diff --git a/.gitignore b/.gitignore
index 1109a75..890d16c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,12 +1,32 @@
-*.iml
+# Gradle
 .gradle/
-/local.properties
-/.idea/
+build/
+*/build/
+
+# Android Studio
+.idea/
+*.iml
+
+# Local config
+local.properties
+
+# Logs
+*.log
+
+# OS
 .DS_Store
-/build/
-/captures/
+
+# APK outputs
+*.apk
+
+# Keystore (VERY IMPORTANT)
+*.jks
+*.keystore
+
+# Secrets
+secrets.properties
+.env
+
+# NDK
 .externalNativeBuild/
 .cxx/
-app/build/
-
-local.properties
diff --git a/PROJECT_STATE.md b/PROJECT_STATE.md
index be3a009..6f5a1ca 100644
--- a/PROJECT_STATE.md
+++ b/PROJECT_STATE.md
@@ -1,50 +1,16 @@
-# PROJECT_STATE.md
-
-## Project
-- Name: follow-me
-- App label: otb-tcom
-- Version: v0.1.0
-- Build date: 2026-03-16
-- Platform: Android
-- Package: top.outsidethebox.followme
-- Minimum Android version: 6.0 (API 23)
-
-## Current scope
-Working Android client scaffold for GPS tracking into OTB Tracker.
-
-## Current implemented features
-- Foreground tracking service
-- HTTPS primary ingest endpoint
-- HTTP fallback ingest endpoint
-- Device-local default-to-HTTP after 3 consecutive HTTPS fallback events
-- X-API-Key token header
-- Minimal installer/settings screen
-- Save/start/stop controls
-- Reboot restart when tracking was already enabled
-- Location payload fields aligned to provided ingest contract
-
-## Not yet implemented
-- Backend onboarding flow for freeadmin/drone install paths
-- Token issuance / enrollment API
-- Local queueing for offline retry backlog
-- Battery optimization exemption helper UI
-- Geofence pill creation in app
-- Admin / drone role-aware UI behavior
-- Play Store packaging / signing / release pipeline
-- Linux and Windows tracker clients
-
-## Endpoint contract
-Primary:
-- https://otb-tracker.outsidethebox.top/api/gps-ingest
-
-Fallback:
-- http://otb-tracker.outsidethebox.top/api/gps-ingest
-
-Header:
-- X-API-Key: token
-
-Method:
-- POST
-
-## Source label
-- Default source string: otb-tcom
+# follow-me-android Project State
+
+## Current State
+- Existing working build confirmed
+- Used for live GPS tracking
+- Integrated with otb-tracker backend
+
+## Next Steps
+- Align with follow-me-v2 API
+- Add token-based authentication
+- Improve retry + offline queue
+- Add configurable tracking modes
+
+## Notes
+- Must remain lightweight for older devices
+- Stability > features
diff --git a/README.md b/README.md
index 18423bc..c92be53 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,31 @@
-# follow-me
+# follow-me-android
 
-android app for https://otb-tracker.outsidethebox.top tracking
\ No newline at end of file
+Android client for the OTB Follow-me GPS tracking platform.
+
+## Version
+v0.5.x (existing working build baseline)
+
+## Purpose
+- Sends GPS data to Follow-me backend
+- Supports low-power and legacy Android devices
+- Works with follow-me-v2 backend
+
+## Features (planned / current)
+- GPS tracking with configurable interval
+- Background operation
+- Retry + offline buffering
+- Device ID + network binding
+- API key / token authentication (future)
+
+## Backend
+- OTB Tracker / follow-me-v2 API
+- Endpoint: /api/gps-ingest
+
+## Notes
+- Designed to work on older Android devices (Android 6+)
+- No Google Play dependency required
+- APK distribution via services portal
+
+## Security
+- No secrets committed
+- Device tokens handled per install
diff --git a/app.bak.20260330-214820/build.gradle.kts b/app.bak.20260330-214820/build.gradle.kts
new file mode 100644
index 0000000..6cc823e
--- /dev/null
+++ b/app.bak.20260330-214820/build.gradle.kts
@@ -0,0 +1,61 @@
+plugins {
+    id("com.android.application")
+    id("org.jetbrains.kotlin.android")
+}
+
+android {
+    namespace = "top.outsidethebox.followme"
+    compileSdk = 34
+
+    defaultConfig {
+        applicationId = "top.outsidethebox.followme"
+        minSdk = 23
+        targetSdk = 34
+        versionCode = 4
+        versionName = "0.4.0"
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+        }
+        debug {
+            isMinifyEnabled = false
+        }
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+        isCoreLibraryDesugaringEnabled = true
+    }
+
+    kotlinOptions {
+        jvmTarget = "17"
+    }
+
+    buildFeatures {
+        viewBinding = true
+    }
+}
+
+dependencies {
+    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.1.5")
+
+    implementation("androidx.core:core-ktx:1.12.0")
+    implementation("androidx.appcompat:appcompat:1.7.0")
+    implementation("com.google.android.material:material:1.11.0")
+    implementation("androidx.activity:activity-ktx:1.8.2")
+    implementation("androidx.constraintlayout:constraintlayout:2.1.4")
+    implementation("androidx.lifecycle:lifecycle-service:2.7.0")
+    implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.7.0")
+    implementation("com.google.android.gms:play-services-location:21.2.0")
+    implementation("com.squareup.okhttp3:okhttp:4.12.0")
+    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3")
+}
diff --git a/app.bak.20260330-214820/proguard-rules.pro b/app.bak.20260330-214820/proguard-rules.pro
new file mode 100644
index 0000000..a1e5cc2
--- /dev/null
+++ b/app.bak.20260330-214820/proguard-rules.pro
@@ -0,0 +1 @@
+# No custom rules yet.
diff --git a/app.bak.20260330-214820/src/main/AndroidManifest.xml b/app.bak.20260330-214820/src/main/AndroidManifest.xml
new file mode 100644
index 0000000..eaba08c
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/AndroidManifest.xml
@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
+    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
+    <uses-permission android:name="android.permission.WAKE_LOCK" />
+    <uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="follow-me"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.FollowMe"
+        android:usesCleartextTraffic="true">
+
+        <activity
+            android:name=".ui.MainActivity"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+        <service
+            android:name=".service.TrackingService"
+            android:enabled="true"
+            android:exported="false"
+            android:foregroundServiceType="location" />
+
+        <receiver
+            android:name=".service.BootReceiver"
+            android:enabled="true"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.BOOT_COMPLETED" />
+                <action android:name="android.intent.action.MY_PACKAGE_REPLACED" />
+            </intent-filter>
+        </receiver>
+    </application>
+
+</manifest>
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/data/AppPrefs.kt b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/data/AppPrefs.kt
new file mode 100644
index 0000000..1b9dc72
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/data/AppPrefs.kt
@@ -0,0 +1,52 @@
+package top.outsidethebox.followme.data
+
+import android.content.Context
+import android.content.SharedPreferences
+
+class AppPrefs(context: Context) {
+    private val prefs: SharedPreferences = context.getSharedPreferences(PREF_NAME, Context.MODE_PRIVATE)
+
+    fun getToken(): String = prefs.getString(KEY_TOKEN, "") ?: ""
+    fun setToken(value: String) = prefs.edit().putString(KEY_TOKEN, value).apply()
+
+    fun getRole(): String = prefs.getString(KEY_ROLE, "drone") ?: "drone"
+    fun setRole(value: String) = prefs.edit().putString(KEY_ROLE, value).apply()
+
+    fun getNetworkNote(): String = prefs.getString(KEY_NETWORK_NOTE, "") ?: ""
+    fun setNetworkNote(value: String) = prefs.edit().putString(KEY_NETWORK_NOTE, value).apply()
+
+    fun getSource(): String = prefs.getString(KEY_SOURCE, DEFAULT_SOURCE) ?: DEFAULT_SOURCE
+    fun setSource(value: String) = prefs.edit().putString(KEY_SOURCE, value).apply()
+
+    fun isTrackingEnabled(): Boolean = prefs.getBoolean(KEY_TRACKING_ENABLED, false)
+    fun setTrackingEnabled(value: Boolean) = prefs.edit().putBoolean(KEY_TRACKING_ENABLED, value).apply()
+
+    fun getConsecutiveHttpsFallbacks(): Int = prefs.getInt(KEY_HTTPS_FALLBACKS, 0)
+    fun setConsecutiveHttpsFallbacks(value: Int) = prefs.edit().putInt(KEY_HTTPS_FALLBACKS, value).apply()
+
+    fun getPreferredTransport(): String = prefs.getString(KEY_PREFERRED_TRANSPORT, TRANSPORT_HTTPS) ?: TRANSPORT_HTTPS
+    fun setPreferredTransport(value: String) = prefs.edit().putString(KEY_PREFERRED_TRANSPORT, value).apply()
+
+    fun getLastUpload(): String = prefs.getString(KEY_LAST_UPLOAD, "never") ?: "never"
+    fun setLastUpload(value: String) = prefs.edit().putString(KEY_LAST_UPLOAD, value).apply()
+
+    fun resetHttpsFallbackCounter() = setConsecutiveHttpsFallbacks(0)
+
+    companion object {
+        private const val PREF_NAME = "follow_me_prefs"
+        private const val KEY_TOKEN = "token"
+        private const val KEY_ROLE = "role"
+        private const val KEY_NETWORK_NOTE = "network_note"
+        private const val KEY_SOURCE = "source"
+        private const val KEY_TRACKING_ENABLED = "tracking_enabled"
+        private const val KEY_HTTPS_FALLBACKS = "https_fallbacks"
+        private const val KEY_PREFERRED_TRANSPORT = "preferred_transport"
+        private const val KEY_LAST_UPLOAD = "last_upload"
+
+        const val TRANSPORT_HTTPS = "https"
+        const val TRANSPORT_HTTP = "http"
+        const val DEFAULT_SOURCE = "otb-tcom"
+        const val HTTPS_ENDPOINT = "https://otb-tracker.outsidethebox.top/api/gps-ingest"
+        const val HTTP_ENDPOINT = "http://otb-tracker.outsidethebox.top/api/gps-ingest"
+    }
+}
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt
new file mode 100644
index 0000000..b91dad8
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt
@@ -0,0 +1,27 @@
+package top.outsidethebox.followme.data
+
+import org.json.JSONObject
+
+data class GpsPayload(
+    val latitude: Double,
+    val longitude: Double,
+    val speedKmh: Double? = null,
+    val accuracyM: Float? = null,
+    val headingDeg: Float? = null,
+    val altitudeM: Double? = null,
+    val recordedAt: String? = null,
+    val source: String = AppPrefs.DEFAULT_SOURCE
+) {
+    fun toJson(): String {
+        val json = JSONObject()
+        json.put("latitude", latitude)
+        json.put("longitude", longitude)
+        speedKmh?.let { json.put("speed_kmh", it) }
+        accuracyM?.let { json.put("accuracy_m", it) }
+        headingDeg?.let { json.put("heading_deg", it) }
+        altitudeM?.let { json.put("altitude_m", it) }
+        recordedAt?.let { json.put("recorded_at", it) }
+        json.put("source", source)
+        return json.toString()
+    }
+}
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/data/IngestRepository.kt b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/data/IngestRepository.kt
new file mode 100644
index 0000000..d6e3b7e
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/data/IngestRepository.kt
@@ -0,0 +1,99 @@
+package top.outsidethebox.followme.data
+
+import android.content.Context
+import okhttp3.MediaType.Companion.toMediaType
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import okhttp3.RequestBody.Companion.toRequestBody
+import java.io.IOException
+import java.util.concurrent.TimeUnit
+
+data class IngestResult(
+    val success: Boolean,
+    val usedTransport: String,
+    val responseBody: String? = null,
+    val errorMessage: String? = null
+)
+
+class IngestRepository(context: Context) {
+    private val prefs = AppPrefs(context.applicationContext)
+    private val jsonType = "application/json; charset=utf-8".toMediaType()
+
+    private val client: OkHttpClient = OkHttpClient.Builder()
+        .connectTimeout(10, TimeUnit.SECONDS)
+        .readTimeout(15, TimeUnit.SECONDS)
+        .writeTimeout(15, TimeUnit.SECONDS)
+        .retryOnConnectionFailure(true)
+        .build()
+
+    fun send(payload: GpsPayload): IngestResult {
+        val token = prefs.getToken().trim()
+        if (token.isEmpty()) {
+            return IngestResult(false, prefs.getPreferredTransport(), errorMessage = "Missing device token")
+        }
+
+        val preferred = prefs.getPreferredTransport()
+        return if (preferred == AppPrefs.TRANSPORT_HTTP) {
+            sendHttpOnly(token, payload)
+        } else {
+            sendHttpsThenFallback(token, payload)
+        }
+    }
+
+    private fun sendHttpsThenFallback(token: String, payload: GpsPayload): IngestResult {
+        val httpsResult = post(AppPrefs.HTTPS_ENDPOINT, token, payload)
+        if (httpsResult.success) {
+            prefs.resetHttpsFallbackCounter()
+            prefs.setPreferredTransport(AppPrefs.TRANSPORT_HTTPS)
+            return httpsResult.copy(usedTransport = AppPrefs.TRANSPORT_HTTPS)
+        }
+
+        val httpResult = post(AppPrefs.HTTP_ENDPOINT, token, payload)
+        if (httpResult.success) {
+            val newCount = prefs.getConsecutiveHttpsFallbacks() + 1
+            prefs.setConsecutiveHttpsFallbacks(newCount)
+            if (newCount >= 3) {
+                prefs.setPreferredTransport(AppPrefs.TRANSPORT_HTTP)
+            }
+            return httpResult.copy(usedTransport = AppPrefs.TRANSPORT_HTTP)
+        }
+
+        return IngestResult(
+            success = false,
+            usedTransport = AppPrefs.TRANSPORT_HTTPS,
+            errorMessage = httpsResult.errorMessage ?: httpResult.errorMessage
+        )
+    }
+
+    private fun sendHttpOnly(token: String, payload: GpsPayload): IngestResult {
+        val result = post(AppPrefs.HTTP_ENDPOINT, token, payload)
+        return if (result.success) {
+            result.copy(usedTransport = AppPrefs.TRANSPORT_HTTP)
+        } else {
+            result
+        }
+    }
+
+    private fun post(url: String, token: String, payload: GpsPayload): IngestResult {
+        val body = payload.toJson().toRequestBody(jsonType)
+        val request = Request.Builder()
+            .url(url)
+            .post(body)
+            .header("X-API-Key", token)
+            .header("Content-Type", "application/json")
+            .build()
+
+        return try {
+            client.newCall(request).execute().use { response ->
+                val text = response.body?.string().orEmpty()
+                if (response.isSuccessful) {
+                    IngestResult(true, if (url.startsWith("https")) AppPrefs.TRANSPORT_HTTPS else AppPrefs.TRANSPORT_HTTP, text)
+                } else {
+                    IngestResult(false, if (url.startsWith("https")) AppPrefs.TRANSPORT_HTTPS else AppPrefs.TRANSPORT_HTTP, text, "HTTP ${response.code}")
+                }
+            }
+        } catch (e: IOException) {
+            IngestResult(false, if (url.startsWith("https")) AppPrefs.TRANSPORT_HTTPS else AppPrefs.TRANSPORT_HTTP, errorMessage = e.message)
+        }
+    }
+}
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/location/TrackingMode.kt b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/location/TrackingMode.kt
new file mode 100644
index 0000000..a9571c9
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/location/TrackingMode.kt
@@ -0,0 +1,6 @@
+package top.outsidethebox.followme.location
+
+enum class TrackingMode(val intervalMs: Long) {
+    MOVING(10_000L),
+    IDLE(300_000L)
+}
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/BootReceiver.kt b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/BootReceiver.kt
new file mode 100644
index 0000000..98d0a3f
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/BootReceiver.kt
@@ -0,0 +1,18 @@
+package top.outsidethebox.followme.service
+
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import top.outsidethebox.followme.data.AppPrefs
+
+class BootReceiver : BroadcastReceiver() {
+    override fun onReceive(context: Context, intent: Intent?) {
+        val action = intent?.action ?: return
+        if (action == Intent.ACTION_BOOT_COMPLETED || action == Intent.ACTION_MY_PACKAGE_REPLACED) {
+            val prefs = AppPrefs(context.applicationContext)
+            if (prefs.isTrackingEnabled()) {
+                TrackingService.start(context)
+            }
+        }
+    }
+}
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt
new file mode 100644
index 0000000..37c1c78
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt
@@ -0,0 +1,298 @@
+package top.outsidethebox.followme.service
+
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Build
+import android.os.Bundle
+import android.os.IBinder
+import android.util.Log
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.common.ConnectionResult
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationCallback: LocationCallback? = null
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(R.mipmap.ic_launcher)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+                android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION
+            } else {
+                0
+            }
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val playServicesOk =
+            GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(this) == ConnectionResult.SUCCESS
+
+        if (playServicesOk) {
+            try {
+                val request = LocationRequest.Builder(
+                    Priority.PRIORITY_HIGH_ACCURACY,
+                    15000L
+                )
+                    .setMinUpdateIntervalMillis(5000L)
+                    .setMinUpdateDistanceMeters(10f)
+                    .setWaitForAccurateLocation(false)
+                    .build()
+
+                locationCallback = object : LocationCallback() {
+                    override fun onLocationResult(result: LocationResult) {
+                        val location = result.lastLocation ?: return
+                        val nextMode = decideMode(location)
+                        if (nextMode != currentMode) {
+                            startLocationUpdates(nextMode)
+                            return
+                        }
+                        uploadLocation(location)
+                    }
+                }
+
+                fusedLocationClient.requestLocationUpdates(
+                    request,
+                    locationCallback!!,
+                    mainLooper
+                )
+
+                Log.d(TAG, "Using FusedLocationProviderClient")
+                return
+            } catch (e: Exception) {
+                Log.w(TAG, "Fused location failed, falling back to LocationManager", e)
+            }
+        } else {
+            Log.w(TAG, "Google Play Services unavailable, using LocationManager fallback")
+        }
+
+        startLegacyGpsFallback()
+    }
+
+    @Suppress("MissingPermission")
+    private fun startLegacyGpsFallback() {
+        val lm = locationManager ?: return
+
+        val minTimeMs = 15000L
+        val minDistanceM = 10f
+
+        gpsLocationListener = object : LocationListener {
+            override fun onLocationChanged(location: Location) {
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                    return
+                }
+                uploadLocation(location)
+            }
+
+            override fun onStatusChanged(provider: String?, status: Int, extras: Bundle?) {}
+            override fun onProviderEnabled(provider: String) {}
+            override fun onProviderDisabled(provider: String) {}
+        }
+
+        var requested = false
+
+        try {
+            if (lm.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
+                lm.requestLocationUpdates(
+                    LocationManager.GPS_PROVIDER,
+                    minTimeMs,
+                    minDistanceM,
+                    gpsLocationListener!!,
+                    mainLooper
+                )
+                requested = true
+                Log.d(TAG, "Requested GPS_PROVIDER updates")
+            }
+        } catch (e: Exception) {
+            Log.w(TAG, "GPS_PROVIDER request failed", e)
+        }
+
+        try {
+            if (lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER)) {
+                lm.requestLocationUpdates(
+                    LocationManager.NETWORK_PROVIDER,
+                    minTimeMs,
+                    minDistanceM,
+                    gpsLocationListener!!,
+                    mainLooper
+                )
+                requested = true
+                Log.d(TAG, "Requested NETWORK_PROVIDER updates")
+            }
+        } catch (e: Exception) {
+            Log.w(TAG, "NETWORK_PROVIDER request failed", e)
+        }
+
+        if (!requested) {
+            Log.w(TAG, "No location providers available for fallback")
+        }
+    }
+
+    private fun stopLocationUpdates() {
+        try {
+            locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        } catch (_: Exception) {
+        }
+        locationCallback = null
+
+        try {
+            gpsLocationListener?.let { listener ->
+                locationManager?.removeUpdates(listener)
+            }
+        } catch (_: Exception) {
+        }
+        gpsLocationListener = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.millisToIsoUtc(location.time),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val TAG = "TrackingService"
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-162412 b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-162412
new file mode 100644
index 0000000..16d7ff2
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-162412
@@ -0,0 +1,206 @@
+package top.outsidethebox.followme.service
+
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Bundle
+import android.util.Log
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.common.ConnectionResult
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    companion object {
+        private const val TAG = "TrackingService"
+    }
+    private var locationCallback: LocationCallback? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val request = LocationRequest.Builder(
+            Priority.PRIORITY_HIGH_ACCURACY,
+            15000L
+        )
+            .setMinUpdateIntervalMillis(5000L)
+            .setMinUpdateDistanceMeters(10f)
+            .setWaitForAccurateLocation(false)
+            .build()
+
+        locationCallback = object : LocationCallback() {
+            override fun onLocationResult(result: LocationResult) {
+                val location = result.lastLocation ?: return
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                }
+                uploadLocation(location)
+            }
+        }
+
+        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+    }
+
+    private fun stopLocationUpdates() {
+        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        locationCallback = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.nowIsoUtc(),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-164620 b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-164620
new file mode 100644
index 0000000..16d7ff2
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-164620
@@ -0,0 +1,206 @@
+package top.outsidethebox.followme.service
+
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Bundle
+import android.util.Log
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.common.ConnectionResult
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    companion object {
+        private const val TAG = "TrackingService"
+    }
+    private var locationCallback: LocationCallback? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val request = LocationRequest.Builder(
+            Priority.PRIORITY_HIGH_ACCURACY,
+            15000L
+        )
+            .setMinUpdateIntervalMillis(5000L)
+            .setMinUpdateDistanceMeters(10f)
+            .setWaitForAccurateLocation(false)
+            .build()
+
+        locationCallback = object : LocationCallback() {
+            override fun onLocationResult(result: LocationResult) {
+                val location = result.lastLocation ?: return
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                }
+                uploadLocation(location)
+            }
+        }
+
+        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+    }
+
+    private fun stopLocationUpdates() {
+        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        locationCallback = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.nowIsoUtc(),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171557 b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171557
new file mode 100644
index 0000000..16d7ff2
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171557
@@ -0,0 +1,206 @@
+package top.outsidethebox.followme.service
+
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Bundle
+import android.util.Log
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.common.ConnectionResult
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    companion object {
+        private const val TAG = "TrackingService"
+    }
+    private var locationCallback: LocationCallback? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val request = LocationRequest.Builder(
+            Priority.PRIORITY_HIGH_ACCURACY,
+            15000L
+        )
+            .setMinUpdateIntervalMillis(5000L)
+            .setMinUpdateDistanceMeters(10f)
+            .setWaitForAccurateLocation(false)
+            .build()
+
+        locationCallback = object : LocationCallback() {
+            override fun onLocationResult(result: LocationResult) {
+                val location = result.lastLocation ?: return
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                }
+                uploadLocation(location)
+            }
+        }
+
+        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+    }
+
+    private fun stopLocationUpdates() {
+        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        locationCallback = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.nowIsoUtc(),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171616 b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171616
new file mode 100644
index 0000000..16d7ff2
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171616
@@ -0,0 +1,206 @@
+package top.outsidethebox.followme.service
+
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Bundle
+import android.util.Log
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.common.ConnectionResult
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    companion object {
+        private const val TAG = "TrackingService"
+    }
+    private var locationCallback: LocationCallback? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val request = LocationRequest.Builder(
+            Priority.PRIORITY_HIGH_ACCURACY,
+            15000L
+        )
+            .setMinUpdateIntervalMillis(5000L)
+            .setMinUpdateDistanceMeters(10f)
+            .setWaitForAccurateLocation(false)
+            .build()
+
+        locationCallback = object : LocationCallback() {
+            override fun onLocationResult(result: LocationResult) {
+                val location = result.lastLocation ?: return
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                }
+                uploadLocation(location)
+            }
+        }
+
+        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+    }
+
+    private fun stopLocationUpdates() {
+        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        locationCallback = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.nowIsoUtc(),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt
new file mode 100644
index 0000000..952e654
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt
@@ -0,0 +1,108 @@
+package top.outsidethebox.followme.ui
+
+import android.Manifest
+import android.content.pm.PackageManager
+import android.os.Build
+import android.os.Bundle
+import android.widget.Toast
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.content.ContextCompat
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.databinding.ActivityMainBinding
+import top.outsidethebox.followme.service.TrackingService
+
+class MainActivity : AppCompatActivity() {
+    private lateinit var binding: ActivityMainBinding
+    private lateinit var prefs: AppPrefs
+
+    private val permissionLauncher = registerForActivityResult(
+        ActivityResultContracts.RequestMultiplePermissions()
+    ) { refreshUi() }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        binding = ActivityMainBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+        prefs = AppPrefs(applicationContext)
+
+        binding.endpointView.text = buildString {
+            append("Primary: ")
+            append(AppPrefs.HTTPS_ENDPOINT)
+            append("\nFallback: ")
+            append(AppPrefs.HTTP_ENDPOINT)
+        }
+
+        populateFields()
+        wireActions()
+        refreshUi()
+    }
+
+    override fun onResume() {
+        super.onResume()
+        refreshUi()
+    }
+
+    private fun populateFields() {
+        binding.tokenInput.setText(prefs.getToken())
+        binding.roleInput.setText(prefs.getRole())
+        binding.networkInput.setText(prefs.getNetworkNote())
+        binding.sourceInput.setText(prefs.getSource())
+    }
+
+    private fun wireActions() {
+        binding.saveButton.setOnClickListener {
+            saveSettings()
+            Toast.makeText(this, "Saved", Toast.LENGTH_SHORT).show()
+            refreshUi()
+        }
+
+        binding.startButton.setOnClickListener {
+            saveSettings()
+            if (!hasBaseLocationPermission()) {
+                requestPermissions()
+                return@setOnClickListener
+            }
+            TrackingService.start(this)
+            prefs.setTrackingEnabled(true)
+            refreshUi()
+        }
+
+        binding.stopButton.setOnClickListener {
+            TrackingService.stop(this)
+            prefs.setTrackingEnabled(false)
+            refreshUi()
+        }
+    }
+
+    private fun saveSettings() {
+        prefs.setToken(binding.tokenInput.text?.toString()?.trim().orEmpty())
+        prefs.setRole(binding.roleInput.text?.toString()?.trim().orEmpty())
+        prefs.setNetworkNote(binding.networkInput.text?.toString()?.trim().orEmpty())
+        prefs.setSource(binding.sourceInput.text?.toString()?.trim().orEmpty().ifBlank { AppPrefs.DEFAULT_SOURCE })
+    }
+
+    private fun refreshUi() {
+        val protocol = prefs.getPreferredTransport().uppercase()
+        binding.protocolView.text = "Preferred protocol: $protocol (HTTPS fallback count: ${prefs.getConsecutiveHttpsFallbacks()})"
+        binding.lastUploadView.text = "Last upload: ${prefs.getLastUpload()}"
+        binding.statusView.text = if (prefs.isTrackingEnabled()) "Status: running" else "Status: stopped"
+    }
+
+    private fun hasBaseLocationPermission(): Boolean {
+        val fine = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun requestPermissions() {
+        val permissions = mutableListOf(
+            Manifest.permission.ACCESS_FINE_LOCATION,
+            Manifest.permission.ACCESS_COARSE_LOCATION
+        )
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            permissions += Manifest.permission.ACCESS_BACKGROUND_LOCATION
+        }
+        permissionLauncher.launch(permissions.toTypedArray())
+    }
+}
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt.bak.20260316-205644 b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt.bak.20260316-205644
new file mode 100644
index 0000000..2f6253b
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt.bak.20260316-205644
@@ -0,0 +1,108 @@
+package top.outsidethebox.followme.ui
+
+import android.Manifest
+import android.content.pm.PackageManager
+import android.os.Build
+import android.os.Bundle
+import android.widget.Toast
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.content.ContextCompat
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.databinding.ActivityMainBinding
+import top.outsidethebox.followme.service.TrackingService
+
+class MainActivity : AppCompatActivity() {
+    private lateinit var binding: ActivityMainBinding
+    private lateinit var prefs: AppPrefs
+
+    private val permissionLauncher = registerForActivityResult(
+        ActivityResultContracts.RequestMultiplePermissions()
+    ) { refreshUi() }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        binding = ActivityMainBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+        prefs = AppPrefs(applicationContext)
+
+        binding.endpointView.text = buildString {
+            append("Primary: ")
+            append(AppPrefs.HTTPS_ENDPOINT)
+            append("\nFallback: ")
+            append(AppPrefs.HTTP_ENDPOINT)
+        }
+
+        populateFields()
+        wireActions()
+        refreshUi()
+    }
+
+    override fun onResume() {
+        super.onResume()
+        refreshUi()
+    }
+
+    private fun populateFields() {
+        binding.tokenInput.setText(prefs.getToken())
+        binding.roleInput.setText(prefs.getRole())
+        binding.networkInput.setText(prefs.getNetworkNote())
+        binding.sourceInput.setText(prefs.getSource())
+    }
+
+    private fun wireActions() {
+        binding.saveButton.setOnClickListener {
+            saveSettings()
+            Toast.makeText(this, "Saved", Toast.LENGTH_SHORT).show()
+            refreshUi()
+        }
+
+        binding.startButton.setOnClickListener {
+            saveSettings()
+            if (!hasBaseLocationPermission()) {
+                requestPermissions()
+                return@setOnClickListener
+            }
+            TrackingService.start(this)
+            prefs.setTrackingEnabled(true)
+            refreshUi()
+        }
+
+        binding.stopButton.setOnClickListener {
+            TrackingService.stop(this)
+            prefs.setTrackingEnabled(false)
+            refreshUi()
+        }
+    }
+
+    private fun saveSettings() {
+        prefs.setToken(binding.tokenInput.text?.toString()?.trim().orEmpty())
+        prefs.setRole(binding.roleInput.text?.toString()?.trim().orEmpty())
+        prefs.setNetworkNote(binding.networkInput.text?.toString()?.trim().orEmpty())
+        prefs.setSource(binding.sourceInput.text?.toString()?.trim().ifBlank { AppPrefs.DEFAULT_SOURCE })
+    }
+
+    private fun refreshUi() {
+        val protocol = prefs.getPreferredTransport().uppercase()
+        binding.protocolView.text = "Preferred protocol: $protocol (HTTPS fallback count: ${prefs.getConsecutiveHttpsFallbacks()})"
+        binding.lastUploadView.text = "Last upload: ${prefs.getLastUpload()}"
+        binding.statusView.text = if (prefs.isTrackingEnabled()) "Status: running" else "Status: stopped"
+    }
+
+    private fun hasBaseLocationPermission(): Boolean {
+        val fine = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun requestPermissions() {
+        val permissions = mutableListOf(
+            Manifest.permission.ACCESS_FINE_LOCATION,
+            Manifest.permission.ACCESS_COARSE_LOCATION
+        )
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            permissions += Manifest.permission.ACCESS_BACKGROUND_LOCATION
+        }
+        permissionLauncher.launch(permissions.toTypedArray())
+    }
+}
diff --git a/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/util/TimeUtils.kt b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/util/TimeUtils.kt
new file mode 100644
index 0000000..e01ddfb
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/java/top/outsidethebox/followme/util/TimeUtils.kt
@@ -0,0 +1,29 @@
+package top.outsidethebox.followme.util
+
+import java.text.SimpleDateFormat
+import java.util.Date
+import java.util.Locale
+import java.util.TimeZone
+
+object TimeUtils {
+    private val isoFormatter = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US).apply {
+        timeZone = TimeZone.getTimeZone("UTC")
+    }
+
+    private val prettyLocalFormatter = SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.US)
+
+    @Synchronized
+    fun nowIsoUtc(): String {
+        return isoFormatter.format(Date())
+    }
+
+    @Synchronized
+    fun millisToIsoUtc(millis: Long): String {
+        return isoFormatter.format(Date(millis))
+    }
+
+    @Synchronized
+    fun nowPrettyLocal(): String {
+        return prettyLocalFormatter.format(Date())
+    }
+}
diff --git a/app.bak.20260330-214820/src/main/res/drawable/ic_launcher_foreground.png b/app.bak.20260330-214820/src/main/res/drawable/ic_launcher_foreground.png
new file mode 100644
index 0000000..2860387
Binary files /dev/null and b/app.bak.20260330-214820/src/main/res/drawable/ic_launcher_foreground.png differ
diff --git a/app.bak.20260330-214820/src/main/res/drawable/otb_logo.png b/app.bak.20260330-214820/src/main/res/drawable/otb_logo.png
new file mode 100644
index 0000000..dd9f3fa
Binary files /dev/null and b/app.bak.20260330-214820/src/main/res/drawable/otb_logo.png differ
diff --git a/app.bak.20260330-214820/src/main/res/layout/activity_main.xml b/app.bak.20260330-214820/src/main/res/layout/activity_main.xml
new file mode 100644
index 0000000..2ed98ab
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/res/layout/activity_main.xml
@@ -0,0 +1,160 @@
+<?xml version="1.0" encoding="utf-8"?>
+<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="vertical"
+        android:padding="16dp">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center_vertical">
+
+            <ImageView
+                android:id="@+id/headerLogo"
+                android:layout_width="36dp"
+                android:layout_height="36dp"
+                android:layout_marginEnd="10dp"
+                android:adjustViewBounds="true"
+                android:contentDescription="OTB logo"
+                android:src="@drawable/otb_logo" />
+
+            <TextView
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="follow-me"
+                android:textSize="24sp"
+                android:textStyle="bold" />
+        </LinearLayout>
+
+        <TextView
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="6dp"
+            android:text="Operational app name: follow-me"
+            android:textSize="14sp" />
+
+        <com.google.android.material.textfield.TextInputLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="16dp"
+            android:hint="Device token (X-API-Key)">
+
+            <com.google.android.material.textfield.TextInputEditText
+                android:id="@+id/tokenInput"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:inputType="textNoSuggestions" />
+        </com.google.android.material.textfield.TextInputLayout>
+
+        <com.google.android.material.textfield.TextInputLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:hint="Install role (freeadmin or drone)">
+
+            <com.google.android.material.textfield.TextInputEditText
+                android:id="@+id/roleInput"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="drone" />
+        </com.google.android.material.textfield.TextInputLayout>
+
+        <com.google.android.material.textfield.TextInputLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:hint="Network name / code (local note)">
+
+            <com.google.android.material.textfield.TextInputEditText
+                android:id="@+id/networkInput"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content" />
+        </com.google.android.material.textfield.TextInputLayout>
+
+        <com.google.android.material.textfield.TextInputLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:hint="Source label">
+
+            <com.google.android.material.textfield.TextInputEditText
+                android:id="@+id/sourceInput"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="otb-tcom" />
+        </com.google.android.material.textfield.TextInputLayout>
+
+        <TextView
+            android:id="@+id/endpointView"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="14dp"
+            android:text="Endpoints"
+            android:textSize="14sp" />
+
+        <TextView
+            android:id="@+id/statusView"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="14dp"
+            android:text="Status: stopped"
+            android:textStyle="bold" />
+
+        <TextView
+            android:id="@+id/lastUploadView"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="8dp"
+            android:text="Last upload: never" />
+
+        <TextView
+            android:id="@+id/protocolView"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="8dp"
+            android:text="Preferred protocol: HTTPS" />
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="16dp"
+            android:gravity="center"
+            android:orientation="horizontal">
+
+            <com.google.android.material.button.MaterialButton
+                android:id="@+id/saveButton"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Save" />
+
+            <Space
+                android:layout_width="12dp"
+                android:layout_height="1dp" />
+
+            <com.google.android.material.button.MaterialButton
+                android:id="@+id/startButton"
+                style="@style/Widget.MaterialComponents.Button"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Start" />
+        </LinearLayout>
+
+        <com.google.android.material.button.MaterialButton
+            android:id="@+id/stopButton"
+            style="@style/Widget.MaterialComponents.Button.OutlinedButton"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:text="Stop" />
+
+    </LinearLayout>
+</ScrollView>
diff --git a/app.bak.20260330-214820/src/main/res/mipmap-hdpi/ic_launcher.png b/app.bak.20260330-214820/src/main/res/mipmap-hdpi/ic_launcher.png
new file mode 100644
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diff --git a/app.bak.20260330-214820/src/main/res/mipmap-hdpi/ic_launcher_round.png b/app.bak.20260330-214820/src/main/res/mipmap-hdpi/ic_launcher_round.png
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diff --git a/app.bak.20260330-214820/src/main/res/mipmap-mdpi/ic_launcher.png b/app.bak.20260330-214820/src/main/res/mipmap-mdpi/ic_launcher.png
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diff --git a/app.bak.20260330-214820/src/main/res/mipmap-mdpi/ic_launcher_round.png b/app.bak.20260330-214820/src/main/res/mipmap-mdpi/ic_launcher_round.png
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diff --git a/app.bak.20260330-214820/src/main/res/mipmap-xhdpi/ic_launcher.png b/app.bak.20260330-214820/src/main/res/mipmap-xhdpi/ic_launcher.png
new file mode 100644
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diff --git a/app.bak.20260330-214820/src/main/res/mipmap-xhdpi/ic_launcher_round.png b/app.bak.20260330-214820/src/main/res/mipmap-xhdpi/ic_launcher_round.png
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index 0000000..b4442ee
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diff --git a/app.bak.20260330-214820/src/main/res/mipmap-xxhdpi/ic_launcher.png b/app.bak.20260330-214820/src/main/res/mipmap-xxhdpi/ic_launcher.png
new file mode 100644
index 0000000..2ceebd1
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diff --git a/app.bak.20260330-214820/src/main/res/mipmap-xxhdpi/ic_launcher_round.png b/app.bak.20260330-214820/src/main/res/mipmap-xxhdpi/ic_launcher_round.png
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index 0000000..2ceebd1
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diff --git a/app.bak.20260330-214820/src/main/res/mipmap-xxxhdpi/ic_launcher.png b/app.bak.20260330-214820/src/main/res/mipmap-xxxhdpi/ic_launcher.png
new file mode 100644
index 0000000..38bb200
Binary files /dev/null and b/app.bak.20260330-214820/src/main/res/mipmap-xxxhdpi/ic_launcher.png differ
diff --git a/app.bak.20260330-214820/src/main/res/mipmap-xxxhdpi/ic_launcher_round.png b/app.bak.20260330-214820/src/main/res/mipmap-xxxhdpi/ic_launcher_round.png
new file mode 100644
index 0000000..38bb200
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diff --git a/app.bak.20260330-214820/src/main/res/values/colors.xml b/app.bak.20260330-214820/src/main/res/values/colors.xml
new file mode 100644
index 0000000..ab35b9f
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/res/values/colors.xml
@@ -0,0 +1,7 @@
+<resources>
+    <color name="purple_500">#455A64</color>
+    <color name="purple_700">#263238</color>
+    <color name="teal_200">#80CBC4</color>
+    <color name="white">#FFFFFF</color>
+    <color name="black">#000000</color>
+</resources>
diff --git a/app.bak.20260330-214820/src/main/res/values/strings.xml b/app.bak.20260330-214820/src/main/res/values/strings.xml
new file mode 100644
index 0000000..1c75390
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/res/values/strings.xml
@@ -0,0 +1,6 @@
+<resources>
+    <string name="app_name">follow-me</string>
+    <string name="notification_channel_name">Tracking</string>
+    <string name="notification_title">otb-tcom tracking active</string>
+    <string name="notification_text">Posting location updates to follow-me</string>
+</resources>
diff --git a/app.bak.20260330-214820/src/main/res/values/themes.xml b/app.bak.20260330-214820/src/main/res/values/themes.xml
new file mode 100644
index 0000000..da57f2d
--- /dev/null
+++ b/app.bak.20260330-214820/src/main/res/values/themes.xml
@@ -0,0 +1,9 @@
+<resources xmlns:tools="http://schemas.android.com/tools">
+    <style name="Theme.FollowMe" parent="Theme.MaterialComponents.DayNight.NoActionBar">
+        <item name="colorPrimary">@color/purple_500</item>
+        <item name="colorPrimaryVariant">@color/purple_700</item>
+        <item name="colorOnPrimary">@color/white</item>
+        <item name="colorSecondary">@color/teal_200</item>
+        <item name="android:statusBarColor" tools:targetApi="l">@color/purple_700</item>
+    </style>
+</resources>
diff --git a/app.bak.identity.20260330-222009/build.gradle.kts b/app.bak.identity.20260330-222009/build.gradle.kts
new file mode 100644
index 0000000..6cc823e
--- /dev/null
+++ b/app.bak.identity.20260330-222009/build.gradle.kts
@@ -0,0 +1,61 @@
+plugins {
+    id("com.android.application")
+    id("org.jetbrains.kotlin.android")
+}
+
+android {
+    namespace = "top.outsidethebox.followme"
+    compileSdk = 34
+
+    defaultConfig {
+        applicationId = "top.outsidethebox.followme"
+        minSdk = 23
+        targetSdk = 34
+        versionCode = 4
+        versionName = "0.4.0"
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+        }
+        debug {
+            isMinifyEnabled = false
+        }
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+        isCoreLibraryDesugaringEnabled = true
+    }
+
+    kotlinOptions {
+        jvmTarget = "17"
+    }
+
+    buildFeatures {
+        viewBinding = true
+    }
+}
+
+dependencies {
+    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.1.5")
+
+    implementation("androidx.core:core-ktx:1.12.0")
+    implementation("androidx.appcompat:appcompat:1.7.0")
+    implementation("com.google.android.material:material:1.11.0")
+    implementation("androidx.activity:activity-ktx:1.8.2")
+    implementation("androidx.constraintlayout:constraintlayout:2.1.4")
+    implementation("androidx.lifecycle:lifecycle-service:2.7.0")
+    implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.7.0")
+    implementation("com.google.android.gms:play-services-location:21.2.0")
+    implementation("com.squareup.okhttp3:okhttp:4.12.0")
+    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3")
+}
diff --git a/app.bak.identity.20260330-222009/proguard-rules.pro b/app.bak.identity.20260330-222009/proguard-rules.pro
new file mode 100644
index 0000000..a1e5cc2
--- /dev/null
+++ b/app.bak.identity.20260330-222009/proguard-rules.pro
@@ -0,0 +1 @@
+# No custom rules yet.
diff --git a/app.bak.identity.20260330-222009/src/main/AndroidManifest.xml b/app.bak.identity.20260330-222009/src/main/AndroidManifest.xml
new file mode 100644
index 0000000..eaba08c
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/AndroidManifest.xml
@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
+    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
+    <uses-permission android:name="android.permission.WAKE_LOCK" />
+    <uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="follow-me"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.FollowMe"
+        android:usesCleartextTraffic="true">
+
+        <activity
+            android:name=".ui.MainActivity"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+        <service
+            android:name=".service.TrackingService"
+            android:enabled="true"
+            android:exported="false"
+            android:foregroundServiceType="location" />
+
+        <receiver
+            android:name=".service.BootReceiver"
+            android:enabled="true"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.BOOT_COMPLETED" />
+                <action android:name="android.intent.action.MY_PACKAGE_REPLACED" />
+            </intent-filter>
+        </receiver>
+    </application>
+
+</manifest>
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/data/AppPrefs.kt b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/data/AppPrefs.kt
new file mode 100644
index 0000000..1b9dc72
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/data/AppPrefs.kt
@@ -0,0 +1,52 @@
+package top.outsidethebox.followme.data
+
+import android.content.Context
+import android.content.SharedPreferences
+
+class AppPrefs(context: Context) {
+    private val prefs: SharedPreferences = context.getSharedPreferences(PREF_NAME, Context.MODE_PRIVATE)
+
+    fun getToken(): String = prefs.getString(KEY_TOKEN, "") ?: ""
+    fun setToken(value: String) = prefs.edit().putString(KEY_TOKEN, value).apply()
+
+    fun getRole(): String = prefs.getString(KEY_ROLE, "drone") ?: "drone"
+    fun setRole(value: String) = prefs.edit().putString(KEY_ROLE, value).apply()
+
+    fun getNetworkNote(): String = prefs.getString(KEY_NETWORK_NOTE, "") ?: ""
+    fun setNetworkNote(value: String) = prefs.edit().putString(KEY_NETWORK_NOTE, value).apply()
+
+    fun getSource(): String = prefs.getString(KEY_SOURCE, DEFAULT_SOURCE) ?: DEFAULT_SOURCE
+    fun setSource(value: String) = prefs.edit().putString(KEY_SOURCE, value).apply()
+
+    fun isTrackingEnabled(): Boolean = prefs.getBoolean(KEY_TRACKING_ENABLED, false)
+    fun setTrackingEnabled(value: Boolean) = prefs.edit().putBoolean(KEY_TRACKING_ENABLED, value).apply()
+
+    fun getConsecutiveHttpsFallbacks(): Int = prefs.getInt(KEY_HTTPS_FALLBACKS, 0)
+    fun setConsecutiveHttpsFallbacks(value: Int) = prefs.edit().putInt(KEY_HTTPS_FALLBACKS, value).apply()
+
+    fun getPreferredTransport(): String = prefs.getString(KEY_PREFERRED_TRANSPORT, TRANSPORT_HTTPS) ?: TRANSPORT_HTTPS
+    fun setPreferredTransport(value: String) = prefs.edit().putString(KEY_PREFERRED_TRANSPORT, value).apply()
+
+    fun getLastUpload(): String = prefs.getString(KEY_LAST_UPLOAD, "never") ?: "never"
+    fun setLastUpload(value: String) = prefs.edit().putString(KEY_LAST_UPLOAD, value).apply()
+
+    fun resetHttpsFallbackCounter() = setConsecutiveHttpsFallbacks(0)
+
+    companion object {
+        private const val PREF_NAME = "follow_me_prefs"
+        private const val KEY_TOKEN = "token"
+        private const val KEY_ROLE = "role"
+        private const val KEY_NETWORK_NOTE = "network_note"
+        private const val KEY_SOURCE = "source"
+        private const val KEY_TRACKING_ENABLED = "tracking_enabled"
+        private const val KEY_HTTPS_FALLBACKS = "https_fallbacks"
+        private const val KEY_PREFERRED_TRANSPORT = "preferred_transport"
+        private const val KEY_LAST_UPLOAD = "last_upload"
+
+        const val TRANSPORT_HTTPS = "https"
+        const val TRANSPORT_HTTP = "http"
+        const val DEFAULT_SOURCE = "otb-tcom"
+        const val HTTPS_ENDPOINT = "https://otb-tracker.outsidethebox.top/api/gps-ingest"
+        const val HTTP_ENDPOINT = "http://otb-tracker.outsidethebox.top/api/gps-ingest"
+    }
+}
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt
new file mode 100644
index 0000000..b91dad8
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt
@@ -0,0 +1,27 @@
+package top.outsidethebox.followme.data
+
+import org.json.JSONObject
+
+data class GpsPayload(
+    val latitude: Double,
+    val longitude: Double,
+    val speedKmh: Double? = null,
+    val accuracyM: Float? = null,
+    val headingDeg: Float? = null,
+    val altitudeM: Double? = null,
+    val recordedAt: String? = null,
+    val source: String = AppPrefs.DEFAULT_SOURCE
+) {
+    fun toJson(): String {
+        val json = JSONObject()
+        json.put("latitude", latitude)
+        json.put("longitude", longitude)
+        speedKmh?.let { json.put("speed_kmh", it) }
+        accuracyM?.let { json.put("accuracy_m", it) }
+        headingDeg?.let { json.put("heading_deg", it) }
+        altitudeM?.let { json.put("altitude_m", it) }
+        recordedAt?.let { json.put("recorded_at", it) }
+        json.put("source", source)
+        return json.toString()
+    }
+}
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/data/IngestRepository.kt b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/data/IngestRepository.kt
new file mode 100644
index 0000000..d6e3b7e
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/data/IngestRepository.kt
@@ -0,0 +1,99 @@
+package top.outsidethebox.followme.data
+
+import android.content.Context
+import okhttp3.MediaType.Companion.toMediaType
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import okhttp3.RequestBody.Companion.toRequestBody
+import java.io.IOException
+import java.util.concurrent.TimeUnit
+
+data class IngestResult(
+    val success: Boolean,
+    val usedTransport: String,
+    val responseBody: String? = null,
+    val errorMessage: String? = null
+)
+
+class IngestRepository(context: Context) {
+    private val prefs = AppPrefs(context.applicationContext)
+    private val jsonType = "application/json; charset=utf-8".toMediaType()
+
+    private val client: OkHttpClient = OkHttpClient.Builder()
+        .connectTimeout(10, TimeUnit.SECONDS)
+        .readTimeout(15, TimeUnit.SECONDS)
+        .writeTimeout(15, TimeUnit.SECONDS)
+        .retryOnConnectionFailure(true)
+        .build()
+
+    fun send(payload: GpsPayload): IngestResult {
+        val token = prefs.getToken().trim()
+        if (token.isEmpty()) {
+            return IngestResult(false, prefs.getPreferredTransport(), errorMessage = "Missing device token")
+        }
+
+        val preferred = prefs.getPreferredTransport()
+        return if (preferred == AppPrefs.TRANSPORT_HTTP) {
+            sendHttpOnly(token, payload)
+        } else {
+            sendHttpsThenFallback(token, payload)
+        }
+    }
+
+    private fun sendHttpsThenFallback(token: String, payload: GpsPayload): IngestResult {
+        val httpsResult = post(AppPrefs.HTTPS_ENDPOINT, token, payload)
+        if (httpsResult.success) {
+            prefs.resetHttpsFallbackCounter()
+            prefs.setPreferredTransport(AppPrefs.TRANSPORT_HTTPS)
+            return httpsResult.copy(usedTransport = AppPrefs.TRANSPORT_HTTPS)
+        }
+
+        val httpResult = post(AppPrefs.HTTP_ENDPOINT, token, payload)
+        if (httpResult.success) {
+            val newCount = prefs.getConsecutiveHttpsFallbacks() + 1
+            prefs.setConsecutiveHttpsFallbacks(newCount)
+            if (newCount >= 3) {
+                prefs.setPreferredTransport(AppPrefs.TRANSPORT_HTTP)
+            }
+            return httpResult.copy(usedTransport = AppPrefs.TRANSPORT_HTTP)
+        }
+
+        return IngestResult(
+            success = false,
+            usedTransport = AppPrefs.TRANSPORT_HTTPS,
+            errorMessage = httpsResult.errorMessage ?: httpResult.errorMessage
+        )
+    }
+
+    private fun sendHttpOnly(token: String, payload: GpsPayload): IngestResult {
+        val result = post(AppPrefs.HTTP_ENDPOINT, token, payload)
+        return if (result.success) {
+            result.copy(usedTransport = AppPrefs.TRANSPORT_HTTP)
+        } else {
+            result
+        }
+    }
+
+    private fun post(url: String, token: String, payload: GpsPayload): IngestResult {
+        val body = payload.toJson().toRequestBody(jsonType)
+        val request = Request.Builder()
+            .url(url)
+            .post(body)
+            .header("X-API-Key", token)
+            .header("Content-Type", "application/json")
+            .build()
+
+        return try {
+            client.newCall(request).execute().use { response ->
+                val text = response.body?.string().orEmpty()
+                if (response.isSuccessful) {
+                    IngestResult(true, if (url.startsWith("https")) AppPrefs.TRANSPORT_HTTPS else AppPrefs.TRANSPORT_HTTP, text)
+                } else {
+                    IngestResult(false, if (url.startsWith("https")) AppPrefs.TRANSPORT_HTTPS else AppPrefs.TRANSPORT_HTTP, text, "HTTP ${response.code}")
+                }
+            }
+        } catch (e: IOException) {
+            IngestResult(false, if (url.startsWith("https")) AppPrefs.TRANSPORT_HTTPS else AppPrefs.TRANSPORT_HTTP, errorMessage = e.message)
+        }
+    }
+}
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/location/TrackingMode.kt b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/location/TrackingMode.kt
new file mode 100644
index 0000000..a9571c9
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/location/TrackingMode.kt
@@ -0,0 +1,6 @@
+package top.outsidethebox.followme.location
+
+enum class TrackingMode(val intervalMs: Long) {
+    MOVING(10_000L),
+    IDLE(300_000L)
+}
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/BootReceiver.kt b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/BootReceiver.kt
new file mode 100644
index 0000000..98d0a3f
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/BootReceiver.kt
@@ -0,0 +1,18 @@
+package top.outsidethebox.followme.service
+
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import top.outsidethebox.followme.data.AppPrefs
+
+class BootReceiver : BroadcastReceiver() {
+    override fun onReceive(context: Context, intent: Intent?) {
+        val action = intent?.action ?: return
+        if (action == Intent.ACTION_BOOT_COMPLETED || action == Intent.ACTION_MY_PACKAGE_REPLACED) {
+            val prefs = AppPrefs(context.applicationContext)
+            if (prefs.isTrackingEnabled()) {
+                TrackingService.start(context)
+            }
+        }
+    }
+}
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt
new file mode 100644
index 0000000..37c1c78
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt
@@ -0,0 +1,298 @@
+package top.outsidethebox.followme.service
+
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Build
+import android.os.Bundle
+import android.os.IBinder
+import android.util.Log
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.common.ConnectionResult
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationCallback: LocationCallback? = null
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(R.mipmap.ic_launcher)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+                android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION
+            } else {
+                0
+            }
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val playServicesOk =
+            GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(this) == ConnectionResult.SUCCESS
+
+        if (playServicesOk) {
+            try {
+                val request = LocationRequest.Builder(
+                    Priority.PRIORITY_HIGH_ACCURACY,
+                    15000L
+                )
+                    .setMinUpdateIntervalMillis(5000L)
+                    .setMinUpdateDistanceMeters(10f)
+                    .setWaitForAccurateLocation(false)
+                    .build()
+
+                locationCallback = object : LocationCallback() {
+                    override fun onLocationResult(result: LocationResult) {
+                        val location = result.lastLocation ?: return
+                        val nextMode = decideMode(location)
+                        if (nextMode != currentMode) {
+                            startLocationUpdates(nextMode)
+                            return
+                        }
+                        uploadLocation(location)
+                    }
+                }
+
+                fusedLocationClient.requestLocationUpdates(
+                    request,
+                    locationCallback!!,
+                    mainLooper
+                )
+
+                Log.d(TAG, "Using FusedLocationProviderClient")
+                return
+            } catch (e: Exception) {
+                Log.w(TAG, "Fused location failed, falling back to LocationManager", e)
+            }
+        } else {
+            Log.w(TAG, "Google Play Services unavailable, using LocationManager fallback")
+        }
+
+        startLegacyGpsFallback()
+    }
+
+    @Suppress("MissingPermission")
+    private fun startLegacyGpsFallback() {
+        val lm = locationManager ?: return
+
+        val minTimeMs = 15000L
+        val minDistanceM = 10f
+
+        gpsLocationListener = object : LocationListener {
+            override fun onLocationChanged(location: Location) {
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                    return
+                }
+                uploadLocation(location)
+            }
+
+            override fun onStatusChanged(provider: String?, status: Int, extras: Bundle?) {}
+            override fun onProviderEnabled(provider: String) {}
+            override fun onProviderDisabled(provider: String) {}
+        }
+
+        var requested = false
+
+        try {
+            if (lm.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
+                lm.requestLocationUpdates(
+                    LocationManager.GPS_PROVIDER,
+                    minTimeMs,
+                    minDistanceM,
+                    gpsLocationListener!!,
+                    mainLooper
+                )
+                requested = true
+                Log.d(TAG, "Requested GPS_PROVIDER updates")
+            }
+        } catch (e: Exception) {
+            Log.w(TAG, "GPS_PROVIDER request failed", e)
+        }
+
+        try {
+            if (lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER)) {
+                lm.requestLocationUpdates(
+                    LocationManager.NETWORK_PROVIDER,
+                    minTimeMs,
+                    minDistanceM,
+                    gpsLocationListener!!,
+                    mainLooper
+                )
+                requested = true
+                Log.d(TAG, "Requested NETWORK_PROVIDER updates")
+            }
+        } catch (e: Exception) {
+            Log.w(TAG, "NETWORK_PROVIDER request failed", e)
+        }
+
+        if (!requested) {
+            Log.w(TAG, "No location providers available for fallback")
+        }
+    }
+
+    private fun stopLocationUpdates() {
+        try {
+            locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        } catch (_: Exception) {
+        }
+        locationCallback = null
+
+        try {
+            gpsLocationListener?.let { listener ->
+                locationManager?.removeUpdates(listener)
+            }
+        } catch (_: Exception) {
+        }
+        gpsLocationListener = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.millisToIsoUtc(location.time),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val TAG = "TrackingService"
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-162412 b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-162412
new file mode 100644
index 0000000..16d7ff2
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-162412
@@ -0,0 +1,206 @@
+package top.outsidethebox.followme.service
+
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Bundle
+import android.util.Log
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.common.ConnectionResult
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    companion object {
+        private const val TAG = "TrackingService"
+    }
+    private var locationCallback: LocationCallback? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val request = LocationRequest.Builder(
+            Priority.PRIORITY_HIGH_ACCURACY,
+            15000L
+        )
+            .setMinUpdateIntervalMillis(5000L)
+            .setMinUpdateDistanceMeters(10f)
+            .setWaitForAccurateLocation(false)
+            .build()
+
+        locationCallback = object : LocationCallback() {
+            override fun onLocationResult(result: LocationResult) {
+                val location = result.lastLocation ?: return
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                }
+                uploadLocation(location)
+            }
+        }
+
+        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+    }
+
+    private fun stopLocationUpdates() {
+        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        locationCallback = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.nowIsoUtc(),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-164620 b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-164620
new file mode 100644
index 0000000..16d7ff2
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-164620
@@ -0,0 +1,206 @@
+package top.outsidethebox.followme.service
+
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Bundle
+import android.util.Log
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.common.ConnectionResult
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    companion object {
+        private const val TAG = "TrackingService"
+    }
+    private var locationCallback: LocationCallback? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val request = LocationRequest.Builder(
+            Priority.PRIORITY_HIGH_ACCURACY,
+            15000L
+        )
+            .setMinUpdateIntervalMillis(5000L)
+            .setMinUpdateDistanceMeters(10f)
+            .setWaitForAccurateLocation(false)
+            .build()
+
+        locationCallback = object : LocationCallback() {
+            override fun onLocationResult(result: LocationResult) {
+                val location = result.lastLocation ?: return
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                }
+                uploadLocation(location)
+            }
+        }
+
+        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+    }
+
+    private fun stopLocationUpdates() {
+        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        locationCallback = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.nowIsoUtc(),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171557 b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171557
new file mode 100644
index 0000000..16d7ff2
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171557
@@ -0,0 +1,206 @@
+package top.outsidethebox.followme.service
+
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Bundle
+import android.util.Log
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.common.ConnectionResult
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    companion object {
+        private const val TAG = "TrackingService"
+    }
+    private var locationCallback: LocationCallback? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val request = LocationRequest.Builder(
+            Priority.PRIORITY_HIGH_ACCURACY,
+            15000L
+        )
+            .setMinUpdateIntervalMillis(5000L)
+            .setMinUpdateDistanceMeters(10f)
+            .setWaitForAccurateLocation(false)
+            .build()
+
+        locationCallback = object : LocationCallback() {
+            override fun onLocationResult(result: LocationResult) {
+                val location = result.lastLocation ?: return
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                }
+                uploadLocation(location)
+            }
+        }
+
+        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+    }
+
+    private fun stopLocationUpdates() {
+        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        locationCallback = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.nowIsoUtc(),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171616 b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171616
new file mode 100644
index 0000000..16d7ff2
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171616
@@ -0,0 +1,206 @@
+package top.outsidethebox.followme.service
+
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Bundle
+import android.util.Log
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.common.ConnectionResult
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    companion object {
+        private const val TAG = "TrackingService"
+    }
+    private var locationCallback: LocationCallback? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val request = LocationRequest.Builder(
+            Priority.PRIORITY_HIGH_ACCURACY,
+            15000L
+        )
+            .setMinUpdateIntervalMillis(5000L)
+            .setMinUpdateDistanceMeters(10f)
+            .setWaitForAccurateLocation(false)
+            .build()
+
+        locationCallback = object : LocationCallback() {
+            override fun onLocationResult(result: LocationResult) {
+                val location = result.lastLocation ?: return
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                }
+                uploadLocation(location)
+            }
+        }
+
+        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+    }
+
+    private fun stopLocationUpdates() {
+        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        locationCallback = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.nowIsoUtc(),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt
new file mode 100644
index 0000000..952e654
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt
@@ -0,0 +1,108 @@
+package top.outsidethebox.followme.ui
+
+import android.Manifest
+import android.content.pm.PackageManager
+import android.os.Build
+import android.os.Bundle
+import android.widget.Toast
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.content.ContextCompat
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.databinding.ActivityMainBinding
+import top.outsidethebox.followme.service.TrackingService
+
+class MainActivity : AppCompatActivity() {
+    private lateinit var binding: ActivityMainBinding
+    private lateinit var prefs: AppPrefs
+
+    private val permissionLauncher = registerForActivityResult(
+        ActivityResultContracts.RequestMultiplePermissions()
+    ) { refreshUi() }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        binding = ActivityMainBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+        prefs = AppPrefs(applicationContext)
+
+        binding.endpointView.text = buildString {
+            append("Primary: ")
+            append(AppPrefs.HTTPS_ENDPOINT)
+            append("\nFallback: ")
+            append(AppPrefs.HTTP_ENDPOINT)
+        }
+
+        populateFields()
+        wireActions()
+        refreshUi()
+    }
+
+    override fun onResume() {
+        super.onResume()
+        refreshUi()
+    }
+
+    private fun populateFields() {
+        binding.tokenInput.setText(prefs.getToken())
+        binding.roleInput.setText(prefs.getRole())
+        binding.networkInput.setText(prefs.getNetworkNote())
+        binding.sourceInput.setText(prefs.getSource())
+    }
+
+    private fun wireActions() {
+        binding.saveButton.setOnClickListener {
+            saveSettings()
+            Toast.makeText(this, "Saved", Toast.LENGTH_SHORT).show()
+            refreshUi()
+        }
+
+        binding.startButton.setOnClickListener {
+            saveSettings()
+            if (!hasBaseLocationPermission()) {
+                requestPermissions()
+                return@setOnClickListener
+            }
+            TrackingService.start(this)
+            prefs.setTrackingEnabled(true)
+            refreshUi()
+        }
+
+        binding.stopButton.setOnClickListener {
+            TrackingService.stop(this)
+            prefs.setTrackingEnabled(false)
+            refreshUi()
+        }
+    }
+
+    private fun saveSettings() {
+        prefs.setToken(binding.tokenInput.text?.toString()?.trim().orEmpty())
+        prefs.setRole(binding.roleInput.text?.toString()?.trim().orEmpty())
+        prefs.setNetworkNote(binding.networkInput.text?.toString()?.trim().orEmpty())
+        prefs.setSource(binding.sourceInput.text?.toString()?.trim().orEmpty().ifBlank { AppPrefs.DEFAULT_SOURCE })
+    }
+
+    private fun refreshUi() {
+        val protocol = prefs.getPreferredTransport().uppercase()
+        binding.protocolView.text = "Preferred protocol: $protocol (HTTPS fallback count: ${prefs.getConsecutiveHttpsFallbacks()})"
+        binding.lastUploadView.text = "Last upload: ${prefs.getLastUpload()}"
+        binding.statusView.text = if (prefs.isTrackingEnabled()) "Status: running" else "Status: stopped"
+    }
+
+    private fun hasBaseLocationPermission(): Boolean {
+        val fine = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun requestPermissions() {
+        val permissions = mutableListOf(
+            Manifest.permission.ACCESS_FINE_LOCATION,
+            Manifest.permission.ACCESS_COARSE_LOCATION
+        )
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            permissions += Manifest.permission.ACCESS_BACKGROUND_LOCATION
+        }
+        permissionLauncher.launch(permissions.toTypedArray())
+    }
+}
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt.bak.20260316-205644 b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt.bak.20260316-205644
new file mode 100644
index 0000000..2f6253b
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt.bak.20260316-205644
@@ -0,0 +1,108 @@
+package top.outsidethebox.followme.ui
+
+import android.Manifest
+import android.content.pm.PackageManager
+import android.os.Build
+import android.os.Bundle
+import android.widget.Toast
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.content.ContextCompat
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.databinding.ActivityMainBinding
+import top.outsidethebox.followme.service.TrackingService
+
+class MainActivity : AppCompatActivity() {
+    private lateinit var binding: ActivityMainBinding
+    private lateinit var prefs: AppPrefs
+
+    private val permissionLauncher = registerForActivityResult(
+        ActivityResultContracts.RequestMultiplePermissions()
+    ) { refreshUi() }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        binding = ActivityMainBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+        prefs = AppPrefs(applicationContext)
+
+        binding.endpointView.text = buildString {
+            append("Primary: ")
+            append(AppPrefs.HTTPS_ENDPOINT)
+            append("\nFallback: ")
+            append(AppPrefs.HTTP_ENDPOINT)
+        }
+
+        populateFields()
+        wireActions()
+        refreshUi()
+    }
+
+    override fun onResume() {
+        super.onResume()
+        refreshUi()
+    }
+
+    private fun populateFields() {
+        binding.tokenInput.setText(prefs.getToken())
+        binding.roleInput.setText(prefs.getRole())
+        binding.networkInput.setText(prefs.getNetworkNote())
+        binding.sourceInput.setText(prefs.getSource())
+    }
+
+    private fun wireActions() {
+        binding.saveButton.setOnClickListener {
+            saveSettings()
+            Toast.makeText(this, "Saved", Toast.LENGTH_SHORT).show()
+            refreshUi()
+        }
+
+        binding.startButton.setOnClickListener {
+            saveSettings()
+            if (!hasBaseLocationPermission()) {
+                requestPermissions()
+                return@setOnClickListener
+            }
+            TrackingService.start(this)
+            prefs.setTrackingEnabled(true)
+            refreshUi()
+        }
+
+        binding.stopButton.setOnClickListener {
+            TrackingService.stop(this)
+            prefs.setTrackingEnabled(false)
+            refreshUi()
+        }
+    }
+
+    private fun saveSettings() {
+        prefs.setToken(binding.tokenInput.text?.toString()?.trim().orEmpty())
+        prefs.setRole(binding.roleInput.text?.toString()?.trim().orEmpty())
+        prefs.setNetworkNote(binding.networkInput.text?.toString()?.trim().orEmpty())
+        prefs.setSource(binding.sourceInput.text?.toString()?.trim().ifBlank { AppPrefs.DEFAULT_SOURCE })
+    }
+
+    private fun refreshUi() {
+        val protocol = prefs.getPreferredTransport().uppercase()
+        binding.protocolView.text = "Preferred protocol: $protocol (HTTPS fallback count: ${prefs.getConsecutiveHttpsFallbacks()})"
+        binding.lastUploadView.text = "Last upload: ${prefs.getLastUpload()}"
+        binding.statusView.text = if (prefs.isTrackingEnabled()) "Status: running" else "Status: stopped"
+    }
+
+    private fun hasBaseLocationPermission(): Boolean {
+        val fine = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun requestPermissions() {
+        val permissions = mutableListOf(
+            Manifest.permission.ACCESS_FINE_LOCATION,
+            Manifest.permission.ACCESS_COARSE_LOCATION
+        )
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            permissions += Manifest.permission.ACCESS_BACKGROUND_LOCATION
+        }
+        permissionLauncher.launch(permissions.toTypedArray())
+    }
+}
diff --git a/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/util/TimeUtils.kt b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/util/TimeUtils.kt
new file mode 100644
index 0000000..e01ddfb
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/java/top/outsidethebox/followme/util/TimeUtils.kt
@@ -0,0 +1,29 @@
+package top.outsidethebox.followme.util
+
+import java.text.SimpleDateFormat
+import java.util.Date
+import java.util.Locale
+import java.util.TimeZone
+
+object TimeUtils {
+    private val isoFormatter = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US).apply {
+        timeZone = TimeZone.getTimeZone("UTC")
+    }
+
+    private val prettyLocalFormatter = SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.US)
+
+    @Synchronized
+    fun nowIsoUtc(): String {
+        return isoFormatter.format(Date())
+    }
+
+    @Synchronized
+    fun millisToIsoUtc(millis: Long): String {
+        return isoFormatter.format(Date(millis))
+    }
+
+    @Synchronized
+    fun nowPrettyLocal(): String {
+        return prettyLocalFormatter.format(Date())
+    }
+}
diff --git a/app.bak.identity.20260330-222009/src/main/res/drawable/ic_launcher_foreground.png b/app.bak.identity.20260330-222009/src/main/res/drawable/ic_launcher_foreground.png
new file mode 100644
index 0000000..2860387
Binary files /dev/null and b/app.bak.identity.20260330-222009/src/main/res/drawable/ic_launcher_foreground.png differ
diff --git a/app.bak.identity.20260330-222009/src/main/res/drawable/otb_logo.png b/app.bak.identity.20260330-222009/src/main/res/drawable/otb_logo.png
new file mode 100644
index 0000000..dd9f3fa
Binary files /dev/null and b/app.bak.identity.20260330-222009/src/main/res/drawable/otb_logo.png differ
diff --git a/app.bak.identity.20260330-222009/src/main/res/layout/activity_main.xml b/app.bak.identity.20260330-222009/src/main/res/layout/activity_main.xml
new file mode 100644
index 0000000..2ed98ab
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/res/layout/activity_main.xml
@@ -0,0 +1,160 @@
+<?xml version="1.0" encoding="utf-8"?>
+<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="vertical"
+        android:padding="16dp">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center_vertical">
+
+            <ImageView
+                android:id="@+id/headerLogo"
+                android:layout_width="36dp"
+                android:layout_height="36dp"
+                android:layout_marginEnd="10dp"
+                android:adjustViewBounds="true"
+                android:contentDescription="OTB logo"
+                android:src="@drawable/otb_logo" />
+
+            <TextView
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="follow-me"
+                android:textSize="24sp"
+                android:textStyle="bold" />
+        </LinearLayout>
+
+        <TextView
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="6dp"
+            android:text="Operational app name: follow-me"
+            android:textSize="14sp" />
+
+        <com.google.android.material.textfield.TextInputLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="16dp"
+            android:hint="Device token (X-API-Key)">
+
+            <com.google.android.material.textfield.TextInputEditText
+                android:id="@+id/tokenInput"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:inputType="textNoSuggestions" />
+        </com.google.android.material.textfield.TextInputLayout>
+
+        <com.google.android.material.textfield.TextInputLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:hint="Install role (freeadmin or drone)">
+
+            <com.google.android.material.textfield.TextInputEditText
+                android:id="@+id/roleInput"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="drone" />
+        </com.google.android.material.textfield.TextInputLayout>
+
+        <com.google.android.material.textfield.TextInputLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:hint="Network name / code (local note)">
+
+            <com.google.android.material.textfield.TextInputEditText
+                android:id="@+id/networkInput"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content" />
+        </com.google.android.material.textfield.TextInputLayout>
+
+        <com.google.android.material.textfield.TextInputLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:hint="Source label">
+
+            <com.google.android.material.textfield.TextInputEditText
+                android:id="@+id/sourceInput"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:text="otb-tcom" />
+        </com.google.android.material.textfield.TextInputLayout>
+
+        <TextView
+            android:id="@+id/endpointView"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="14dp"
+            android:text="Endpoints"
+            android:textSize="14sp" />
+
+        <TextView
+            android:id="@+id/statusView"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="14dp"
+            android:text="Status: stopped"
+            android:textStyle="bold" />
+
+        <TextView
+            android:id="@+id/lastUploadView"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="8dp"
+            android:text="Last upload: never" />
+
+        <TextView
+            android:id="@+id/protocolView"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="8dp"
+            android:text="Preferred protocol: HTTPS" />
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="16dp"
+            android:gravity="center"
+            android:orientation="horizontal">
+
+            <com.google.android.material.button.MaterialButton
+                android:id="@+id/saveButton"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Save" />
+
+            <Space
+                android:layout_width="12dp"
+                android:layout_height="1dp" />
+
+            <com.google.android.material.button.MaterialButton
+                android:id="@+id/startButton"
+                style="@style/Widget.MaterialComponents.Button"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Start" />
+        </LinearLayout>
+
+        <com.google.android.material.button.MaterialButton
+            android:id="@+id/stopButton"
+            style="@style/Widget.MaterialComponents.Button.OutlinedButton"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:text="Stop" />
+
+    </LinearLayout>
+</ScrollView>
diff --git a/app.bak.identity.20260330-222009/src/main/res/mipmap-hdpi/ic_launcher.png b/app.bak.identity.20260330-222009/src/main/res/mipmap-hdpi/ic_launcher.png
new file mode 100644
index 0000000..859d5c5
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diff --git a/app.bak.identity.20260330-222009/src/main/res/mipmap-hdpi/ic_launcher_round.png b/app.bak.identity.20260330-222009/src/main/res/mipmap-hdpi/ic_launcher_round.png
new file mode 100644
index 0000000..859d5c5
Binary files /dev/null and b/app.bak.identity.20260330-222009/src/main/res/mipmap-hdpi/ic_launcher_round.png differ
diff --git a/app.bak.identity.20260330-222009/src/main/res/mipmap-mdpi/ic_launcher.png b/app.bak.identity.20260330-222009/src/main/res/mipmap-mdpi/ic_launcher.png
new file mode 100644
index 0000000..3735675
Binary files /dev/null and b/app.bak.identity.20260330-222009/src/main/res/mipmap-mdpi/ic_launcher.png differ
diff --git a/app.bak.identity.20260330-222009/src/main/res/mipmap-mdpi/ic_launcher_round.png b/app.bak.identity.20260330-222009/src/main/res/mipmap-mdpi/ic_launcher_round.png
new file mode 100644
index 0000000..3735675
Binary files /dev/null and b/app.bak.identity.20260330-222009/src/main/res/mipmap-mdpi/ic_launcher_round.png differ
diff --git a/app.bak.identity.20260330-222009/src/main/res/mipmap-xhdpi/ic_launcher.png b/app.bak.identity.20260330-222009/src/main/res/mipmap-xhdpi/ic_launcher.png
new file mode 100644
index 0000000..b4442ee
Binary files /dev/null and b/app.bak.identity.20260330-222009/src/main/res/mipmap-xhdpi/ic_launcher.png differ
diff --git a/app.bak.identity.20260330-222009/src/main/res/mipmap-xhdpi/ic_launcher_round.png b/app.bak.identity.20260330-222009/src/main/res/mipmap-xhdpi/ic_launcher_round.png
new file mode 100644
index 0000000..b4442ee
Binary files /dev/null and b/app.bak.identity.20260330-222009/src/main/res/mipmap-xhdpi/ic_launcher_round.png differ
diff --git a/app.bak.identity.20260330-222009/src/main/res/mipmap-xxhdpi/ic_launcher.png b/app.bak.identity.20260330-222009/src/main/res/mipmap-xxhdpi/ic_launcher.png
new file mode 100644
index 0000000..2ceebd1
Binary files /dev/null and b/app.bak.identity.20260330-222009/src/main/res/mipmap-xxhdpi/ic_launcher.png differ
diff --git a/app.bak.identity.20260330-222009/src/main/res/mipmap-xxhdpi/ic_launcher_round.png b/app.bak.identity.20260330-222009/src/main/res/mipmap-xxhdpi/ic_launcher_round.png
new file mode 100644
index 0000000..2ceebd1
Binary files /dev/null and b/app.bak.identity.20260330-222009/src/main/res/mipmap-xxhdpi/ic_launcher_round.png differ
diff --git a/app.bak.identity.20260330-222009/src/main/res/mipmap-xxxhdpi/ic_launcher.png b/app.bak.identity.20260330-222009/src/main/res/mipmap-xxxhdpi/ic_launcher.png
new file mode 100644
index 0000000..38bb200
Binary files /dev/null and b/app.bak.identity.20260330-222009/src/main/res/mipmap-xxxhdpi/ic_launcher.png differ
diff --git a/app.bak.identity.20260330-222009/src/main/res/mipmap-xxxhdpi/ic_launcher_round.png b/app.bak.identity.20260330-222009/src/main/res/mipmap-xxxhdpi/ic_launcher_round.png
new file mode 100644
index 0000000..38bb200
Binary files /dev/null and b/app.bak.identity.20260330-222009/src/main/res/mipmap-xxxhdpi/ic_launcher_round.png differ
diff --git a/app.bak.identity.20260330-222009/src/main/res/values/colors.xml b/app.bak.identity.20260330-222009/src/main/res/values/colors.xml
new file mode 100644
index 0000000..ab35b9f
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/res/values/colors.xml
@@ -0,0 +1,7 @@
+<resources>
+    <color name="purple_500">#455A64</color>
+    <color name="purple_700">#263238</color>
+    <color name="teal_200">#80CBC4</color>
+    <color name="white">#FFFFFF</color>
+    <color name="black">#000000</color>
+</resources>
diff --git a/app.bak.identity.20260330-222009/src/main/res/values/strings.xml b/app.bak.identity.20260330-222009/src/main/res/values/strings.xml
new file mode 100644
index 0000000..1c75390
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/res/values/strings.xml
@@ -0,0 +1,6 @@
+<resources>
+    <string name="app_name">follow-me</string>
+    <string name="notification_channel_name">Tracking</string>
+    <string name="notification_title">otb-tcom tracking active</string>
+    <string name="notification_text">Posting location updates to follow-me</string>
+</resources>
diff --git a/app.bak.identity.20260330-222009/src/main/res/values/themes.xml b/app.bak.identity.20260330-222009/src/main/res/values/themes.xml
new file mode 100644
index 0000000..da57f2d
--- /dev/null
+++ b/app.bak.identity.20260330-222009/src/main/res/values/themes.xml
@@ -0,0 +1,9 @@
+<resources xmlns:tools="http://schemas.android.com/tools">
+    <style name="Theme.FollowMe" parent="Theme.MaterialComponents.DayNight.NoActionBar">
+        <item name="colorPrimary">@color/purple_500</item>
+        <item name="colorPrimaryVariant">@color/purple_700</item>
+        <item name="colorOnPrimary">@color/white</item>
+        <item name="colorSecondary">@color/teal_200</item>
+        <item name="android:statusBarColor" tools:targetApi="l">@color/purple_700</item>
+    </style>
+</resources>
diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index 17c9064..d2f6f42 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -11,8 +11,8 @@ android {
         applicationId = "top.outsidethebox.followme"
         minSdk = 23
         targetSdk = 34
-        versionCode = 1
-        versionName = "0.1.0"
+        versionCode = 5
+        versionName = "0.5.0"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }
@@ -25,11 +25,15 @@ android {
                 "proguard-rules.pro"
             )
         }
+        debug {
+            isMinifyEnabled = false
+        }
     }
 
     compileOptions {
         sourceCompatibility = JavaVersion.VERSION_17
         targetCompatibility = JavaVersion.VERSION_17
+        isCoreLibraryDesugaringEnabled = true
     }
 
     kotlinOptions {
@@ -42,6 +46,8 @@ android {
 }
 
 dependencies {
+    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.1.5")
+
     implementation("androidx.core:core-ktx:1.12.0")
     implementation("androidx.appcompat:appcompat:1.7.0")
     implementation("com.google.android.material:material:1.11.0")
diff --git a/app/build.gradle.kts.bak.fix.20260330-222351 b/app/build.gradle.kts.bak.fix.20260330-222351
new file mode 100644
index 0000000..6cc823e
--- /dev/null
+++ b/app/build.gradle.kts.bak.fix.20260330-222351
@@ -0,0 +1,61 @@
+plugins {
+    id("com.android.application")
+    id("org.jetbrains.kotlin.android")
+}
+
+android {
+    namespace = "top.outsidethebox.followme"
+    compileSdk = 34
+
+    defaultConfig {
+        applicationId = "top.outsidethebox.followme"
+        minSdk = 23
+        targetSdk = 34
+        versionCode = 4
+        versionName = "0.4.0"
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+        }
+        debug {
+            isMinifyEnabled = false
+        }
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+        isCoreLibraryDesugaringEnabled = true
+    }
+
+    kotlinOptions {
+        jvmTarget = "17"
+    }
+
+    buildFeatures {
+        viewBinding = true
+    }
+}
+
+dependencies {
+    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.1.5")
+
+    implementation("androidx.core:core-ktx:1.12.0")
+    implementation("androidx.appcompat:appcompat:1.7.0")
+    implementation("com.google.android.material:material:1.11.0")
+    implementation("androidx.activity:activity-ktx:1.8.2")
+    implementation("androidx.constraintlayout:constraintlayout:2.1.4")
+    implementation("androidx.lifecycle:lifecycle-service:2.7.0")
+    implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.7.0")
+    implementation("com.google.android.gms:play-services-location:21.2.0")
+    implementation("com.squareup.okhttp3:okhttp:4.12.0")
+    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-android:1.7.3")
+}
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 21ca131..eaba08c 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -5,16 +5,15 @@
     <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
     <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
-    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_LOCATION" />
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
     <uses-permission android:name="android.permission.WAKE_LOCK" />
     <uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
 
     <application
         android:allowBackup="true"
-        android:icon="@drawable/ic_launcher_foreground"
-        android:label="otb-tcom"
-        android:roundIcon="@drawable/ic_launcher_foreground"
+        android:icon="@mipmap/ic_launcher"
+        android:label="follow-me"
+        android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/Theme.FollowMe"
         android:usesCleartextTraffic="true">
diff --git a/app/src/main/java/top/outsidethebox/followme/DeviceIdentity.kt b/app/src/main/java/top/outsidethebox/followme/DeviceIdentity.kt
new file mode 100644
index 0000000..02530a3
--- /dev/null
+++ b/app/src/main/java/top/outsidethebox/followme/DeviceIdentity.kt
@@ -0,0 +1,39 @@
+package top.outsidethebox.followme
+
+import android.content.Context
+import android.provider.Settings
+import java.util.UUID
+
+object DeviceIdentity {
+    fun get(context: Context): Triple<String, String, String> {
+        val prefs = context.getSharedPreferences("followme_prefs", Context.MODE_PRIVATE)
+
+        var uuid = prefs.getString("device_uuid", null)
+        if (uuid.isNullOrBlank()) {
+            uuid = UUID.randomUUID().toString()
+            prefs.edit().putString("device_uuid", uuid).apply()
+        }
+
+        val androidId = Settings.Secure.getString(
+            context.contentResolver,
+            Settings.Secure.ANDROID_ID
+        ) ?: ""
+
+        val manufacturer = android.os.Build.MANUFACTURER.orEmpty().trim()
+        val model = android.os.Build.MODEL.orEmpty().trim()
+        val shortId = uuid.takeLast(4)
+
+        val baseName = listOf(manufacturer, model)
+            .filter { it.isNotBlank() }
+            .joinToString("-")
+            .replace("\\s+".toRegex(), "-")
+
+        val deviceName = if (baseName.isBlank()) {
+            "android-$shortId"
+        } else {
+            "$baseName-$shortId"
+        }
+
+        return Triple(uuid, androidId, deviceName)
+    }
+}
diff --git a/app/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt b/app/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt
index b91dad8..b6a5d15 100644
--- a/app/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt
+++ b/app/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt
@@ -1,8 +1,11 @@
 package top.outsidethebox.followme.data
 
+import android.content.Context
 import org.json.JSONObject
+import top.outsidethebox.followme.DeviceIdentity
 
 data class GpsPayload(
+    val context: Context,
     val latitude: Double,
     val longitude: Double,
     val speedKmh: Double? = null,
@@ -14,14 +17,21 @@ data class GpsPayload(
 ) {
     fun toJson(): String {
         val json = JSONObject()
+        val (deviceUuid, androidId, deviceName) = DeviceIdentity.get(context)
+
         json.put("latitude", latitude)
         json.put("longitude", longitude)
+        json.put("device_uuid", deviceUuid)
+        json.put("android_id", androidId)
+        json.put("device_name", deviceName)
+
         speedKmh?.let { json.put("speed_kmh", it) }
         accuracyM?.let { json.put("accuracy_m", it) }
         headingDeg?.let { json.put("heading_deg", it) }
         altitudeM?.let { json.put("altitude_m", it) }
         recordedAt?.let { json.put("recorded_at", it) }
         json.put("source", source)
+
         return json.toString()
     }
 }
diff --git a/app/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt.bak.fix.20260330-222351 b/app/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt.bak.fix.20260330-222351
new file mode 100644
index 0000000..65d730b
--- /dev/null
+++ b/app/src/main/java/top/outsidethebox/followme/data/GpsPayload.kt.bak.fix.20260330-222351
@@ -0,0 +1,34 @@
+import top.outsidethebox.followme.DeviceIdentity
+import android.content.Context
+package top.outsidethebox.followme.data
+
+import org.json.JSONObject
+
+data class GpsPayload(
+    val context: Context,
+    val latitude: Double,
+    val longitude: Double,
+    val speedKmh: Double? = null,
+    val accuracyM: Float? = null,
+    val headingDeg: Float? = null,
+    val altitudeM: Double? = null,
+    val recordedAt: String? = null,
+    val source: String = AppPrefs.DEFAULT_SOURCE
+) {
+    fun toJson(): String {
+        val json = JSONObject()
+        val (deviceUuid, androidId, deviceName) = DeviceIdentity.get(context)
+        json.put("device_uuid", deviceUuid)
+        json.put("android_id", androidId)
+        json.put("device_name", deviceName)
+        json.put("latitude", latitude)
+        json.put("longitude", longitude)
+        speedKmh?.let { json.put("speed_kmh", it) }
+        accuracyM?.let { json.put("accuracy_m", it) }
+        headingDeg?.let { json.put("heading_deg", it) }
+        altitudeM?.let { json.put("altitude_m", it) }
+        recordedAt?.let { json.put("recorded_at", it) }
+        json.put("source", source)
+        return json.toString()
+    }
+}
diff --git a/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt b/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt
index 9e95e45..8c7d99a 100644
--- a/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt
+++ b/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt
@@ -10,11 +10,17 @@ import android.content.Context
 import android.content.Intent
 import android.content.pm.PackageManager
 import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
 import android.os.Build
+import android.os.Bundle
 import android.os.IBinder
+import android.util.Log
 import androidx.core.app.ActivityCompat
 import androidx.core.app.NotificationCompat
 import androidx.core.app.ServiceCompat
+import com.google.android.gms.common.ConnectionResult
+import com.google.android.gms.common.GoogleApiAvailability
 import com.google.android.gms.location.FusedLocationProviderClient
 import com.google.android.gms.location.LocationCallback
 import com.google.android.gms.location.LocationRequest
@@ -42,12 +48,15 @@ class TrackingService : Service() {
 
     private var currentMode: TrackingMode = TrackingMode.MOVING
     private var locationCallback: LocationCallback? = null
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
 
     override fun onCreate() {
         super.onCreate()
         prefs = AppPrefs(applicationContext)
         repository = IngestRepository(applicationContext)
         fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
         createNotificationChannel()
     }
 
@@ -77,7 +86,7 @@ class TrackingService : Service() {
         val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
             .setContentTitle(getString(R.string.notification_title))
             .setContentText(getString(R.string.notification_text))
-            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setSmallIcon(R.mipmap.ic_launcher)
             .setContentIntent(pendingIntent)
             .setOngoing(true)
             .build()
@@ -86,7 +95,11 @@ class TrackingService : Service() {
             this,
             NOTIFICATION_ID,
             notification,
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+                android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION
+            } else {
+                0
+            }
         )
     }
 
@@ -96,28 +109,125 @@ class TrackingService : Service() {
         stopLocationUpdates()
         currentMode = mode
 
-        val request = LocationRequest.Builder(Priority.PRIORITY_HIGH_ACCURACY, mode.intervalMs)
-            .setMinUpdateIntervalMillis(mode.intervalMs)
-            .setWaitForAccurateLocation(false)
-            .build()
+        val playServicesOk =
+            GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(this) == ConnectionResult.SUCCESS
+
+        if (playServicesOk) {
+            try {
+                val request = LocationRequest.Builder(
+                    Priority.PRIORITY_HIGH_ACCURACY,
+                    15000L
+                )
+                    .setMinUpdateIntervalMillis(5000L)
+                    .setMinUpdateDistanceMeters(10f)
+                    .setWaitForAccurateLocation(false)
+                    .build()
+
+                locationCallback = object : LocationCallback() {
+                    override fun onLocationResult(result: LocationResult) {
+                        val location = result.lastLocation ?: return
+                        val nextMode = decideMode(location)
+                        if (nextMode != currentMode) {
+                            startLocationUpdates(nextMode)
+                            return
+                        }
+                        uploadLocation(location)
+                    }
+                }
+
+                fusedLocationClient.requestLocationUpdates(
+                    request,
+                    locationCallback!!,
+                    mainLooper
+                )
+
+                Log.d(TAG, "Using FusedLocationProviderClient")
+                return
+            } catch (e: Exception) {
+                Log.w(TAG, "Fused location failed, falling back to LocationManager", e)
+            }
+        } else {
+            Log.w(TAG, "Google Play Services unavailable, using LocationManager fallback")
+        }
+
+        startLegacyGpsFallback()
+    }
+
+    @Suppress("MissingPermission")
+    private fun startLegacyGpsFallback() {
+        val lm = locationManager ?: return
+
+        val minTimeMs = 15000L
+        val minDistanceM = 10f
 
-        locationCallback = object : LocationCallback() {
-            override fun onLocationResult(result: LocationResult) {
-                val location = result.lastLocation ?: return
+        gpsLocationListener = object : LocationListener {
+            override fun onLocationChanged(location: Location) {
                 val nextMode = decideMode(location)
                 if (nextMode != currentMode) {
                     startLocationUpdates(nextMode)
+                    return
                 }
                 uploadLocation(location)
             }
+
+            override fun onStatusChanged(provider: String?, status: Int, extras: Bundle?) {}
+            override fun onProviderEnabled(provider: String) {}
+            override fun onProviderDisabled(provider: String) {}
         }
 
-        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+        var requested = false
+
+        try {
+            if (lm.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
+                lm.requestLocationUpdates(
+                    LocationManager.GPS_PROVIDER,
+                    minTimeMs,
+                    minDistanceM,
+                    gpsLocationListener!!,
+                    mainLooper
+                )
+                requested = true
+                Log.d(TAG, "Requested GPS_PROVIDER updates")
+            }
+        } catch (e: Exception) {
+            Log.w(TAG, "GPS_PROVIDER request failed", e)
+        }
+
+        try {
+            if (lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER)) {
+                lm.requestLocationUpdates(
+                    LocationManager.NETWORK_PROVIDER,
+                    minTimeMs,
+                    minDistanceM,
+                    gpsLocationListener!!,
+                    mainLooper
+                )
+                requested = true
+                Log.d(TAG, "Requested NETWORK_PROVIDER updates")
+            }
+        } catch (e: Exception) {
+            Log.w(TAG, "NETWORK_PROVIDER request failed", e)
+        }
+
+        if (!requested) {
+            Log.w(TAG, "No location providers available for fallback")
+        }
     }
 
     private fun stopLocationUpdates() {
-        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        try {
+            locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        } catch (_: Exception) {
+        }
         locationCallback = null
+
+        try {
+            gpsLocationListener?.let { listener ->
+                locationManager?.removeUpdates(listener)
+            }
+        } catch (_: Exception) {
+        }
+        gpsLocationListener = null
     }
 
     private fun decideMode(location: Location): TrackingMode {
@@ -128,13 +238,14 @@ class TrackingService : Service() {
     private fun uploadLocation(location: Location) {
         val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
         val payload = GpsPayload(
+            context = this,
             latitude = location.latitude,
             longitude = location.longitude,
             speedKmh = speedKmh,
             accuracyM = if (location.hasAccuracy()) location.accuracy else null,
             headingDeg = if (location.hasBearing()) location.bearing else null,
             altitudeM = if (location.hasAltitude()) location.altitude else null,
-            recordedAt = TimeUtils.nowIsoUtc(),
+            recordedAt = TimeUtils.millisToIsoUtc(location.time),
             source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
         )
 
@@ -168,6 +279,7 @@ class TrackingService : Service() {
     }
 
     companion object {
+        private const val TAG = "TrackingService"
         private const val CHANNEL_ID = "follow_me_tracking"
         private const val NOTIFICATION_ID = 7001
 
diff --git a/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-162412 b/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-162412
new file mode 100644
index 0000000..16d7ff2
--- /dev/null
+++ b/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-162412
@@ -0,0 +1,206 @@
+package top.outsidethebox.followme.service
+
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Bundle
+import android.util.Log
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.common.ConnectionResult
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    companion object {
+        private const val TAG = "TrackingService"
+    }
+    private var locationCallback: LocationCallback? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val request = LocationRequest.Builder(
+            Priority.PRIORITY_HIGH_ACCURACY,
+            15000L
+        )
+            .setMinUpdateIntervalMillis(5000L)
+            .setMinUpdateDistanceMeters(10f)
+            .setWaitForAccurateLocation(false)
+            .build()
+
+        locationCallback = object : LocationCallback() {
+            override fun onLocationResult(result: LocationResult) {
+                val location = result.lastLocation ?: return
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                }
+                uploadLocation(location)
+            }
+        }
+
+        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+    }
+
+    private fun stopLocationUpdates() {
+        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        locationCallback = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.nowIsoUtc(),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-164620 b/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-164620
new file mode 100644
index 0000000..16d7ff2
--- /dev/null
+++ b/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-164620
@@ -0,0 +1,206 @@
+package top.outsidethebox.followme.service
+
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Bundle
+import android.util.Log
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.common.ConnectionResult
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    companion object {
+        private const val TAG = "TrackingService"
+    }
+    private var locationCallback: LocationCallback? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val request = LocationRequest.Builder(
+            Priority.PRIORITY_HIGH_ACCURACY,
+            15000L
+        )
+            .setMinUpdateIntervalMillis(5000L)
+            .setMinUpdateDistanceMeters(10f)
+            .setWaitForAccurateLocation(false)
+            .build()
+
+        locationCallback = object : LocationCallback() {
+            override fun onLocationResult(result: LocationResult) {
+                val location = result.lastLocation ?: return
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                }
+                uploadLocation(location)
+            }
+        }
+
+        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+    }
+
+    private fun stopLocationUpdates() {
+        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        locationCallback = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.nowIsoUtc(),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171557 b/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171557
new file mode 100644
index 0000000..16d7ff2
--- /dev/null
+++ b/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171557
@@ -0,0 +1,206 @@
+package top.outsidethebox.followme.service
+
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Bundle
+import android.util.Log
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.common.ConnectionResult
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    companion object {
+        private const val TAG = "TrackingService"
+    }
+    private var locationCallback: LocationCallback? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val request = LocationRequest.Builder(
+            Priority.PRIORITY_HIGH_ACCURACY,
+            15000L
+        )
+            .setMinUpdateIntervalMillis(5000L)
+            .setMinUpdateDistanceMeters(10f)
+            .setWaitForAccurateLocation(false)
+            .build()
+
+        locationCallback = object : LocationCallback() {
+            override fun onLocationResult(result: LocationResult) {
+                val location = result.lastLocation ?: return
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                }
+                uploadLocation(location)
+            }
+        }
+
+        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+    }
+
+    private fun stopLocationUpdates() {
+        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        locationCallback = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.nowIsoUtc(),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171616 b/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171616
new file mode 100644
index 0000000..16d7ff2
--- /dev/null
+++ b/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.20260318-171616
@@ -0,0 +1,206 @@
+package top.outsidethebox.followme.service
+
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Bundle
+import android.util.Log
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.common.ConnectionResult
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.os.Build
+import android.os.IBinder
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    companion object {
+        private const val TAG = "TrackingService"
+    }
+    private var locationCallback: LocationCallback? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(android.R.drawable.ic_menu_mylocation)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION else 0
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val request = LocationRequest.Builder(
+            Priority.PRIORITY_HIGH_ACCURACY,
+            15000L
+        )
+            .setMinUpdateIntervalMillis(5000L)
+            .setMinUpdateDistanceMeters(10f)
+            .setWaitForAccurateLocation(false)
+            .build()
+
+        locationCallback = object : LocationCallback() {
+            override fun onLocationResult(result: LocationResult) {
+                val location = result.lastLocation ?: return
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                }
+                uploadLocation(location)
+            }
+        }
+
+        fusedLocationClient.requestLocationUpdates(request, locationCallback!!, mainLooper)
+    }
+
+    private fun stopLocationUpdates() {
+        locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        locationCallback = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.nowIsoUtc(),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.fix.20260330-222351 b/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.fix.20260330-222351
new file mode 100644
index 0000000..8c7d99a
--- /dev/null
+++ b/app/src/main/java/top/outsidethebox/followme/service/TrackingService.kt.bak.fix.20260330-222351
@@ -0,0 +1,299 @@
+package top.outsidethebox.followme.service
+
+import android.Manifest
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.location.Location
+import android.location.LocationListener
+import android.location.LocationManager
+import android.os.Build
+import android.os.Bundle
+import android.os.IBinder
+import android.util.Log
+import androidx.core.app.ActivityCompat
+import androidx.core.app.NotificationCompat
+import androidx.core.app.ServiceCompat
+import com.google.android.gms.common.ConnectionResult
+import com.google.android.gms.common.GoogleApiAvailability
+import com.google.android.gms.location.FusedLocationProviderClient
+import com.google.android.gms.location.LocationCallback
+import com.google.android.gms.location.LocationRequest
+import com.google.android.gms.location.LocationResult
+import com.google.android.gms.location.LocationServices
+import com.google.android.gms.location.Priority
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.launch
+import top.outsidethebox.followme.R
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.data.GpsPayload
+import top.outsidethebox.followme.data.IngestRepository
+import top.outsidethebox.followme.location.TrackingMode
+import top.outsidethebox.followme.ui.MainActivity
+import top.outsidethebox.followme.util.TimeUtils
+
+class TrackingService : Service() {
+    private lateinit var fusedLocationClient: FusedLocationProviderClient
+    private lateinit var prefs: AppPrefs
+    private lateinit var repository: IngestRepository
+    private val scope = CoroutineScope(Dispatchers.IO + Job())
+
+    private var currentMode: TrackingMode = TrackingMode.MOVING
+    private var locationCallback: LocationCallback? = null
+    private var locationManager: LocationManager? = null
+    private var gpsLocationListener: LocationListener? = null
+
+    override fun onCreate() {
+        super.onCreate()
+        prefs = AppPrefs(applicationContext)
+        repository = IngestRepository(applicationContext)
+        fusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
+        locationManager = getSystemService(LOCATION_SERVICE) as LocationManager
+        createNotificationChannel()
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        prefs.setTrackingEnabled(true)
+        startAsForeground()
+        startLocationUpdates(currentMode)
+        return START_STICKY
+    }
+
+    override fun onDestroy() {
+        stopLocationUpdates()
+        scope.cancel()
+        super.onDestroy()
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun startAsForeground() {
+        val pendingIntent = PendingIntent.getActivity(
+            this,
+            1001,
+            Intent(this, MainActivity::class.java),
+            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+        )
+
+        val notification: Notification = NotificationCompat.Builder(this, CHANNEL_ID)
+            .setContentTitle(getString(R.string.notification_title))
+            .setContentText(getString(R.string.notification_text))
+            .setSmallIcon(R.mipmap.ic_launcher)
+            .setContentIntent(pendingIntent)
+            .setOngoing(true)
+            .build()
+
+        ServiceCompat.startForeground(
+            this,
+            NOTIFICATION_ID,
+            notification,
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+                android.content.pm.ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION
+            } else {
+                0
+            }
+        )
+    }
+
+    private fun startLocationUpdates(mode: TrackingMode) {
+        if (!hasLocationPermission()) return
+
+        stopLocationUpdates()
+        currentMode = mode
+
+        val playServicesOk =
+            GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(this) == ConnectionResult.SUCCESS
+
+        if (playServicesOk) {
+            try {
+                val request = LocationRequest.Builder(
+                    Priority.PRIORITY_HIGH_ACCURACY,
+                    15000L
+                )
+                    .setMinUpdateIntervalMillis(5000L)
+                    .setMinUpdateDistanceMeters(10f)
+                    .setWaitForAccurateLocation(false)
+                    .build()
+
+                locationCallback = object : LocationCallback() {
+                    override fun onLocationResult(result: LocationResult) {
+                        val location = result.lastLocation ?: return
+                        val nextMode = decideMode(location)
+                        if (nextMode != currentMode) {
+                            startLocationUpdates(nextMode)
+                            return
+                        }
+                        uploadLocation(location)
+                    }
+                }
+
+                fusedLocationClient.requestLocationUpdates(
+                    request,
+                    locationCallback!!,
+                    mainLooper
+                )
+
+                Log.d(TAG, "Using FusedLocationProviderClient")
+                return
+            } catch (e: Exception) {
+                Log.w(TAG, "Fused location failed, falling back to LocationManager", e)
+            }
+        } else {
+            Log.w(TAG, "Google Play Services unavailable, using LocationManager fallback")
+        }
+
+        startLegacyGpsFallback()
+    }
+
+    @Suppress("MissingPermission")
+    private fun startLegacyGpsFallback() {
+        val lm = locationManager ?: return
+
+        val minTimeMs = 15000L
+        val minDistanceM = 10f
+
+        gpsLocationListener = object : LocationListener {
+            override fun onLocationChanged(location: Location) {
+                val nextMode = decideMode(location)
+                if (nextMode != currentMode) {
+                    startLocationUpdates(nextMode)
+                    return
+                }
+                uploadLocation(location)
+            }
+
+            override fun onStatusChanged(provider: String?, status: Int, extras: Bundle?) {}
+            override fun onProviderEnabled(provider: String) {}
+            override fun onProviderDisabled(provider: String) {}
+        }
+
+        var requested = false
+
+        try {
+            if (lm.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
+                lm.requestLocationUpdates(
+                    LocationManager.GPS_PROVIDER,
+                    minTimeMs,
+                    minDistanceM,
+                    gpsLocationListener!!,
+                    mainLooper
+                )
+                requested = true
+                Log.d(TAG, "Requested GPS_PROVIDER updates")
+            }
+        } catch (e: Exception) {
+            Log.w(TAG, "GPS_PROVIDER request failed", e)
+        }
+
+        try {
+            if (lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER)) {
+                lm.requestLocationUpdates(
+                    LocationManager.NETWORK_PROVIDER,
+                    minTimeMs,
+                    minDistanceM,
+                    gpsLocationListener!!,
+                    mainLooper
+                )
+                requested = true
+                Log.d(TAG, "Requested NETWORK_PROVIDER updates")
+            }
+        } catch (e: Exception) {
+            Log.w(TAG, "NETWORK_PROVIDER request failed", e)
+        }
+
+        if (!requested) {
+            Log.w(TAG, "No location providers available for fallback")
+        }
+    }
+
+    private fun stopLocationUpdates() {
+        try {
+            locationCallback?.let { fusedLocationClient.removeLocationUpdates(it) }
+        } catch (_: Exception) {
+        }
+        locationCallback = null
+
+        try {
+            gpsLocationListener?.let { listener ->
+                locationManager?.removeUpdates(listener)
+            }
+        } catch (_: Exception) {
+        }
+        gpsLocationListener = null
+    }
+
+    private fun decideMode(location: Location): TrackingMode {
+        val speedKmh = if (location.hasSpeed()) location.speed * 3.6 else 0.0
+        return if (speedKmh >= 8.0) TrackingMode.MOVING else TrackingMode.IDLE
+    }
+
+    private fun uploadLocation(location: Location) {
+        val speedKmh = if (location.hasSpeed()) (location.speed * 3.6) else 0.0
+        val payload = GpsPayload(
+            context = this,
+            latitude = location.latitude,
+            longitude = location.longitude,
+            speedKmh = speedKmh,
+            accuracyM = if (location.hasAccuracy()) location.accuracy else null,
+            headingDeg = if (location.hasBearing()) location.bearing else null,
+            altitudeM = if (location.hasAltitude()) location.altitude else null,
+            recordedAt = TimeUtils.millisToIsoUtc(location.time),
+            source = prefs.getSource().ifBlank { AppPrefs.DEFAULT_SOURCE }
+        )
+
+        scope.launch {
+            val result = repository.send(payload)
+            val status = if (result.success) {
+                "${TimeUtils.nowPrettyLocal()} via ${result.usedTransport.uppercase()}"
+            } else {
+                "failed ${TimeUtils.nowPrettyLocal()} (${result.errorMessage ?: "unknown"})"
+            }
+            prefs.setLastUpload(status)
+        }
+    }
+
+    private fun hasLocationPermission(): Boolean {
+        val fine = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                CHANNEL_ID,
+                getString(R.string.notification_channel_name),
+                NotificationManager.IMPORTANCE_LOW
+            )
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    companion object {
+        private const val TAG = "TrackingService"
+        private const val CHANNEL_ID = "follow_me_tracking"
+        private const val NOTIFICATION_ID = 7001
+
+        fun start(context: Context) {
+            val intent = Intent(context, TrackingService::class.java)
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+                context.startForegroundService(intent)
+            } else {
+                context.startService(intent)
+            }
+        }
+
+        fun stop(context: Context) {
+            context.stopService(Intent(context, TrackingService::class.java))
+        }
+    }
+}
diff --git a/app/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt.bak.20260316-205644 b/app/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt.bak.20260316-205644
new file mode 100644
index 0000000..2f6253b
--- /dev/null
+++ b/app/src/main/java/top/outsidethebox/followme/ui/MainActivity.kt.bak.20260316-205644
@@ -0,0 +1,108 @@
+package top.outsidethebox.followme.ui
+
+import android.Manifest
+import android.content.pm.PackageManager
+import android.os.Build
+import android.os.Bundle
+import android.widget.Toast
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.content.ContextCompat
+import top.outsidethebox.followme.data.AppPrefs
+import top.outsidethebox.followme.databinding.ActivityMainBinding
+import top.outsidethebox.followme.service.TrackingService
+
+class MainActivity : AppCompatActivity() {
+    private lateinit var binding: ActivityMainBinding
+    private lateinit var prefs: AppPrefs
+
+    private val permissionLauncher = registerForActivityResult(
+        ActivityResultContracts.RequestMultiplePermissions()
+    ) { refreshUi() }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        binding = ActivityMainBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+        prefs = AppPrefs(applicationContext)
+
+        binding.endpointView.text = buildString {
+            append("Primary: ")
+            append(AppPrefs.HTTPS_ENDPOINT)
+            append("\nFallback: ")
+            append(AppPrefs.HTTP_ENDPOINT)
+        }
+
+        populateFields()
+        wireActions()
+        refreshUi()
+    }
+
+    override fun onResume() {
+        super.onResume()
+        refreshUi()
+    }
+
+    private fun populateFields() {
+        binding.tokenInput.setText(prefs.getToken())
+        binding.roleInput.setText(prefs.getRole())
+        binding.networkInput.setText(prefs.getNetworkNote())
+        binding.sourceInput.setText(prefs.getSource())
+    }
+
+    private fun wireActions() {
+        binding.saveButton.setOnClickListener {
+            saveSettings()
+            Toast.makeText(this, "Saved", Toast.LENGTH_SHORT).show()
+            refreshUi()
+        }
+
+        binding.startButton.setOnClickListener {
+            saveSettings()
+            if (!hasBaseLocationPermission()) {
+                requestPermissions()
+                return@setOnClickListener
+            }
+            TrackingService.start(this)
+            prefs.setTrackingEnabled(true)
+            refreshUi()
+        }
+
+        binding.stopButton.setOnClickListener {
+            TrackingService.stop(this)
+            prefs.setTrackingEnabled(false)
+            refreshUi()
+        }
+    }
+
+    private fun saveSettings() {
+        prefs.setToken(binding.tokenInput.text?.toString()?.trim().orEmpty())
+        prefs.setRole(binding.roleInput.text?.toString()?.trim().orEmpty())
+        prefs.setNetworkNote(binding.networkInput.text?.toString()?.trim().orEmpty())
+        prefs.setSource(binding.sourceInput.text?.toString()?.trim().ifBlank { AppPrefs.DEFAULT_SOURCE })
+    }
+
+    private fun refreshUi() {
+        val protocol = prefs.getPreferredTransport().uppercase()
+        binding.protocolView.text = "Preferred protocol: $protocol (HTTPS fallback count: ${prefs.getConsecutiveHttpsFallbacks()})"
+        binding.lastUploadView.text = "Last upload: ${prefs.getLastUpload()}"
+        binding.statusView.text = if (prefs.isTrackingEnabled()) "Status: running" else "Status: stopped"
+    }
+
+    private fun hasBaseLocationPermission(): Boolean {
+        val fine = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        val coarse = ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED
+        return fine || coarse
+    }
+
+    private fun requestPermissions() {
+        val permissions = mutableListOf(
+            Manifest.permission.ACCESS_FINE_LOCATION,
+            Manifest.permission.ACCESS_COARSE_LOCATION
+        )
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            permissions += Manifest.permission.ACCESS_BACKGROUND_LOCATION
+        }
+        permissionLauncher.launch(permissions.toTypedArray())
+    }
+}
diff --git a/app/src/main/java/top/outsidethebox/followme/util/TimeUtils.kt b/app/src/main/java/top/outsidethebox/followme/util/TimeUtils.kt
index 231fa0e..e01ddfb 100644
--- a/app/src/main/java/top/outsidethebox/followme/util/TimeUtils.kt
+++ b/app/src/main/java/top/outsidethebox/followme/util/TimeUtils.kt
@@ -1,16 +1,29 @@
 package top.outsidethebox.followme.util
 
-import java.time.Instant
-import java.time.ZoneId
-import java.time.format.DateTimeFormatter
+import java.text.SimpleDateFormat
+import java.util.Date
 import java.util.Locale
+import java.util.TimeZone
 
 object TimeUtils {
-    private val localFormatter: DateTimeFormatter =
-        DateTimeFormatter.ofPattern("yyyy-MM-dd hh:mm:ss a z", Locale.US)
-            .withZone(ZoneId.systemDefault())
+    private val isoFormatter = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US).apply {
+        timeZone = TimeZone.getTimeZone("UTC")
+    }
 
-    fun nowIsoUtc(): String = Instant.now().toString()
+    private val prettyLocalFormatter = SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.US)
 
-    fun nowPrettyLocal(): String = localFormatter.format(Instant.now())
+    @Synchronized
+    fun nowIsoUtc(): String {
+        return isoFormatter.format(Date())
+    }
+
+    @Synchronized
+    fun millisToIsoUtc(millis: Long): String {
+        return isoFormatter.format(Date(millis))
+    }
+
+    @Synchronized
+    fun nowPrettyLocal(): String {
+        return prettyLocalFormatter.format(Date())
+    }
 }
diff --git a/app/src/main/res/drawable/ic_launcher_foreground.png b/app/src/main/res/drawable/ic_launcher_foreground.png
new file mode 100644
index 0000000..2860387
Binary files /dev/null and b/app/src/main/res/drawable/ic_launcher_foreground.png differ
diff --git a/app/src/main/res/drawable/ic_launcher_foreground.xml b/app/src/main/res/drawable/ic_launcher_foreground.xml
deleted file mode 100644
index 37e5bdb..0000000
--- a/app/src/main/res/drawable/ic_launcher_foreground.xml
+++ /dev/null
@@ -1,12 +0,0 @@
-<vector xmlns:android="http://schemas.android.com/apk/res/android"
-    android:width="108dp"
-    android:height="108dp"
-    android:viewportWidth="108"
-    android:viewportHeight="108">
-    <path
-        android:fillColor="#263238"
-        android:pathData="M18,18h72v72h-72z" />
-    <path
-        android:fillColor="#80CBC4"
-        android:pathData="M54,22c-12.7,0 -23,10.3 -23,23c0,16.5 23,41 23,41s23,-24.5 23,-41c0,-12.7 -10.3,-23 -23,-23zM54,56c-6.1,0 -11,-4.9 -11,-11s4.9,-11 11,-11s11,4.9 11,11s-4.9,11 -11,11z" />
-</vector>
diff --git a/app/src/main/res/drawable/otb_logo.png b/app/src/main/res/drawable/otb_logo.png
new file mode 100644
index 0000000..dd9f3fa
Binary files /dev/null and b/app/src/main/res/drawable/otb_logo.png differ
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index 23619fc..2ed98ab 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -10,18 +10,34 @@
         android:orientation="vertical"
         android:padding="16dp">
 
-        <TextView
+        <LinearLayout
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:text="follow-me installer"
-            android:textSize="24sp"
-            android:textStyle="bold" />
+            android:orientation="horizontal"
+            android:gravity="center_vertical">
+
+            <ImageView
+                android:id="@+id/headerLogo"
+                android:layout_width="36dp"
+                android:layout_height="36dp"
+                android:layout_marginEnd="10dp"
+                android:adjustViewBounds="true"
+                android:contentDescription="OTB logo"
+                android:src="@drawable/otb_logo" />
+
+            <TextView
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="follow-me"
+                android:textSize="24sp"
+                android:textStyle="bold" />
+        </LinearLayout>
 
         <TextView
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:layout_marginTop="6dp"
-            android:text="Operational app name: otb-tcom"
+            android:text="Operational app name: follow-me"
             android:textSize="14sp" />
 
         <com.google.android.material.textfield.TextInputLayout
diff --git a/app/src/main/res/mipmap-hdpi/ic_launcher.png b/app/src/main/res/mipmap-hdpi/ic_launcher.png
new file mode 100644
index 0000000..dd9f3fa
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diff --git a/app/src/main/res/mipmap-hdpi/ic_launcher_round.png b/app/src/main/res/mipmap-hdpi/ic_launcher_round.png
new file mode 100644
index 0000000..dd9f3fa
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diff --git a/app/src/main/res/mipmap-mdpi/ic_launcher.png b/app/src/main/res/mipmap-mdpi/ic_launcher.png
new file mode 100644
index 0000000..dd9f3fa
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diff --git a/app/src/main/res/mipmap-mdpi/ic_launcher_round.png b/app/src/main/res/mipmap-mdpi/ic_launcher_round.png
new file mode 100644
index 0000000..dd9f3fa
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diff --git a/app/src/main/res/mipmap-xhdpi/ic_launcher.png b/app/src/main/res/mipmap-xhdpi/ic_launcher.png
new file mode 100644
index 0000000..dd9f3fa
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diff --git a/app/src/main/res/mipmap-xhdpi/ic_launcher_round.png b/app/src/main/res/mipmap-xhdpi/ic_launcher_round.png
new file mode 100644
index 0000000..dd9f3fa
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diff --git a/app/src/main/res/mipmap-xxhdpi/ic_launcher.png b/app/src/main/res/mipmap-xxhdpi/ic_launcher.png
new file mode 100644
index 0000000..dd9f3fa
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diff --git a/app/src/main/res/mipmap-xxhdpi/ic_launcher_round.png b/app/src/main/res/mipmap-xxhdpi/ic_launcher_round.png
new file mode 100644
index 0000000..dd9f3fa
Binary files /dev/null and b/app/src/main/res/mipmap-xxhdpi/ic_launcher_round.png differ
diff --git a/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png b/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png
new file mode 100644
index 0000000..dd9f3fa
Binary files /dev/null and b/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png differ
diff --git a/app/src/main/res/mipmap-xxxhdpi/ic_launcher_round.png b/app/src/main/res/mipmap-xxxhdpi/ic_launcher_round.png
new file mode 100644
index 0000000..dd9f3fa
Binary files /dev/null and b/app/src/main/res/mipmap-xxxhdpi/ic_launcher_round.png differ
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 226839a..1c75390 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -1,5 +1,5 @@
 <resources>
-    <string name="app_name">otb-tcom</string>
+    <string name="app_name">follow-me</string>
     <string name="notification_channel_name">Tracking</string>
     <string name="notification_title">otb-tcom tracking active</string>
     <string name="notification_text">Posting location updates to follow-me</string>
diff --git a/backups/follow-me-v0.4.0.zip b/backups/follow-me-v0.4.0.zip
new file mode 100644
index 0000000..fe2d25e
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