidx.compose.material3.Button
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.saveable.rememberSaveable
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.input.ImeAction
+import androidx.compose.ui.text.input.PasswordVisualTransformation
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+import com.geozoner.app.R
+
+@Composable
+fun LoginScreen(
+    onLoginSuccess: () -> Unit,
+    onNavigateToRegister: () -> Unit,
+    viewModel: AuthViewModel = hiltViewModel(),
+) {
+    val state by viewModel.loginState.collectAsState()
+    var username by rememberSaveable { mutableStateOf("") }
+    var password by rememberSaveable { mutableStateOf("") }
+
+    LaunchedEffect(state.isSuccess) {
+        if (state.isSuccess) onLoginSuccess()
+    }
+
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(24.dp),
+        verticalArrangement = Arrangement.Center,
+        horizontalAlignment = Alignment.CenterHorizontally,
+    ) {
+        Text(
+            text = stringResource(R.string.login_title),
+            style = MaterialTheme.typography.headlineLarge,
+        )
+
+        Spacer(modifier = Modifier.height(32.dp))
+
+        OutlinedTextField(
+            value = username,
+            onValueChange = { username = it },
+            label = { Text(stringResource(R.string.username_hint)) },
+            singleLine = true,
+            keyboardOptions = KeyboardOptions(imeAction = ImeAction.Next),
+            modifier = Modifier.fillMaxWidth(),
+        )
+
+        Spacer(modifier = Modifier.height(12.dp))
+
+        OutlinedTextField(
+            value = password,
+            onValueChange = { password = it },
+            label = { Text(stringResource(R.string.password_hint)) },
+            singleLine = true,
+            visualTransformation = PasswordVisualTransformation(),
+            keyboardOptions = KeyboardOptions(imeAction = ImeAction.Done),
+            modifier = Modifier.fillMaxWidth(),
+        )
+
+        if (state.error != null) {
+            Spacer(modifier = Modifier.height(8.dp))
+            Text(
+                text = state.error!!,
+                color = MaterialTheme.colorScheme.error,
+                style = MaterialTheme.typography.bodySmall,
+            )
+        }
+
+        Spacer(modifier = Modifier.height(24.dp))
+
+        Button(
+            onClick = { viewModel.login(username.trim(), password) },
+            enabled = username.isNotBlank() && password.isNotBlank() && !state.isLoading,
+            modifier = Modifier.fillMaxWidth(),
+        ) {
+            if (state.isLoading) {
+                CircularProgressIndicator(
+                    modifier = Modifier.height(20.dp),
+                    color = MaterialTheme.colorScheme.onPrimary,
+                    strokeWidth = 2.dp,
+                )
+            } else {
+                Text(stringResource(R.string.login_button))
+            }
+        }
+
+        Spacer(modifier = Modifier.height(12.dp))
+
+        TextButton(onClick = onNavigateToRegister) {
+            Text(stringResource(R.string.switch_to_register))
+        }
+    }
+}

app/src/main/java/com/geozoner/app/ui/auth/RegisterScreen.kt

@@ -0,0 +1,127 @@
+package com.geozoner.app.ui.auth
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.text.KeyboardOptions
+import androidx.compose.material3.Button
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedTextField
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.saveable.rememberSaveable
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.input.ImeAction
+import androidx.compose.ui.text.input.PasswordVisualTransformation
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+import com.geozoner.app.R
+
+@Composable
+fun RegisterScreen(
+    onRegisterSuccess: () -> Unit,
+    onNavigateToLogin: () -> Unit,
+    viewModel: AuthViewModel = hiltViewModel(),
+) {
+    val state by viewModel.registerState.collectAsState()
+    var username by rememberSaveable { mutableStateOf("") }
+    var email by rememberSaveable { mutableStateOf("") }
+    var password by rememberSaveable { mutableStateOf("") }
+
+    LaunchedEffect(state.isSuccess) {
+        if (state.isSuccess) onRegisterSuccess()
+    }
+
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(24.dp),
+        verticalArrangement = Arrangement.Center,
+        horizontalAlignment = Alignment.CenterHorizontally,
+    ) {
+        Text(
+            text = stringResource(R.string.register_title),
+            style = MaterialTheme.typography.headlineLarge,
+        )
+
+        Spacer(modifier = Modifier.height(32.dp))
+
+        OutlinedTextField(
+            value = username,
+            onValueChange = { username = it },
+            label = { Text(stringResource(R.string.username_hint)) },
+            singleLine = true,
+            keyboardOptions = KeyboardOptions(imeAction = ImeAction.Next),
+            modifier = Modifier.fillMaxWidth(),
+        )
+
+        Spacer(modifier = Modifier.height(12.dp))
+
+        OutlinedTextField(
+            value = email,
+            onValueChange = { email = it },
+            label = { Text(stringResource(R.string.email_hint)) },
+            singleLine = true,
+            keyboardOptions = KeyboardOptions(imeAction = ImeAction.Next),
+            modifier = Modifier.fillMaxWidth(),
+        )
+
+        Spacer(modifier = Modifier.height(12.dp))
+
+        OutlinedTextField(
+            value = password,
+            onValueChange = { password = it },
+            label = { Text(stringResource(R.string.password_hint)) },
+            singleLine = true,
+            visualTransformation = PasswordVisualTransformation(),
+            keyboardOptions = KeyboardOptions(imeAction = ImeAction.Done),
+            modifier = Modifier.fillMaxWidth(),
+        )
+
+        if (state.error != null) {
+            Spacer(modifier = Modifier.height(8.dp))
+            Text(
+                text = state.error!!,
+                color = MaterialTheme.colorScheme.error,
+                style = MaterialTheme.typography.bodySmall,
+            )
+        }
+
+        Spacer(modifier = Modifier.height(24.dp))
+
+        Button(
+            onClick = { viewModel.register(username.trim(), email.trim(), password) },
+            enabled = username.isNotBlank() && email.isNotBlank() && password.isNotBlank() && !state.isLoading,
+            modifier = Modifier.fillMaxWidth(),
+        ) {
+            if (state.isLoading) {
+                CircularProgressIndicator(
+                    modifier = Modifier.height(20.dp),
+                    color = MaterialTheme.colorScheme.onPrimary,
+                    strokeWidth = 2.dp,
+                )
+            } else {
+                Text(stringResource(R.string.register_button))
+            }
+        }
+
+        Spacer(modifier = Modifier.height(12.dp))
+
+        TextButton(onClick = onNavigateToLogin) {
+            Text(stringResource(R.string.switch_to_login))
+        }
+    }
+}

app/src/main/java/com/geozoner/app/ui/friends/FriendsScreen.kt

@@ -0,0 +1,52 @@
+package com.geozoner.app.ui.friends
+
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+import com.geozoner.app.R
+
+/**
+ * Friends screen — list friends, add by username, remove.
+ * TODO: Fetch from GET /friends, POST /friends, DELETE /friends/{id}.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun FriendsScreen(
+    onNavigateBack: () -> Unit,
+) {
+    Column(modifier = Modifier.fillMaxSize()) {
+        TopAppBar(
+            title = { Text(stringResource(R.string.friends_title)) },
+            navigationIcon = {
+                IconButton(onClick = onNavigateBack) {
+                    Icon(Icons.AutoMirrored.Filled.ArrowBack, contentDescription = "Back")
+                }
+            },
+        )
+
+        Column(
+            modifier = Modifier
+                .fillMaxSize()
+                .padding(24.dp),
+            horizontalAlignment = Alignment.CenterHorizontally,
+        ) {
+            Text(
+                text = "Friends list will appear here",
+                style = MaterialTheme.typography.bodyLarge,
+            )
+        }
+    }
+}

app/src/main/java/com/geozoner/app/ui/history/ActivityHistoryScreen.kt

@@ -0,0 +1,50 @@
+package com.geozoner.app.ui.history
+
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.dp
+
+/**
+ * Activity history screen — list past activities with stats.
+ * TODO: Fetch from GET /activities, show distance/duration/zone area.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun ActivityHistoryScreen(
+    onNavigateBack: () -> Unit,
+) {
+    Column(modifier = Modifier.fillMaxSize()) {
+        TopAppBar(
+            title = { Text("Activity History") },
+            navigationIcon = {
+                IconButton(onClick = onNavigateBack) {
+                    Icon(Icons.AutoMirrored.Filled.ArrowBack, contentDescription = "Back")
+                }
+            },
+        )
+
+        Column(
+            modifier = Modifier
+                .fillMaxSize()
+                .padding(24.dp),
+            horizontalAlignment = Alignment.CenterHorizontally,
+        ) {
+            Text(
+                text = "Activity history will appear here",
+                style = MaterialTheme.typography.bodyLarge,
+            )
+        }
+    }
+}

app/src/main/java/com/geozoner/app/ui/leaderboard/LeaderboardScreen.kt

@@ -0,0 +1,46 @@
+package com.geozoner.app.ui.leaderboard
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+import com.geozoner.app.R
+
+/**
+ * Leaderboard screen — shows friend ranking by total points.
+ * TODO: Fetch from GET /leaderboard, display ranked list with stats.
+ */
+@Composable
+fun LeaderboardScreen(
+    onNavigateToFriends: () -> Unit,
+) {
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(24.dp),
+        verticalArrangement = Arrangement.Center,
+        horizontalAlignment = Alignment.CenterHorizontally,
+    ) {
+        Text(
+            text = stringResource(R.string.leaderboard_title),
+            style = MaterialTheme.typography.headlineMedium,
+        )
+
+        Text(
+            text = "Friend leaderboard will appear here",
+            style = MaterialTheme.typography.bodyLarge,
+        )
+
+        TextButton(onClick = onNavigateToFriends) {
+            Text(stringResource(R.string.add_friend))
+        }
+    }
+}

app/src/main/java/com/geozoner/app/ui/map/MapScreen.kt

@@ -0,0 +1,26 @@
+package com.geozoner.app.ui.map
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+
+/**
+ * Map screen — will display Mapbox map with zone polygons.
+ * TODO: Integrate Mapbox SDK, render own + friend zones, live GPS track.
+ */
+@Composable
+fun MapScreen() {
+    Box(
+        modifier = Modifier.fillMaxSize(),
+        contentAlignment = Alignment.Center,
+    ) {
+        Text(
+            text = "Map Screen\n(Mapbox integration pending)",
+            style = MaterialTheme.typography.headlineMedium,
+        )
+    }
+}

app/src/main/java/com/geozoner/app/ui/navigation/NavGraph.kt

@@ -0,0 +1,106 @@
+package com.geozoner.app.ui.navigation
+
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.navigation.NavHostController
+import androidx.navigation.compose.NavHost
+import androidx.navigation.compose.composable
+import com.geozoner.app.ui.auth.LoginScreen
+import com.geozoner.app.ui.auth.RegisterScreen
+import com.geozoner.app.ui.map.MapScreen
+import com.geozoner.app.ui.activity.TrackActivityScreen
+import com.geozoner.app.ui.leaderboard.LeaderboardScreen
+import com.geozoner.app.ui.profile.ProfileScreen
+import com.geozoner.app.ui.friends.FriendsScreen
+import com.geozoner.app.ui.history.ActivityHistoryScreen
+
+@Composable
+fun NavGraph(
+    navController: NavHostController,
+    startDestination: String,
+    modifier: Modifier = Modifier,
+) {
+    NavHost(
+        navController = navController,
+        startDestination = startDestination,
+        modifier = modifier,
+    ) {
+        // Auth flow
+        composable(Screen.Login.route) {
+            LoginScreen(
+                onLoginSuccess = {
+                    navController.navigate(Screen.Map.route) {
+                        popUpTo(Screen.Login.route) { inclusive = true }
+                    }
+                },
+                onNavigateToRegister = {
+                    navController.navigate(Screen.Register.route)
+                },
+            )
+        }
+
+        composable(Screen.Register.route) {
+            RegisterScreen(
+                onRegisterSuccess = {
+                    navController.navigate(Screen.Login.route) {
+                        popUpTo(Screen.Register.route) { inclusive = true }
+                    }
+                },
+                onNavigateToLogin = {
+                    navController.popBackStack()
+                },
+            )
+        }
+
+        // Main flow
+        composable(Screen.Map.route) {
+            MapScreen()
+        }
+
+        composable(Screen.TrackActivity.route) {
+            TrackActivityScreen(
+                onActivityFinished = {
+                    navController.navigate(Screen.Map.route) {
+                        popUpTo(Screen.Map.route) { inclusive = true }
+                    }
+                },
+            )
+        }
+
+        composable(Screen.Leaderboard.route) {
+            LeaderboardScreen(
+                onNavigateToFriends = {
+                    navController.navigate(Screen.Friends.route)
+                },
+            )
+        }
+
+        composable(Screen.Profile.route) {
+            ProfileScreen(
+                onLogout = {
+                    navController.navigate(Screen.Login.route) {
+                        popUpTo(0) { inclusive = true }
+                    }
+                },
+                onNavigateToHistory = {
+                    navController.navigate(Screen.ActivityHistory.route)
+                },
+                onNavigateToFriends = {
+                    navController.navigate(Screen.Friends.route)
+                },
+            )
+        }
+
+        composable(Screen.Friends.route) {
+            FriendsScreen(
+                onNavigateBack = { navController.popBackStack() },
+            )
+        }
+
+        composable(Screen.ActivityHistory.route) {
+            ActivityHistoryScreen(
+                onNavigateBack = { navController.popBackStack() },
+            )
+        }
+    }
+}

app/src/main/java/com/geozoner/app/ui/navigation/Screen.kt

@@ -0,0 +1,36 @@
+package com.geozoner.app.ui.navigation
+
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.EmojiEvents
+import androidx.compose.material.icons.filled.Map
+import androidx.compose.material.icons.filled.Person
+import androidx.compose.material.icons.automirrored.filled.DirectionsRun
+import androidx.compose.ui.graphics.vector.ImageVector
+
+sealed class Screen(val route: String) {
+    // Auth
+    data object Login : Screen("login")
+    data object Register : Screen("register")
+
+    // Main
+    data object Map : Screen("map")
+    data object TrackActivity : Screen("track_activity")
+    data object Leaderboard : Screen("leaderboard")
+    data object Profile : Screen("profile")
+    data object Friends : Screen("friends")
+    data object ActivityHistory : Screen("activity_history")
+    data object ActivityDetail : Screen("activity_detail/{activityId}") {
+        fun createRoute(activityId: String) = "activity_detail/$activityId"
+    }
+}
+
+enum class BottomNavItem(
+    val screen: Screen,
+    val icon: ImageVector,
+    val label: String,
+) {
+    Map(Screen.Map, Icons.Default.Map, "Map"),
+    Activity(Screen.TrackActivity, Icons.AutoMirrored.Filled.DirectionsRun, "Activity"),
+    Leaderboard(Screen.Leaderboard, Icons.Default.EmojiEvents, "Leaderboard"),
+    Profile(Screen.Profile, Icons.Default.Person, "Profile"),
+}

app/src/main/java/com/geozoner/app/ui/profile/ProfileScreen.kt

@@ -0,0 +1,68 @@
+package com.geozoner.app.ui.profile
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Button
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedButton
+import androidx.compose.material3.Text
+import androidx.compose.material3.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.unit.dp
+import com.geozoner.app.R
+
+/**
+ * Profile screen — shows user stats, avatar, links to friends and history.
+ * TODO: Fetch from GET /users/me and GET /users/{id}/stats.
+ */
+@Composable
+fun ProfileScreen(
+    onLogout: () -> Unit,
+    onNavigateToHistory: () -> Unit,
+    onNavigateToFriends: () -> Unit,
+) {
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(24.dp),
+        verticalArrangement = Arrangement.Center,
+        horizontalAlignment = Alignment.CenterHorizontally,
+    ) {
+        Text(
+            text = stringResource(R.string.profile_title),
+            style = MaterialTheme.typography.headlineMedium,
+        )
+
+        Spacer(modifier = Modifier.height(16.dp))
+
+        Text(
+            text = "User stats will appear here",
+            style = MaterialTheme.typography.bodyLarge,
+        )
+
+        Spacer(modifier = Modifier.height(24.dp))
+
+        OutlinedButton(onClick = onNavigateToHistory) {
+            Text("Activity History")
+        }
+
+        Spacer(modifier = Modifier.height(8.dp))
+
+        OutlinedButton(onClick = onNavigateToFriends) {
+            Text(stringResource(R.string.friends_title))
+        }
+
+        Spacer(modifier = Modifier.height(24.dp))
+
+        Button(onClick = onLogout) {
+            Text(stringResource(R.string.logout))
+        }
+    }
+}

app/src/main/java/com/geozoner/app/ui/theme/Color.kt

@@ -0,0 +1,56 @@
+package com.geozoner.app.ui.theme
+
+import androidx.compose.ui.graphics.Color
+
+// Primary — Green (territory / nature)
+val Green10 = Color(0xFF0A3A0A)
+val Green20 = Color(0xFF1B5E20)
+val Green30 = Color(0xFF2E7D32)
+val Green40 = Color(0xFF388E3C)
+val Green80 = Color(0xFFA5D6A7)
+val Green90 = Color(0xFFC8E6C9)
+
+// Secondary — Cyan (water / exploration)
+val Cyan10 = Color(0xFF003F47)
+val Cyan20 = Color(0xFF006064)
+val Cyan30 = Color(0xFF00838F)
+val Cyan40 = Color(0xFF00ACC1)
+val Cyan80 = Color(0xFF80DEEA)
+val Cyan90 = Color(0xFFB2EBF2)
+
+// Tertiary — Amber (achievements / energy)
+val Amber10 = Color(0xFF3E2700)
+val Amber20 = Color(0xFF5D3F00)
+val Amber30 = Color(0xFF7C5800)
+val Amber40 = Color(0xFFFFA000)
+val Amber80 = Color(0xFFFFE082)
+val Amber90 = Color(0xFFFFF8E1)
+
+// Error
+val Red10 = Color(0xFF410002)
+val Red20 = Color(0xFF690005)
+val Red30 = Color(0xFF93000A)
+val Red40 = Color(0xFFB3261E)
+val Red80 = Color(0xFFF2B8B5)
+val Red90 = Color(0xFFF9DEDC)
+
+// Neutral
+val Grey10 = Color(0xFF1C1B1F)
+val Grey20 = Color(0xFF313033)
+val Grey90 = Color(0xFFE6E1E5)
+val Grey95 = Color(0xFFF4EFF4)
+val Grey99 = Color(0xFFFFFBFE)
+
+// Zone colors — one per player on the map
+val ZoneColors = listOf(
+    Color(0xFF4CAF50), // Green
+    Color(0xFF2196F3), // Blue
+    Color(0xFFFF9800), // Orange
+    Color(0xFF9C27B0), // Purple
+    Color(0xFFF44336), // Red
+    Color(0xFF009688), // Teal
+    Color(0xFFFF5722), // Deep Orange
+    Color(0xFF3F51B5), // Indigo
+    Color(0xFFCDDC39), // Lime
+    Color(0xFFE91E63), // Pink
+)

app/src/main/java/com/geozoner/app/ui/theme/Theme.kt

@@ -0,0 +1,83 @@
+package com.geozoner.app.ui.theme
+
+import android.app.Activity
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.darkColorScheme
+import androidx.compose.material3.lightColorScheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.SideEffect
+import androidx.compose.ui.platform.LocalView
+import androidx.core.view.WindowCompat
+
+private val LightColorScheme = lightColorScheme(
+    primary = Green40,
+    onPrimary = Grey99,
+    primaryContainer = Green90,
+    onPrimaryContainer = Green10,
+    secondary = Cyan40,
+    onSecondary = Grey99,
+    secondaryContainer = Cyan90,
+    onSecondaryContainer = Cyan10,
+    tertiary = Amber40,
+    onTertiary = Grey99,
+    tertiaryContainer = Amber90,
+    onTertiaryContainer = Amber10,
+    error = Red40,
+    onError = Grey99,
+    errorContainer = Red90,
+    onErrorContainer = Red10,
+    background = Grey99,
+    onBackground = Grey10,
+    surface = Grey99,
+    onSurface = Grey10,
+    surfaceVariant = Grey95,
+    onSurfaceVariant = Grey20,
+)
+
+private val DarkColorScheme = darkColorScheme(
+    primary = Green80,
+    onPrimary = Green20,
+    primaryContainer = Green30,
+    onPrimaryContainer = Green90,
+    secondary = Cyan80,
+    onSecondary = Cyan20,
+    secondaryContainer = Cyan30,
+    onSecondaryContainer = Cyan90,
+    tertiary = Amber80,
+    onTertiary = Amber20,
+    tertiaryContainer = Amber30,
+    onTertiaryContainer = Amber90,
+    error = Red80,
+    onError = Red20,
+    errorContainer = Red30,
+    onErrorContainer = Red90,
+    background = Grey10,
+    onBackground = Grey90,
+    surface = Grey10,
+    onSurface = Grey90,
+    surfaceVariant = Grey20,
+    onSurfaceVariant = Grey90,
+)
+
+@Composable
+fun GeoZonerTheme(
+    darkTheme: Boolean = isSystemInDarkTheme(),
+    content: @Composable () -> Unit,
+) {
+    val colorScheme = if (darkTheme) DarkColorScheme else LightColorScheme
+
+    val view = LocalView.current
+    if (!view.isInEditMode) {
+        SideEffect {
+            val window = (view.context as Activity).window
+            WindowCompat.getInsetsController(window, view).isAppearanceLightStatusBars = !darkTheme
+        }
+    }
+
+    MaterialTheme(
+        colorScheme = colorScheme,
+        typography = Typography,
+        content = content,
+    )
+}

app/src/main/java/com/geozoner/app/ui/theme/Type.kt

@@ -0,0 +1,70 @@
+package com.geozoner.app.ui.theme
+
+import androidx.compose.material3.Typography
+import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.sp
+
+val Typography = Typography(
+    displayLarge = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Normal,
+        fontSize = 57.sp,
+        lineHeight = 64.sp,
+        letterSpacing = (-0.25).sp,
+    ),
+    headlineLarge = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Bold,
+        fontSize = 32.sp,
+        lineHeight = 40.sp,
+    ),
+    headlineMedium = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Bold,
+        fontSize = 28.sp,
+        lineHeight = 36.sp,
+    ),
+    titleLarge = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.SemiBold,
+        fontSize = 22.sp,
+        lineHeight = 28.sp,
+    ),
+    titleMedium = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Medium,
+        fontSize = 16.sp,
+        lineHeight = 24.sp,
+        letterSpacing = 0.15.sp,
+    ),
+    bodyLarge = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Normal,
+        fontSize = 16.sp,
+        lineHeight = 24.sp,
+        letterSpacing = 0.5.sp,
+    ),
+    bodyMedium = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Normal,
+        fontSize = 14.sp,
+        lineHeight = 20.sp,
+        letterSpacing = 0.25.sp,
+    ),
+    labelLarge = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Medium,
+        fontSize = 14.sp,
+        lineHeight = 20.sp,
+        letterSpacing = 0.1.sp,
+    ),
+    labelSmall = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Medium,
+        fontSize = 11.sp,
+        lineHeight = 16.sp,
+        letterSpacing = 0.5.sp,
+    ),
+)

app/src/main/java/com/geozoner/app/util/Constants.kt

@@ -0,0 +1,27 @@
+package com.geozoner.app.util
+
+/**
+ * App-wide constants derived from the GeoZoner PRD.
+ */
+object Constants {
+    // GPS settings
+    const val GPS_INTERVAL_FOREGROUND_MS = 3_000L
+    const val GPS_INTERVAL_BACKGROUND_MS = 5_000L
+    const val MAX_HDOP = 4.0
+    const val MAX_GPS_ACCURACY_M = 20f
+
+    // Zone rules
+    const val LOOP_CLOSURE_RADIUS_M = 50.0
+    const val MIN_ZONE_AREA_M2 = 5_000.0
+
+    // Anti-cheat
+    const val MAX_RUN_SPEED_KMH = 60.0
+
+    // Scoring
+    const val POINTS_PER_1000_M2 = 1
+    const val CAPTURE_BONUS_PTS = 50
+    const val ACTIVITY_BONUS_PTS_PER_KM = 10
+    const val DEFENSE_BONUS_MULTIPLIER = 0.20
+    const val STREAK_MULTIPLIER_PER_DAY = 0.05
+    const val MAX_STREAK_MULTIPLIER = 2.0
+}

app/src/main/res/values/colors.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="geozoner_primary">#FF2E7D32</color>
+    <color name="geozoner_primary_dark">#FF1B5E20</color>
+    <color name="geozoner_secondary">#FF00ACC1</color>
+    <color name="geozoner_background">#FFFAFAFA</color>
+</resources>

app/src/main/res/values/strings.xml

@@ -0,0 +1,52 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="app_name">GeoZoner</string>
+
+    <!-- Navigation -->
+    <string name="nav_map">Map</string>
+    <string name="nav_activity">Activity</string>
+    <string name="nav_leaderboard">Leaderboard</string>
+    <string name="nav_profile">Profile</string>
+
+    <!-- Auth -->
+    <string name="login_title">Welcome back</string>
+    <string name="register_title">Create account</string>
+    <string name="username_hint">Username</string>
+    <string name="email_hint">Email</string>
+    <string name="password_hint">Password</string>
+    <string name="login_button">Log in</string>
+    <string name="register_button">Sign up</string>
+    <string name="switch_to_register">Don\'t have an account? Sign up</string>
+    <string name="switch_to_login">Already have an account? Log in</string>
+
+    <!-- Activity Tracking -->
+    <string name="start_activity">Start Activity</string>
+    <string name="finish_activity">Finish</string>
+    <string name="loop_detected">Loop detected ✓</string>
+    <string name="select_activity_type">Select activity type</string>
+    <string name="activity_run">Run</string>
+    <string name="activity_cycle">Cycle</string>
+    <string name="activity_walk">Walk</string>
+    <string name="activity_hike">Hike</string>
+
+    <!-- Tracking notification -->
+    <string name="tracking_notification_channel">Activity Tracking</string>
+    <string name="tracking_notification_title">Recording activity</string>
+    <string name="tracking_notification_text">GeoZoner is tracking your route</string>
+
+    <!-- Friends -->
+    <string name="friends_title">Friends</string>
+    <string name="add_friend">Add friend</string>
+    <string name="add_friend_hint">Enter username</string>
+
+    <!-- Leaderboard -->
+    <string name="leaderboard_title">Leaderboard</string>
+
+    <!-- Profile -->
+    <string name="profile_title">Profile</string>
+    <string name="total_area">Total Area</string>
+    <string name="total_points">Total Points</string>
+    <string name="zone_count">Zones</string>
+    <string name="activity_count">Activities</string>
+    <string name="logout">Log out</string>
+</resources>

app/src/main/res/values/themes.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <style name="Theme.GeoZoner" parent="android:Theme.Material.Light.NoActionBar">
+        <item name="android:statusBarColor">@android:color/transparent</item>
+        <item name="android:navigationBarColor">@android:color/transparent</item>
+    </style>
+</resources>

app/src/main/res/xml/backup_rules.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<full-backup-content>
+    <exclude domain="sharedpref" path="." />
+    <exclude domain="database" path="." />
+</full-backup-content>