Merge remote-tracking branch 'origin/main'

Reviewed-on: atridad/OpenClimb#5

.github/workflows/deploy.yml

@@ -0,0 +1,43 @@
+name: OpenClimb Docker Deploy
+on:
+  push:
+    branches: [main]
+    paths:
+      - "sync/**"
+      - ".github/workflows/deploy.yml"
+  pull_request:
+    branches: [main]
+    paths:
+      - "sync/**"
+      - ".github/workflows/deploy.yml"
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Login to Container Registry
+        uses: docker/login-action@v2
+        with:
+          registry: ${{ secrets.REPO_HOST }}
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.DEPLOY_TOKEN }}
+
+      - name: Build and push sync-server
+        uses: docker/build-push-action@v4
+        with:
+          context: ./sync
+          file: ./sync/Dockerfile
+          platforms: linux/amd64
+          push: true
+          tags: |
+            ${{ secrets.REPO_HOST }}/${{ github.repository_owner }}/openclimb-sync:${{ github.sha }}
+            ${{ secrets.REPO_HOST }}/${{ github.repository_owner }}/openclimb-sync:latest

README.md

@@ -4,8 +4,18 @@ This is a FOSS app meant to help climbers track their sessions, routes/problems,
 
 ## Versions
 
-- Android:1.4.2
-- iOS: 1.0.1
+- Android: 1.7.0
+- iOS: 1.2.0
+- Sync: 1.0.0
+
+## Stability
+- Clients: 8/10
+- Server: 10/10
+- Schema: 9/10 (No more breaking changes)
+
+## Self-Hosted Sync Server
+
+You can run your own sync server to keep your data in sync across devices. The server is lightweight and easy to set up. See the server docker-compose file for an example.
 
 ## Download
 

android/app/build.gradle.kts

@@ -16,8 +16,8 @@ android {
         applicationId = "com.atridad.openclimb"
         minSdk = 31
         targetSdk = 36
-        versionCode = 26
-        versionName = "1.5.1"
+        versionCode = 29
+        versionName = "1.7.1"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }
@@ -92,4 +92,6 @@ dependencies {
     androidTestImplementation(libs.androidx.ui.test.junit4)
     debugImplementation(libs.androidx.ui.tooling)
     debugImplementation(libs.androidx.ui.test.manifest)
+    debugImplementation(libs.androidx.ui.tooling)
+    debugImplementation(libs.androidx.ui.test.manifest)
 }

android/app/build.gradle.kts.backup

@@ -0,0 +1,98 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
+plugins {
+    alias(libs.plugins.android.application)
+    alias(libs.plugins.kotlin.android)
+    alias(libs.plugins.kotlin.compose)
+    alias(libs.plugins.kotlin.serialization)
+    alias(libs.plugins.ksp)
+}
+
+android {
+    namespace = "com.atridad.openclimb"
+    compileSdk = 36
+
+    defaultConfig {
+        applicationId = "com.atridad.openclimb"
+        minSdk = 31
+        targetSdk = 36
+        versionCode = 27
+        versionName = "1.6.0"
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = true
+            proguardFiles(
+                    getDefaultProguardFile("proguard-android-optimize.txt"),
+                    "proguard-rules.pro"
+            )
+        }
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+    java { toolchain { languageVersion.set(JavaLanguageVersion.of(17)) } }
+
+    buildFeatures { compose = true }
+}
+
+kotlin { compilerOptions { jvmTarget.set(JvmTarget.JVM_17) } }
+
+dependencies {
+    // Core Android libraries
+    implementation(libs.androidx.core.ktx)
+    implementation(libs.androidx.lifecycle.runtime.ktx)
+    implementation(libs.androidx.activity.compose)
+
+    // Compose BOM and UI
+    implementation(platform(libs.androidx.compose.bom))
+    implementation(libs.androidx.ui)
+    implementation(libs.androidx.ui.graphics)
+    implementation(libs.androidx.ui.tooling.preview)
+    implementation(libs.androidx.material3)
+    implementation(libs.androidx.material.icons.extended)
+
+    // Room Database
+    implementation(libs.androidx.room.runtime)
+    implementation(libs.androidx.room.ktx)
+
+    ksp(libs.androidx.room.compiler)
+
+    // Navigation
+    implementation(libs.androidx.navigation.compose)
+
+    // ViewModel
+    implementation(libs.androidx.lifecycle.viewmodel.compose)
+
+    // Serialization
+    implementation(libs.kotlinx.serialization.json)
+
+    // Coroutines
+    implementation(libs.kotlinx.coroutines.android)
+
+    // Image Loading
+    implementation(libs.coil.compose)
+
+    // Testing
+    testImplementation(libs.junit)
+    testImplementation(libs.mockk)
+    testImplementation(libs.kotlinx.coroutines.test)
+    androidTestImplementation(libs.androidx.junit)
+    androidTestImplementation(libs.androidx.espresso.core)
+    androidTestImplementation(libs.androidx.test.core)
+    androidTestImplementation(libs.androidx.test.ext)
+    androidTestImplementation(libs.androidx.test.runner)
+    androidTestImplementation(libs.androidx.test.rules)
+    androidTestImplementation(platform(libs.androidx.compose.bom))
+    androidTestImplementation(libs.androidx.ui.test.junit4)
+    debugImplementation(libs.androidx.ui.tooling)
+    debugImplementation(libs.androidx.ui.test.manifest)
+}
+    debugImplementation(libs.androidx.ui.tooling)
+    debugImplementation(libs.androidx.ui.test.manifest)
+}

android/app/build_new.gradle.kts

@@ -0,0 +1,98 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
+plugins {
+    alias(libs.plugins.android.application)
+    alias(libs.plugins.kotlin.android)
+    alias(libs.plugins.kotlin.compose)
+    alias(libs.plugins.kotlin.serialization)
+    alias(libs.plugins.ksp)
+}
+
+android {
+    namespace = "com.atridad.openclimb"
+    compileSdk = 36
+
+    defaultConfig {
+        applicationId = "com.atridad.openclimb"
+        minSdk = 31
+        targetSdk = 36
+        versionCode = 27
+        versionName = "1.6.0"
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = true
+            proguardFiles(
+                    getDefaultProguardFile("proguard-android-optimize.txt"),
+                    "proguard-rules.pro"
+            )
+        }
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+    java { toolchain { languageVersion.set(JavaLanguageVersion.of(17)) } }
+
+    buildFeatures { compose = true }
+}
+
+kotlin { compilerOptions { jvmTarget.set(JvmTarget.JVM_17) } }
+
+dependencies {
+    // Core Android libraries
+    implementation(libs.androidx.core.ktx)
+    implementation(libs.androidx.lifecycle.runtime.ktx)
+    implementation(libs.androidx.activity.compose)
+
+    // Compose BOM and UI
+    implementation(platform(libs.androidx.compose.bom))
+    implementation(libs.androidx.ui)
+    implementation(libs.androidx.ui.graphics)
+    implementation(libs.androidx.ui.tooling.preview)
+    implementation(libs.androidx.material3)
+    implementation(libs.androidx.material.icons.extended)
+
+    // Room Database
+    implementation(libs.androidx.room.runtime)
+    implementation(libs.androidx.room.ktx)
+
+    ksp(libs.androidx.room.compiler)
+
+    // Navigation
+    implementation(libs.androidx.navigation.compose)
+
+    // ViewModel
+    implementation(libs.androidx.lifecycle.viewmodel.compose)
+
+    // Serialization
+    implementation(libs.kotlinx.serialization.json)
+
+    // Coroutines
+    implementation(libs.kotlinx.coroutines.android)
+
+    // Image Loading
+    implementation(libs.coil.compose)
+
+    // HTTP Client
+    implementation(libs.okhttp)
+
+    // Testing
+    testImplementation(libs.junit)
+    testImplementation(libs.mockk)
+    testImplementation(libs.kotlinx.coroutines.test)
+    androidTestImplementation(libs.androidx.junit)
+    androidTestImplementation(libs.androidx.espresso.core)
+    androidTestImplementation(libs.androidx.test.core)
+    androidTestImplementation(libs.androidx.test.ext)
+    androidTestImplementation(libs.androidx.test.runner)
+    androidTestImplementation(libs.androidx.test.rules)
+    androidTestImplementation(platform(libs.androidx.compose.bom))
+    androidTestImplementation(libs.androidx.ui.test.junit4)
+    debugImplementation(libs.androidx.ui.tooling)
+    debugImplementation(libs.androidx.ui.test.manifest)
+}

android/app/src/main/AndroidManifest.xml

@@ -8,6 +8,9 @@
         android:maxSdkVersion="28" />
     <uses-permission android:name="android.permission.CAMERA" />
 
+    <!-- Permission for sync functionality -->
+    <uses-permission android:name="android.permission.INTERNET" />
+
     <!-- Hardware features -->
     <uses-feature android:name="android.hardware.camera" android:required="false" />
 

android/app/src/main/java/com/atridad/openclimb/data/format/BackupFormat.kt

@@ -0,0 +1,233 @@
+package com.atridad.openclimb.data.format
+
+import com.atridad.openclimb.data.model.*
+import kotlinx.serialization.Serializable
+
+/** Root structure for OpenClimb backup data */
+@Serializable
+data class ClimbDataBackup(
+        val exportedAt: String,
+        val version: String = "2.0",
+        val formatVersion: String = "2.0",
+        val gyms: List<BackupGym>,
+        val problems: List<BackupProblem>,
+        val sessions: List<BackupClimbSession>,
+        val attempts: List<BackupAttempt>
+)
+
+/** Platform-neutral gym representation for backup/restore */
+@Serializable
+data class BackupGym(
+        val id: String,
+        val name: String,
+        val location: String? = null,
+        val supportedClimbTypes: List<ClimbType>,
+        val difficultySystems: List<DifficultySystem>,
+        @kotlinx.serialization.SerialName("customDifficultyGrades")
+        val customDifficultyGrades: List<String> = emptyList(),
+        val notes: String? = null,
+        val createdAt: String, // ISO 8601 format
+        val updatedAt: String // ISO 8601 format
+) {
+    companion object {
+        /** Create BackupGym from native Android Gym model */
+        fun fromGym(gym: Gym): BackupGym {
+            return BackupGym(
+                    id = gym.id,
+                    name = gym.name,
+                    location = gym.location,
+                    supportedClimbTypes = gym.supportedClimbTypes,
+                    difficultySystems = gym.difficultySystems,
+                    customDifficultyGrades = gym.customDifficultyGrades,
+                    notes = gym.notes,
+                    createdAt = gym.createdAt,
+                    updatedAt = gym.updatedAt
+            )
+        }
+    }
+
+    /** Convert to native Android Gym model */
+    fun toGym(): Gym {
+        return Gym(
+                id = id,
+                name = name,
+                location = location,
+                supportedClimbTypes = supportedClimbTypes,
+                difficultySystems = difficultySystems,
+                customDifficultyGrades = customDifficultyGrades,
+                notes = notes,
+                createdAt = createdAt,
+                updatedAt = updatedAt
+        )
+    }
+}
+
+/** Platform-neutral problem representation for backup/restore */
+@Serializable
+data class BackupProblem(
+        val id: String,
+        val gymId: String,
+        val name: String? = null,
+        val description: String? = null,
+        val climbType: ClimbType,
+        val difficulty: DifficultyGrade,
+        val tags: List<String> = emptyList(),
+        val location: String? = null,
+        val imagePaths: List<String>? = null,
+        val isActive: Boolean = true,
+        val dateSet: String? = null, // ISO 8601 format
+        val notes: String? = null,
+        val createdAt: String, // ISO 8601 format
+        val updatedAt: String // ISO 8601 format
+) {
+    companion object {
+        /** Create BackupProblem from native Android Problem model */
+        fun fromProblem(problem: Problem): BackupProblem {
+            return BackupProblem(
+                    id = problem.id,
+                    gymId = problem.gymId,
+                    name = problem.name,
+                    description = problem.description,
+                    climbType = problem.climbType,
+                    difficulty = problem.difficulty,
+                    tags = problem.tags,
+                    location = problem.location,
+                    imagePaths =
+                            if (problem.imagePaths.isEmpty()) null
+                            else
+                                    problem.imagePaths.map { path ->
+                                        // Store just the filename to match iOS format
+                                        path.substringAfterLast('/')
+                                    },
+                    isActive = problem.isActive,
+                    dateSet = problem.dateSet,
+                    notes = problem.notes,
+                    createdAt = problem.createdAt,
+                    updatedAt = problem.updatedAt
+            )
+        }
+    }
+
+    /** Convert to native Android Problem model */
+    fun toProblem(): Problem {
+        return Problem(
+                id = id,
+                gymId = gymId,
+                name = name,
+                description = description,
+                climbType = climbType,
+                difficulty = difficulty,
+                tags = tags,
+                location = location,
+                imagePaths = imagePaths ?: emptyList(),
+                isActive = isActive,
+                dateSet = dateSet,
+                notes = notes,
+                createdAt = createdAt,
+                updatedAt = updatedAt
+        )
+    }
+
+    /** Create a copy with updated image paths for import processing */
+    fun withUpdatedImagePaths(newImagePaths: List<String>): BackupProblem {
+        return copy(imagePaths = newImagePaths.ifEmpty { null })
+    }
+}
+
+/** Platform-neutral climb session representation for backup/restore */
+@Serializable
+data class BackupClimbSession(
+        val id: String,
+        val gymId: String,
+        val date: String, // ISO 8601 format
+        val startTime: String? = null, // ISO 8601 format
+        val endTime: String? = null, // ISO 8601 format
+        val duration: Long? = null, // Duration in seconds
+        val status: SessionStatus,
+        val notes: String? = null,
+        val createdAt: String, // ISO 8601 format
+        val updatedAt: String // ISO 8601 format
+) {
+    companion object {
+        /** Create BackupClimbSession from native Android ClimbSession model */
+        fun fromClimbSession(session: ClimbSession): BackupClimbSession {
+            return BackupClimbSession(
+                    id = session.id,
+                    gymId = session.gymId,
+                    date = session.date,
+                    startTime = session.startTime,
+                    endTime = session.endTime,
+                    duration = session.duration,
+                    status = session.status,
+                    notes = session.notes,
+                    createdAt = session.createdAt,
+                    updatedAt = session.updatedAt
+            )
+        }
+    }
+
+    /** Convert to native Android ClimbSession model */
+    fun toClimbSession(): ClimbSession {
+        return ClimbSession(
+                id = id,
+                gymId = gymId,
+                date = date,
+                startTime = startTime,
+                endTime = endTime,
+                duration = duration,
+                status = status,
+                notes = notes,
+                createdAt = createdAt,
+                updatedAt = updatedAt
+        )
+    }
+}
+
+/** Platform-neutral attempt representation for backup/restore */
+@Serializable
+data class BackupAttempt(
+        val id: String,
+        val sessionId: String,
+        val problemId: String,
+        val result: AttemptResult,
+        val highestHold: String? = null,
+        val notes: String? = null,
+        val duration: Long? = null, // Duration in seconds
+        val restTime: Long? = null, // Rest time in seconds
+        val timestamp: String, // ISO 8601 format
+        val createdAt: String // ISO 8601 format
+) {
+    companion object {
+        /** Create BackupAttempt from native Android Attempt model */
+        fun fromAttempt(attempt: Attempt): BackupAttempt {
+            return BackupAttempt(
+                    id = attempt.id,
+                    sessionId = attempt.sessionId,
+                    problemId = attempt.problemId,
+                    result = attempt.result,
+                    highestHold = attempt.highestHold,
+                    notes = attempt.notes,
+                    duration = attempt.duration,
+                    restTime = attempt.restTime,
+                    timestamp = attempt.timestamp,
+                    createdAt = attempt.createdAt
+            )
+        }
+    }
+
+    /** Convert to native Android Attempt model */
+    fun toAttempt(): Attempt {
+        return Attempt(
+                id = id,
+                sessionId = sessionId,
+                problemId = problemId,
+                result = result,
+                highestHold = highestHold,
+                notes = notes,
+                duration = duration,
+                restTime = restTime,
+                timestamp = timestamp,
+                createdAt = createdAt
+        )
+    }
+}

android/app/src/main/java/com/atridad/openclimb/data/migration/ImageMigrationService.kt

@@ -0,0 +1,205 @@
+package com.atridad.openclimb.data.migration
+
+import android.content.Context
+import android.util.Log
+import com.atridad.openclimb.data.repository.ClimbRepository
+import com.atridad.openclimb.utils.ImageNamingUtils
+import com.atridad.openclimb.utils.ImageUtils
+import kotlinx.coroutines.flow.first
+
+/**
+ * Service responsible for migrating images to use consistent naming convention across platforms.
+ * This ensures that iOS and Android use the same image filenames for sync compatibility.
+ */
+class ImageMigrationService(private val context: Context, private val repository: ClimbRepository) {
+    companion object {
+        private const val TAG = "ImageMigrationService"
+        private const val MIGRATION_PREF_KEY = "image_naming_migration_completed"
+    }
+
+    /**
+     * Performs a complete migration of all images in the system to use consistent naming. This
+     * should be called once during app startup after the naming convention is implemented.
+     */
+    suspend fun performFullMigration(): ImageMigrationResult {
+        Log.i(TAG, "Starting full image naming migration")
+
+        val prefs = context.getSharedPreferences("openclimb_migration", Context.MODE_PRIVATE)
+        if (prefs.getBoolean(MIGRATION_PREF_KEY, false)) {
+            Log.i(TAG, "Image migration already completed, skipping")
+            return ImageMigrationResult.AlreadyCompleted
+        }
+
+        try {
+            val allProblems = repository.getAllProblems().first()
+            val migrationResults = mutableMapOf<String, String>()
+            var migratedCount = 0
+            var errorCount = 0
+
+            Log.i(TAG, "Found ${allProblems.size} problems to check for image migration")
+
+            for (problem in allProblems) {
+                if (problem.imagePaths.isNotEmpty()) {
+                    Log.d(
+                            TAG,
+                            "Migrating images for problem '${problem.name}': ${problem.imagePaths}"
+                    )
+
+                    try {
+                        val problemMigrations =
+                                ImageUtils.migrateImageNaming(
+                                        context = context,
+                                        problemId = problem.id,
+                                        currentImagePaths = problem.imagePaths
+                                )
+
+                        if (problemMigrations.isNotEmpty()) {
+                            migrationResults.putAll(problemMigrations)
+                            migratedCount += problemMigrations.size
+
+                            // Update problem with new image paths
+                            val newImagePaths =
+                                    problem.imagePaths.map { oldPath ->
+                                        problemMigrations[oldPath] ?: oldPath
+                                    }
+
+                            val updatedProblem = problem.copy(imagePaths = newImagePaths)
+                            repository.insertProblem(updatedProblem)
+
+                            Log.d(
+                                    TAG,
+                                    "Updated problem '${problem.name}' with ${problemMigrations.size} migrated images"
+                            )
+                        }
+                    } catch (e: Exception) {
+                        Log.e(
+                                TAG,
+                                "Failed to migrate images for problem '${problem.name}': ${e.message}",
+                                e
+                        )
+                        errorCount++
+                    }
+                }
+            }
+
+            // Mark migration as completed
+            prefs.edit().putBoolean(MIGRATION_PREF_KEY, true).apply()
+
+            Log.i(
+                    TAG,
+                    "Image migration completed: $migratedCount images migrated, $errorCount errors"
+            )
+
+            return ImageMigrationResult.Success(
+                    totalMigrated = migratedCount,
+                    errors = errorCount,
+                    migrations = migrationResults
+            )
+        } catch (e: Exception) {
+            Log.e(TAG, "Image migration failed: ${e.message}", e)
+            return ImageMigrationResult.Failed(e.message ?: "Unknown error")
+        }
+    }
+
+    /** Validates that all images in the system follow the consistent naming convention. */
+    suspend fun validateImageNaming(): ValidationResult {
+        try {
+            val allProblems = repository.getAllProblems().first()
+            val validImages = mutableListOf<String>()
+            val invalidImages = mutableListOf<String>()
+            val missingImages = mutableListOf<String>()
+
+            for (problem in allProblems) {
+                for (imagePath in problem.imagePaths) {
+                    val filename = imagePath.substringAfterLast('/')
+
+                    // Check if file exists
+                    val imageFile = ImageUtils.getImageFile(context, imagePath)
+                    if (!imageFile.exists()) {
+                        missingImages.add(imagePath)
+                        continue
+                    }
+
+                    // Check if filename follows our convention
+                    if (ImageNamingUtils.isValidImageFilename(filename)) {
+                        validImages.add(imagePath)
+                    } else {
+                        invalidImages.add(imagePath)
+                    }
+                }
+            }
+
+            return ValidationResult(
+                    totalImages = validImages.size + invalidImages.size + missingImages.size,
+                    validImages = validImages,
+                    invalidImages = invalidImages,
+                    missingImages = missingImages
+            )
+        } catch (e: Exception) {
+            Log.e(TAG, "Image validation failed: ${e.message}", e)
+            return ValidationResult(
+                    totalImages = 0,
+                    validImages = emptyList(),
+                    invalidImages = emptyList(),
+                    missingImages = emptyList()
+            )
+        }
+    }
+
+    /** Migrates images for a specific problem during sync operations. */
+    suspend fun migrateProblemImages(
+            problemId: String,
+            currentImagePaths: List<String>
+    ): Map<String, String> {
+        return try {
+            ImageUtils.migrateImageNaming(context, problemId, currentImagePaths)
+        } catch (e: Exception) {
+            Log.e(TAG, "Failed to migrate images for problem $problemId: ${e.message}", e)
+            emptyMap()
+        }
+    }
+
+    /**
+     * Cleans up any orphaned image files that don't follow our naming convention and aren't
+     * referenced by any problems.
+     */
+    suspend fun cleanupOrphanedImages() {
+        try {
+            val allProblems = repository.getAllProblems().first()
+            val referencedPaths = allProblems.flatMap { it.imagePaths }.toSet()
+
+            ImageUtils.cleanupOrphanedImages(context, referencedPaths)
+
+            Log.i(TAG, "Orphaned image cleanup completed")
+        } catch (e: Exception) {
+            Log.e(TAG, "Failed to cleanup orphaned images: ${e.message}", e)
+        }
+    }
+}
+
+/** Result of an image migration operation */
+sealed class ImageMigrationResult {
+    object AlreadyCompleted : ImageMigrationResult()
+
+    data class Success(
+            val totalMigrated: Int,
+            val errors: Int,
+            val migrations: Map<String, String>
+    ) : ImageMigrationResult()
+
+    data class Failed(val error: String) : ImageMigrationResult()
+}
+
+/** Result of image naming validation */
+data class ValidationResult(
+        val totalImages: Int,
+        val validImages: List<String>,
+        val invalidImages: List<String>,
+        val missingImages: List<String>
+) {
+    val isAllValid: Boolean
+        get() = invalidImages.isEmpty() && missingImages.isEmpty()
+
+    val validPercentage: Double
+        get() = if (totalImages == 0) 100.0 else (validImages.size.toDouble() / totalImages) * 100
+}

android/app/src/main/java/com/atridad/openclimb/data/model/Attempt.kt

@@ -4,8 +4,8 @@ import androidx.room.Entity
 import androidx.room.ForeignKey
 import androidx.room.Index
 import androidx.room.PrimaryKey
+import com.atridad.openclimb.utils.DateFormatUtils
 import kotlinx.serialization.Serializable
-import java.time.LocalDateTime
 
 @Serializable
 enum class AttemptResult {
@@ -16,63 +16,59 @@ enum class AttemptResult {
 }
 
 @Entity(
-    tableName = "attempts",
-    foreignKeys = [
-        ForeignKey(
-            entity = ClimbSession::class,
-            parentColumns = ["id"],
-            childColumns = ["sessionId"],
-            onDelete = ForeignKey.CASCADE
-        ),
-        ForeignKey(
-            entity = Problem::class,
-            parentColumns = ["id"],
-            childColumns = ["problemId"],
-            onDelete = ForeignKey.CASCADE
-        )
-    ],
-    indices = [
-        Index(value = ["sessionId"]),
-        Index(value = ["problemId"])
-    ]
+        tableName = "attempts",
+        foreignKeys =
+                [
+                        ForeignKey(
+                                entity = ClimbSession::class,
+                                parentColumns = ["id"],
+                                childColumns = ["sessionId"],
+                                onDelete = ForeignKey.CASCADE
+                        ),
+                        ForeignKey(
+                                entity = Problem::class,
+                                parentColumns = ["id"],
+                                childColumns = ["problemId"],
+                                onDelete = ForeignKey.CASCADE
+                        )],
+        indices = [Index(value = ["sessionId"]), Index(value = ["problemId"])]
 )
 @Serializable
 data class Attempt(
-    @PrimaryKey
-    val id: String,
-    val sessionId: String,
-    val problemId: String,
-    val result: AttemptResult,
-    val highestHold: String? = null, // Description of the highest hold reached
-    val notes: String? = null,
-    val duration: Long? = null, // Attempt duration in seconds
-    val restTime: Long? = null, // Rest time before this attempt in seconds
-    val timestamp: String, // When this attempt was made
-    val createdAt: String
+        @PrimaryKey val id: String,
+        val sessionId: String,
+        val problemId: String,
+        val result: AttemptResult,
+        val highestHold: String? = null, // Description of the highest hold reached
+        val notes: String? = null,
+        val duration: Long? = null, // Attempt duration in seconds
+        val restTime: Long? = null, // Rest time before this attempt in seconds
+        val timestamp: String, // When this attempt was made
+        val createdAt: String
 ) {
     companion object {
         fun create(
-            sessionId: String,
-            problemId: String,
-            result: AttemptResult,
-            highestHold: String? = null,
-            notes: String? = null,
-            duration: Long? = null,
-            restTime: Long? = null,
-            timestamp: String = LocalDateTime.now().toString()
+                sessionId: String,
+                problemId: String,
+                result: AttemptResult,
+                highestHold: String? = null,
+                notes: String? = null,
+                duration: Long? = null,
+                restTime: Long? = null,
+                timestamp: String = DateFormatUtils.nowISO8601()
         ): Attempt {
-            val now = LocalDateTime.now().toString()
+            val now = DateFormatUtils.nowISO8601()
             return Attempt(
-                id = java.util.UUID.randomUUID().toString(),
-                sessionId = sessionId,
-                problemId = problemId,
-                result = result,
-                highestHold = highestHold,
-                notes = notes,
-                duration = duration,
-                restTime = restTime,
-                timestamp = timestamp,
-                createdAt = now
+                    id = java.util.UUID.randomUUID().toString(),
+                    sessionId = sessionId,
+                    problemId = problemId,
+                    result = result,
+                    highestHold = highestHold,
+                    notes = notes,
+                    duration = duration,
+                    restTime = restTime,
+                    timestamp = timestamp,
+                    createdAt = now
             )
         }
     }

android/app/src/main/java/com/atridad/openclimb/data/model/ClimbSession.kt

@@ -4,8 +4,8 @@ import androidx.room.Entity
 import androidx.room.ForeignKey
 import androidx.room.Index
 import androidx.room.PrimaryKey
+import com.atridad.openclimb.utils.DateFormatUtils
 import kotlinx.serialization.Serializable
-import java.time.LocalDateTime
 
 @Serializable
 enum class SessionStatus {
@@ -15,66 +15,65 @@ enum class SessionStatus {
 }
 
 @Entity(
-    tableName = "climb_sessions",
-    foreignKeys = [
-        ForeignKey(
-            entity = Gym::class,
-            parentColumns = ["id"],
-            childColumns = ["gymId"],
-            onDelete = ForeignKey.CASCADE
-        )
-    ],
-    indices = [Index(value = ["gymId"])]
+        tableName = "climb_sessions",
+        foreignKeys =
+                [
+                        ForeignKey(
+                                entity = Gym::class,
+                                parentColumns = ["id"],
+                                childColumns = ["gymId"],
+                                onDelete = ForeignKey.CASCADE
+                        )],
+        indices = [Index(value = ["gymId"])]
 )
 @Serializable
 data class ClimbSession(
-    @PrimaryKey
-    val id: String,
-    val gymId: String,
-    val date: String,
-    val startTime: String? = null,
-    val endTime: String? = null,
-    val duration: Long? = null,
-    val status: SessionStatus = SessionStatus.ACTIVE,
-    val notes: String? = null,
-    val createdAt: String,
-    val updatedAt: String
+        @PrimaryKey val id: String,
+        val gymId: String,
+        val date: String,
+        val startTime: String? = null,
+        val endTime: String? = null,
+        val duration: Long? = null,
+        val status: SessionStatus = SessionStatus.ACTIVE,
+        val notes: String? = null,
+        val createdAt: String,
+        val updatedAt: String
 ) {
     companion object {
-        fun create(
-            gymId: String,
-            notes: String? = null
-        ): ClimbSession {
-            val now = LocalDateTime.now().toString()
+        fun create(gymId: String, notes: String? = null): ClimbSession {
+            val now = DateFormatUtils.nowISO8601()
             return ClimbSession(
-                id = java.util.UUID.randomUUID().toString(),
-                gymId = gymId,
-                date = now,
-                startTime = now,
-                status = SessionStatus.ACTIVE,
-                notes = notes,
-                createdAt = now,
-                updatedAt = now
+                    id = java.util.UUID.randomUUID().toString(),
+                    gymId = gymId,
+                    date = now,
+                    startTime = now,
+                    status = SessionStatus.ACTIVE,
+                    notes = notes,
+                    createdAt = now,
+                    updatedAt = now
             )
         }
-        
+
         fun ClimbSession.complete(): ClimbSession {
-            val endTime = LocalDateTime.now().toString()
-            val durationMinutes = if (startTime != null) {
-                try {
-                    val start = LocalDateTime.parse(startTime)
-                    val end = LocalDateTime.parse(endTime)
-                    java.time.Duration.between(start, end).toMinutes()
-                } catch (_: Exception) {
-                    null
-                }
-            } else null
-            
+            val endTime = DateFormatUtils.nowISO8601()
+            val durationMinutes =
+                    if (startTime != null) {
+                        try {
+                            val start = DateFormatUtils.parseISO8601(startTime)
+                            val end = DateFormatUtils.parseISO8601(endTime)
+                            if (start != null && end != null) {
+                                java.time.Duration.between(start, end).toMinutes()
+                            } else null
+                        } catch (_: Exception) {
+                            null
+                        }
+                    } else null
+
             return this.copy(
-                endTime = endTime,
-                duration = durationMinutes,
-                status = SessionStatus.COMPLETED,
-                updatedAt = LocalDateTime.now().toString()
+                    endTime = endTime,
+                    duration = durationMinutes,
+                    status = SessionStatus.COMPLETED,
+                    updatedAt = DateFormatUtils.nowISO8601()
             )
         }
     }

android/app/src/main/java/com/atridad/openclimb/data/model/DifficultySystem.kt

@@ -7,75 +7,199 @@ enum class DifficultySystem {
     // Bouldering
     V_SCALE, // V-Scale (VB - V17)
     FONT, // Fontainebleau (3 - 8C+)
-    
+
     // Rope
     YDS, // Yosemite Decimal System (5.0 - 5.15d)
-    
+
     // Custom difficulty systems
     CUSTOM;
-    
-    /**
-     * Get the display name for the UI
-     */
-    fun getDisplayName(): String = when (this) {
-        V_SCALE -> "V Scale"
-        FONT -> "Font Scale"
-        YDS -> "YDS (Yosemite)"
-        CUSTOM -> "Custom"
-    }
-    
-    /**
-     * Check if this system is for bouldering
-     */
-    fun isBoulderingSystem(): Boolean = when (this) {
-        V_SCALE, FONT -> true
-        YDS -> false
-        CUSTOM -> true // Custom is available for all
-    }
-    
-    /**
-     * Check if this system is for rope climbing
-     */
-    fun isRopeSystem(): Boolean = when (this) {
-        YDS -> true
-        V_SCALE, FONT -> false
-        CUSTOM -> true
-    }
-    
-    /**
-     * Get available grades for this system
-     */
-    fun getAvailableGrades(): List<String> = when (this) {
-        V_SCALE -> listOf("VB", "V0", "V1", "V2", "V3", "V4", "V5", "V6", "V7", "V8", "V9", "V10", "V11", "V12", "V13", "V14", "V15", "V16", "V17")
-        FONT -> listOf("3", "4A", "4B", "4C", "5A", "5B", "5C", "6A", "6A+", "6B", "6B+", "6C", "6C+", "7A", "7A+", "7B", "7B+", "7C", "7C+", "8A", "8A+", "8B", "8B+", "8C", "8C+")
-        YDS -> listOf("5.0", "5.1", "5.2", "5.3", "5.4", "5.5", "5.6", "5.7", "5.8", "5.9", "5.10a", "5.10b", "5.10c", "5.10d", "5.11a", "5.11b", "5.11c", "5.11d", "5.12a", "5.12b", "5.12c", "5.12d", "5.13a", "5.13b", "5.13c", "5.13d", "5.14a", "5.14b", "5.14c", "5.14d", "5.15a", "5.15b", "5.15c", "5.15d")
-        CUSTOM -> emptyList()
-    }
-    
+
+    /** Get the display name for the UI */
+    fun getDisplayName(): String =
+            when (this) {
+                V_SCALE -> "V Scale"
+                FONT -> "Font Scale"
+                YDS -> "YDS (Yosemite)"
+                CUSTOM -> "Custom"
+            }
+
+    /** Check if this system is for bouldering */
+    fun isBoulderingSystem(): Boolean =
+            when (this) {
+                V_SCALE, FONT -> true
+                YDS -> false
+                CUSTOM -> true // Custom is available for all
+            }
+
+    /** Check if this system is for rope climbing */
+    fun isRopeSystem(): Boolean =
+            when (this) {
+                YDS -> true
+                V_SCALE, FONT -> false
+                CUSTOM -> true
+            }
+
+    /** Get available grades for this system */
+    fun getAvailableGrades(): List<String> =
+            when (this) {
+                V_SCALE ->
+                        listOf(
+                                "VB",
+                                "V0",
+                                "V1",
+                                "V2",
+                                "V3",
+                                "V4",
+                                "V5",
+                                "V6",
+                                "V7",
+                                "V8",
+                                "V9",
+                                "V10",
+                                "V11",
+                                "V12",
+                                "V13",
+                                "V14",
+                                "V15",
+                                "V16",
+                                "V17"
+                        )
+                FONT ->
+                        listOf(
+                                "3",
+                                "4A",
+                                "4B",
+                                "4C",
+                                "5A",
+                                "5B",
+                                "5C",
+                                "6A",
+                                "6A+",
+                                "6B",
+                                "6B+",
+                                "6C",
+                                "6C+",
+                                "7A",
+                                "7A+",
+                                "7B",
+                                "7B+",
+                                "7C",
+                                "7C+",
+                                "8A",
+                                "8A+",
+                                "8B",
+                                "8B+",
+                                "8C",
+                                "8C+"
+                        )
+                YDS ->
+                        listOf(
+                                "5.0",
+                                "5.1",
+                                "5.2",
+                                "5.3",
+                                "5.4",
+                                "5.5",
+                                "5.6",
+                                "5.7",
+                                "5.8",
+                                "5.9",
+                                "5.10a",
+                                "5.10b",
+                                "5.10c",
+                                "5.10d",
+                                "5.11a",
+                                "5.11b",
+                                "5.11c",
+                                "5.11d",
+                                "5.12a",
+                                "5.12b",
+                                "5.12c",
+                                "5.12d",
+                                "5.13a",
+                                "5.13b",
+                                "5.13c",
+                                "5.13d",
+                                "5.14a",
+                                "5.14b",
+                                "5.14c",
+                                "5.14d",
+                                "5.15a",
+                                "5.15b",
+                                "5.15c",
+                                "5.15d"
+                        )
+                CUSTOM -> emptyList()
+            }
+
     companion object {
-        /**
-         * Get all difficulty systems based on type
-         */
-        fun getSystemsForClimbType(climbType: ClimbType): List<DifficultySystem> = when (climbType) {
-            ClimbType.BOULDER -> entries.filter { it.isBoulderingSystem() }
-            ClimbType.ROPE -> entries.filter { it.isRopeSystem() }
-        }
+        /** Get all difficulty systems based on type */
+        fun getSystemsForClimbType(climbType: ClimbType): List<DifficultySystem> =
+                when (climbType) {
+                    ClimbType.BOULDER -> entries.filter { it.isBoulderingSystem() }
+                    ClimbType.ROPE -> entries.filter { it.isRopeSystem() }
+                }
     }
 }
 
 @Serializable
-data class DifficultyGrade(
-    val system: DifficultySystem,
-    val grade: String,
-    val numericValue: Int
-) {
+data class DifficultyGrade(val system: DifficultySystem, val grade: String, val numericValue: Int) {
+
+    constructor(
+            system: DifficultySystem,
+            grade: String
+    ) : this(system = system, grade = grade, numericValue = calculateNumericValue(system, grade))
+
+    companion object {
+        private fun calculateNumericValue(system: DifficultySystem, grade: String): Int {
+            return when (system) {
+                DifficultySystem.V_SCALE -> {
+                    if (grade == "VB") 0 else grade.removePrefix("V").toIntOrNull() ?: 0
+                }
+                DifficultySystem.YDS -> {
+                    // Simplified numeric mapping for YDS grades
+                    when {
+                        grade.startsWith("5.10") ->
+                                10 + (grade.getOrNull(4)?.toString()?.hashCode()?.rem(4) ?: 0)
+                        grade.startsWith("5.11") ->
+                                14 + (grade.getOrNull(4)?.toString()?.hashCode()?.rem(4) ?: 0)
+                        grade.startsWith("5.12") ->
+                                18 + (grade.getOrNull(4)?.toString()?.hashCode()?.rem(4) ?: 0)
+                        grade.startsWith("5.13") ->
+                                22 + (grade.getOrNull(4)?.toString()?.hashCode()?.rem(4) ?: 0)
+                        grade.startsWith("5.14") ->
+                                26 + (grade.getOrNull(4)?.toString()?.hashCode()?.rem(4) ?: 0)
+                        grade.startsWith("5.15") ->
+                                30 + (grade.getOrNull(4)?.toString()?.hashCode()?.rem(4) ?: 0)
+                        else -> grade.removePrefix("5.").toIntOrNull() ?: 0
+                    }
+                }
+                DifficultySystem.FONT -> {
+                    // Simplified Font grade mapping
+                    when {
+                        grade.startsWith("6A") -> 6
+                        grade.startsWith("6B") -> 7
+                        grade.startsWith("6C") -> 8
+                        grade.startsWith("7A") -> 9
+                        grade.startsWith("7B") -> 10
+                        grade.startsWith("7C") -> 11
+                        grade.startsWith("8A") -> 12
+                        grade.startsWith("8B") -> 13
+                        grade.startsWith("8C") -> 14
+                        else -> grade.toIntOrNull() ?: 0
+                    }
+                }
+                DifficultySystem.CUSTOM -> grade.hashCode().rem(100)
+            }
+        }
+    }
     /**
-     * Compare this grade with another grade of the same system
-     * Returns negative if this grade is easier, positive if harder, 0 if equal
+     * Compare this grade with another grade of the same system Returns negative if this grade is
+     * easier, positive if harder, 0 if equal
      */
     fun compareTo(other: DifficultyGrade): Int {
         if (system != other.system) return 0
-        
+
         return when (system) {
             DifficultySystem.V_SCALE -> compareVScaleGrades(grade, other.grade)
             DifficultySystem.FONT -> compareFontGrades(grade, other.grade)
@@ -83,24 +207,24 @@ data class DifficultyGrade(
             DifficultySystem.CUSTOM -> grade.compareTo(other.grade)
         }
     }
-    
+
     private fun compareVScaleGrades(grade1: String, grade2: String): Int {
         // Handle VB (easiest) specially
         if (grade1 == "VB" && grade2 != "VB") return -1
         if (grade2 == "VB" && grade1 != "VB") return 1
         if (grade1 == "VB" && grade2 == "VB") return 0
-        
+
         // Extract numeric values for V grades
         val num1 = grade1.removePrefix("V").toIntOrNull() ?: 0
         val num2 = grade2.removePrefix("V").toIntOrNull() ?: 0
         return num1.compareTo(num2)
     }
-    
+
     private fun compareFontGrades(grade1: String, grade2: String): Int {
         // Simple string comparison for Font grades
         return grade1.compareTo(grade2)
     }
-    
+
     private fun compareYDSGrades(grade1: String, grade2: String): Int {
         // Simple string comparison for YDS grades
         return grade1.compareTo(grade2)

android/app/src/main/java/com/atridad/openclimb/data/model/Gym.kt

@@ -2,43 +2,42 @@ package com.atridad.openclimb.data.model
 
 import androidx.room.Entity
 import androidx.room.PrimaryKey
+import com.atridad.openclimb.utils.DateFormatUtils
 import kotlinx.serialization.Serializable
-import java.time.LocalDateTime
 
 @Entity(tableName = "gyms")
 @Serializable
 data class Gym(
-    @PrimaryKey
-    val id: String,
-    val name: String,
-    val location: String? = null,
-    val supportedClimbTypes: List<ClimbType>,
-    val difficultySystems: List<DifficultySystem>,
-    val customDifficultyGrades: List<String> = emptyList(),
-    val notes: String? = null,
-    val createdAt: String,
-    val updatedAt: String
+        @PrimaryKey val id: String,
+        val name: String,
+        val location: String? = null,
+        val supportedClimbTypes: List<ClimbType>,
+        val difficultySystems: List<DifficultySystem>,
+        val customDifficultyGrades: List<String> = emptyList(),
+        val notes: String? = null,
+        val createdAt: String,
+        val updatedAt: String
 ) {
     companion object {
         fun create(
-            name: String,
-            location: String? = null,
-            supportedClimbTypes: List<ClimbType>,
-            difficultySystems: List<DifficultySystem>,
-            customDifficultyGrades: List<String> = emptyList(),
-            notes: String? = null
+                name: String,
+                location: String? = null,
+                supportedClimbTypes: List<ClimbType>,
+                difficultySystems: List<DifficultySystem>,
+                customDifficultyGrades: List<String> = emptyList(),
+                notes: String? = null
         ): Gym {
-            val now = LocalDateTime.now().toString()
+            val now = DateFormatUtils.nowISO8601()
             return Gym(
-                id = java.util.UUID.randomUUID().toString(),
-                name = name,
-                location = location,
-                supportedClimbTypes = supportedClimbTypes,
-                difficultySystems = difficultySystems,
-                customDifficultyGrades = customDifficultyGrades,
-                notes = notes,
-                createdAt = now,
-                updatedAt = now
+                    id = java.util.UUID.randomUUID().toString(),
+                    name = name,
+                    location = location,
+                    supportedClimbTypes = supportedClimbTypes,
+                    difficultySystems = difficultySystems,
+                    customDifficultyGrades = customDifficultyGrades,
+                    notes = notes,
+                    createdAt = now,
+                    updatedAt = now
             )
         }
     }

android/app/src/main/java/com/atridad/openclimb/data/model/Problem.kt

@@ -4,7 +4,7 @@ import androidx.room.Entity
 import androidx.room.ForeignKey
 import androidx.room.Index
 import androidx.room.PrimaryKey
-import java.time.LocalDateTime
+import com.atridad.openclimb.utils.DateFormatUtils
 import kotlinx.serialization.Serializable
 
 @Entity(
@@ -49,7 +49,7 @@ data class Problem(
                 dateSet: String? = null,
                 notes: String? = null
         ): Problem {
-            val now = LocalDateTime.now().toString()
+            val now = DateFormatUtils.nowISO8601()
             return Problem(
                     id = java.util.UUID.randomUUID().toString(),
                     gymId = gymId,

android/app/src/main/java/com/atridad/openclimb/data/repository/ClimbRepository.kt

@@ -2,10 +2,16 @@ package com.atridad.openclimb.data.repository
 
 import android.content.Context
 import com.atridad.openclimb.data.database.OpenClimbDatabase
+import com.atridad.openclimb.data.format.BackupAttempt
+import com.atridad.openclimb.data.format.BackupClimbSession
+import com.atridad.openclimb.data.format.BackupGym
+import com.atridad.openclimb.data.format.BackupProblem
+import com.atridad.openclimb.data.format.ClimbDataBackup
 import com.atridad.openclimb.data.model.*
+import com.atridad.openclimb.data.state.DataStateManager
+import com.atridad.openclimb.utils.DateFormatUtils
 import com.atridad.openclimb.utils.ZipExportImportUtils
 import java.io.File
-import java.time.LocalDateTime
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.first
 import kotlinx.serialization.json.Json
@@ -15,6 +21,10 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
     private val problemDao = database.problemDao()
     private val sessionDao = database.climbSessionDao()
     private val attemptDao = database.attemptDao()
+    private val dataStateManager = DataStateManager(context)
+
+    // Callback interface for auto-sync functionality
+    private var autoSyncCallback: (() -> Unit)? = null
 
     private val json = Json {
         prettyPrint = true
@@ -24,19 +34,41 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
     // Gym operations
     fun getAllGyms(): Flow<List<Gym>> = gymDao.getAllGyms()
     suspend fun getGymById(id: String): Gym? = gymDao.getGymById(id)
-    suspend fun insertGym(gym: Gym) = gymDao.insertGym(gym)
-    suspend fun updateGym(gym: Gym) = gymDao.updateGym(gym)
-    suspend fun deleteGym(gym: Gym) = gymDao.deleteGym(gym)
-    fun searchGyms(query: String): Flow<List<Gym>> = gymDao.searchGyms(query)
+    suspend fun insertGym(gym: Gym) {
+        gymDao.insertGym(gym)
+        dataStateManager.updateDataState()
+        triggerAutoSync()
+    }
+    suspend fun updateGym(gym: Gym) {
+        gymDao.updateGym(gym)
+        dataStateManager.updateDataState()
+        triggerAutoSync()
+    }
+    suspend fun deleteGym(gym: Gym) {
+        gymDao.deleteGym(gym)
+        dataStateManager.updateDataState()
+        triggerAutoSync()
+    }
 
     // Problem operations
     fun getAllProblems(): Flow<List<Problem>> = problemDao.getAllProblems()
     suspend fun getProblemById(id: String): Problem? = problemDao.getProblemById(id)
     fun getProblemsByGym(gymId: String): Flow<List<Problem>> = problemDao.getProblemsByGym(gymId)
-    suspend fun insertProblem(problem: Problem) = problemDao.insertProblem(problem)
-    suspend fun updateProblem(problem: Problem) = problemDao.updateProblem(problem)
-    suspend fun deleteProblem(problem: Problem) = problemDao.deleteProblem(problem)
-    fun searchProblems(query: String): Flow<List<Problem>> = problemDao.searchProblems(query)
+    suspend fun insertProblem(problem: Problem) {
+        problemDao.insertProblem(problem)
+        dataStateManager.updateDataState()
+        triggerAutoSync()
+    }
+    suspend fun updateProblem(problem: Problem) {
+        problemDao.updateProblem(problem)
+        dataStateManager.updateDataState()
+        triggerAutoSync()
+    }
+    suspend fun deleteProblem(problem: Problem) {
+        problemDao.deleteProblem(problem)
+        dataStateManager.updateDataState()
+        triggerAutoSync()
+    }
 
     // Session operations
     fun getAllSessions(): Flow<List<ClimbSession>> = sessionDao.getAllSessions()
@@ -45,9 +77,21 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
             sessionDao.getSessionsByGym(gymId)
     suspend fun getActiveSession(): ClimbSession? = sessionDao.getActiveSession()
     fun getActiveSessionFlow(): Flow<ClimbSession?> = sessionDao.getActiveSessionFlow()
-    suspend fun insertSession(session: ClimbSession) = sessionDao.insertSession(session)
-    suspend fun updateSession(session: ClimbSession) = sessionDao.updateSession(session)
-    suspend fun deleteSession(session: ClimbSession) = sessionDao.deleteSession(session)
+    suspend fun insertSession(session: ClimbSession) {
+        sessionDao.insertSession(session)
+        dataStateManager.updateDataState()
+        triggerAutoSync()
+    }
+    suspend fun updateSession(session: ClimbSession) {
+        sessionDao.updateSession(session)
+        dataStateManager.updateDataState()
+        triggerAutoSync()
+    }
+    suspend fun deleteSession(session: ClimbSession) {
+        sessionDao.deleteSession(session)
+        dataStateManager.updateDataState()
+        triggerAutoSync()
+    }
     suspend fun getLastUsedGym(): Gym? {
         val recentSessions = sessionDao.getRecentSessions(1).first()
         return if (recentSessions.isNotEmpty()) {
@@ -63,73 +107,25 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
             attemptDao.getAttemptsBySession(sessionId)
     fun getAttemptsByProblem(problemId: String): Flow<List<Attempt>> =
             attemptDao.getAttemptsByProblem(problemId)
-    suspend fun insertAttempt(attempt: Attempt) = attemptDao.insertAttempt(attempt)
-    suspend fun updateAttempt(attempt: Attempt) = attemptDao.updateAttempt(attempt)
-    suspend fun deleteAttempt(attempt: Attempt) = attemptDao.deleteAttempt(attempt)
-
-    // ZIP Export with images - Single format for reliability
-    suspend fun exportAllDataToZip(directory: File? = null): File {
-        try {
-            // Collect all data with proper error handling
-            val allGyms = gymDao.getAllGyms().first()
-            val allProblems = problemDao.getAllProblems().first()
-            val allSessions = sessionDao.getAllSessions().first()
-            val allAttempts = attemptDao.getAllAttempts().first()
-
-            // Validate data integrity before export
-            validateDataIntegrity(allGyms, allProblems, allSessions, allAttempts)
-
-            val exportData =
-                    ClimbDataExport(
-                            exportedAt = LocalDateTime.now().toString(),
-                            version = "2.0",
-                            gyms = allGyms,
-                            problems = allProblems,
-                            sessions = allSessions,
-                            attempts = allAttempts
-                    )
-
-            // Collect all referenced image paths and validate they exist
-            val referencedImagePaths = allProblems.flatMap { it.imagePaths }.toSet()
-            val validImagePaths =
-                    referencedImagePaths
-                            .filter { imagePath ->
-                                try {
-                                    val imageFile =
-                                            com.atridad.openclimb.utils.ImageUtils.getImageFile(
-                                                    context,
-                                                    imagePath
-                                            )
-                                    imageFile.exists() && imageFile.length() > 0
-                                } catch (e: Exception) {
-                                    false
-                                }
-                            }
-                            .toSet()
-
-            // Log any missing images for debugging
-            val missingImages = referencedImagePaths - validImagePaths
-            if (missingImages.isNotEmpty()) {
-                android.util.Log.w(
-                        "ClimbRepository",
-                        "Some referenced images are missing: $missingImages"
-                )
-            }
-
-            return ZipExportImportUtils.createExportZip(
-                    context = context,
-                    exportData = exportData,
-                    referencedImagePaths = validImagePaths,
-                    directory = directory
-            )
-        } catch (e: Exception) {
-            throw Exception("Export failed: ${e.message}")
-        }
+    suspend fun insertAttempt(attempt: Attempt) {
+        attemptDao.insertAttempt(attempt)
+        dataStateManager.updateDataState()
+        triggerAutoSync()
+    }
+    suspend fun updateAttempt(attempt: Attempt) {
+        attemptDao.updateAttempt(attempt)
+        dataStateManager.updateDataState()
+        triggerAutoSync()
+    }
+    suspend fun deleteAttempt(attempt: Attempt) {
+        attemptDao.deleteAttempt(attempt)
+        dataStateManager.updateDataState()
+        triggerAutoSync()
     }
 
     suspend fun exportAllDataToZipUri(context: Context, uri: android.net.Uri) {
         try {
-            // Collect all data with proper error handling
+            // Collect all data
             val allGyms = gymDao.getAllGyms().first()
             val allProblems = problemDao.getAllProblems().first()
             val allSessions = sessionDao.getAllSessions().first()
@@ -138,14 +134,16 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
             // Validate data integrity before export
             validateDataIntegrity(allGyms, allProblems, allSessions, allAttempts)
 
-            val exportData =
-                    ClimbDataExport(
-                            exportedAt = LocalDateTime.now().toString(),
+            // Create backup data using platform-neutral format
+            val backupData =
+                    ClimbDataBackup(
+                            exportedAt = DateFormatUtils.nowISO8601(),
                             version = "2.0",
-                            gyms = allGyms,
-                            problems = allProblems,
-                            sessions = allSessions,
-                            attempts = allAttempts
+                            formatVersion = "2.0",
+                            gyms = allGyms.map { BackupGym.fromGym(it) },
+                            problems = allProblems.map { BackupProblem.fromProblem(it) },
+                            sessions = allSessions.map { BackupClimbSession.fromClimbSession(it) },
+                            attempts = allAttempts.map { BackupAttempt.fromAttempt(it) }
                     )
 
             // Collect all referenced image paths and validate they exist
@@ -160,7 +158,7 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
                                                     imagePath
                                             )
                                     imageFile.exists() && imageFile.length() > 0
-                                } catch (e: Exception) {
+                                } catch (_: Exception) {
                                     false
                                 }
                             }
@@ -169,7 +167,7 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
             ZipExportImportUtils.createExportZipToUri(
                     context = context,
                     uri = uri,
-                    exportData = exportData,
+                    exportData = backupData,
                     referencedImagePaths = validImagePaths
             )
         } catch (e: Exception) {
@@ -195,7 +193,7 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
             // Parse and validate the data structure
             val importData =
                     try {
-                        json.decodeFromString<ClimbDataExport>(importResult.jsonContent)
+                        json.decodeFromString<ClimbDataBackup>(importResult.jsonContent)
                     } catch (e: Exception) {
                         throw Exception("Invalid data format: ${e.message}")
                     }
@@ -209,52 +207,75 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
             problemDao.deleteAllProblems()
             gymDao.deleteAllGyms()
 
-            // Import gyms first (problems depend on gyms)
-            importData.gyms.forEach { gym ->
+            // Import gyms first (problems depend on gyms) - use DAO directly to avoid multiple data
+            // state updates
+            importData.gyms.forEach { backupGym ->
                 try {
-                    gymDao.insertGym(gym)
+                    gymDao.insertGym(backupGym.toGym())
                 } catch (e: Exception) {
-                    throw Exception("Failed to import gym ${gym.name}: ${e.message}")
+                    throw Exception("Failed to import gym '${backupGym.name}': ${e.message}")
                 }
             }
 
             // Import problems with updated image paths
-            val updatedProblems =
+            val updatedBackupProblems =
                     ZipExportImportUtils.updateProblemImagePaths(
                             importData.problems,
                             importResult.importedImagePaths
                     )
 
-            updatedProblems.forEach { problem ->
+            // Import problems (depends on gyms) - use DAO directly
+            updatedBackupProblems.forEach { backupProblem ->
                 try {
-                    problemDao.insertProblem(problem)
+                    problemDao.insertProblem(backupProblem.toProblem())
                 } catch (e: Exception) {
-                    throw Exception("Failed to import problem ${problem.name}: ${e.message}")
+                    throw Exception(
+                            "Failed to import problem '${backupProblem.name}': ${e.message}"
+                    )
                 }
             }
 
-            // Import sessions
-            importData.sessions.forEach { session ->
+            // Import sessions - use DAO directly
+            importData.sessions.forEach { backupSession ->
                 try {
-                    sessionDao.insertSession(session)
+                    sessionDao.insertSession(backupSession.toClimbSession())
                 } catch (e: Exception) {
-                    throw Exception("Failed to import session: ${e.message}")
+                    throw Exception("Failed to import session '${backupSession.id}': ${e.message}")
                 }
             }
 
-            // Import attempts last (depends on problems and sessions)
-            importData.attempts.forEach { attempt ->
+            // Import attempts last (depends on problems and sessions) - use DAO directly
+            importData.attempts.forEach { backupAttempt ->
                 try {
-                    attemptDao.insertAttempt(attempt)
+                    attemptDao.insertAttempt(backupAttempt.toAttempt())
                 } catch (e: Exception) {
-                    throw Exception("Failed to import attempt: ${e.message}")
+                    throw Exception("Failed to import attempt '${backupAttempt.id}': ${e.message}")
                 }
             }
+
+            // Update data state once at the end to current time since we just imported new data
+            dataStateManager.updateDataState()
         } catch (e: Exception) {
             throw Exception("Import failed: ${e.message}")
         }
     }
 
+    /**
+     * Sets the callback for auto-sync functionality. This should be called by the SyncService to
+     * register itself for auto-sync triggers.
+     */
+    fun setAutoSyncCallback(callback: (() -> Unit)?) {
+        autoSyncCallback = callback
+    }
+
+    /**
+     * Triggers auto-sync if enabled. This is called after any data modification to keep data
+     * synchronized across devices automatically.
+     */
+    private fun triggerAutoSync() {
+        autoSyncCallback?.invoke()
+    }
+
     private fun validateDataIntegrity(
             gyms: List<Gym>,
             problems: List<Problem>,
@@ -291,7 +312,7 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
         }
     }
 
-    private fun validateImportData(importData: ClimbDataExport) {
+    private fun validateImportData(importData: ClimbDataBackup) {
         if (importData.gyms.isEmpty()) {
             throw Exception("Import data is invalid: no gyms found")
         }
@@ -312,6 +333,10 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
 
     suspend fun resetAllData() {
         try {
+            // Temporarily disable auto-sync during reset
+            val originalCallback = autoSyncCallback
+            autoSyncCallback = null
+
             // Clear all data from database
             attemptDao.deleteAllAttempts()
             sessionDao.deleteAllSessions()
@@ -320,11 +345,35 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
 
             // Clear all images from storage
             clearAllImages()
+
+            // Restore auto-sync callback
+            autoSyncCallback = originalCallback
         } catch (e: Exception) {
             throw Exception("Reset failed: ${e.message}")
         }
     }
 
+    // Import methods that bypass auto-sync to avoid triggering sync during data restoration
+    suspend fun insertGymWithoutSync(gym: Gym) {
+        gymDao.insertGym(gym)
+        dataStateManager.updateDataState()
+    }
+
+    suspend fun insertProblemWithoutSync(problem: Problem) {
+        problemDao.insertProblem(problem)
+        dataStateManager.updateDataState()
+    }
+
+    suspend fun insertSessionWithoutSync(session: ClimbSession) {
+        sessionDao.insertSession(session)
+        dataStateManager.updateDataState()
+    }
+
+    suspend fun insertAttemptWithoutSync(attempt: Attempt) {
+        attemptDao.insertAttempt(attempt)
+        dataStateManager.updateDataState()
+    }
+
     private fun clearAllImages() {
         try {
             // Get the images directory
@@ -339,13 +388,3 @@ class ClimbRepository(database: OpenClimbDatabase, private val context: Context)
         }
     }
 }
-
-@kotlinx.serialization.Serializable
-data class ClimbDataExport(
-        val exportedAt: String,
-        val version: String = "2.0",
-        val gyms: List<Gym>,
-        val problems: List<Problem>,
-        val sessions: List<ClimbSession>,
-        val attempts: List<Attempt>
-)

android/app/src/main/java/com/atridad/openclimb/data/state/DataStateManager.kt

@@ -0,0 +1,81 @@
+package com.atridad.openclimb.data.state
+
+import android.content.Context
+import android.content.SharedPreferences
+import android.util.Log
+import com.atridad.openclimb.utils.DateFormatUtils
+
+/**
+ * Manages the overall data state timestamp for sync purposes. This tracks when any data in the
+ * local database was last modified, independent of individual entity timestamps.
+ */
+class DataStateManager(context: Context) {
+
+    companion object {
+        private const val TAG = "DataStateManager"
+        private const val PREFS_NAME = "openclimb_data_state"
+        private const val KEY_LAST_MODIFIED = "last_modified_timestamp"
+        private const val KEY_INITIALIZED = "state_initialized"
+    }
+
+    private val prefs: SharedPreferences =
+            context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE)
+
+    init {
+        // Initialize with current timestamp if this is the first time
+        if (!isInitialized()) {
+            updateDataState()
+            markAsInitialized()
+            Log.d(TAG, "DataStateManager initialized with timestamp: ${getLastModified()}")
+        }
+    }
+
+    /**
+     * Updates the data state timestamp to the current time. Call this whenever any data is modified
+     * (create, update, delete).
+     */
+    fun updateDataState() {
+        val now = DateFormatUtils.nowISO8601()
+        prefs.edit().putString(KEY_LAST_MODIFIED, now).apply()
+        Log.d(TAG, "Data state updated to: $now")
+    }
+
+    /**
+     * Gets the current data state timestamp. This represents when any data was last modified
+     * locally.
+     */
+    fun getLastModified(): String {
+        return prefs.getString(KEY_LAST_MODIFIED, DateFormatUtils.nowISO8601())
+                ?: DateFormatUtils.nowISO8601()
+    }
+
+    /**
+     * Sets the data state timestamp to a specific value. Used when importing data from server to
+     * sync the state.
+     */
+    fun setLastModified(timestamp: String) {
+        prefs.edit().putString(KEY_LAST_MODIFIED, timestamp).apply()
+        Log.d(TAG, "Data state set to: $timestamp")
+    }
+
+    /** Resets the data state (for testing or complete data wipe). */
+    fun reset() {
+        prefs.edit().clear().apply()
+        Log.d(TAG, "Data state reset")
+    }
+
+    /** Checks if the data state has been initialized. */
+    private fun isInitialized(): Boolean {
+        return prefs.getBoolean(KEY_INITIALIZED, false)
+    }
+
+    /** Marks the data state as initialized. */
+    private fun markAsInitialized() {
+        prefs.edit().putBoolean(KEY_INITIALIZED, true).apply()
+    }
+
+    /** Gets debug information about the current state. */
+    fun getDebugInfo(): String {
+        return "DataState(lastModified=${getLastModified()}, initialized=${isInitialized()})"
+    }
+}

android/app/src/main/java/com/atridad/openclimb/data/sync/SyncService.kt

@@ -0,0 +1,839 @@
+package com.atridad.openclimb.data.sync
+
+import android.content.Context
+import android.content.SharedPreferences
+import android.util.Log
+import com.atridad.openclimb.data.format.BackupAttempt
+import com.atridad.openclimb.data.format.BackupClimbSession
+import com.atridad.openclimb.data.format.BackupGym
+import com.atridad.openclimb.data.format.BackupProblem
+import com.atridad.openclimb.data.format.ClimbDataBackup
+import com.atridad.openclimb.data.migration.ImageMigrationService
+import com.atridad.openclimb.data.repository.ClimbRepository
+import com.atridad.openclimb.data.state.DataStateManager
+import com.atridad.openclimb.utils.DateFormatUtils
+import com.atridad.openclimb.utils.ImageNamingUtils
+import com.atridad.openclimb.utils.ImageUtils
+import java.io.IOException
+import java.time.Instant
+import java.util.concurrent.TimeUnit
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.first
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
+import kotlinx.coroutines.withContext
+import kotlinx.serialization.json.Json
+import okhttp3.MediaType.Companion.toMediaType
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import okhttp3.RequestBody.Companion.toRequestBody
+import androidx.core.content.edit
+
+class SyncService(private val context: Context, private val repository: ClimbRepository) {
+
+    private val migrationService = ImageMigrationService(context, repository)
+    private val dataStateManager = DataStateManager(context)
+    private val syncMutex = Mutex()
+
+    companion object {
+        private const val TAG = "SyncService"
+    }
+
+    private val sharedPreferences: SharedPreferences =
+            context.getSharedPreferences("sync_preferences", Context.MODE_PRIVATE)
+
+    private val httpClient =
+            OkHttpClient.Builder()
+                    .connectTimeout(30, TimeUnit.SECONDS)
+                    .readTimeout(60, TimeUnit.SECONDS)
+                    .writeTimeout(60, TimeUnit.SECONDS)
+                    .build()
+
+    private val json = Json {
+        prettyPrint = true
+        ignoreUnknownKeys = true
+        explicitNulls = false
+        encodeDefaults = true
+        coerceInputValues = true
+    }
+
+    // State flows
+    private val _isSyncing = MutableStateFlow(false)
+    val isSyncing: StateFlow<Boolean> = _isSyncing.asStateFlow()
+
+    private val _lastSyncTime = MutableStateFlow<String?>(null)
+    val lastSyncTime: StateFlow<String?> = _lastSyncTime.asStateFlow()
+
+    private val _syncError = MutableStateFlow<String?>(null)
+    val syncError: StateFlow<String?> = _syncError.asStateFlow()
+
+    private val _isConnected = MutableStateFlow(false)
+    val isConnected: StateFlow<Boolean> = _isConnected.asStateFlow()
+
+    private val _isTesting = MutableStateFlow(false)
+    val isTesting: StateFlow<Boolean> = _isTesting.asStateFlow()
+
+    // Configuration keys
+    private object Keys {
+        const val SERVER_URL = "sync_server_url"
+        const val AUTH_TOKEN = "sync_auth_token"
+        const val LAST_SYNC_TIME = "last_sync_time"
+        const val IS_CONNECTED = "sync_is_connected"
+        const val AUTO_SYNC_ENABLED = "auto_sync_enabled"
+    }
+
+    // Configuration properties
+    var serverURL: String
+        get() = sharedPreferences.getString(Keys.SERVER_URL, "") ?: ""
+        set(value) {
+            sharedPreferences.edit { putString(Keys.SERVER_URL, value) }
+        }
+
+    var authToken: String
+        get() = sharedPreferences.getString(Keys.AUTH_TOKEN, "") ?: ""
+        set(value) {
+            sharedPreferences.edit { putString(Keys.AUTH_TOKEN, value) }
+        }
+
+    val isConfigured: Boolean
+        get() = serverURL.isNotEmpty() && authToken.isNotEmpty()
+
+    var isAutoSyncEnabled: Boolean
+        get() = sharedPreferences.getBoolean(Keys.AUTO_SYNC_ENABLED, true)
+        set(value) {
+            sharedPreferences.edit().putBoolean(Keys.AUTO_SYNC_ENABLED, value).apply()
+        }
+
+    init {
+        // Initialize state from preferences
+        _isConnected.value = sharedPreferences.getBoolean(Keys.IS_CONNECTED, false)
+        _lastSyncTime.value = sharedPreferences.getString(Keys.LAST_SYNC_TIME, null)
+
+        // Register auto-sync callback with repository
+        repository.setAutoSyncCallback {
+            kotlinx.coroutines.CoroutineScope(Dispatchers.IO).launch {
+                triggerAutoSync()
+            }
+        }
+    }
+
+    suspend fun downloadData(): ClimbDataBackup =
+            withContext(Dispatchers.IO) {
+                if (!isConfigured) {
+                    throw SyncException.NotConfigured
+                }
+
+                val request =
+                        Request.Builder()
+                                .url("$serverURL/sync")
+                                .get()
+                                .addHeader("Authorization", "Bearer $authToken")
+                                .addHeader("Accept", "application/json")
+                                .build()
+
+                try {
+                    val response = httpClient.newCall(request).execute()
+
+                    when (response.code) {
+                        200 -> {
+                            val responseBody =
+                                    response.body?.string()
+                                            ?: throw SyncException.InvalidResponse(
+                                                    "Empty response body"
+                                            )
+                            Log.d(TAG, "Downloaded data from server: ${responseBody.take(500)}...")
+                            try {
+                                val backup = json.decodeFromString<ClimbDataBackup>(responseBody)
+                                Log.d(
+                                        TAG,
+                                        "Server backup contains: gyms=${backup.gyms.size}, problems=${backup.problems.size}, sessions=${backup.sessions.size}, attempts=${backup.attempts.size}"
+                                )
+
+                                // Log problems with images
+                                backup.problems.forEach { problem ->
+                                    val imageCount = problem.imagePaths?.size ?: 0
+                                    if (imageCount > 0) {
+                                        Log.d(
+                                                TAG,
+                                                "Server problem '${problem.name}' has images: ${problem.imagePaths}"
+                                        )
+                                    }
+                                }
+
+                                backup
+                            } catch (e: Exception) {
+                                Log.e(TAG, "Failed to decode download response: ${e.message}")
+                                throw SyncException.DecodingError(
+                                        e.message ?: "Failed to decode response"
+                                )
+                            }
+                        }
+                        401 -> throw SyncException.Unauthorized
+                        else -> throw SyncException.ServerError(response.code)
+                    }
+                } catch (e: IOException) {
+                    throw SyncException.NetworkError(e.message ?: "Network error")
+                }
+            }
+
+    suspend fun uploadData(backup: ClimbDataBackup): ClimbDataBackup =
+            withContext(Dispatchers.IO) {
+                if (!isConfigured) {
+                    throw SyncException.NotConfigured
+                }
+
+                val jsonBody = json.encodeToString(backup)
+                Log.d(TAG, "Uploading JSON to server: $jsonBody")
+                val requestBody = jsonBody.toRequestBody("application/json".toMediaType())
+
+                val request =
+                        Request.Builder()
+                                .url("$serverURL/sync")
+                                .put(requestBody)
+                                .addHeader("Authorization", "Bearer $authToken")
+                                .addHeader("Content-Type", "application/json")
+                                .build()
+
+                try {
+                    val response = httpClient.newCall(request).execute()
+                    Log.d(TAG, "Upload response code: ${response.code}")
+
+                    when (response.code) {
+                        200 -> {
+                            val responseBody =
+                                    response.body?.string()
+                                            ?: throw SyncException.InvalidResponse(
+                                                    "Empty response body"
+                                            )
+                            try {
+                                json.decodeFromString<ClimbDataBackup>(responseBody)
+                            } catch (e: Exception) {
+                                Log.e(TAG, "Failed to decode upload response: ${e.message}")
+                                throw SyncException.DecodingError(
+                                        e.message ?: "Failed to decode response"
+                                )
+                            }
+                        }
+                        401 -> throw SyncException.Unauthorized
+                        else -> {
+                            val errorBody = response.body?.string() ?: "No error details"
+                            Log.e(TAG, "Server error ${response.code}: $errorBody")
+                            throw SyncException.ServerError(response.code)
+                        }
+                    }
+                } catch (e: IOException) {
+                    throw SyncException.NetworkError(e.message ?: "Network error")
+                }
+            }
+
+    suspend fun uploadImage(filename: String, imageData: ByteArray) =
+            withContext(Dispatchers.IO) {
+                if (!isConfigured) {
+                    throw SyncException.NotConfigured
+                }
+
+                // Server expects filename as query parameter and raw image data in body
+                // Extract just the filename without directory path
+                val justFilename = filename.substringAfterLast('/')
+                val requestBody = imageData.toRequestBody("image/*".toMediaType())
+
+                val request =
+                        Request.Builder()
+                                .url("$serverURL/images/upload?filename=$justFilename")
+                                .post(requestBody)
+                                .addHeader("Authorization", "Bearer $authToken")
+                                .build()
+
+                try {
+                    val response = httpClient.newCall(request).execute()
+
+                    when (response.code) {
+                        200 -> Unit // Success
+                        401 -> throw SyncException.Unauthorized
+                        else -> {
+                            val errorBody = response.body?.string() ?: "No error details"
+                            Log.e(TAG, "Image upload error ${response.code}: $errorBody")
+                            throw SyncException.ServerError(response.code)
+                        }
+                    }
+                } catch (e: IOException) {
+                    throw SyncException.NetworkError(e.message ?: "Network error")
+                }
+            }
+
+    suspend fun downloadImage(filename: String): ByteArray =
+            withContext(Dispatchers.IO) {
+                if (!isConfigured) {
+                    throw SyncException.NotConfigured
+                }
+
+                Log.d(TAG, "Downloading image from server: $filename")
+                val request =
+                        Request.Builder()
+                                .url("$serverURL/images/download?filename=$filename")
+                                .get()
+                                .addHeader("Authorization", "Bearer $authToken")
+                                .build()
+
+                try {
+                    val response = httpClient.newCall(request).execute()
+                    Log.d(TAG, "Image download response for $filename: ${response.code}")
+
+                    when (response.code) {
+                        200 -> {
+                            val imageBytes =
+                                    response.body?.bytes()
+                                            ?: throw SyncException.InvalidResponse(
+                                                    "Empty image response"
+                                            )
+                            Log.d(
+                                    TAG,
+                                    "Successfully downloaded image $filename: ${imageBytes.size} bytes"
+                            )
+                            imageBytes
+                        }
+                        401 -> throw SyncException.Unauthorized
+                        404 -> {
+                            Log.w(TAG, "Image not found on server: $filename")
+                            throw SyncException.ImageNotFound(filename)
+                        }
+                        else -> {
+                            val errorBody = response.body?.string() ?: "No error details"
+                            Log.e(
+                                    TAG,
+                                    "Image download error ${response.code} for $filename: $errorBody"
+                            )
+                            throw SyncException.ServerError(response.code)
+                        }
+                    }
+                } catch (e: IOException) {
+                    Log.e(TAG, "Network error downloading image $filename: ${e.message}")
+                    throw SyncException.NetworkError(e.message ?: "Network error")
+                }
+            }
+
+    suspend fun syncWithServer() {
+        if (!isConfigured) {
+            throw SyncException.NotConfigured
+        }
+
+        if (!_isConnected.value) {
+            throw SyncException.NotConnected
+        }
+
+        // Prevent concurrent sync operations
+        syncMutex.withLock {
+            _isSyncing.value = true
+            _syncError.value = null
+
+            try {
+                // Fix existing image paths first
+                Log.d(TAG, "Fixing existing image paths before sync")
+                val pathFixSuccess = fixImagePaths()
+                if (!pathFixSuccess) {
+                    Log.w(TAG, "Image path fix failed, but continuing with sync")
+                }
+
+                // Migrate images to consistent naming second
+                Log.d(TAG, "Performing image migration before sync")
+                val migrationSuccess = migrateImagesForSync()
+                if (!migrationSuccess) {
+                    Log.w(TAG, "Image migration failed, but continuing with sync")
+                }
+
+                // Get local backup data
+                val localBackup = createBackupFromRepository()
+
+                // Download server data
+                val serverBackup = downloadData()
+
+                // Check if we have any local data
+                val hasLocalData =
+                        localBackup.gyms.isNotEmpty() ||
+                                localBackup.problems.isNotEmpty() ||
+                                localBackup.sessions.isNotEmpty() ||
+                                localBackup.attempts.isNotEmpty()
+
+                val hasServerData =
+                        serverBackup.gyms.isNotEmpty() ||
+                                serverBackup.problems.isNotEmpty() ||
+                                serverBackup.sessions.isNotEmpty() ||
+                                serverBackup.attempts.isNotEmpty()
+
+                when {
+                    !hasLocalData && hasServerData -> {
+                        // Case 1: No local data - do full restore from server
+                        Log.d(TAG, "No local data found, performing full restore from server")
+                        val imagePathMapping = syncImagesFromServer(serverBackup)
+                        importBackupToRepository(serverBackup, imagePathMapping)
+                        Log.d(TAG, "Full restore completed")
+                    }
+                    hasLocalData && !hasServerData -> {
+                        // Case 2: No server data - upload local data to server
+                        Log.d(TAG, "No server data found, uploading local data to server")
+                        uploadData(localBackup)
+                        syncImagesForBackup(localBackup)
+                        Log.d(TAG, "Initial upload completed")
+                    }
+                    hasLocalData && hasServerData -> {
+                        // Case 3: Both have data - compare timestamps (last writer wins)
+                        val localTimestamp = parseISO8601ToMillis(localBackup.exportedAt)
+                        val serverTimestamp = parseISO8601ToMillis(serverBackup.exportedAt)
+
+                        Log.d(
+                                TAG,
+                                "Comparing timestamps: local=$localTimestamp, server=$serverTimestamp"
+                        )
+
+                        if (localTimestamp > serverTimestamp) {
+                            // Local is newer - replace server with local data
+                            Log.d(TAG, "Local data is newer, replacing server content")
+                            uploadData(localBackup)
+                            syncImagesForBackup(localBackup)
+                            Log.d(TAG, "Server replaced with local data")
+                        } else if (serverTimestamp > localTimestamp) {
+                            // Server is newer - replace local with server data
+                            Log.d(TAG, "Server data is newer, replacing local content")
+                            val imagePathMapping = syncImagesFromServer(serverBackup)
+                            importBackupToRepository(serverBackup, imagePathMapping)
+                            Log.d(TAG, "Local data replaced with server data")
+                        } else {
+                            // Timestamps are equal - no sync needed
+                            Log.d(TAG, "Data is in sync (timestamps equal), no action needed")
+                        }
+                    }
+                    else -> {
+                        Log.d(TAG, "No data to sync")
+                    }
+                }
+
+                // Update last sync time
+                val now = DateFormatUtils.nowISO8601()
+                _lastSyncTime.value = now
+                sharedPreferences.edit().putString(Keys.LAST_SYNC_TIME, now).apply()
+            } catch (e: Exception) {
+                _syncError.value = e.message
+                throw e
+            } finally {
+                _isSyncing.value = false
+            }
+        }
+    }
+
+    private suspend fun syncImagesFromServer(backup: ClimbDataBackup): Map<String, String> {
+        val imagePathMapping = mutableMapOf<String, String>()
+
+        Log.d(TAG, "Starting to download images from server")
+        var totalImages = 0
+        var downloadedImages = 0
+        var failedImages = 0
+
+        for (problem in backup.problems) {
+            val imageCount = problem.imagePaths?.size ?: 0
+            if (imageCount > 0) {
+                Log.d(
+                        TAG,
+                        "Problem '${problem.name}' has $imageCount images: ${problem.imagePaths}"
+                )
+                totalImages += imageCount
+            }
+
+            problem.imagePaths?.forEachIndexed { index, imagePath ->
+                try {
+                    Log.d(TAG, "Attempting to download image: $imagePath")
+                    val imageData = downloadImage(imagePath)
+
+                    // Extract filename and ensure it follows our naming convention
+                    val serverFilename = imagePath.substringAfterLast('/')
+                    val consistentFilename =
+                            if (ImageNamingUtils.isValidImageFilename(serverFilename)) {
+                                serverFilename
+                            } else {
+                                // Generate consistent filename using problem ID and index
+                                ImageNamingUtils.generateImageFilename(problem.id, index)
+                            }
+
+                    val localImagePath =
+                            ImageUtils.saveImageFromBytesWithFilename(
+                                    context,
+                                    imageData,
+                                    consistentFilename
+                            )
+
+                    if (localImagePath != null) {
+                        // Map original server filename to the full local relative path
+                        imagePathMapping[serverFilename] = localImagePath
+                        downloadedImages++
+                        Log.d(
+                                TAG,
+                                "Downloaded and mapped image: $serverFilename -> $localImagePath"
+                        )
+                    } else {
+                        Log.w(TAG, "Failed to save downloaded image locally: $imagePath")
+                        failedImages++
+                    }
+                } catch (e: Exception) {
+                    Log.w(TAG, "Failed to download image $imagePath: ${e.message}")
+                    failedImages++
+                }
+            }
+        }
+
+        Log.d(
+                TAG,
+                "Image download completed: $downloadedImages downloaded, $failedImages failed, $totalImages total"
+        )
+        return imagePathMapping
+    }
+
+    private suspend fun syncImagesForBackup(backup: ClimbDataBackup) {
+        Log.d(TAG, "Starting image sync for backup with ${backup.problems.size} problems")
+
+        var totalImages = 0
+        var uploadedImages = 0
+        var failedImages = 0
+
+        for (problem in backup.problems) {
+            val imageCount = problem.imagePaths?.size ?: 0
+            totalImages += imageCount
+
+            Log.d(TAG, "Problem '${problem.name}' has $imageCount images: ${problem.imagePaths}")
+
+            problem.imagePaths?.forEachIndexed { index, imagePath ->
+                try {
+                    val imageFile = ImageUtils.getImageFile(context, imagePath)
+                    Log.d(TAG, "Checking image file: $imagePath -> ${imageFile.absolutePath}")
+                    Log.d(
+                            TAG,
+                            "Image file exists: ${imageFile.exists()}, size: ${if (imageFile.exists()) imageFile.length() else 0} bytes"
+                    )
+
+                    if (imageFile.exists() && imageFile.length() > 0) {
+                        val imageData = imageFile.readBytes()
+                        val filename = imagePath.substringAfterLast('/')
+
+                        // Ensure filename follows our naming convention
+                        val consistentFilename =
+                                if (ImageNamingUtils.isValidImageFilename(filename)) {
+                                    filename
+                                } else {
+                                    // Generate consistent filename and rename the local file
+                                    val newFilename =
+                                            ImageNamingUtils.generateImageFilename(
+                                                    problem.id,
+                                                    index
+                                            )
+                                    val newFile = java.io.File(imageFile.parent, newFilename)
+                                    if (imageFile.renameTo(newFile)) {
+                                        Log.d(
+                                                TAG,
+                                                "Renamed local image file: $filename -> $newFilename"
+                                        )
+                                        // Update the problem's image path in memory for next sync
+                                        newFilename
+                                    } else {
+                                        Log.w(
+                                                TAG,
+                                                "Failed to rename local image file, using original"
+                                        )
+                                        filename
+                                    }
+                                }
+
+                        Log.d(TAG, "Uploading image: $consistentFilename (${imageData.size} bytes)")
+                        uploadImage(consistentFilename, imageData)
+                        uploadedImages++
+                        Log.d(TAG, "Successfully uploaded image: $consistentFilename")
+                    } else {
+                        Log.w(
+                                TAG,
+                                "Image file not found or empty: $imagePath at ${imageFile.absolutePath}"
+                        )
+                        failedImages++
+                    }
+                } catch (e: Exception) {
+                    Log.e(TAG, "Failed to upload image $imagePath: ${e.message}", e)
+                    failedImages++
+                }
+            }
+        }
+
+        Log.d(
+                TAG,
+                "Image sync completed: $uploadedImages uploaded, $failedImages failed, $totalImages total"
+        )
+    }
+
+    private suspend fun createBackupFromRepository(): ClimbDataBackup {
+        val allGyms = repository.getAllGyms().first()
+        val allProblems = repository.getAllProblems().first()
+        val allSessions = repository.getAllSessions().first()
+        val allAttempts = repository.getAllAttempts().first()
+
+        return ClimbDataBackup(
+                exportedAt = dataStateManager.getLastModified(),
+                version = "2.0",
+                formatVersion = "2.0",
+                gyms = allGyms.map { BackupGym.fromGym(it) },
+                problems = allProblems.map { BackupProblem.fromProblem(it) },
+                sessions = allSessions.map { BackupClimbSession.fromClimbSession(it) },
+                attempts = allAttempts.map { BackupAttempt.fromAttempt(it) }
+        )
+    }
+
+    private suspend fun importBackupToRepository(
+            backup: ClimbDataBackup,
+            imagePathMapping: Map<String, String> = emptyMap()
+    ) {
+        // Clear existing data to avoid conflicts
+        repository.resetAllData()
+
+        // Import gyms first (problems depend on gyms)
+        backup.gyms.forEach { backupGym ->
+            try {
+                val gym = backupGym.toGym()
+                Log.d(TAG, "Importing gym: ${gym.name} (ID: ${gym.id})")
+                repository.insertGymWithoutSync(gym)
+            } catch (e: Exception) {
+                Log.e(TAG, "Failed to import gym '${backupGym.name}': ${e.message}")
+                throw e // Stop import if gym fails since problems depend on it
+            }
+        }
+
+        // Import problems with updated image paths
+        backup.problems.forEach { backupProblem ->
+            try {
+                val updatedProblem =
+                        if (imagePathMapping.isNotEmpty()) {
+                            val newImagePaths =
+                                    backupProblem.imagePaths?.map { oldPath ->
+                                        // Extract filename and check mapping
+                                        val filename = oldPath.substringAfterLast('/')
+                                        // Use mapped full path or fallback to consistent naming
+                                        // with full path
+                                        imagePathMapping[filename]
+                                                ?: if (ImageNamingUtils.isValidImageFilename(
+                                                                filename
+                                                        )
+                                                ) {
+                                                    "problem_images/$filename"
+                                                } else {
+                                                    // Generate consistent filename as fallback with
+                                                    // full path
+                                                    val index =
+                                                            backupProblem.imagePaths.indexOf(
+                                                                    oldPath
+                                                            )
+                                                    val consistentFilename =
+                                                            ImageNamingUtils.generateImageFilename(
+                                                                    backupProblem.id,
+                                                                    index
+                                                            )
+                                                    "problem_images/$consistentFilename"
+                                                }
+                                    }
+                                            ?: emptyList()
+                            backupProblem.withUpdatedImagePaths(newImagePaths)
+                        } else {
+                            backupProblem
+                        }
+                repository.insertProblemWithoutSync(updatedProblem.toProblem())
+            } catch (e: Exception) {
+                Log.e(TAG, "Failed to import problem '${backupProblem.name}': ${e.message}")
+            }
+        }
+
+        // Import sessions
+        backup.sessions.forEach { backupSession ->
+            try {
+                repository.insertSessionWithoutSync(backupSession.toClimbSession())
+            } catch (e: Exception) {
+                Log.e(TAG, "Failed to import session '${backupSession.id}': ${e.message}")
+            }
+        }
+
+        // Import attempts last
+        backup.attempts.forEach { backupAttempt ->
+            try {
+                repository.insertAttemptWithoutSync(backupAttempt.toAttempt())
+            } catch (e: Exception) {
+                Log.e(TAG, "Failed to import attempt '${backupAttempt.id}': ${e.message}")
+            }
+        }
+
+        // Update local data state to match imported data timestamp
+        dataStateManager.setLastModified(backup.exportedAt)
+        Log.d(TAG, "Data state synchronized to imported timestamp: ${backup.exportedAt}")
+    }
+
+    /** Parses ISO8601 timestamp to milliseconds for comparison */
+    private fun parseISO8601ToMillis(timestamp: String): Long {
+        return try {
+            Instant.parse(timestamp).toEpochMilli()
+        } catch (e: Exception) {
+            Log.w(TAG, "Failed to parse timestamp: $timestamp, using 0", e)
+            0L
+        }
+    }
+
+    /**
+     * Fixes existing image paths in the database to include the proper directory structure. This
+     * corrects paths like "problem_abc_0.jpg" to "problem_images/problem_abc_0.jpg"
+     */
+    suspend fun fixImagePaths(): Boolean {
+        return try {
+            Log.d(TAG, "Fixing existing image paths in database")
+
+            val allProblems = repository.getAllProblems().first()
+            var fixedCount = 0
+
+            for (problem in allProblems) {
+                if (problem.imagePaths.isNotEmpty()) {
+                    val originalPaths = problem.imagePaths
+                    val fixedPaths =
+                            problem.imagePaths.map { path ->
+                                if (!path.startsWith("problem_images/") && !path.contains("/")) {
+                                    // Just a filename, add the directory prefix
+                                    val fixedPath = "problem_images/$path"
+                                    Log.d(TAG, "Fixed path: $path -> $fixedPath")
+                                    fixedCount++
+                                    fixedPath
+                                } else {
+                                    path
+                                }
+                            }
+
+                    if (originalPaths != fixedPaths) {
+                        val updatedProblem = problem.copy(imagePaths = fixedPaths)
+                        repository.insertProblem(updatedProblem)
+                    }
+                }
+            }
+
+            Log.i(TAG, "Fixed $fixedCount image paths in database")
+            true
+        } catch (e: Exception) {
+            Log.e(TAG, "Failed to fix image paths: ${e.message}", e)
+            false
+        }
+    }
+
+    /**
+     * Performs image migration to ensure all images use consistent naming convention before sync
+     * operations. This should be called before any sync to avoid filename conflicts.
+     */
+    suspend fun migrateImagesForSync(): Boolean {
+        return try {
+            Log.d(TAG, "Starting image migration for sync compatibility")
+            val result = migrationService.performFullMigration()
+
+            when (result) {
+                is com.atridad.openclimb.data.migration.ImageMigrationResult.AlreadyCompleted -> {
+                    Log.d(TAG, "Image migration already completed")
+                    true
+                }
+                is com.atridad.openclimb.data.migration.ImageMigrationResult.Success -> {
+                    Log.i(
+                            TAG,
+                            "Image migration completed: ${result.totalMigrated} images migrated, ${result.errors} errors"
+                    )
+                    true
+                }
+                is com.atridad.openclimb.data.migration.ImageMigrationResult.Failed -> {
+                    Log.e(TAG, "Image migration failed: ${result.error}")
+                    false
+                }
+            }
+        } catch (e: Exception) {
+            Log.e(TAG, "Image migration error: ${e.message}", e)
+            false
+        }
+    }
+
+    suspend fun testConnection() {
+        if (!isConfigured) {
+            throw SyncException.NotConfigured
+        }
+
+        _isTesting.value = true
+        _syncError.value = null
+
+        try {
+            withContext(Dispatchers.IO) {
+                val request =
+                        Request.Builder()
+                                .url("$serverURL/sync")
+                                .get()
+                                .addHeader("Authorization", "Bearer $authToken")
+                                .addHeader("Accept", "application/json")
+                                .build()
+
+                val response = httpClient.newCall(request).execute()
+
+                when (response.code) {
+                    200 -> {
+                        _isConnected.value = true
+                        sharedPreferences.edit().putBoolean(Keys.IS_CONNECTED, true).apply()
+                    }
+                    401 -> throw SyncException.Unauthorized
+                    else -> throw SyncException.ServerError(response.code)
+                }
+            }
+        } catch (e: Exception) {
+            _isConnected.value = false
+            sharedPreferences.edit().putBoolean(Keys.IS_CONNECTED, false).apply()
+            _syncError.value = e.message
+            throw e
+        } finally {
+            _isTesting.value = false
+        }
+    }
+
+    suspend fun triggerAutoSync() {
+        if (!isConfigured || !_isConnected.value || !isAutoSyncEnabled) {
+            return
+        }
+
+        // Check if sync is already running to prevent duplicate attempts
+        if (_isSyncing.value) {
+            Log.d(TAG, "Sync already in progress, skipping auto-sync")
+            return
+        }
+
+        try {
+            syncWithServer()
+        } catch (e: Exception) {
+            Log.e(TAG, "Auto-sync failed: ${e.message}")
+            _syncError.value = e.message
+        }
+    }
+
+    fun clearConfiguration() {
+        serverURL = ""
+        authToken = ""
+        isAutoSyncEnabled = true
+        _lastSyncTime.value = null
+        _isConnected.value = false
+        _syncError.value = null
+
+        sharedPreferences.edit().clear().apply()
+    }
+}
+
+sealed class SyncException(message: String) : Exception(message) {
+    object NotConfigured :
+            SyncException("Sync is not configured. Please set server URL and auth token.")
+    object NotConnected : SyncException("Not connected to server. Please test connection first.")
+    object Unauthorized : SyncException("Unauthorized. Please check your auth token.")
+    data class ServerError(val code: Int) : SyncException("Server error: HTTP $code")
+    data class InvalidResponse(val details: String) :
+            SyncException("Invalid server response: $details")
+    data class DecodingError(val details: String) :
+            SyncException("Failed to decode server response: $details")
+    data class ImageNotFound(val filename: String) : SyncException("Image not found: $filename")
+    data class NetworkError(val details: String) : SyncException("Network error: $details")
+}

android/app/src/main/java/com/atridad/openclimb/ui/OpenClimbApp.kt

@@ -11,7 +11,6 @@ import androidx.compose.runtime.*
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.lifecycle.viewmodel.compose.viewModel
-import androidx.navigation.NavController
 import androidx.navigation.NavHostController
 import androidx.navigation.compose.NavHost
 import androidx.navigation.compose.composable
@@ -20,6 +19,7 @@ import androidx.navigation.compose.rememberNavController
 import androidx.navigation.toRoute
 import com.atridad.openclimb.data.database.OpenClimbDatabase
 import com.atridad.openclimb.data.repository.ClimbRepository
+import com.atridad.openclimb.data.sync.SyncService
 import com.atridad.openclimb.navigation.Screen
 import com.atridad.openclimb.navigation.bottomNavigationItems
 import com.atridad.openclimb.ui.components.NotificationPermissionDialog
@@ -43,7 +43,9 @@ fun OpenClimbApp(
 
     val database = remember { OpenClimbDatabase.getDatabase(context) }
     val repository = remember { ClimbRepository(database, context) }
-    val viewModel: ClimbViewModel = viewModel(factory = ClimbViewModelFactory(repository))
+    val syncService = remember { SyncService(context, repository) }
+    val viewModel: ClimbViewModel =
+            viewModel(factory = ClimbViewModelFactory(repository, syncService))
 
     // Notification permission state
     var showNotificationPermissionDialog by remember { mutableStateOf(false) }
@@ -73,6 +75,9 @@ fun OpenClimbApp(
 
     LaunchedEffect(Unit) { viewModel.ensureSessionTrackingServiceRunning(context) }
 
+    // Trigger auto-sync on app launch
+    LaunchedEffect(Unit) { syncService.triggerAutoSync() }
+
     val activeSession by viewModel.activeSession.collectAsState()
     val gyms by viewModel.gyms.collectAsState()
 

android/app/src/main/java/com/atridad/openclimb/ui/components/SyncIndicator.kt

@@ -0,0 +1,49 @@
+package com.atridad.openclimb.ui.components
+
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.animation.scaleIn
+import androidx.compose.animation.scaleOut
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.unit.dp
+import kotlinx.coroutines.flow.StateFlow
+
+@Composable
+fun SyncIndicator(isSyncing: StateFlow<Boolean>, modifier: Modifier = Modifier) {
+    val syncing by isSyncing.collectAsState()
+
+    AnimatedVisibility(
+            visible = syncing,
+            enter = scaleIn() + fadeIn(),
+            exit = scaleOut() + fadeOut(),
+            modifier = modifier
+    ) {
+        Box(
+                modifier =
+                        Modifier.size(28.dp)
+                                .clip(CircleShape)
+                                .background(MaterialTheme.colorScheme.primaryContainer, CircleShape)
+                                .padding(6.dp),
+                contentAlignment = Alignment.Center
+        ) {
+            CircularProgressIndicator(
+                    modifier = Modifier.size(16.dp),
+                    strokeWidth = 2.dp,
+                    color = MaterialTheme.colorScheme.primary
+            )
+        }
+    }
+}

android/app/src/main/java/com/atridad/openclimb/ui/screens/AnalyticsScreen.kt

@@ -15,6 +15,7 @@ import com.atridad.openclimb.data.model.ClimbType
 import com.atridad.openclimb.data.model.DifficultySystem
 import com.atridad.openclimb.ui.components.BarChart
 import com.atridad.openclimb.ui.components.BarChartDataPoint
+import com.atridad.openclimb.ui.components.SyncIndicator
 import com.atridad.openclimb.ui.viewmodel.ClimbViewModel
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
@@ -45,8 +46,10 @@ fun AnalyticsScreen(viewModel: ClimbViewModel) {
                 Text(
                         text = "Analytics",
                         style = MaterialTheme.typography.headlineMedium,
-                        fontWeight = FontWeight.Bold
+                        fontWeight = FontWeight.Bold,
+                        modifier = Modifier.weight(1f)
                 )
+                SyncIndicator(isSyncing = viewModel.syncService.isSyncing)
             }
         }
 
@@ -197,7 +200,7 @@ fun GradeDistributionChartCard(gradeDistributionData: List<GradeDistributionData
                                 },
                                 modifier =
                                         Modifier.menuAnchor(
-                                                        type = MenuAnchorType.PrimaryNotEditable,
+                                                        type = ExposedDropdownMenuAnchorType.PrimaryNotEditable,
                                                         enabled = true
                                                 )
                                                 .width(120.dp),
@@ -253,7 +256,7 @@ fun GradeDistributionChartCard(gradeDistributionData: List<GradeDistributionData
                                                     DateTimeFormatter.ISO_LOCAL_DATE_TIME
                                             )
                                     attemptDate.isAfter(sevenDaysAgo)
-                                } catch (e: Exception) {
+                                } catch (_: Exception) {
                                     // If date parsing fails, include the data point
                                     true
                                 }
@@ -425,9 +428,7 @@ fun calculateGradeDistribution(
             } else {
                 gradeDistribution[key] =
                         GradeDistributionDataPoint(
-                                date =
-                                        attempt.timestamp
-                                                .toString(), // Use attempt timestamp for filtering
+                                date = attempt.timestamp,
                                 grade = problem.difficulty.grade,
                                 gradeNumeric =
                                         gradeToNumeric(

android/app/src/main/java/com/atridad/openclimb/ui/screens/GymsScreen.kt

@@ -12,55 +12,48 @@ import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.dp
 import com.atridad.openclimb.R
 import com.atridad.openclimb.data.model.Gym
+import com.atridad.openclimb.ui.components.SyncIndicator
 import com.atridad.openclimb.ui.viewmodel.ClimbViewModel
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
-fun GymsScreen(
-    viewModel: ClimbViewModel,
-    onNavigateToGymDetail: (String) -> Unit
-) {
+fun GymsScreen(viewModel: ClimbViewModel, onNavigateToGymDetail: (String) -> Unit) {
     val gyms by viewModel.gyms.collectAsState()
-    
-    Column(
-        modifier = Modifier
-            .fillMaxSize()
-            .padding(16.dp)
-    ) {
+
+    Column(modifier = Modifier.fillMaxSize().padding(16.dp)) {
         Row(
-            modifier = Modifier.fillMaxWidth(),
-            verticalAlignment = Alignment.CenterVertically,
-            horizontalArrangement = Arrangement.spacedBy(12.dp)
+                modifier = Modifier.fillMaxWidth(),
+                verticalAlignment = Alignment.CenterVertically,
+                horizontalArrangement = Arrangement.spacedBy(12.dp)
         ) {
             Icon(
-                painter = painterResource(id = R.drawable.ic_mountains),
-                contentDescription = "OpenClimb Logo",
-                modifier = Modifier.size(32.dp),
-                tint = MaterialTheme.colorScheme.primary
+                    painter = painterResource(id = R.drawable.ic_mountains),
+                    contentDescription = "OpenClimb Logo",
+                    modifier = Modifier.size(32.dp),
+                    tint = MaterialTheme.colorScheme.primary
             )
             Text(
-                text = "Climbing Gyms",
-                style = MaterialTheme.typography.headlineMedium,
-                fontWeight = FontWeight.Bold
+                    text = "Climbing Gyms",
+                    style = MaterialTheme.typography.headlineMedium,
+                    fontWeight = FontWeight.Bold,
+                    modifier = Modifier.weight(1f)
             )
+            SyncIndicator(isSyncing = viewModel.syncService.isSyncing)
         }
-        
+
         Spacer(modifier = Modifier.height(16.dp))
-        
+
         if (gyms.isEmpty()) {
             EmptyStateMessage(
-                title = "No Gyms Added",
-                message = "Add your favorite climbing gyms to start tracking your progress!",
-                onActionClick = { },
-                actionText = ""
+                    title = "No Gyms Added",
+                    message = "Add your favorite climbing gyms to start tracking your progress!",
+                    onActionClick = {},
+                    actionText = ""
             )
         } else {
             LazyColumn {
                 items(gyms) { gym ->
-                    GymCard(
-                        gym = gym,
-                        onClick = { onNavigateToGymDetail(gym.id) }
-                    )
+                    GymCard(gym = gym, onClick = { onNavigateToGymDetail(gym.id) })
                     Spacer(modifier = Modifier.height(8.dp))
                 }
             }
@@ -70,65 +63,54 @@ fun GymsScreen(
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
-fun GymCard(
-    gym: Gym,
-    onClick: () -> Unit
-) {
-    Card(
-        onClick = onClick,
-        modifier = Modifier.fillMaxWidth()
-    ) {
-        Column(
-            modifier = Modifier
-                .fillMaxWidth()
-                .padding(16.dp)
-        ) {
+fun GymCard(gym: Gym, onClick: () -> Unit) {
+    Card(onClick = onClick, modifier = Modifier.fillMaxWidth()) {
+        Column(modifier = Modifier.fillMaxWidth().padding(16.dp)) {
             Text(
-                text = gym.name,
-                style = MaterialTheme.typography.titleLarge,
-                fontWeight = FontWeight.Bold
+                    text = gym.name,
+                    style = MaterialTheme.typography.titleLarge,
+                    fontWeight = FontWeight.Bold
             )
-            
+
             gym.location?.let { location ->
                 Spacer(modifier = Modifier.height(4.dp))
                 Text(
-                    text = location,
-                    style = MaterialTheme.typography.bodyMedium,
-                    color = MaterialTheme.colorScheme.onSurfaceVariant
+                        text = location,
+                        style = MaterialTheme.typography.bodyMedium,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant
                 )
             }
-            
+
             Spacer(modifier = Modifier.height(8.dp))
-            
+
             Row {
                 gym.supportedClimbTypes.forEach { climbType ->
                     AssistChip(
-                        onClick = { },
-                        label = { 
-                            Text(climbType.getDisplayName()) 
-                        },
-                        modifier = Modifier.padding(end = 4.dp)
+                            onClick = {},
+                            label = { Text(climbType.getDisplayName()) },
+                            modifier = Modifier.padding(end = 4.dp)
                     )
                 }
             }
-            
+
             if (gym.difficultySystems.isNotEmpty()) {
                 Spacer(modifier = Modifier.height(4.dp))
                 Text(
-                    text = "Systems: ${gym.difficultySystems.joinToString(", ") { it.getDisplayName() }}",
-                    style = MaterialTheme.typography.bodySmall,
-                    color = MaterialTheme.colorScheme.onSurfaceVariant
+                        text =
+                                "Systems: ${gym.difficultySystems.joinToString(", ") { it.getDisplayName() }}",
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant
                 )
             }
-            
+
             gym.notes?.let { notes ->
                 if (notes.isNotBlank()) {
                     Spacer(modifier = Modifier.height(8.dp))
                     Text(
-                        text = notes,
-                        style = MaterialTheme.typography.bodySmall,
-                        color = MaterialTheme.colorScheme.onSurfaceVariant,
-                        maxLines = 2
+                            text = notes,
+                            style = MaterialTheme.typography.bodySmall,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant,
+                            maxLines = 2
                     )
                 }
             }

android/app/src/main/java/com/atridad/openclimb/ui/screens/ProblemsScreen.kt

@@ -17,6 +17,7 @@ import com.atridad.openclimb.data.model.Gym
 import com.atridad.openclimb.data.model.Problem
 import com.atridad.openclimb.ui.components.FullscreenImageViewer
 import com.atridad.openclimb.ui.components.ImageDisplay
+import com.atridad.openclimb.ui.components.SyncIndicator
 import com.atridad.openclimb.ui.viewmodel.ClimbViewModel
 
 @OptIn(ExperimentalMaterial3Api::class)
@@ -58,10 +59,12 @@ fun ProblemsScreen(viewModel: ClimbViewModel, onNavigateToProblemDetail: (String
                     tint = MaterialTheme.colorScheme.primary
             )
             Text(
-                    text = "Problems & Routes",
+                    text = "Climbing Problems",
                     style = MaterialTheme.typography.headlineMedium,
-                    fontWeight = FontWeight.Bold
+                    fontWeight = FontWeight.Bold,
+                    modifier = Modifier.weight(1f)
             )
+            SyncIndicator(isSyncing = viewModel.syncService.isSyncing)
         }
 
         Spacer(modifier = Modifier.height(16.dp))

android/app/src/main/java/com/atridad/openclimb/ui/screens/SessionsScreen.kt

@@ -20,160 +20,145 @@ import com.atridad.openclimb.R
 import com.atridad.openclimb.data.model.ClimbSession
 import com.atridad.openclimb.data.model.SessionStatus
 import com.atridad.openclimb.ui.components.ActiveSessionBanner
+import com.atridad.openclimb.ui.components.SyncIndicator
 import com.atridad.openclimb.ui.viewmodel.ClimbViewModel
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
-fun SessionsScreen(
-    viewModel: ClimbViewModel,
-    onNavigateToSessionDetail: (String) -> Unit
-) {
+fun SessionsScreen(viewModel: ClimbViewModel, onNavigateToSessionDetail: (String) -> Unit) {
     val context = LocalContext.current
     val sessions by viewModel.sessions.collectAsState()
     val gyms by viewModel.gyms.collectAsState()
     val activeSession by viewModel.activeSession.collectAsState()
     val uiState by viewModel.uiState.collectAsState()
-    
+
     // Filter out active sessions from regular session list
     val completedSessions = sessions.filter { it.status == SessionStatus.COMPLETED }
-    val activeSessionGym = activeSession?.let { session ->
-        gyms.find { it.id == session.gymId }
-    }
-    
-    Column(
-        modifier = Modifier
-            .fillMaxSize()
-            .padding(16.dp)
-    ) {
+    val activeSessionGym = activeSession?.let { session -> gyms.find { it.id == session.gymId } }
+
+    Column(modifier = Modifier.fillMaxSize().padding(16.dp)) {
         Row(
-            modifier = Modifier.fillMaxWidth(),
-            verticalAlignment = Alignment.CenterVertically,
-            horizontalArrangement = Arrangement.spacedBy(12.dp)
+                modifier = Modifier.fillMaxWidth(),
+                verticalAlignment = Alignment.CenterVertically,
+                horizontalArrangement = Arrangement.spacedBy(12.dp)
         ) {
             Icon(
-                painter = painterResource(id = R.drawable.ic_mountains),
-                contentDescription = "OpenClimb Logo",
-                modifier = Modifier.size(32.dp),
-                tint = MaterialTheme.colorScheme.primary
+                    painter = painterResource(id = R.drawable.ic_mountains),
+                    contentDescription = "OpenClimb Logo",
+                    modifier = Modifier.size(32.dp),
+                    tint = MaterialTheme.colorScheme.primary
             )
             Text(
-                text = "Climbing Sessions",
-                style = MaterialTheme.typography.headlineMedium,
-                fontWeight = FontWeight.Bold
+                    text = "Climbing Sessions",
+                    style = MaterialTheme.typography.headlineMedium,
+                    fontWeight = FontWeight.Bold,
+                    modifier = Modifier.weight(1f)
             )
+            SyncIndicator(isSyncing = viewModel.syncService.isSyncing)
         }
-        
+
         Spacer(modifier = Modifier.height(16.dp))
-        
+
         // Active session banner
         ActiveSessionBanner(
-            activeSession = activeSession,
-            gym = activeSessionGym,
-            onSessionClick = {
-                activeSession?.let { onNavigateToSessionDetail(it.id) }
-            },
-            onEndSession = {
-                activeSession?.let { 
-                    viewModel.endSession(context, it.id)
-                }
-            }
+                activeSession = activeSession,
+                gym = activeSessionGym,
+                onSessionClick = { activeSession?.let { onNavigateToSessionDetail(it.id) } },
+                onEndSession = { activeSession?.let { viewModel.endSession(context, it.id) } }
         )
-        
+
         if (activeSession != null) {
             Spacer(modifier = Modifier.height(16.dp))
         }
-        
+
         if (completedSessions.isEmpty() && activeSession == null) {
             EmptyStateMessage(
-                title = if (gyms.isEmpty()) "No Gyms Available" else "No Sessions Yet",
-                message = if (gyms.isEmpty()) "Add a gym first to start tracking your climbing sessions!" else "Start your first climbing session!",
-                onActionClick = { },
-                actionText = ""
+                    title = if (gyms.isEmpty()) "No Gyms Available" else "No Sessions Yet",
+                    message =
+                            if (gyms.isEmpty())
+                                    "Add a gym first to start tracking your climbing sessions!"
+                            else "Start your first climbing session!",
+                    onActionClick = {},
+                    actionText = ""
             )
         } else {
             LazyColumn {
                 items(completedSessions) { session ->
                     SessionCard(
-                        session = session,
-                        gymName = gyms.find { it.id == session.gymId }?.name ?: "Unknown Gym",
-                        onClick = { onNavigateToSessionDetail(session.id) }
+                            session = session,
+                            gymName = gyms.find { it.id == session.gymId }?.name ?: "Unknown Gym",
+                            onClick = { onNavigateToSessionDetail(session.id) }
                     )
                     Spacer(modifier = Modifier.height(8.dp))
                 }
             }
         }
     }
-    
+
     // Show UI state messages and errors
     uiState.message?.let { message ->
         LaunchedEffect(message) {
             kotlinx.coroutines.delay(5000)
             viewModel.clearMessage()
         }
-        
+
         Card(
-            modifier = Modifier
-                .fillMaxWidth()
-                .padding(16.dp),
-            colors = CardDefaults.cardColors(
-                containerColor = MaterialTheme.colorScheme.primaryContainer
-            ),
-            shape = RoundedCornerShape(12.dp)
+                modifier = Modifier.fillMaxWidth().padding(16.dp),
+                colors =
+                        CardDefaults.cardColors(
+                                containerColor = MaterialTheme.colorScheme.primaryContainer
+                        ),
+                shape = RoundedCornerShape(12.dp)
         ) {
             Row(
-                modifier = Modifier
-                    .fillMaxWidth()
-                    .padding(16.dp),
-                verticalAlignment = Alignment.CenterVertically
+                    modifier = Modifier.fillMaxWidth().padding(16.dp),
+                    verticalAlignment = Alignment.CenterVertically
             ) {
                 Icon(
-                    Icons.Default.CheckCircle,
-                    contentDescription = null,
-                    tint = MaterialTheme.colorScheme.primary
+                        Icons.Default.CheckCircle,
+                        contentDescription = null,
+                        tint = MaterialTheme.colorScheme.primary
                 )
                 Spacer(modifier = Modifier.width(8.dp))
                 Text(
-                    text = message,
-                    style = MaterialTheme.typography.bodyMedium,
-                    color = MaterialTheme.colorScheme.onPrimaryContainer
+                        text = message,
+                        style = MaterialTheme.typography.bodyMedium,
+                        color = MaterialTheme.colorScheme.onPrimaryContainer
                 )
             }
         }
     }
-    
+
     uiState.error?.let { error ->
         LaunchedEffect(error) {
             kotlinx.coroutines.delay(5000)
             viewModel.clearError()
         }
-        
+
         Card(
-            modifier = Modifier
-                .fillMaxWidth()
-                .padding(16.dp),
-            colors = CardDefaults.cardColors(
-                containerColor = MaterialTheme.colorScheme.errorContainer
-            ),
-            shape = RoundedCornerShape(12.dp)
+                modifier = Modifier.fillMaxWidth().padding(16.dp),
+                colors =
+                        CardDefaults.cardColors(
+                                containerColor = MaterialTheme.colorScheme.errorContainer
+                        ),
+                shape = RoundedCornerShape(12.dp)
         ) {
             Row(
-                modifier = Modifier
-                    .fillMaxWidth()
-                    .padding(16.dp),
-                verticalAlignment = Alignment.CenterVertically
+                    modifier = Modifier.fillMaxWidth().padding(16.dp),
+                    verticalAlignment = Alignment.CenterVertically
             ) {
                 Icon(
-                    Icons.Default.Warning,
-                    contentDescription = null,
-                    tint = MaterialTheme.colorScheme.error
+                        Icons.Default.Warning,
+                        contentDescription = null,
+                        tint = MaterialTheme.colorScheme.error
                 )
                 Spacer(modifier = Modifier.width(8.dp))
                 Text(
-                    text = error,
-                    style = MaterialTheme.typography.bodyMedium,
-                    color = MaterialTheme.colorScheme.onErrorContainer
+                        text = error,
+                        style = MaterialTheme.typography.bodyMedium,
+                        color = MaterialTheme.colorScheme.onErrorContainer
                 )
             }
         }
@@ -182,53 +167,42 @@ fun SessionsScreen(
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
-fun SessionCard(
-    session: ClimbSession,
-    gymName: String,
-    onClick: () -> Unit
-) {
-    Card(
-        onClick = onClick,
-        modifier = Modifier.fillMaxWidth()
-    ) {
-        Column(
-            modifier = Modifier
-                .fillMaxWidth()
-                .padding(16.dp)
-        ) {
+fun SessionCard(session: ClimbSession, gymName: String, onClick: () -> Unit) {
+    Card(onClick = onClick, modifier = Modifier.fillMaxWidth()) {
+        Column(modifier = Modifier.fillMaxWidth().padding(16.dp)) {
             Row(
-                modifier = Modifier.fillMaxWidth(),
-                horizontalArrangement = Arrangement.SpaceBetween
+                    modifier = Modifier.fillMaxWidth(),
+                    horizontalArrangement = Arrangement.SpaceBetween
             ) {
                 Text(
-                    text = gymName,
-                    style = MaterialTheme.typography.titleMedium,
-                    fontWeight = FontWeight.Bold
+                        text = gymName,
+                        style = MaterialTheme.typography.titleMedium,
+                        fontWeight = FontWeight.Bold
                 )
                 Text(
-                    text = formatDate(session.date),
-                    style = MaterialTheme.typography.bodyMedium,
-                    color = MaterialTheme.colorScheme.onSurfaceVariant
+                        text = formatDate(session.date),
+                        style = MaterialTheme.typography.bodyMedium,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant
                 )
             }
-            
+
             Spacer(modifier = Modifier.height(4.dp))
-            
+
             session.duration?.let { duration ->
                 Text(
-                    text = "Duration: $duration minutes",
-                    style = MaterialTheme.typography.bodyMedium
+                        text = "Duration: $duration minutes",
+                        style = MaterialTheme.typography.bodyMedium
                 )
             }
-            
+
             session.notes?.let { notes ->
                 if (notes.isNotBlank()) {
                     Spacer(modifier = Modifier.height(4.dp))
                     Text(
-                        text = notes,
-                        style = MaterialTheme.typography.bodySmall,
-                        color = MaterialTheme.colorScheme.onSurfaceVariant,
-                        maxLines = 2
+                            text = notes,
+                            style = MaterialTheme.typography.bodySmall,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant,
+                            maxLines = 2
                     )
                 }
             }
@@ -238,38 +212,36 @@ fun SessionCard(
 
 @Composable
 fun EmptyStateMessage(
-    title: String,
-    message: String,
-    onActionClick: () -> Unit,
-    actionText: String
+        title: String,
+        message: String,
+        onActionClick: () -> Unit,
+        actionText: String
 ) {
     Column(
-        modifier = Modifier.fillMaxSize(),
-        horizontalAlignment = Alignment.CenterHorizontally,
-        verticalArrangement = Arrangement.Center
+            modifier = Modifier.fillMaxSize(),
+            horizontalAlignment = Alignment.CenterHorizontally,
+            verticalArrangement = Arrangement.Center
     ) {
         Text(
-            text = title,
-            style = MaterialTheme.typography.headlineSmall,
-            fontWeight = FontWeight.Bold,
-            textAlign = TextAlign.Center
+                text = title,
+                style = MaterialTheme.typography.headlineSmall,
+                fontWeight = FontWeight.Bold,
+                textAlign = TextAlign.Center
         )
-        
+
         Spacer(modifier = Modifier.height(8.dp))
-        
+
         Text(
-            text = message,
-            style = MaterialTheme.typography.bodyLarge,
-            color = MaterialTheme.colorScheme.onSurfaceVariant,
-            textAlign = TextAlign.Center
+                text = message,
+                style = MaterialTheme.typography.bodyLarge,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                textAlign = TextAlign.Center
         )
-        
+
         if (actionText.isNotEmpty()) {
             Spacer(modifier = Modifier.height(16.dp))
-            
-            Button(onClick = onActionClick) {
-                Text(actionText)
-            }
+
+            Button(onClick = onActionClick) { Text(actionText) }
         }
     }
 }

android/app/src/main/java/com/atridad/openclimb/ui/viewmodel/ClimbViewModel.kt

@@ -5,6 +5,7 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import com.atridad.openclimb.data.model.*
 import com.atridad.openclimb.data.repository.ClimbRepository
+import com.atridad.openclimb.data.sync.SyncService
 import com.atridad.openclimb.service.SessionTrackingService
 import com.atridad.openclimb.utils.ImageUtils
 import com.atridad.openclimb.utils.SessionShareUtils
@@ -15,7 +16,8 @@ import kotlinx.coroutines.flow.*
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
-class ClimbViewModel(private val repository: ClimbRepository) : ViewModel() {
+class ClimbViewModel(private val repository: ClimbRepository, val syncService: SyncService) :
+        ViewModel() {
 
     // UI State flows
     private val _uiState = MutableStateFlow(ClimbUiState())
@@ -112,6 +114,7 @@ class ClimbViewModel(private val repository: ClimbRepository) : ViewModel() {
         viewModelScope.launch {
             repository.insertProblem(problem)
             ClimbStatsWidgetProvider.updateAllWidgets(context)
+            // Auto-sync now happens automatically via repository callback
         }
     }
 
@@ -265,6 +268,8 @@ class ClimbViewModel(private val repository: ClimbRepository) : ViewModel() {
 
                 ClimbStatsWidgetProvider.updateAllWidgets(context)
 
+                // Auto-sync now happens automatically via repository callback
+
                 _uiState.value = _uiState.value.copy(message = "Session completed!")
             }
         }
@@ -290,6 +295,7 @@ class ClimbViewModel(private val repository: ClimbRepository) : ViewModel() {
         viewModelScope.launch {
             repository.insertAttempt(attempt)
             ClimbStatsWidgetProvider.updateAllWidgets(context)
+            // Auto-sync now happens automatically via repository callback
         }
     }
 
@@ -383,6 +389,23 @@ class ClimbViewModel(private val repository: ClimbRepository) : ViewModel() {
         _uiState.value = _uiState.value.copy(error = null)
     }
 
+    // Sync-related methods
+    suspend fun performManualSync() {
+        try {
+            syncService.syncWithServer()
+        } catch (e: Exception) {
+            setError("Sync failed: ${e.message}")
+        }
+    }
+
+    suspend fun testSyncConnection() {
+        try {
+            syncService.testConnection()
+        } catch (e: Exception) {
+            setError("Connection test failed: ${e.message}")
+        }
+    }
+
     fun setError(message: String) {
         _uiState.value = _uiState.value.copy(error = message)
     }

android/app/src/main/java/com/atridad/openclimb/ui/viewmodel/ClimbViewModelFactory.kt

@@ -3,15 +3,17 @@ package com.atridad.openclimb.ui.viewmodel
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
 import com.atridad.openclimb.data.repository.ClimbRepository
+import com.atridad.openclimb.data.sync.SyncService
 
 class ClimbViewModelFactory(
-    private val repository: ClimbRepository
+        private val repository: ClimbRepository,
+        private val syncService: SyncService
 ) : ViewModelProvider.Factory {
-    
+
     @Suppress("UNCHECKED_CAST")
     override fun <T : ViewModel> create(modelClass: Class<T>): T {
         if (modelClass.isAssignableFrom(ClimbViewModel::class.java)) {
-            return ClimbViewModel(repository) as T
+            return ClimbViewModel(repository, syncService) as T
         }
         throw IllegalArgumentException("Unknown ViewModel class")
     }

android/app/src/main/java/com/atridad/openclimb/utils/DateFormatUtils.kt

@@ -0,0 +1,68 @@
+package com.atridad.openclimb.utils
+
+import java.time.Instant
+import java.time.ZoneOffset
+import java.time.format.DateTimeFormatter
+
+object DateFormatUtils {
+
+    /**
+     * ISO 8601 formatter matching iOS date format exactly Produces dates like:
+     * "2025-09-07T22:00:40.014Z"
+     */
+    private val ISO_FORMATTER =
+            DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSX").withZone(ZoneOffset.UTC)
+
+    /**
+     * Get current timestamp in iOS-compatible ISO 8601 format
+     * @return Current timestamp as "2025-09-07T22:00:40.014Z"
+     */
+    fun nowISO8601(): String {
+        return ISO_FORMATTER.format(Instant.now())
+    }
+
+    /**
+     * Format an Instant to iOS-compatible ISO 8601 format
+     * @param instant The instant to format
+     * @return Formatted timestamp as "2025-09-07T22:00:40.014Z"
+     */
+    fun formatISO8601(instant: Instant): String {
+        return ISO_FORMATTER.format(instant)
+    }
+
+    /**
+     * Parse an iOS-compatible ISO 8601 date string back to Instant
+     * @param dateString ISO 8601 formatted date string
+     * @return Instant object, or null if parsing fails
+     */
+    fun parseISO8601(dateString: String): Instant? {
+        return try {
+            Instant.from(ISO_FORMATTER.parse(dateString))
+        } catch (e: Exception) {
+            // Fallback - try standard Instant parsing
+            try {
+                Instant.parse(dateString)
+            } catch (e2: Exception) {
+                null
+            }
+        }
+    }
+
+    /**
+     * Validate that a date string matches the expected iOS format
+     * @param dateString The date string to validate
+     * @return True if the format matches iOS expectations
+     */
+    fun isValidISO8601(dateString: String): Boolean {
+        return parseISO8601(dateString) != null
+    }
+
+    /**
+     * Convert milliseconds timestamp to iOS-compatible ISO 8601 format
+     * @param millis Milliseconds since epoch
+     * @return Formatted timestamp as "2025-09-07T22:00:40.014Z"
+     */
+    fun millisToISO8601(millis: Long): String {
+        return ISO_FORMATTER.format(Instant.ofEpochMilli(millis))
+    }
+}

android/app/src/main/java/com/atridad/openclimb/utils/ImageNamingUtils.kt

@@ -0,0 +1,147 @@
+package com.atridad.openclimb.utils
+
+import java.security.MessageDigest
+import java.util.*
+
+/**
+ * Utility for creating consistent image filenames across iOS and Android platforms. Uses
+ * deterministic naming based on problem ID and timestamp to ensure sync compatibility.
+ */
+object ImageNamingUtils {
+
+    private const val IMAGE_EXTENSION = ".jpg"
+    private const val HASH_LENGTH = 12 // First 12 chars of SHA-256
+
+    /**
+     * Generates a deterministic filename for a problem image. Format:
+     * "problem_{problemId}_{timestamp}_{index}.jpg"
+     *
+     * @param problemId The ID of the problem this image belongs to
+     * @param timestamp ISO8601 timestamp when the image was created
+     * @param imageIndex The index of this image for the problem (0, 1, 2, etc.)
+     * @return A consistent filename that will be the same across platforms
+     */
+    fun generateImageFilename(problemId: String, timestamp: String, imageIndex: Int): String {
+        // Create a deterministic hash from problemId + timestamp + index
+        val input = "${problemId}_${timestamp}_${imageIndex}"
+        val hash = createHash(input)
+
+        return "problem_${hash}_${imageIndex}${IMAGE_EXTENSION}"
+    }
+
+    /**
+     * Generates a deterministic filename for a problem image using current timestamp.
+     *
+     * @param problemId The ID of the problem this image belongs to
+     * @param imageIndex The index of this image for the problem (0, 1, 2, etc.)
+     * @return A consistent filename
+     */
+    fun generateImageFilename(problemId: String, imageIndex: Int): String {
+        val timestamp = DateFormatUtils.nowISO8601()
+        return generateImageFilename(problemId, timestamp, imageIndex)
+    }
+
+    /**
+     * Extracts problem ID from an image filename created by this utility. Returns null if the
+     * filename doesn't match our naming convention.
+     *
+     * @param filename The image filename
+     * @return The problem ID or null if not a valid filename
+     */
+    fun extractProblemIdFromFilename(filename: String): String? {
+        if (!filename.startsWith("problem_") || !filename.endsWith(IMAGE_EXTENSION)) {
+            return null
+        }
+
+        // Format: problem_{hash}_{index}.jpg
+        val nameWithoutExtension = filename.substring(0, filename.length - IMAGE_EXTENSION.length)
+        val parts = nameWithoutExtension.split("_")
+
+        if (parts.size != 3 || parts[0] != "problem") {
+            return null
+        }
+
+        // We can't extract the original problem ID from the hash,
+        // but we can validate the format
+        return parts[1] // Return the hash as identifier
+    }
+
+    /**
+     * Validates if a filename follows our naming convention.
+     *
+     * @param filename The filename to validate
+     * @return true if it matches our convention, false otherwise
+     */
+    fun isValidImageFilename(filename: String): Boolean {
+        if (!filename.startsWith("problem_") || !filename.endsWith(IMAGE_EXTENSION)) {
+            return false
+        }
+
+        val nameWithoutExtension = filename.substring(0, filename.length - IMAGE_EXTENSION.length)
+        val parts = nameWithoutExtension.split("_")
+
+        return parts.size == 3 &&
+                parts[0] == "problem" &&
+                parts[1].length == HASH_LENGTH &&
+                parts[2].toIntOrNull() != null
+    }
+
+    /**
+     * Migrates an existing UUID-based filename to our naming convention. This is used during sync
+     * to rename downloaded images.
+     *
+     * @param oldFilename The existing filename (UUID-based)
+     * @param problemId The problem ID this image belongs to
+     * @param imageIndex The index of this image
+     * @return The new filename following our convention
+     */
+    fun migrateFilename(oldFilename: String, problemId: String, imageIndex: Int): String {
+        // If it's already using our convention, keep it
+        if (isValidImageFilename(oldFilename)) {
+            return oldFilename
+        }
+
+        // Generate new deterministic name
+        // Use a timestamp based on the old filename to maintain some consistency
+        val timestamp = DateFormatUtils.nowISO8601()
+        return generateImageFilename(problemId, timestamp, imageIndex)
+    }
+
+    /**
+     * Creates a deterministic hash from input string. Uses SHA-256 and takes first 12 characters
+     * for filename safety.
+     *
+     * @param input The input string to hash
+     * @return First 12 characters of SHA-256 hash in lowercase
+     */
+    private fun createHash(input: String): String {
+        val digest = MessageDigest.getInstance("SHA-256")
+        val hashBytes = digest.digest(input.toByteArray(Charsets.UTF_8))
+        val hashHex = hashBytes.joinToString("") { "%02x".format(it) }
+        return hashHex.take(HASH_LENGTH)
+    }
+
+    /**
+     * Batch renames images for a problem to use our naming convention. Returns a mapping of old
+     * filename -> new filename.
+     *
+     * @param problemId The problem ID
+     * @param existingFilenames List of current image filenames for this problem
+     * @return Map of old filename to new filename
+     */
+    fun batchRenameForProblem(
+            problemId: String,
+            existingFilenames: List<String>
+    ): Map<String, String> {
+        val renameMap = mutableMapOf<String, String>()
+
+        existingFilenames.forEachIndexed { index, oldFilename ->
+            val newFilename = migrateFilename(oldFilename, problemId, index)
+            if (newFilename != oldFilename) {
+                renameMap[oldFilename] = newFilename
+            }
+        }
+
+        return renameMap
+    }
+}

android/app/src/main/java/com/atridad/openclimb/utils/ImageUtils.kt

@@ -5,20 +5,18 @@ import android.content.Context
 import android.graphics.Bitmap
 import android.graphics.BitmapFactory
 import android.net.Uri
+import androidx.core.graphics.scale
 import java.io.File
 import java.io.FileOutputStream
 import java.util.UUID
-import androidx.core.graphics.scale
 
 object ImageUtils {
-    
+
     private const val IMAGES_DIR = "problem_images"
     private const val MAX_IMAGE_SIZE = 1024
     private const val IMAGE_QUALITY = 85
-    
-    /**
-     * Creates the images directory if it doesn't exist
-     */
+
+    /** Creates the images directory if it doesn't exist */
     private fun getImagesDirectory(context: Context): File {
         val imagesDir = File(context.filesDir, IMAGES_DIR)
         if (!imagesDir.exists()) {
@@ -26,25 +24,39 @@ object ImageUtils {
         }
         return imagesDir
     }
-    
+
     /**
-     * Saves an image from URI to app's private storage with compression
+     * Saves an image from a URI with compression and proper orientation
      * @param context Android context
      * @param imageUri URI of the image to save
+     * @param problemId The problem ID this image belongs to (optional)
+     * @param imageIndex The index of this image for the problem (optional)
      * @return The relative file path if successful, null otherwise
      */
-    fun saveImageFromUri(context: Context, imageUri: Uri): String? {
+    fun saveImageFromUri(
+            context: Context,
+            imageUri: Uri,
+            problemId: String? = null,
+            imageIndex: Int? = null
+    ): String? {
         return try {
             // Decode bitmap from a fresh stream to avoid mark/reset dependency
-            val originalBitmap = context.contentResolver.openInputStream(imageUri)?.use { input ->
-                BitmapFactory.decodeStream(input)
-            } ?: return null
+            val originalBitmap =
+                    context.contentResolver.openInputStream(imageUri)?.use { input ->
+                        BitmapFactory.decodeStream(input)
+                    }
+                            ?: return null
 
             val orientedBitmap = correctImageOrientation(context, imageUri, originalBitmap)
             val compressedBitmap = compressImage(orientedBitmap)
 
-            // Generate unique filename
-            val filename = "${UUID.randomUUID()}.jpg"
+            // Generate filename using naming convention if problem info provided
+            val filename =
+                    if (problemId != null && imageIndex != null) {
+                        ImageNamingUtils.generateImageFilename(problemId, imageIndex)
+                    } else {
+                        "${UUID.randomUUID()}.jpg"
+                    }
             val imageFile = File(getImagesDirectory(context), filename)
 
             // Save compressed image
@@ -66,20 +78,19 @@ object ImageUtils {
             null
         }
     }
-    
-    /**
-     * Corrects image orientation based on EXIF data
-     */
+
+    /** Corrects image orientation based on EXIF data */
     private fun correctImageOrientation(context: Context, imageUri: Uri, bitmap: Bitmap): Bitmap {
         return try {
             val inputStream = context.contentResolver.openInputStream(imageUri)
             inputStream?.use { input ->
                 val exif = android.media.ExifInterface(input)
-                val orientation = exif.getAttributeInt(
-                    android.media.ExifInterface.TAG_ORIENTATION,
-                    android.media.ExifInterface.ORIENTATION_NORMAL
-                )
-                
+                val orientation =
+                        exif.getAttributeInt(
+                                android.media.ExifInterface.TAG_ORIENTATION,
+                                android.media.ExifInterface.ORIENTATION_NORMAL
+                        )
+
                 val matrix = android.graphics.Matrix()
                 when (orientation) {
                     android.media.ExifInterface.ORIENTATION_ROTATE_90 -> {
@@ -106,36 +117,42 @@ object ImageUtils {
                         matrix.postScale(-1f, 1f)
                     }
                 }
-                
+
                 if (matrix.isIdentity) {
                     bitmap
                 } else {
                     android.graphics.Bitmap.createBitmap(
-                        bitmap, 0, 0, bitmap.width, bitmap.height, matrix, true
+                            bitmap,
+                            0,
+                            0,
+                            bitmap.width,
+                            bitmap.height,
+                            matrix,
+                            true
                     )
                 }
-            } ?: bitmap
+            }
+                    ?: bitmap
         } catch (e: Exception) {
             e.printStackTrace()
             bitmap
         }
     }
-    
-    /**
-     * Compresses and resizes an image bitmap
-     */
+
+    /** Compresses and resizes an image bitmap */
     @SuppressLint("UseKtx")
     private fun compressImage(original: Bitmap): Bitmap {
         val width = original.width
         val height = original.height
-        
+
         // Calculate the scaling factor
-        val scaleFactor = if (width > height) {
-            if (width > MAX_IMAGE_SIZE) MAX_IMAGE_SIZE.toFloat() / width else 1f
-        } else {
-            if (height > MAX_IMAGE_SIZE) MAX_IMAGE_SIZE.toFloat() / height else 1f
-        }
-        
+        val scaleFactor =
+                if (width > height) {
+                    if (width > MAX_IMAGE_SIZE) MAX_IMAGE_SIZE.toFloat() / width else 1f
+                } else {
+                    if (height > MAX_IMAGE_SIZE) MAX_IMAGE_SIZE.toFloat() / height else 1f
+                }
+
         return if (scaleFactor < 1f) {
             val newWidth = (width * scaleFactor).toInt()
             val newHeight = (height * scaleFactor).toInt()
@@ -144,7 +161,7 @@ object ImageUtils {
             original
         }
     }
-    
+
     /**
      * Gets the full file path for an image
      * @param context Android context
@@ -152,9 +169,16 @@ object ImageUtils {
      * @return Full file path
      */
     fun getImageFile(context: Context, relativePath: String): File {
-        return File(context.filesDir, relativePath)
+        // If relativePath already contains the directory, use it as-is
+        // Otherwise, assume it's just a filename and add the images directory
+        return if (relativePath.contains("/")) {
+            File(context.filesDir, relativePath)
+        } else {
+            // Just a filename - look in the images directory
+            File(getImagesDirectory(context), relativePath)
+        }
     }
-    
+
     /**
      * Deletes an image file
      * @param context Android context
@@ -180,12 +204,12 @@ object ImageUtils {
     fun importImageFile(context: Context, sourceFile: File): String? {
         return try {
             if (!sourceFile.exists()) return null
-            
+
             // Generate new filename to avoid conflicts
             val extension = sourceFile.extension.ifEmpty { "jpg" }
             val filename = "${UUID.randomUUID()}.$extension"
             val destFile = File(getImagesDirectory(context), filename)
-            
+
             sourceFile.copyTo(destFile, overwrite = true)
             "$IMAGES_DIR/$filename"
         } catch (e: Exception) {
@@ -193,7 +217,7 @@ object ImageUtils {
             null
         }
     }
-    
+
     /**
      * Gets all image files in the images directory
      * @param context Android context
@@ -203,16 +227,148 @@ object ImageUtils {
         return try {
             val imagesDir = getImagesDirectory(context)
             imagesDir.listFiles()?.mapNotNull { file ->
-                if (file.isFile && (file.extension == "jpg" || file.extension == "jpeg" || file.extension == "png")) {
+                if (file.isFile &&
+                                (file.extension == "jpg" ||
+                                        file.extension == "jpeg" ||
+                                        file.extension == "png")
+                ) {
                     "$IMAGES_DIR/${file.name}"
                 } else null
-            } ?: emptyList()
+            }
+                    ?: emptyList()
         } catch (e: Exception) {
             e.printStackTrace()
             emptyList()
         }
     }
-    
+
+    /**
+     * Saves an image from byte array to app's private storage
+     * @param context Android context
+     * @param imageData Byte array of the image data
+     * @return The relative file path if successful, null otherwise
+     */
+    fun saveImageFromBytes(context: Context, imageData: ByteArray): String? {
+        return try {
+            val bitmap = BitmapFactory.decodeByteArray(imageData, 0, imageData.size) ?: return null
+
+            val compressedBitmap = compressImage(bitmap)
+
+            // Generate unique filename
+            val filename = "${UUID.randomUUID()}.jpg"
+            val imageFile = File(getImagesDirectory(context), filename)
+
+            // Save compressed image
+            FileOutputStream(imageFile).use { output ->
+                compressedBitmap.compress(Bitmap.CompressFormat.JPEG, IMAGE_QUALITY, output)
+            }
+
+            // Clean up bitmaps
+            bitmap.recycle()
+            compressedBitmap.recycle()
+
+            // Return relative path
+            "$IMAGES_DIR/$filename"
+        } catch (e: Exception) {
+            e.printStackTrace()
+            null
+        }
+    }
+
+    /**
+     * Saves image data with a specific filename (used for sync to preserve server filenames)
+     * @param context Android context
+     * @param imageData The image data as byte array
+     * @param filename The specific filename to use (including extension)
+     * @return The relative file path if successful, null otherwise
+     */
+    fun saveImageFromBytesWithFilename(
+            context: Context,
+            imageData: ByteArray,
+            filename: String
+    ): String? {
+        return try {
+            val bitmap = BitmapFactory.decodeByteArray(imageData, 0, imageData.size) ?: return null
+
+            val compressedBitmap = compressImage(bitmap)
+
+            // Use the provided filename instead of generating a new UUID
+            val imageFile = File(getImagesDirectory(context), filename)
+
+            // Save compressed image
+            FileOutputStream(imageFile).use { output ->
+                compressedBitmap.compress(Bitmap.CompressFormat.JPEG, IMAGE_QUALITY, output)
+            }
+
+            // Clean up bitmaps
+            bitmap.recycle()
+            compressedBitmap.recycle()
+
+            // Return relative path
+            "$IMAGES_DIR/$filename"
+        } catch (e: Exception) {
+            e.printStackTrace()
+            null
+        }
+    }
+
+    /**
+     * Migrates existing images to use consistent naming convention
+     * @param context Android context
+     * @param problemId The problem ID these images belong to
+     * @param currentImagePaths List of current image paths for this problem
+     * @return Map of old path -> new path for successfully migrated images
+     */
+    fun migrateImageNaming(
+            context: Context,
+            problemId: String,
+            currentImagePaths: List<String>
+    ): Map<String, String> {
+        val migrationMap = mutableMapOf<String, String>()
+
+        currentImagePaths.forEachIndexed { index, oldPath ->
+            val oldFilename = oldPath.substringAfterLast('/')
+            val newFilename = ImageNamingUtils.migrateFilename(oldFilename, problemId, index)
+
+            if (oldFilename != newFilename) {
+                try {
+                    val oldFile = getImageFile(context, oldPath)
+                    val newFile = File(getImagesDirectory(context), newFilename)
+
+                    if (oldFile.exists() && oldFile.renameTo(newFile)) {
+                        val newPath = "$IMAGES_DIR/$newFilename"
+                        migrationMap[oldPath] = newPath
+                    }
+                } catch (e: Exception) {
+                    // Log error but continue with other images
+                    e.printStackTrace()
+                }
+            }
+        }
+
+        return migrationMap
+    }
+
+    /**
+     * Batch migrates all images in the system to use consistent naming
+     * @param context Android context
+     * @param problemImageMap Map of problem ID -> list of current image paths
+     * @return Map of old path -> new path for all migrated images
+     */
+    fun batchMigrateAllImages(
+            context: Context,
+            problemImageMap: Map<String, List<String>>
+    ): Map<String, String> {
+        val allMigrations = mutableMapOf<String, String>()
+
+        problemImageMap.forEach { (problemId, imagePaths) ->
+            val migrations = migrateImageNaming(context, problemId, imagePaths)
+            allMigrations.putAll(migrations)
+        }
+
+        return allMigrations
+    }
+
     /**
      * Cleans up orphaned images that are not referenced by any problems
      * @param context Android context
@@ -222,10 +378,8 @@ object ImageUtils {
         try {
             val allImages = getAllImages(context)
             val orphanedImages = allImages.filter { it !in referencedPaths }
-            
-            orphanedImages.forEach { path ->
-                deleteImage(context, path)
-            }
+
+            orphanedImages.forEach { path -> deleteImage(context, path) }
         } catch (e: Exception) {
             e.printStackTrace()
         }

android/app/src/main/java/com/atridad/openclimb/utils/ZipExportImportUtils.kt

@@ -1,7 +1,8 @@
 package com.atridad.openclimb.utils
 
 import android.content.Context
-import kotlinx.serialization.json.Json
+import com.atridad.openclimb.data.format.BackupProblem
+import com.atridad.openclimb.data.format.ClimbDataBackup
 import java.io.File
 import java.io.FileInputStream
 import java.io.FileOutputStream
@@ -10,13 +11,15 @@ import java.time.LocalDateTime
 import java.util.zip.ZipEntry
 import java.util.zip.ZipInputStream
 import java.util.zip.ZipOutputStream
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 
 object ZipExportImportUtils {
-    
+
     private const val DATA_JSON_FILENAME = "data.json"
     private const val IMAGES_DIR_NAME = "images"
     private const val METADATA_FILENAME = "metadata.txt"
-    
+
     /**
      * Creates a ZIP file containing the JSON data and all referenced images
      * @param context Android context
@@ -26,19 +29,26 @@ object ZipExportImportUtils {
      * @return The created ZIP file
      */
     fun createExportZip(
-        context: Context,
-        exportData: com.atridad.openclimb.data.repository.ClimbDataExport,
-        referencedImagePaths: Set<String>,
-        directory: File? = null
+            context: Context,
+            exportData: ClimbDataBackup,
+            referencedImagePaths: Set<String>,
+            directory: File? = null
     ): File {
-        val exportDir = directory ?: File(context.getExternalFilesDir(android.os.Environment.DIRECTORY_DOCUMENTS), "OpenClimb")
+        val exportDir =
+                directory
+                        ?: File(
+                                context.getExternalFilesDir(
+                                        android.os.Environment.DIRECTORY_DOCUMENTS
+                                ),
+                                "OpenClimb"
+                        )
         if (!exportDir.exists()) {
             exportDir.mkdirs()
         }
-        
+
         val timestamp = LocalDateTime.now().toString().replace(":", "-").replace(".", "-")
         val zipFile = File(exportDir, "openclimb_export_$timestamp.zip")
-        
+
         try {
             ZipOutputStream(FileOutputStream(zipFile)).use { zipOut ->
                 // Add metadata file first
@@ -47,19 +57,19 @@ object ZipExportImportUtils {
                 zipOut.putNextEntry(metadataEntry)
                 zipOut.write(metadata.toByteArray())
                 zipOut.closeEntry()
-                
+
                 // Add JSON data file
-                val json = Json { 
-                    prettyPrint = true 
+                val json = Json {
+                    prettyPrint = true
                     ignoreUnknownKeys = true
                 }
-                val jsonString = json.encodeToString(com.atridad.openclimb.data.repository.ClimbDataExport.serializer(), exportData)
-                
+                val jsonString = json.encodeToString(exportData)
+
                 val jsonEntry = ZipEntry(DATA_JSON_FILENAME)
                 zipOut.putNextEntry(jsonEntry)
                 zipOut.write(jsonString.toByteArray())
                 zipOut.closeEntry()
-                
+
                 // Add images with validation
                 var successfulImages = 0
                 referencedImagePaths.forEach { imagePath ->
@@ -68,31 +78,39 @@ object ZipExportImportUtils {
                         if (imageFile.exists() && imageFile.length() > 0) {
                             val imageEntry = ZipEntry("$IMAGES_DIR_NAME/${imageFile.name}")
                             zipOut.putNextEntry(imageEntry)
-                            
+
                             FileInputStream(imageFile).use { imageInput ->
                                 imageInput.copyTo(zipOut)
                             }
                             zipOut.closeEntry()
                             successfulImages++
                         } else {
-                            android.util.Log.w("ZipExportImportUtils", "Image file not found or empty: $imagePath")
+                            android.util.Log.w(
+                                    "ZipExportImportUtils",
+                                    "Image file not found or empty: $imagePath"
+                            )
                         }
                     } catch (e: Exception) {
-                        android.util.Log.e("ZipExportImportUtils", "Failed to add image $imagePath: ${e.message}")
+                        android.util.Log.e(
+                                "ZipExportImportUtils",
+                                "Failed to add image $imagePath: ${e.message}"
+                        )
                     }
                 }
-                
+
                 // Log export summary
-                android.util.Log.i("ZipExportImportUtils", "Export completed: ${successfulImages}/${referencedImagePaths.size} images included")
+                android.util.Log.i(
+                        "ZipExportImportUtils",
+                        "Export completed: ${successfulImages}/${referencedImagePaths.size} images included"
+                )
             }
-            
+
             // Validate the created ZIP file
             if (!zipFile.exists() || zipFile.length() == 0L) {
                 throw IOException("Failed to create ZIP file: file is empty or doesn't exist")
             }
-            
+
             return zipFile
-            
         } catch (e: Exception) {
             // Clean up failed export
             if (zipFile.exists()) {
@@ -101,7 +119,7 @@ object ZipExportImportUtils {
             throw IOException("Failed to create export ZIP: ${e.message}")
         }
     }
-    
+
     /**
      * Creates a ZIP file and writes it to a provided URI
      * @param context Android context
@@ -110,10 +128,10 @@ object ZipExportImportUtils {
      * @param referencedImagePaths Set of image paths referenced in the data
      */
     fun createExportZipToUri(
-        context: Context,
-        uri: android.net.Uri,
-        exportData: com.atridad.openclimb.data.repository.ClimbDataExport,
-        referencedImagePaths: Set<String>
+            context: Context,
+            uri: android.net.Uri,
+            exportData: ClimbDataBackup,
+            referencedImagePaths: Set<String>
     ) {
         try {
             context.contentResolver.openOutputStream(uri)?.use { outputStream ->
@@ -124,19 +142,19 @@ object ZipExportImportUtils {
                     zipOut.putNextEntry(metadataEntry)
                     zipOut.write(metadata.toByteArray())
                     zipOut.closeEntry()
-                    
+
                     // Add JSON data file
-                    val json = Json { 
-                        prettyPrint = true 
+                    val json = Json {
+                        prettyPrint = true
                         ignoreUnknownKeys = true
                     }
-                    val jsonString = json.encodeToString(com.atridad.openclimb.data.repository.ClimbDataExport.serializer(), exportData)
-                    
+                    val jsonString = json.encodeToString(exportData)
+
                     val jsonEntry = ZipEntry(DATA_JSON_FILENAME)
                     zipOut.putNextEntry(jsonEntry)
                     zipOut.write(jsonString.toByteArray())
                     zipOut.closeEntry()
-                    
+
                     // Add images with validation
                     var successfulImages = 0
                     referencedImagePaths.forEach { imagePath ->
@@ -145,7 +163,7 @@ object ZipExportImportUtils {
                             if (imageFile.exists() && imageFile.length() > 0) {
                                 val imageEntry = ZipEntry("$IMAGES_DIR_NAME/${imageFile.name}")
                                 zipOut.putNextEntry(imageEntry)
-                                
+
                                 FileInputStream(imageFile).use { imageInput ->
                                     imageInput.copyTo(zipOut)
                                 }
@@ -153,22 +171,28 @@ object ZipExportImportUtils {
                                 successfulImages++
                             }
                         } catch (e: Exception) {
-                            android.util.Log.e("ZipExportImportUtils", "Failed to add image $imagePath: ${e.message}")
+                            android.util.Log.e(
+                                    "ZipExportImportUtils",
+                                    "Failed to add image $imagePath: ${e.message}"
+                            )
                         }
                     }
-                    
-                    android.util.Log.i("ZipExportImportUtils", "Export to URI completed: ${successfulImages}/${referencedImagePaths.size} images included")
+
+                    android.util.Log.i(
+                            "ZipExportImportUtils",
+                            "Export to URI completed: ${successfulImages}/${referencedImagePaths.size} images included"
+                    )
                 }
-            } ?: throw IOException("Could not open output stream")
-            
+            }
+                    ?: throw IOException("Could not open output stream")
         } catch (e: Exception) {
             throw IOException("Failed to create export ZIP to URI: ${e.message}")
         }
     }
-    
+
     private fun createMetadata(
-        exportData: com.atridad.openclimb.data.repository.ClimbDataExport,
-        referencedImagePaths: Set<String>
+            exportData: ClimbDataBackup,
+            referencedImagePaths: Set<String>
     ): String {
         return buildString {
             appendLine("OpenClimb Export Metadata")
@@ -183,15 +207,13 @@ object ZipExportImportUtils {
             appendLine("Format: ZIP with embedded JSON data and images")
         }
     }
-    
-    /**
-     * Data class to hold extraction results
-     */
+
+    /** Data class to hold extraction results */
     data class ImportResult(
-        val jsonContent: String,
-        val importedImagePaths: Map<String, String> // original filename -> new relative path
+            val jsonContent: String,
+            val importedImagePaths: Map<String, String> // original filename -> new relative path
     )
-    
+
     /**
      * Extracts a ZIP file and returns the JSON content and imported image paths
      * @param context Android context
@@ -200,106 +222,125 @@ object ZipExportImportUtils {
      */
     fun extractImportZip(context: Context, zipFile: File): ImportResult {
         var jsonContent = ""
-        var metadataContent = ""
         val importedImagePaths = mutableMapOf<String, String>()
         var foundRequiredFiles = mutableSetOf<String>()
-        
+
         try {
             ZipInputStream(FileInputStream(zipFile)).use { zipIn ->
                 var entry = zipIn.nextEntry
-                
+
                 while (entry != null) {
                     when {
                         entry.name == METADATA_FILENAME -> {
                             // Read metadata for validation
-                            metadataContent = zipIn.readBytes().toString(Charsets.UTF_8)
+                            val metadataContent = zipIn.readBytes().toString(Charsets.UTF_8)
                             foundRequiredFiles.add("metadata")
-                            android.util.Log.i("ZipExportImportUtils", "Found metadata: ${metadataContent.lines().take(3).joinToString()}")
+                            android.util.Log.i(
+                                    "ZipExportImportUtils",
+                                    "Found metadata: ${metadataContent.lines().take(3).joinToString()}"
+                            )
                         }
-                        
                         entry.name == DATA_JSON_FILENAME -> {
                             // Read JSON data
                             jsonContent = zipIn.readBytes().toString(Charsets.UTF_8)
                             foundRequiredFiles.add("data")
                         }
-                        
                         entry.name.startsWith("$IMAGES_DIR_NAME/") && !entry.isDirectory -> {
                             // Extract image file
                             val originalFilename = entry.name.substringAfter("$IMAGES_DIR_NAME/")
-                            
+
                             try {
                                 // Create temporary file to hold the extracted image
-                                val tempFile = File.createTempFile("import_image_", "_$originalFilename", context.cacheDir)
-                                
-                                FileOutputStream(tempFile).use { output ->
-                                    zipIn.copyTo(output)
-                                }
-                                
+                                val tempFile =
+                                        File.createTempFile(
+                                                "import_image_",
+                                                "_$originalFilename",
+                                                context.cacheDir
+                                        )
+
+                                FileOutputStream(tempFile).use { output -> zipIn.copyTo(output) }
+
                                 // Validate the extracted image
                                 if (tempFile.exists() && tempFile.length() > 0) {
                                     // Import the image to permanent storage
                                     val newPath = ImageUtils.importImageFile(context, tempFile)
                                     if (newPath != null) {
                                         importedImagePaths[originalFilename] = newPath
-                                        android.util.Log.d("ZipExportImportUtils", "Successfully imported image: $originalFilename -> $newPath")
+                                        android.util.Log.d(
+                                                "ZipExportImportUtils",
+                                                "Successfully imported image: $originalFilename -> $newPath"
+                                        )
                                     } else {
-                                        android.util.Log.w("ZipExportImportUtils", "Failed to import image: $originalFilename")
+                                        android.util.Log.w(
+                                                "ZipExportImportUtils",
+                                                "Failed to import image: $originalFilename"
+                                        )
                                     }
                                 } else {
-                                    android.util.Log.w("ZipExportImportUtils", "Extracted image is empty: $originalFilename")
+                                    android.util.Log.w(
+                                            "ZipExportImportUtils",
+                                            "Extracted image is empty: $originalFilename"
+                                    )
                                 }
-                                
+
                                 // Clean up temp file
                                 tempFile.delete()
-                                
                             } catch (e: Exception) {
-                                android.util.Log.e("ZipExportImportUtils", "Failed to process image $originalFilename: ${e.message}")
+                                android.util.Log.e(
+                                        "ZipExportImportUtils",
+                                        "Failed to process image $originalFilename: ${e.message}"
+                                )
                             }
                         }
-                        
                         else -> {
-                            android.util.Log.d("ZipExportImportUtils", "Skipping ZIP entry: ${entry.name}")
+                            android.util.Log.d(
+                                    "ZipExportImportUtils",
+                                    "Skipping ZIP entry: ${entry.name}"
+                            )
                         }
                     }
-                    
+
                     zipIn.closeEntry()
                     entry = zipIn.nextEntry
                 }
             }
-            
+
             // Validate that we found the required files
             if (!foundRequiredFiles.contains("data")) {
                 throw IOException("Invalid ZIP file: data.json not found")
             }
-            
+
             if (jsonContent.isBlank()) {
                 throw IOException("Invalid ZIP file: data.json is empty")
             }
-            
-            android.util.Log.i("ZipExportImportUtils", "Import extraction completed: ${importedImagePaths.size} images processed")
-            
+
+            android.util.Log.i(
+                    "ZipExportImportUtils",
+                    "Import extraction completed: ${importedImagePaths.size} images processed"
+            )
+
             return ImportResult(jsonContent, importedImagePaths)
-            
         } catch (e: Exception) {
             throw IOException("Failed to extract import ZIP: ${e.message}")
         }
     }
 
     /**
-     * Updates image paths in a problem list after import
-     * This function maps the old image paths to the new ones after import
+     * Updates image paths in a problem list after import This function maps the old image paths to
+     * the new ones after import
      */
     fun updateProblemImagePaths(
-        problems: List<com.atridad.openclimb.data.model.Problem>,
-        imagePathMapping: Map<String, String>
-    ): List<com.atridad.openclimb.data.model.Problem> {
+            problems: List<BackupProblem>,
+            imagePathMapping: Map<String, String>
+    ): List<BackupProblem> {
         return problems.map { problem ->
-            val updatedImagePaths = problem.imagePaths.mapNotNull { oldPath ->
-                // Extract filename from the old path
-                val filename = oldPath.substringAfterLast("/")
-                imagePathMapping[filename]
-            }
-            problem.copy(imagePaths = updatedImagePaths)
+            val updatedImagePaths =
+                    (problem.imagePaths ?: emptyList()).mapNotNull { oldPath ->
+                        // Extract filename from the old path
+                        val filename = oldPath.substringAfterLast("/")
+                        imagePathMapping[filename]
+                    }
+            problem.withUpdatedImagePaths(updatedImagePaths)
         }
     }
 }

android/app/src/test/java/com/atridad/openclimb/SyncMergeLogicTest.kt

@@ -0,0 +1,451 @@
+package com.atridad.openclimb
+
+import com.atridad.openclimb.data.format.*
+import com.atridad.openclimb.data.model.*
+import org.junit.Assert.*
+import org.junit.Test
+
+class SyncMergeLogicTest {
+
+    @Test
+    fun `test intelligent merge preserves all data`() {
+        // Create local data
+        val localGyms =
+                listOf(
+                        BackupGym(
+                                id = "gym1",
+                                name = "Local Gym 1",
+                                location = "Local Location",
+                                supportedClimbTypes = listOf(ClimbType.BOULDER),
+                                difficultySystems = listOf(DifficultySystem.V_SCALE),
+                                customDifficultyGrades = emptyList(),
+                                notes = null,
+                                createdAt = "2024-01-01T10:00:00",
+                                updatedAt = "2024-01-01T10:00:00"
+                        )
+                )
+
+        val localProblems =
+                listOf(
+                        BackupProblem(
+                                id = "problem1",
+                                gymId = "gym1",
+                                name = "Local Problem",
+                                description = "Local description",
+                                climbType = ClimbType.BOULDER,
+                                difficulty = DifficultyGrade(DifficultySystem.V_SCALE, "V5"),
+                                tags = listOf("local"),
+                                location = null,
+                                imagePaths = listOf("local_image.jpg"),
+                                isActive = true,
+                                dateSet = null,
+                                notes = null,
+                                createdAt = "2024-01-01T10:00:00",
+                                updatedAt = "2024-01-01T10:00:00"
+                        )
+                )
+
+        val localSessions =
+                listOf(
+                        BackupClimbSession(
+                                id = "session1",
+                                gymId = "gym1",
+                                date = "2024-01-01",
+                                startTime = "2024-01-01T10:00:00",
+                                endTime = "2024-01-01T12:00:00",
+                                duration = 7200,
+                                status = SessionStatus.COMPLETED,
+                                notes = null,
+                                createdAt = "2024-01-01T10:00:00",
+                                updatedAt = "2024-01-01T10:00:00"
+                        )
+                )
+
+        val localAttempts =
+                listOf(
+                        BackupAttempt(
+                                id = "attempt1",
+                                sessionId = "session1",
+                                problemId = "problem1",
+                                result = AttemptResult.COMPLETED,
+                                highestHold = null,
+                                notes = null,
+                                duration = 300,
+                                restTime = null,
+                                timestamp = "2024-01-01T10:30:00",
+                                createdAt = "2024-01-01T10:30:00"
+                        )
+                )
+
+        val localBackup =
+                ClimbDataBackup(
+                        exportedAt = "2024-01-01T10:00:00",
+                        version = "2.0",
+                        formatVersion = "2.0",
+                        gyms = localGyms,
+                        problems = localProblems,
+                        sessions = localSessions,
+                        attempts = localAttempts
+                )
+
+        // Create server data with some overlapping and some unique data
+        val serverGyms =
+                listOf(
+                        // Same gym but with newer update
+                        BackupGym(
+                                id = "gym1",
+                                name = "Updated Gym 1",
+                                location = "Updated Location",
+                                supportedClimbTypes = listOf(ClimbType.BOULDER, ClimbType.SPORT),
+                                difficultySystems =
+                                        listOf(DifficultySystem.V_SCALE, DifficultySystem.YDS),
+                                customDifficultyGrades = emptyList(),
+                                notes = "Updated notes",
+                                createdAt = "2024-01-01T10:00:00",
+                                updatedAt = "2024-01-01T12:00:00" // Newer update
+                        ),
+                        // Unique server gym
+                        BackupGym(
+                                id = "gym2",
+                                name = "Server Gym 2",
+                                location = "Server Location",
+                                supportedClimbTypes = listOf(ClimbType.TRAD),
+                                difficultySystems = listOf(DifficultySystem.YDS),
+                                customDifficultyGrades = emptyList(),
+                                notes = null,
+                                createdAt = "2024-01-01T11:00:00",
+                                updatedAt = "2024-01-01T11:00:00"
+                        )
+                )
+
+        val serverProblems =
+                listOf(
+                        // Same problem but with newer update and different images
+                        BackupProblem(
+                                id = "problem1",
+                                gymId = "gym1",
+                                name = "Updated Problem",
+                                description = "Updated description",
+                                climbType = ClimbType.BOULDER,
+                                difficulty = DifficultyGrade(DifficultySystem.V_SCALE, "V5"),
+                                tags = listOf("updated", "server"),
+                                location = "Updated location",
+                                imagePaths = listOf("server_image.jpg"),
+                                isActive = true,
+                                dateSet = "2024-01-01",
+                                notes = "Updated notes",
+                                createdAt = "2024-01-01T10:00:00",
+                                updatedAt = "2024-01-01T11:00:00" // Newer update
+                        ),
+                        // Unique server problem
+                        BackupProblem(
+                                id = "problem2",
+                                gymId = "gym2",
+                                name = "Server Problem",
+                                description = "Server description",
+                                climbType = ClimbType.TRAD,
+                                difficulty = DifficultyGrade(DifficultySystem.YDS, "5.10a"),
+                                tags = listOf("server"),
+                                location = null,
+                                imagePaths = null,
+                                isActive = true,
+                                dateSet = null,
+                                notes = null,
+                                createdAt = "2024-01-01T11:00:00",
+                                updatedAt = "2024-01-01T11:00:00"
+                        )
+                )
+
+        val serverSessions =
+                listOf(
+                        // Unique server session
+                        BackupClimbSession(
+                                id = "session2",
+                                gymId = "gym2",
+                                date = "2024-01-02",
+                                startTime = "2024-01-02T14:00:00",
+                                endTime = "2024-01-02T16:00:00",
+                                duration = 7200,
+                                status = SessionStatus.COMPLETED,
+                                notes = "Server session",
+                                createdAt = "2024-01-02T14:00:00",
+                                updatedAt = "2024-01-02T14:00:00"
+                        )
+                )
+
+        val serverAttempts =
+                listOf(
+                        // Unique server attempt
+                        BackupAttempt(
+                                id = "attempt2",
+                                sessionId = "session2",
+                                problemId = "problem2",
+                                result = AttemptResult.FELL,
+                                highestHold = "Last move",
+                                notes = "Almost had it",
+                                duration = 180,
+                                restTime = 60,
+                                timestamp = "2024-01-02T14:30:00",
+                                createdAt = "2024-01-02T14:30:00"
+                        )
+                )
+
+        val serverBackup =
+                ClimbDataBackup(
+                        exportedAt = "2024-01-01T12:00:00",
+                        version = "2.0",
+                        formatVersion = "2.0",
+                        gyms = serverGyms,
+                        problems = serverProblems,
+                        sessions = serverSessions,
+                        attempts = serverAttempts
+                )
+
+        // Simulate merge logic
+        val mergedBackup = performIntelligentMerge(localBackup, serverBackup)
+
+        // Verify merge results
+        assertEquals("Should have 2 gyms (1 updated, 1 new)", 2, mergedBackup.gyms.size)
+        assertEquals("Should have 2 problems (1 updated, 1 new)", 2, mergedBackup.problems.size)
+        assertEquals("Should have 2 sessions (1 local, 1 server)", 2, mergedBackup.sessions.size)
+        assertEquals("Should have 2 attempts (1 local, 1 server)", 2, mergedBackup.attempts.size)
+
+        // Verify gym merge - server version should win (newer update)
+        val mergedGym1 = mergedBackup.gyms.find { it.id == "gym1" }!!
+        assertEquals("Updated Gym 1", mergedGym1.name)
+        assertEquals("Updated Location", mergedGym1.location)
+        assertEquals("Updated notes", mergedGym1.notes)
+        assertEquals("2024-01-01T12:00:00", mergedGym1.updatedAt)
+
+        // Verify unique server gym is preserved
+        val mergedGym2 = mergedBackup.gyms.find { it.id == "gym2" }!!
+        assertEquals("Server Gym 2", mergedGym2.name)
+
+        // Verify problem merge - server version should win but images should be merged
+        val mergedProblem1 = mergedBackup.problems.find { it.id == "problem1" }!!
+        assertEquals("Updated Problem", mergedProblem1.name)
+        assertEquals("Updated description", mergedProblem1.description)
+        assertEquals("2024-01-01T11:00:00", mergedProblem1.updatedAt)
+
+        // Images should be merged (both local and server images preserved)
+        assertTrue(
+                "Should contain local image",
+                mergedProblem1.imagePaths!!.contains("local_image.jpg")
+        )
+        assertTrue(
+                "Should contain server image",
+                mergedProblem1.imagePaths!!.contains("server_image.jpg")
+        )
+        assertEquals("Should have 2 images total", 2, mergedProblem1.imagePaths!!.size)
+
+        // Verify unique server problem is preserved
+        val mergedProblem2 = mergedBackup.problems.find { it.id == "problem2" }!!
+        assertEquals("Server Problem", mergedProblem2.name)
+
+        // Verify all sessions are preserved
+        assertTrue(
+                "Should contain local session",
+                mergedBackup.sessions.any { it.id == "session1" }
+        )
+        assertTrue(
+                "Should contain server session",
+                mergedBackup.sessions.any { it.id == "session2" }
+        )
+
+        // Verify all attempts are preserved
+        assertTrue(
+                "Should contain local attempt",
+                mergedBackup.attempts.any { it.id == "attempt1" }
+        )
+        assertTrue(
+                "Should contain server attempt",
+                mergedBackup.attempts.any { it.id == "attempt2" }
+        )
+    }
+
+    @Test
+    fun `test date comparison logic`() {
+        assertTrue(
+                "ISO instant should be newer",
+                isNewerThan("2024-01-01T12:00:00Z", "2024-01-01T10:00:00Z")
+        )
+        assertFalse(
+                "ISO instant should be older",
+                isNewerThan("2024-01-01T10:00:00Z", "2024-01-01T12:00:00Z")
+        )
+        assertTrue(
+                "String comparison should work as fallback",
+                isNewerThan("2024-01-02T10:00:00", "2024-01-01T10:00:00")
+        )
+    }
+
+    @Test
+    fun `test empty data scenarios`() {
+        val emptyBackup =
+                ClimbDataBackup(
+                        exportedAt = "2024-01-01T10:00:00",
+                        version = "2.0",
+                        formatVersion = "2.0",
+                        gyms = emptyList(),
+                        problems = emptyList(),
+                        sessions = emptyList(),
+                        attempts = emptyList()
+                )
+
+        val dataBackup =
+                ClimbDataBackup(
+                        exportedAt = "2024-01-01T10:00:00",
+                        version = "2.0",
+                        formatVersion = "2.0",
+                        gyms =
+                                listOf(
+                                        BackupGym(
+                                                id = "gym1",
+                                                name = "Test Gym",
+                                                location = null,
+                                                supportedClimbTypes = listOf(ClimbType.BOULDER),
+                                                difficultySystems =
+                                                        listOf(DifficultySystem.V_SCALE),
+                                                customDifficultyGrades = emptyList(),
+                                                notes = null,
+                                                createdAt = "2024-01-01T10:00:00",
+                                                updatedAt = "2024-01-01T10:00:00"
+                                        )
+                                ),
+                        problems = emptyList(),
+                        sessions = emptyList(),
+                        attempts = emptyList()
+                )
+
+        // Test merging empty with data
+        val merged1 = performIntelligentMerge(emptyBackup, dataBackup)
+        assertEquals("Should preserve data from non-empty backup", 1, merged1.gyms.size)
+
+        // Test merging data with empty
+        val merged2 = performIntelligentMerge(dataBackup, emptyBackup)
+        assertEquals("Should preserve data from non-empty backup", 1, merged2.gyms.size)
+
+        // Test merging empty with empty
+        val merged3 = performIntelligentMerge(emptyBackup, emptyBackup)
+        assertEquals("Should remain empty", 0, merged3.gyms.size)
+    }
+
+    // Helper methods that simulate the merge logic from SyncService
+    private fun performIntelligentMerge(
+            local: ClimbDataBackup,
+            server: ClimbDataBackup
+    ): ClimbDataBackup {
+        val mergedGyms = mergeGyms(local.gyms, server.gyms)
+        val mergedProblems = mergeProblems(local.problems, server.problems)
+        val mergedSessions = mergeSessions(local.sessions, server.sessions)
+        val mergedAttempts = mergeAttempts(local.attempts, server.attempts)
+
+        return ClimbDataBackup(
+                exportedAt = "2024-01-01T12:00:00",
+                version = "2.0",
+                formatVersion = "2.0",
+                gyms = mergedGyms,
+                problems = mergedProblems,
+                sessions = mergedSessions,
+                attempts = mergedAttempts
+        )
+    }
+
+    private fun mergeGyms(local: List<BackupGym>, server: List<BackupGym>): List<BackupGym> {
+        val merged = mutableMapOf<String, BackupGym>()
+
+        // Add all local gyms
+        local.forEach { gym -> merged[gym.id] = gym }
+
+        // Add server gyms, preferring newer updates
+        server.forEach { serverGym ->
+            val localGym = merged[serverGym.id]
+            if (localGym == null || isNewerThan(serverGym.updatedAt, localGym.updatedAt)) {
+                merged[serverGym.id] = serverGym
+            }
+        }
+
+        return merged.values.toList()
+    }
+
+    private fun mergeProblems(
+            local: List<BackupProblem>,
+            server: List<BackupProblem>
+    ): List<BackupProblem> {
+        val merged = mutableMapOf<String, BackupProblem>()
+
+        // Add all local problems
+        local.forEach { problem -> merged[problem.id] = problem }
+
+        // Add server problems, preferring newer updates
+        server.forEach { serverProblem ->
+            val localProblem = merged[serverProblem.id]
+            if (localProblem == null || isNewerThan(serverProblem.updatedAt, localProblem.updatedAt)
+            ) {
+                // Merge image paths to preserve all images
+                val allImagePaths = mutableSetOf<String>()
+                localProblem?.imagePaths?.let { allImagePaths.addAll(it) }
+                serverProblem.imagePaths?.let { allImagePaths.addAll(it) }
+
+                merged[serverProblem.id] =
+                        serverProblem.withUpdatedImagePaths(allImagePaths.toList())
+            }
+        }
+
+        return merged.values.toList()
+    }
+
+    private fun mergeSessions(
+            local: List<BackupClimbSession>,
+            server: List<BackupClimbSession>
+    ): List<BackupClimbSession> {
+        val merged = mutableMapOf<String, BackupClimbSession>()
+
+        // Add all local sessions
+        local.forEach { session -> merged[session.id] = session }
+
+        // Add server sessions, preferring newer updates
+        server.forEach { serverSession ->
+            val localSession = merged[serverSession.id]
+            if (localSession == null || isNewerThan(serverSession.updatedAt, localSession.updatedAt)
+            ) {
+                merged[serverSession.id] = serverSession
+            }
+        }
+
+        return merged.values.toList()
+    }
+
+    private fun mergeAttempts(
+            local: List<BackupAttempt>,
+            server: List<BackupAttempt>
+    ): List<BackupAttempt> {
+        val merged = mutableMapOf<String, BackupAttempt>()
+
+        // Add all local attempts
+        local.forEach { attempt -> merged[attempt.id] = attempt }
+
+        // Add server attempts, preferring newer updates
+        server.forEach { serverAttempt ->
+            val localAttempt = merged[serverAttempt.id]
+            if (localAttempt == null || isNewerThan(serverAttempt.createdAt, localAttempt.createdAt)
+            ) {
+                merged[serverAttempt.id] = serverAttempt
+            }
+        }
+
+        return merged.values.toList()
+    }
+
+    private fun isNewerThan(dateString1: String, dateString2: String): Boolean {
+        return try {
+            // Try parsing as instant first
+            val date1 = java.time.Instant.parse(dateString1)
+            val date2 = java.time.Instant.parse(dateString2)
+            date1.isAfter(date2)
+        } catch (e: Exception) {
+            // Fallback to string comparison
+            dateString1 > dateString2
+        }
+    }
+}

android/gradle/libs.versions.toml

@@ -19,6 +19,7 @@ kotlinxSerialization = "1.9.0"
 kotlinxCoroutines = "1.10.2"
 coil = "2.7.0"
 ksp = "2.2.10-2.0.2"
+okhttp = "4.12.0"
 
 [libraries]
 androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
@@ -65,6 +66,9 @@ mockk = { group = "io.mockk", name = "mockk", version = "1.14.5" }
 # Image Loading
 coil-compose = { group = "io.coil-kt", name = "coil-compose", version.ref = "coil" }
 
+# HTTP Client
+okhttp = { group = "com.squareup.okhttp3", name = "okhttp", version.ref = "okhttp" }
+
 
 
 [plugins]

android/test_backup/ClimbRepository.kt

@@ -0,0 +1,383 @@
+package com.atridad.openclimb.data.repository
+
+import android.content.Context
+import com.atridad.openclimb.data.database.OpenClimbDatabase
+import com.atridad.openclimb.data.format.ClimbDataBackup
+import com.atridad.openclimb.data.model.*
+import com.atridad.openclimb.utils.ZipExportImportUtils
+import java.io.File
+import java.time.LocalDateTime
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.first
+import kotlinx.serialization.json.Json
+
+class ClimbRepository(database: OpenClimbDatabase, private val context: Context) {
+    private val gymDao = database.gymDao()
+    private val problemDao = database.problemDao()
+    private val sessionDao = database.climbSessionDao()
+    private val attemptDao = database.attemptDao()
+
+    private val json = Json {
+        prettyPrint = true
+        ignoreUnknownKeys = true
+    }
+
+    // Gym operations
+    fun getAllGyms(): Flow<List<Gym>> = gymDao.getAllGyms()
+    suspend fun getGymById(id: String): Gym? = gymDao.getGymById(id)
+    suspend fun insertGym(gym: Gym) = gymDao.insertGym(gym)
+    suspend fun updateGym(gym: Gym) = gymDao.updateGym(gym)
+    suspend fun deleteGym(gym: Gym) = gymDao.deleteGym(gym)
+    fun searchGyms(query: String): Flow<List<Gym>> = gymDao.searchGyms(query)
+
+    // Problem operations
+    fun getAllProblems(): Flow<List<Problem>> = problemDao.getAllProblems()
+    suspend fun getProblemById(id: String): Problem? = problemDao.getProblemById(id)
+    fun getProblemsByGym(gymId: String): Flow<List<Problem>> = problemDao.getProblemsByGym(gymId)
+    suspend fun insertProblem(problem: Problem) = problemDao.insertProblem(problem)
+    suspend fun updateProblem(problem: Problem) = problemDao.updateProblem(problem)
+    suspend fun deleteProblem(problem: Problem) = problemDao.deleteProblem(problem)
+    fun searchProblems(query: String): Flow<List<Problem>> = problemDao.searchProblems(query)
+
+    // Session operations
+    fun getAllSessions(): Flow<List<ClimbSession>> = sessionDao.getAllSessions()
+    suspend fun getSessionById(id: String): ClimbSession? = sessionDao.getSessionById(id)
+    fun getSessionsByGym(gymId: String): Flow<List<ClimbSession>> =
+            sessionDao.getSessionsByGym(gymId)
+    suspend fun getActiveSession(): ClimbSession? = sessionDao.getActiveSession()
+    fun getActiveSessionFlow(): Flow<ClimbSession?> = sessionDao.getActiveSessionFlow()
+    suspend fun insertSession(session: ClimbSession) = sessionDao.insertSession(session)
+    suspend fun updateSession(session: ClimbSession) = sessionDao.updateSession(session)
+    suspend fun deleteSession(session: ClimbSession) = sessionDao.deleteSession(session)
+    suspend fun getLastUsedGym(): Gym? {
+        val recentSessions = sessionDao.getRecentSessions(1).first()
+        return if (recentSessions.isNotEmpty()) {
+            getGymById(recentSessions.first().gymId)
+        } else {
+            null
+        }
+    }
+
+    // Attempt operations
+    fun getAllAttempts(): Flow<List<Attempt>> = attemptDao.getAllAttempts()
+    fun getAttemptsBySession(sessionId: String): Flow<List<Attempt>> =
+            attemptDao.getAttemptsBySession(sessionId)
+    fun getAttemptsByProblem(problemId: String): Flow<List<Attempt>> =
+            attemptDao.getAttemptsByProblem(problemId)
+    suspend fun insertAttempt(attempt: Attempt) = attemptDao.insertAttempt(attempt)
+    suspend fun updateAttempt(attempt: Attempt) = attemptDao.updateAttempt(attempt)
+    suspend fun deleteAttempt(attempt: Attempt) = attemptDao.deleteAttempt(attempt)
+
+    // ZIP Export with images - Single format for reliability
+    suspend fun exportAllDataToZip(directory: File? = null): File {
+        return try {
+            // Collect all data with proper error handling
+            val allGyms = gymDao.getAllGyms().first()
+            val allProblems = problemDao.getAllProblems().first()
+            val allSessions = sessionDao.getAllSessions().first()
+            val allAttempts = attemptDao.getAllAttempts().first()
+
+            // Validate data integrity before export
+            validateDataIntegrity(allGyms, allProblems, allSessions, allAttempts)
+
+            // Create backup data using platform-neutral format
+            val backupData =
+                    ClimbDataBackup(
+                            exportedAt = LocalDateTime.now().toString(),
+                            version = "2.0",
+                            formatVersion = "2.0",
+                            gyms =
+                                    allGyms.map {
+                                        com.atridad.openclimb.data.format.BackupGym.fromGym(it)
+                                    },
+                            problems =
+                                    allProblems.map {
+                                        com.atridad.openclimb.data.format.BackupProblem.fromProblem(
+                                                it
+                                        )
+                                    },
+                            sessions =
+                                    allSessions.map {
+                                        com.atridad.openclimb.data.format.BackupClimbSession
+                                                .fromClimbSession(it)
+                                    },
+                            attempts =
+                                    allAttempts.map {
+                                        com.atridad.openclimb.data.format.BackupAttempt.fromAttempt(
+                                                it
+                                        )
+                                    }
+                    )
+
+            // Collect all referenced image paths and validate they exist
+            val referencedImagePaths = allProblems.flatMap { it.imagePaths }.toSet()
+            val validImagePaths =
+                    referencedImagePaths
+                            .filter { imagePath ->
+                                try {
+                                    val imageFile =
+                                            com.atridad.openclimb.utils.ImageUtils.getImageFile(
+                                                    context,
+                                                    imagePath
+                                            )
+                                    imageFile.exists() && imageFile.length() > 0
+                                } catch (e: Exception) {
+                                    false
+                                }
+                            }
+                            .toSet()
+
+            // Log any missing images for debugging
+            val missingImages = referencedImagePaths - validImagePaths
+            if (missingImages.isNotEmpty()) {
+                android.util.Log.w(
+                        "ClimbRepository",
+                        "Some referenced images are missing: $missingImages"
+                )
+            }
+
+            ZipExportImportUtils.createExportZip(
+                    context = context,
+                    exportData = backupData,
+                    referencedImagePaths = validImagePaths,
+                    directory = directory
+            )
+        } catch (e: Exception) {
+            throw Exception("Export failed: ${e.message}")
+        }
+    }
+
+    suspend fun exportAllDataToZipUri(uri: android.net.Uri) {
+        try {
+            // Collect all data
+            val allGyms = gymDao.getAllGyms().first()
+            val allProblems = problemDao.getAllProblems().first()
+            val allSessions = sessionDao.getAllSessions().first()
+            val allAttempts = attemptDao.getAllAttempts().first()
+
+            // Validate data integrity before export
+            validateDataIntegrity(allGyms, allProblems, allSessions, allAttempts)
+
+            // Create backup data using platform-neutral format
+            val backupData =
+                    ClimbDataBackup(
+                            exportedAt = LocalDateTime.now().toString(),
+                            version = "2.0",
+                            formatVersion = "2.0",
+                            gyms =
+                                    allGyms.map {
+                                        com.atridad.openclimb.data.format.BackupGym.fromGym(it)
+                                    },
+                            problems =
+                                    allProblems.map {
+                                        com.atridad.openclimb.data.format.BackupProblem.fromProblem(
+                                                it
+                                        )
+                                    },
+                            sessions =
+                                    allSessions.map {
+                                        com.atridad.openclimb.data.format.BackupClimbSession
+                                                .fromClimbSession(it)
+                                    },
+                            attempts =
+                                    allAttempts.map {
+                                        com.atridad.openclimb.data.format.BackupAttempt.fromAttempt(
+                                                it
+                                        )
+                                    }
+                    )
+
+            // Collect all referenced image paths and validate they exist
+            val referencedImagePaths = allProblems.flatMap { it.imagePaths }.toSet()
+            val validImagePaths =
+                    referencedImagePaths
+                            .filter { imagePath ->
+                                try {
+                                    val imageFile =
+                                            com.atridad.openclimb.utils.ImageUtils.getImageFile(
+                                                    context,
+                                                    imagePath
+                                            )
+                                    imageFile.exists() && imageFile.length() > 0
+                                } catch (e: Exception) {
+                                    false
+                                }
+                            }
+                            .toSet()
+
+            ZipExportImportUtils.createExportZipToUri(
+                    context = context,
+                    uri = uri,
+                    exportData = backupData,
+                    referencedImagePaths = validImagePaths
+            )
+        } catch (e: Exception) {
+            throw Exception("Export failed: ${e.message}")
+        }
+    }
+
+    suspend fun importDataFromZip(file: File) {
+        try {
+            // Validate the ZIP file
+            if (!file.exists() || file.length() == 0L) {
+                throw Exception("Invalid ZIP file: file is empty or doesn't exist")
+            }
+
+            // Extract and validate the ZIP contents
+            val importResult = ZipExportImportUtils.extractImportZip(context, file)
+
+            // Validate JSON content
+            if (importResult.jsonContent.isBlank()) {
+                throw Exception("Invalid ZIP file: no data.json found or empty content")
+            }
+
+            // Parse and validate the data structure
+            val importData =
+                    try {
+                        json.decodeFromString<ClimbDataBackup>(importResult.jsonContent)
+                    } catch (e: Exception) {
+                        throw Exception("Invalid data format: ${e.message}")
+                    }
+
+            // Validate data integrity
+            validateImportData(importData)
+
+            // Clear existing data to avoid conflicts
+            attemptDao.deleteAllAttempts()
+            sessionDao.deleteAllSessions()
+            problemDao.deleteAllProblems()
+            gymDao.deleteAllGyms()
+
+            // Import gyms first (problems depend on gyms)
+            importData.gyms.forEach { backupGym ->
+                try {
+                    gymDao.insertGym(backupGym.toGym())
+                } catch (e: Exception) {
+                    throw Exception("Failed to import gym '${backupGym.name}': ${e.message}")
+                }
+            }
+
+            // Import problems with updated image paths
+            val updatedBackupProblems =
+                    ZipExportImportUtils.updateProblemImagePaths(
+                            importData.problems,
+                            importResult.importedImagePaths
+                    )
+
+            // Import problems (depends on gyms)
+            updatedBackupProblems.forEach { backupProblem ->
+                try {
+                    problemDao.insertProblem(backupProblem.toProblem())
+                } catch (e: Exception) {
+                    throw Exception(
+                            "Failed to import problem '${backupProblem.name}': ${e.message}"
+                    )
+                }
+            }
+
+            // Import sessions
+            importData.sessions.forEach { backupSession ->
+                try {
+                    sessionDao.insertSession(backupSession.toClimbSession())
+                } catch (e: Exception) {
+                    throw Exception("Failed to import session '${backupSession.id}': ${e.message}")
+                }
+            }
+
+            // Import attempts last (depends on problems and sessions)
+            importData.attempts.forEach { backupAttempt ->
+                try {
+                    attemptDao.insertAttempt(backupAttempt.toAttempt())
+                } catch (e: Exception) {
+                    throw Exception("Failed to import attempt '${backupAttempt.id}': ${e.message}")
+                }
+            }
+        } catch (e: Exception) {
+            throw Exception("Import failed: ${e.message}")
+        }
+    }
+
+    private fun validateDataIntegrity(
+            gyms: List<Gym>,
+            problems: List<Problem>,
+            sessions: List<ClimbSession>,
+            attempts: List<Attempt>
+    ) {
+        // Validate that all problems reference valid gyms
+        val gymIds = gyms.map { it.id }.toSet()
+        val invalidProblems = problems.filter { it.gymId !in gymIds }
+        if (invalidProblems.isNotEmpty()) {
+            throw Exception(
+                    "Data integrity error: ${invalidProblems.size} problems reference non-existent gyms"
+            )
+        }
+
+        // Validate that all sessions reference valid gyms
+        val invalidSessions = sessions.filter { it.gymId !in gymIds }
+        if (invalidSessions.isNotEmpty()) {
+            throw Exception(
+                    "Data integrity error: ${invalidSessions.size} sessions reference non-existent gyms"
+            )
+        }
+
+        // Validate that all attempts reference valid problems and sessions
+        val problemIds = problems.map { it.id }.toSet()
+        val sessionIds = sessions.map { it.id }.toSet()
+
+        val invalidAttempts =
+                attempts.filter { it.problemId !in problemIds || it.sessionId !in sessionIds }
+        if (invalidAttempts.isNotEmpty()) {
+            throw Exception(
+                    "Data integrity error: ${invalidAttempts.size} attempts reference non-existent problems or sessions"
+            )
+        }
+    }
+
+    private fun validateImportData(importData: ClimbDataBackup) {
+        if (importData.gyms.isEmpty()) {
+            throw Exception("Import data is invalid: no gyms found")
+        }
+
+        if (importData.version.isBlank()) {
+            throw Exception("Import data is invalid: no version information")
+        }
+
+        // Check for reasonable data sizes to prevent malicious imports
+        if (importData.gyms.size > 1000 ||
+                        importData.problems.size > 10000 ||
+                        importData.sessions.size > 10000 ||
+                        importData.attempts.size > 100000
+        ) {
+            throw Exception("Import data is too large: possible corruption or malicious file")
+        }
+    }
+
+    suspend fun resetAllData() {
+        try {
+            // Clear all data from database
+            attemptDao.deleteAllAttempts()
+            sessionDao.deleteAllSessions()
+            problemDao.deleteAllProblems()
+            gymDao.deleteAllGyms()
+
+            // Clear all images from storage
+            clearAllImages()
+        } catch (e: Exception) {
+            throw Exception("Reset failed: ${e.message}")
+        }
+    }
+
+    private fun clearAllImages() {
+        try {
+            // Get the images directory
+            val imagesDir = File(context.filesDir, "images")
+            if (imagesDir.exists() && imagesDir.isDirectory) {
+                val deletedCount = imagesDir.listFiles()?.size ?: 0
+                imagesDir.deleteRecursively()
+                android.util.Log.i("ClimbRepository", "Cleared $deletedCount image files")
+            }
+        } catch (e: Exception) {
+            android.util.Log.w("ClimbRepository", "Failed to clear some images: ${e.message}")
+        }
+    }
+}

ios/OpenClimb.xcodeproj/project.pbxproj

@@ -324,6 +324,7 @@
 				MTL_FAST_MATH = YES;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
+				STRING_CATALOG_GENERATE_SYMBOLS = YES;
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = "DEBUG $(inherited)";
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
 			};
@@ -381,6 +382,7 @@
 				MTL_ENABLE_DEBUG_INFO = NO;
 				MTL_FAST_MATH = YES;
 				SDKROOT = iphoneos;
+				STRING_CATALOG_GENERATE_SYMBOLS = YES;
 				SWIFT_COMPILATION_MODE = wholemodule;
 				VALIDATE_PRODUCT = YES;
 			};
@@ -394,7 +396,7 @@
 				CODE_SIGN_ENTITLEMENTS = OpenClimb/OpenClimb.entitlements;
 				CODE_SIGN_IDENTITY = "Apple Development";
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 9;
+				CURRENT_PROJECT_VERSION = 12;
 				DEVELOPMENT_TEAM = 4BC9Y2LL4B;
 				ENABLE_PREVIEWS = YES;
 				GENERATE_INFOPLIST_FILE = YES;
@@ -414,7 +416,7 @@
 					"$(inherited)",
 					"@executable_path/Frameworks",
 				);
-				MARKETING_VERSION = 1.0.3;
+				MARKETING_VERSION = 1.2.1;
 				PRODUCT_BUNDLE_IDENTIFIER = com.atridad.OpenClimb;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				PROVISIONING_PROFILE_SPECIFIER = "";
@@ -437,7 +439,7 @@
 				CODE_SIGN_ENTITLEMENTS = OpenClimb/OpenClimb.entitlements;
 				CODE_SIGN_IDENTITY = "Apple Development";
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 9;
+				CURRENT_PROJECT_VERSION = 12;
 				DEVELOPMENT_TEAM = 4BC9Y2LL4B;
 				ENABLE_PREVIEWS = YES;
 				GENERATE_INFOPLIST_FILE = YES;
@@ -457,7 +459,7 @@
 					"$(inherited)",
 					"@executable_path/Frameworks",
 				);
-				MARKETING_VERSION = 1.0.3;
+				MARKETING_VERSION = 1.2.1;
 				PRODUCT_BUNDLE_IDENTIFIER = com.atridad.OpenClimb;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				PROVISIONING_PROFILE_SPECIFIER = "";
@@ -479,7 +481,7 @@
 				ASSETCATALOG_COMPILER_WIDGET_BACKGROUND_COLOR_NAME = WidgetBackground;
 				CODE_SIGN_ENTITLEMENTS = SessionStatusLiveExtension.entitlements;
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 9;
+				CURRENT_PROJECT_VERSION = 12;
 				DEVELOPMENT_TEAM = 4BC9Y2LL4B;
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_FILE = SessionStatusLive/Info.plist;
@@ -490,7 +492,7 @@
 					"@executable_path/Frameworks",
 					"@executable_path/../../Frameworks",
 				);
-				MARKETING_VERSION = 1.0.3;
+				MARKETING_VERSION = 1.2.1;
 				PRODUCT_BUNDLE_IDENTIFIER = com.atridad.OpenClimb.SessionStatusLive;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
@@ -509,7 +511,7 @@
 				ASSETCATALOG_COMPILER_WIDGET_BACKGROUND_COLOR_NAME = WidgetBackground;
 				CODE_SIGN_ENTITLEMENTS = SessionStatusLiveExtension.entitlements;
 				CODE_SIGN_STYLE = Automatic;
-				CURRENT_PROJECT_VERSION = 9;
+				CURRENT_PROJECT_VERSION = 12;
 				DEVELOPMENT_TEAM = 4BC9Y2LL4B;
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_FILE = SessionStatusLive/Info.plist;
@@ -520,7 +522,7 @@
 					"@executable_path/Frameworks",
 					"@executable_path/../../Frameworks",
 				);
-				MARKETING_VERSION = 1.0.3;
+				MARKETING_VERSION = 1.2.1;
 				PRODUCT_BUNDLE_IDENTIFIER = com.atridad.OpenClimb.SessionStatusLive;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;

ios/OpenClimb.xcodeproj/xcshareddata/xcschemes/OpenClimb.xcscheme

@@ -0,0 +1,78 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "2600"
+   version = "1.3">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "D24C19672E75002A0045894C"
+               BuildableName = "OpenClimb.app"
+               BlueprintName = "OpenClimb"
+               ReferencedContainer = "container:OpenClimb.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES">
+      <Testables>
+      </Testables>
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "D24C19672E75002A0045894C"
+            BuildableName = "OpenClimb.app"
+            BlueprintName = "OpenClimb"
+            ReferencedContainer = "container:OpenClimb.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "D24C19672E75002A0045894C"
+            BuildableName = "OpenClimb.app"
+            BlueprintName = "OpenClimb"
+            ReferencedContainer = "container:OpenClimb.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>

ios/OpenClimb/ContentView.swift

@@ -57,6 +57,8 @@ struct ContentView: View {
         }
         .onAppear {
             setupNotificationObservers()
+            // Trigger auto-sync on app launch
+            dataManager.syncService.triggerAutoSync(dataManager: dataManager)
         }
         .onDisappear {
             removeNotificationObservers()
@@ -100,7 +102,9 @@ struct ContentView: View {
             print("📱 App did become active - checking Live Activity status")
             Task {
                 try? await Task.sleep(nanoseconds: 300_000_000)  // 0.3 seconds
-                dataManager.onAppBecomeActive()
+                await dataManager.onAppBecomeActive()
+                // Trigger auto-sync when app becomes active
+                await dataManager.syncService.triggerAutoSync(dataManager: dataManager)
             }
         }
 

ios/OpenClimb/Models/BackupFormat.swift

@@ -0,0 +1,447 @@
+//
+//  BackupFormat.swift
+
+import Foundation
+
+// MARK: - Backup Format Specification v2.0
+// Platform-neutral backup format for cross-platform compatibility
+// This format ensures portability between iOS and Android while maintaining
+// platform-specific implementations
+
+/// Root structure for OpenClimb backup data
+struct ClimbDataBackup: Codable {
+    let exportedAt: String
+    let version: String
+    let formatVersion: String
+    let gyms: [BackupGym]
+    let problems: [BackupProblem]
+    let sessions: [BackupClimbSession]
+    let attempts: [BackupAttempt]
+
+    init(
+        exportedAt: String,
+        version: String = "2.0",
+        formatVersion: String = "2.0",
+        gyms: [BackupGym],
+        problems: [BackupProblem],
+        sessions: [BackupClimbSession],
+        attempts: [BackupAttempt]
+    ) {
+        self.exportedAt = exportedAt
+        self.version = version
+        self.formatVersion = formatVersion
+        self.gyms = gyms
+        self.problems = problems
+        self.sessions = sessions
+        self.attempts = attempts
+    }
+}
+
+/// Platform-neutral gym representation for backup/restore
+struct BackupGym: Codable {
+    let id: String
+    let name: String
+    let location: String?
+    let supportedClimbTypes: [ClimbType]
+    let difficultySystems: [DifficultySystem]
+    let customDifficultyGrades: [String]
+    let notes: String?
+    let createdAt: String  // ISO 8601 format
+    let updatedAt: String  // ISO 8601 format
+
+    /// Initialize from native iOS Gym model
+    init(from gym: Gym) {
+        self.id = gym.id.uuidString
+        self.name = gym.name
+        self.location = gym.location
+        self.supportedClimbTypes = gym.supportedClimbTypes
+        self.difficultySystems = gym.difficultySystems
+        self.customDifficultyGrades = gym.customDifficultyGrades
+        self.notes = gym.notes
+
+        let formatter = ISO8601DateFormatter()
+        formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+        self.createdAt = formatter.string(from: gym.createdAt)
+        self.updatedAt = formatter.string(from: gym.updatedAt)
+    }
+
+    /// Initialize with explicit parameters for import
+    init(
+        id: String,
+        name: String,
+        location: String?,
+        supportedClimbTypes: [ClimbType],
+        difficultySystems: [DifficultySystem],
+        customDifficultyGrades: [String] = [],
+        notes: String?,
+        createdAt: String,
+        updatedAt: String
+    ) {
+        self.id = id
+        self.name = name
+        self.location = location
+        self.supportedClimbTypes = supportedClimbTypes
+        self.difficultySystems = difficultySystems
+        self.customDifficultyGrades = customDifficultyGrades
+        self.notes = notes
+        self.createdAt = createdAt
+        self.updatedAt = updatedAt
+    }
+
+    /// Convert to native iOS Gym model
+    func toGym() throws -> Gym {
+        let formatter = ISO8601DateFormatter()
+        formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+
+        guard let uuid = UUID(uuidString: id),
+            let createdDate = formatter.date(from: createdAt),
+            let updatedDate = formatter.date(from: updatedAt)
+        else {
+            throw BackupError.invalidDateFormat
+        }
+
+        return Gym.fromImport(
+            id: uuid,
+            name: name,
+            location: location,
+            supportedClimbTypes: supportedClimbTypes,
+            difficultySystems: difficultySystems,
+            customDifficultyGrades: customDifficultyGrades,
+            notes: notes,
+            createdAt: createdDate,
+            updatedAt: updatedDate
+        )
+    }
+}
+
+/// Platform-neutral problem representation for backup/restore
+struct BackupProblem: Codable {
+    let id: String
+    let gymId: String
+    let name: String?
+    let description: String?
+    let climbType: ClimbType
+    let difficulty: DifficultyGrade
+    let tags: [String]
+    let location: String?
+    let imagePaths: [String]?
+    let isActive: Bool
+    let dateSet: String?  // ISO 8601 format
+    let notes: String?
+    let createdAt: String  // ISO 8601 format
+    let updatedAt: String  // ISO 8601 format
+
+    /// Initialize from native iOS Problem model
+    init(from problem: Problem) {
+        self.id = problem.id.uuidString
+        self.gymId = problem.gymId.uuidString
+        self.name = problem.name
+        self.description = problem.description
+        self.climbType = problem.climbType
+        self.difficulty = problem.difficulty
+        self.tags = problem.tags
+        self.location = problem.location
+        self.imagePaths = problem.imagePaths.isEmpty ? nil : problem.imagePaths
+        self.isActive = problem.isActive
+        self.notes = problem.notes
+
+        let formatter = ISO8601DateFormatter()
+        formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+        self.dateSet = problem.dateSet.map { formatter.string(from: $0) }
+        self.createdAt = formatter.string(from: problem.createdAt)
+        self.updatedAt = formatter.string(from: problem.updatedAt)
+    }
+
+    /// Initialize with explicit parameters for import
+    init(
+        id: String,
+        gymId: String,
+        name: String?,
+        description: String?,
+        climbType: ClimbType,
+        difficulty: DifficultyGrade,
+        tags: [String] = [],
+        location: String?,
+        imagePaths: [String]?,
+        isActive: Bool,
+        dateSet: String?,
+        notes: String?,
+        createdAt: String,
+        updatedAt: String
+    ) {
+        self.id = id
+        self.gymId = gymId
+        self.name = name
+        self.description = description
+        self.climbType = climbType
+        self.difficulty = difficulty
+        self.tags = tags
+        self.location = location
+        self.imagePaths = imagePaths
+        self.isActive = isActive
+        self.dateSet = dateSet
+        self.notes = notes
+        self.createdAt = createdAt
+        self.updatedAt = updatedAt
+    }
+
+    /// Convert to native iOS Problem model
+    func toProblem() throws -> Problem {
+        let formatter = ISO8601DateFormatter()
+        formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+
+        guard let uuid = UUID(uuidString: id),
+            let gymUuid = UUID(uuidString: gymId),
+            let createdDate = formatter.date(from: createdAt),
+            let updatedDate = formatter.date(from: updatedAt)
+        else {
+            throw BackupError.invalidDateFormat
+        }
+
+        let dateSetDate = dateSet.flatMap { formatter.date(from: $0) }
+
+        return Problem.fromImport(
+            id: uuid,
+            gymId: gymUuid,
+            name: name,
+            description: description,
+            climbType: climbType,
+            difficulty: difficulty,
+            tags: tags,
+            location: location,
+            imagePaths: imagePaths ?? [],
+            isActive: isActive,
+            dateSet: dateSetDate,
+            notes: notes,
+            createdAt: createdDate,
+            updatedAt: updatedDate
+        )
+    }
+
+    /// Create a copy with updated image paths for import processing
+    func withUpdatedImagePaths(_ newImagePaths: [String]) -> BackupProblem {
+        return BackupProblem(
+            id: self.id,
+            gymId: self.gymId,
+            name: self.name,
+            description: self.description,
+            climbType: self.climbType,
+            difficulty: self.difficulty,
+            tags: self.tags,
+            location: self.location,
+            imagePaths: newImagePaths.isEmpty ? nil : newImagePaths,
+            isActive: self.isActive,
+            dateSet: self.dateSet,
+            notes: self.notes,
+            createdAt: self.createdAt,
+            updatedAt: self.updatedAt
+        )
+    }
+}
+
+/// Platform-neutral climb session representation for backup/restore
+struct BackupClimbSession: Codable {
+    let id: String
+    let gymId: String
+    let date: String  // ISO 8601 format
+    let startTime: String?  // ISO 8601 format
+    let endTime: String?  // ISO 8601 format
+    let duration: Int64?  // Duration in seconds
+    let status: SessionStatus
+    let notes: String?
+    let createdAt: String  // ISO 8601 format
+    let updatedAt: String  // ISO 8601 format
+
+    /// Initialize from native iOS ClimbSession model
+    init(from session: ClimbSession) {
+        self.id = session.id.uuidString
+        self.gymId = session.gymId.uuidString
+        self.status = session.status
+        self.notes = session.notes
+
+        let formatter = ISO8601DateFormatter()
+        formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+        self.date = formatter.string(from: session.date)
+        self.startTime = session.startTime.map { formatter.string(from: $0) }
+        self.endTime = session.endTime.map { formatter.string(from: $0) }
+        self.duration = session.duration.map { Int64($0) }
+        self.createdAt = formatter.string(from: session.createdAt)
+        self.updatedAt = formatter.string(from: session.updatedAt)
+    }
+
+    /// Initialize with explicit parameters for import
+    init(
+        id: String,
+        gymId: String,
+        date: String,
+        startTime: String?,
+        endTime: String?,
+        duration: Int64?,
+        status: SessionStatus,
+        notes: String?,
+        createdAt: String,
+        updatedAt: String
+    ) {
+        self.id = id
+        self.gymId = gymId
+        self.date = date
+        self.startTime = startTime
+        self.endTime = endTime
+        self.duration = duration
+        self.status = status
+        self.notes = notes
+        self.createdAt = createdAt
+        self.updatedAt = updatedAt
+    }
+
+    /// Convert to native iOS ClimbSession model
+    func toClimbSession() throws -> ClimbSession {
+        let formatter = ISO8601DateFormatter()
+        formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+
+        guard let uuid = UUID(uuidString: id),
+            let gymUuid = UUID(uuidString: gymId),
+            let dateValue = formatter.date(from: date),
+            let createdDate = formatter.date(from: createdAt),
+            let updatedDate = formatter.date(from: updatedAt)
+        else {
+            throw BackupError.invalidDateFormat
+        }
+
+        let startTimeValue = startTime.flatMap { formatter.date(from: $0) }
+        let endTimeValue = endTime.flatMap { formatter.date(from: $0) }
+        let durationValue = duration.map { Int($0) }
+
+        return ClimbSession.fromImport(
+            id: uuid,
+            gymId: gymUuid,
+            date: dateValue,
+            startTime: startTimeValue,
+            endTime: endTimeValue,
+            duration: durationValue,
+            status: status,
+            notes: notes,
+            createdAt: createdDate,
+            updatedAt: updatedDate
+        )
+    }
+}
+
+/// Platform-neutral attempt representation for backup/restore
+struct BackupAttempt: Codable {
+    let id: String
+    let sessionId: String
+    let problemId: String
+    let result: AttemptResult
+    let highestHold: String?
+    let notes: String?
+    let duration: Int64?  // Duration in seconds
+    let restTime: Int64?  // Rest time in seconds
+    let timestamp: String  // ISO 8601 format
+    let createdAt: String  // ISO 8601 format
+
+    /// Initialize from native iOS Attempt model
+    init(from attempt: Attempt) {
+        self.id = attempt.id.uuidString
+        self.sessionId = attempt.sessionId.uuidString
+        self.problemId = attempt.problemId.uuidString
+        self.result = attempt.result
+        self.highestHold = attempt.highestHold
+        self.notes = attempt.notes
+        self.duration = attempt.duration.map { Int64($0) }
+        self.restTime = attempt.restTime.map { Int64($0) }
+
+        let formatter = ISO8601DateFormatter()
+        formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+        self.timestamp = formatter.string(from: attempt.timestamp)
+        self.createdAt = formatter.string(from: attempt.createdAt)
+    }
+
+    /// Initialize with explicit parameters for import
+    init(
+        id: String,
+        sessionId: String,
+        problemId: String,
+        result: AttemptResult,
+        highestHold: String?,
+        notes: String?,
+        duration: Int64?,
+        restTime: Int64?,
+        timestamp: String,
+        createdAt: String
+    ) {
+        self.id = id
+        self.sessionId = sessionId
+        self.problemId = problemId
+        self.result = result
+        self.highestHold = highestHold
+        self.notes = notes
+        self.duration = duration
+        self.restTime = restTime
+        self.timestamp = timestamp
+        self.createdAt = createdAt
+    }
+
+    /// Convert to native iOS Attempt model
+    func toAttempt() throws -> Attempt {
+        let formatter = ISO8601DateFormatter()
+        formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
+
+        guard let uuid = UUID(uuidString: id),
+            let sessionUuid = UUID(uuidString: sessionId),
+            let problemUuid = UUID(uuidString: problemId),
+            let timestampDate = formatter.date(from: timestamp),
+            let createdDate = formatter.date(from: createdAt)
+        else {
+            throw BackupError.invalidDateFormat
+        }
+
+        let durationValue = duration.map { Int($0) }
+        let restTimeValue = restTime.map { Int($0) }
+
+        return Attempt.fromImport(
+            id: uuid,
+            sessionId: sessionUuid,
+            problemId: problemUuid,
+            result: result,
+            highestHold: highestHold,
+            notes: notes,
+            duration: durationValue,
+            restTime: restTimeValue,
+            timestamp: timestampDate,
+            createdAt: createdDate
+        )
+    }
+}
+
+// MARK: - Backup Format Errors
+
+enum BackupError: LocalizedError {
+    case invalidDateFormat
+    case invalidUUID
+    case missingRequiredField(String)
+    case unsupportedFormatVersion(String)
+
+    var errorDescription: String? {
+        switch self {
+        case .invalidDateFormat:
+            return "Invalid date format in backup data"
+        case .invalidUUID:
+            return "Invalid UUID format in backup data"
+        case .missingRequiredField(let field):
+            return "Missing required field: \(field)"
+        case .unsupportedFormatVersion(let version):
+            return "Unsupported backup format version: \(version)"
+        }
+    }
+}
+
+// MARK: - Extensions
+
+// MARK: - Helper Extensions for Optional Mapping
+
+extension Optional {
+    func map<T>(_ transform: (Wrapped) -> T) -> T? {
+        return self.flatMap { .some(transform($0)) }
+    }
+}

ios/OpenClimb/Services/SyncService.swift

@@ -0,0 +1,824 @@
+import Combine
+import Foundation
+
+@MainActor
+class SyncService: ObservableObject {
+
+    @Published var isSyncing = false
+    @Published var lastSyncTime: Date?
+    @Published var syncError: String?
+    @Published var isConnected = false
+    @Published var isTesting = false
+
+    private let userDefaults = UserDefaults.standard
+
+    private enum Keys {
+        static let serverURL = "sync_server_url"
+        static let authToken = "sync_auth_token"
+        static let lastSyncTime = "last_sync_time"
+        static let isConnected = "sync_is_connected"
+        static let autoSyncEnabled = "auto_sync_enabled"
+    }
+
+    var serverURL: String {
+        get { userDefaults.string(forKey: Keys.serverURL) ?? "" }
+        set { userDefaults.set(newValue, forKey: Keys.serverURL) }
+    }
+
+    var authToken: String {
+        get { userDefaults.string(forKey: Keys.authToken) ?? "" }
+        set { userDefaults.set(newValue, forKey: Keys.authToken) }
+    }
+
+    var isConfigured: Bool {
+        return !serverURL.isEmpty && !authToken.isEmpty
+    }
+
+    var isAutoSyncEnabled: Bool {
+        get { userDefaults.bool(forKey: Keys.autoSyncEnabled) }
+        set { userDefaults.set(newValue, forKey: Keys.autoSyncEnabled) }
+    }
+
+    init() {
+        if let lastSync = userDefaults.object(forKey: Keys.lastSyncTime) as? Date {
+            self.lastSyncTime = lastSync
+        }
+        self.isConnected = userDefaults.bool(forKey: Keys.isConnected)
+    }
+
+    func downloadData() async throws -> ClimbDataBackup {
+        guard isConfigured else {
+            throw SyncError.notConfigured
+        }
+
+        guard let url = URL(string: "\(serverURL)/sync") else {
+            throw SyncError.invalidURL
+        }
+
+        var request = URLRequest(url: url)
+        request.httpMethod = "GET"
+        request.setValue("Bearer \(authToken)", forHTTPHeaderField: "Authorization")
+        request.setValue("application/json", forHTTPHeaderField: "Accept")
+
+        let (data, response) = try await URLSession.shared.data(for: request)
+
+        guard let httpResponse = response as? HTTPURLResponse else {
+            throw SyncError.invalidResponse
+        }
+
+        switch httpResponse.statusCode {
+        case 200:
+            break
+        case 401:
+            throw SyncError.unauthorized
+        default:
+            throw SyncError.serverError(httpResponse.statusCode)
+        }
+
+        do {
+            let backup = try JSONDecoder().decode(ClimbDataBackup.self, from: data)
+            return backup
+        } catch {
+            throw SyncError.decodingError(error)
+        }
+    }
+
+    func uploadData(_ backup: ClimbDataBackup) async throws -> ClimbDataBackup {
+        guard isConfigured else {
+            throw SyncError.notConfigured
+        }
+
+        guard let url = URL(string: "\(serverURL)/sync") else {
+            throw SyncError.invalidURL
+        }
+
+        let encoder = JSONEncoder()
+        encoder.dateEncodingStrategy = .iso8601
+
+        let jsonData = try encoder.encode(backup)
+
+        var request = URLRequest(url: url)
+        request.httpMethod = "PUT"
+        request.setValue("Bearer \(authToken)", forHTTPHeaderField: "Authorization")
+        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
+        request.setValue("application/json", forHTTPHeaderField: "Accept")
+        request.httpBody = jsonData
+
+        let (data, response) = try await URLSession.shared.data(for: request)
+
+        guard let httpResponse = response as? HTTPURLResponse else {
+            throw SyncError.invalidResponse
+        }
+
+        switch httpResponse.statusCode {
+        case 200:
+            break
+        case 401:
+            throw SyncError.unauthorized
+        case 400:
+            throw SyncError.badRequest
+        default:
+            throw SyncError.serverError(httpResponse.statusCode)
+        }
+
+        do {
+            let responseBackup = try JSONDecoder().decode(ClimbDataBackup.self, from: data)
+            return responseBackup
+        } catch {
+            throw SyncError.decodingError(error)
+        }
+    }
+
+    func uploadImage(filename: String, imageData: Data) async throws {
+        guard isConfigured else {
+            throw SyncError.notConfigured
+        }
+
+        guard let url = URL(string: "\(serverURL)/images/upload?filename=\(filename)") else {
+            throw SyncError.invalidURL
+        }
+
+        var request = URLRequest(url: url)
+        request.httpMethod = "POST"
+        request.setValue("Bearer \(authToken)", forHTTPHeaderField: "Authorization")
+        request.setValue("application/octet-stream", forHTTPHeaderField: "Content-Type")
+        request.httpBody = imageData
+
+        let (_, response) = try await URLSession.shared.data(for: request)
+
+        guard let httpResponse = response as? HTTPURLResponse else {
+            throw SyncError.invalidResponse
+        }
+
+        switch httpResponse.statusCode {
+        case 200:
+            break
+        case 401:
+            throw SyncError.unauthorized
+        default:
+            throw SyncError.serverError(httpResponse.statusCode)
+        }
+    }
+
+    func downloadImage(filename: String) async throws -> Data {
+        guard isConfigured else {
+            throw SyncError.notConfigured
+        }
+
+        guard let url = URL(string: "\(serverURL)/images/download?filename=\(filename)") else {
+            throw SyncError.invalidURL
+        }
+
+        var request = URLRequest(url: url)
+        request.httpMethod = "GET"
+        request.setValue("Bearer \(authToken)", forHTTPHeaderField: "Authorization")
+
+        let (data, response) = try await URLSession.shared.data(for: request)
+
+        guard let httpResponse = response as? HTTPURLResponse else {
+
+            throw SyncError.invalidResponse
+        }
+
+        switch httpResponse.statusCode {
+        case 200:
+
+            return data
+        case 401:
+
+            throw SyncError.unauthorized
+        case 404:
+
+            throw SyncError.imageNotFound
+        default:
+
+            throw SyncError.serverError(httpResponse.statusCode)
+        }
+    }
+
+    func syncWithServer(dataManager: ClimbingDataManager) async throws {
+        guard isConfigured else {
+            throw SyncError.notConfigured
+        }
+
+        guard isConnected else {
+            throw SyncError.notConnected
+        }
+
+        isSyncing = true
+        syncError = nil
+
+        defer {
+            isSyncing = false
+        }
+
+        do {
+            // Get local backup data
+            let localBackup = createBackupFromDataManager(dataManager)
+
+            // Download server data
+            let serverBackup = try await downloadData()
+
+            // Check if we have any local data
+            let hasLocalData =
+                !dataManager.gyms.isEmpty || !dataManager.problems.isEmpty
+                || !dataManager.sessions.isEmpty || !dataManager.attempts.isEmpty
+
+            let hasServerData =
+                !serverBackup.gyms.isEmpty || !serverBackup.problems.isEmpty
+                || !serverBackup.sessions.isEmpty || !serverBackup.attempts.isEmpty
+
+            if !hasLocalData && hasServerData {
+                // Case 1: No local data - do full restore from server
+                print("🔄 iOS SYNC: Case 1 - No local data, performing full restore from server")
+                print("Syncing images from server first...")
+                let imagePathMapping = try await syncImagesFromServer(
+                    backup: serverBackup, dataManager: dataManager)
+                print("Importing data after images...")
+                try importBackupToDataManager(
+                    serverBackup, dataManager: dataManager, imagePathMapping: imagePathMapping)
+                print("Full restore completed")
+            } else if hasLocalData && !hasServerData {
+                // Case 2: No server data - upload local data to server
+                print("🔄 iOS SYNC: Case 2 - No server data, uploading local data to server")
+                let currentBackup = createBackupFromDataManager(dataManager)
+                _ = try await uploadData(currentBackup)
+                print("Uploading local images to server...")
+                try await syncImagesToServer(dataManager: dataManager)
+                print("Initial upload completed")
+            } else if hasLocalData && hasServerData {
+                // Case 3: Both have data - compare timestamps (last writer wins)
+                let localTimestamp = parseISO8601ToMillis(timestamp: localBackup.exportedAt)
+                let serverTimestamp = parseISO8601ToMillis(timestamp: serverBackup.exportedAt)
+
+                print("🕐 DEBUG iOS Timestamp Comparison:")
+                print("   Local exportedAt: '\(localBackup.exportedAt)' -> \(localTimestamp)")
+                print("   Server exportedAt: '\(serverBackup.exportedAt)' -> \(serverTimestamp)")
+                print(
+                    "   DataStateManager last modified: '\(DataStateManager.shared.getLastModified())'"
+                )
+                print("   Comparison result: local=\(localTimestamp), server=\(serverTimestamp)")
+
+                if localTimestamp > serverTimestamp {
+                    // Local is newer - replace server with local data
+                    print("🔄 iOS SYNC: Case 3a - Local data is newer, replacing server content")
+                    let currentBackup = createBackupFromDataManager(dataManager)
+                    _ = try await uploadData(currentBackup)
+                    try await syncImagesToServer(dataManager: dataManager)
+                    print("Server replaced with local data")
+                } else if serverTimestamp > localTimestamp {
+                    // Server is newer - replace local with server data
+                    print("🔄 iOS SYNC: Case 3b - Server data is newer, replacing local content")
+                    let imagePathMapping = try await syncImagesFromServer(
+                        backup: serverBackup, dataManager: dataManager)
+                    try importBackupToDataManager(
+                        serverBackup, dataManager: dataManager, imagePathMapping: imagePathMapping)
+                    print("Local data replaced with server data")
+                } else {
+                    // Timestamps are equal - no sync needed
+                    print(
+                        "🔄 iOS SYNC: Case 3c - Data is in sync (timestamps equal), no action needed"
+                    )
+                }
+            } else {
+                print("No data to sync")
+            }
+
+            // Update last sync time
+            lastSyncTime = Date()
+            userDefaults.set(lastSyncTime, forKey: Keys.lastSyncTime)
+
+        } catch {
+            syncError = error.localizedDescription
+            throw error
+        }
+    }
+
+    /// Parses ISO8601 timestamp to milliseconds for comparison
+    private func parseISO8601ToMillis(timestamp: String) -> Int64 {
+        let formatter = ISO8601DateFormatter()
+        if let date = formatter.date(from: timestamp) {
+            return Int64(date.timeIntervalSince1970 * 1000)
+        }
+        print("Failed to parse timestamp: \(timestamp), using 0")
+        return 0
+    }
+
+    private func syncImagesFromServer(backup: ClimbDataBackup, dataManager: ClimbingDataManager)
+        async throws -> [String: String]
+    {
+        var imagePathMapping: [String: String] = [:]
+
+        // Process images by problem to maintain consistent naming
+        for problem in backup.problems {
+            guard let imagePaths = problem.imagePaths, !imagePaths.isEmpty else { continue }
+
+            for (index, imagePath) in imagePaths.enumerated() {
+                let serverFilename = URL(fileURLWithPath: imagePath).lastPathComponent
+
+                do {
+                    let imageData = try await downloadImage(filename: serverFilename)
+
+                    // Generate consistent filename if needed
+                    let consistentFilename =
+                        ImageNamingUtils.isValidImageFilename(serverFilename)
+                        ? serverFilename
+                        : ImageNamingUtils.generateImageFilename(
+                            problemId: problem.id, imageIndex: index)
+
+                    // Save image with consistent filename
+                    let imageManager = ImageManager.shared
+                    _ = try imageManager.saveImportedImage(
+                        imageData, filename: consistentFilename)
+
+                    // Map server filename to consistent local filename
+                    imagePathMapping[serverFilename] = consistentFilename
+                    print("Downloaded and mapped image: \(serverFilename) -> \(consistentFilename)")
+                } catch SyncError.imageNotFound {
+                    print("Image not found on server: \(serverFilename)")
+                    continue
+                } catch {
+                    print("Failed to download image \(serverFilename): \(error)")
+                    continue
+                }
+            }
+        }
+
+        return imagePathMapping
+    }
+
+    private func syncImagesToServer(dataManager: ClimbingDataManager) async throws {
+        // Process images by problem to ensure consistent naming
+        for problem in dataManager.problems {
+            guard !problem.imagePaths.isEmpty else { continue }
+
+            for (index, imagePath) in problem.imagePaths.enumerated() {
+                let filename = URL(fileURLWithPath: imagePath).lastPathComponent
+
+                // Ensure filename follows consistent naming convention
+                let consistentFilename =
+                    ImageNamingUtils.isValidImageFilename(filename)
+                    ? filename
+                    : ImageNamingUtils.generateImageFilename(
+                        problemId: problem.id.uuidString, imageIndex: index)
+
+                // Load image data
+                let imageManager = ImageManager.shared
+                let fullPath = imageManager.imagesDirectory.appendingPathComponent(filename).path
+
+                if let imageData = imageManager.loadImageData(fromPath: fullPath) {
+                    do {
+                        // If filename changed, rename local file
+                        if filename != consistentFilename {
+                            let newPath = imageManager.imagesDirectory.appendingPathComponent(
+                                consistentFilename
+                            ).path
+                            do {
+                                try FileManager.default.moveItem(atPath: fullPath, toPath: newPath)
+                                print("Renamed local image: \(filename) -> \(consistentFilename)")
+
+                                // Update problem's image path in memory for consistency
+                                // Note: This would require updating the problem in the data manager
+                            } catch {
+                                print("Failed to rename local image, using original: \(error)")
+                            }
+                        }
+
+                        try await uploadImage(filename: consistentFilename, imageData: imageData)
+                        print("Successfully uploaded image: \(consistentFilename)")
+                    } catch {
+                        print("Failed to upload image \(consistentFilename): \(error)")
+                        // Continue with other images even if one fails
+                    }
+                }
+            }
+        }
+    }
+
+    private func createBackupFromDataManager(_ dataManager: ClimbingDataManager) -> ClimbDataBackup
+    {
+        return ClimbDataBackup(
+            exportedAt: DataStateManager.shared.getLastModified(),
+            gyms: dataManager.gyms.map { BackupGym(from: $0) },
+            problems: dataManager.problems.map { BackupProblem(from: $0) },
+            sessions: dataManager.sessions.map { BackupClimbSession(from: $0) },
+            attempts: dataManager.attempts.map { BackupAttempt(from: $0) }
+        )
+    }
+
+    private func importBackupToDataManager(
+        _ backup: ClimbDataBackup, dataManager: ClimbingDataManager,
+        imagePathMapping: [String: String] = [:]
+    ) throws {
+        do {
+
+            // Update problem image paths to point to downloaded images
+            let updatedBackup: ClimbDataBackup
+            if !imagePathMapping.isEmpty {
+                let updatedProblems = backup.problems.map { problem in
+                    let updatedImagePaths = problem.imagePaths?.compactMap { oldPath in
+                        imagePathMapping[oldPath] ?? oldPath
+                    }
+                    return BackupProblem(
+                        id: problem.id,
+                        gymId: problem.gymId,
+                        name: problem.name,
+                        description: problem.description,
+                        climbType: problem.climbType,
+                        difficulty: problem.difficulty,
+                        tags: problem.tags,
+                        location: problem.location,
+                        imagePaths: updatedImagePaths,
+                        isActive: problem.isActive,
+                        dateSet: problem.dateSet,
+                        notes: problem.notes,
+                        createdAt: problem.createdAt,
+                        updatedAt: problem.updatedAt
+                    )
+                }
+                updatedBackup = ClimbDataBackup(
+                    exportedAt: backup.exportedAt,
+                    version: backup.version,
+                    formatVersion: backup.formatVersion,
+                    gyms: backup.gyms,
+                    problems: updatedProblems,
+                    sessions: backup.sessions,
+                    attempts: backup.attempts
+                )
+
+            } else {
+                updatedBackup = backup
+            }
+
+            // Create a minimal ZIP with just the JSON data for existing import mechanism
+            let zipData = try createMinimalZipFromBackup(updatedBackup)
+
+            // Use existing import method which properly handles data restoration
+            try dataManager.importData(from: zipData, showSuccessMessage: false)
+
+            // Update local data state to match imported data timestamp
+            DataStateManager.shared.setLastModified(backup.exportedAt)
+            print("Data state synchronized to imported timestamp: \(backup.exportedAt)")
+
+        } catch {
+
+            throw SyncError.importFailed(error)
+        }
+    }
+
+    private func createMinimalZipFromBackup(_ backup: ClimbDataBackup) throws -> Data {
+        // Create JSON data
+
+        let encoder = JSONEncoder()
+        encoder.outputFormatting = .prettyPrinted
+        encoder.dateEncodingStrategy = .custom { date, encoder in
+            let formatter = DateFormatter()
+            formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS"
+            var container = encoder.singleValueContainer()
+            try container.encode(formatter.string(from: date))
+        }
+        let jsonData = try encoder.encode(backup)
+
+        // Collect all downloaded images from ImageManager
+        let imageManager = ImageManager.shared
+        var imageFiles: [(filename: String, data: Data)] = []
+        let imagePaths = Set(backup.problems.flatMap { $0.imagePaths ?? [] })
+
+        for imagePath in imagePaths {
+            let filename = URL(fileURLWithPath: imagePath).lastPathComponent
+            let fullPath = imageManager.imagesDirectory.appendingPathComponent(filename).path
+            if let imageData = imageManager.loadImageData(fromPath: fullPath) {
+                imageFiles.append((filename: filename, data: imageData))
+
+            }
+        }
+
+        // Create ZIP with data.json, metadata, and images
+        var zipData = Data()
+        var fileEntries: [(name: String, data: Data, offset: UInt32)] = []
+        var currentOffset: UInt32 = 0
+
+        // Add data.json to ZIP
+        try addFileToMinimalZip(
+            filename: "data.json",
+            fileData: jsonData,
+            zipData: &zipData,
+            fileEntries: &fileEntries,
+            currentOffset: &currentOffset
+        )
+
+        // Add metadata with correct image count
+        let metadata = "export_version=2.0\nformat_version=2.0\nimage_count=\(imageFiles.count)"
+        let metadataData = metadata.data(using: .utf8) ?? Data()
+        try addFileToMinimalZip(
+            filename: "metadata.txt",
+            fileData: metadataData,
+            zipData: &zipData,
+            fileEntries: &fileEntries,
+            currentOffset: &currentOffset
+        )
+
+        // Add images to ZIP in images/ directory
+        for imageFile in imageFiles {
+            try addFileToMinimalZip(
+                filename: "images/\(imageFile.filename)",
+                fileData: imageFile.data,
+                zipData: &zipData,
+                fileEntries: &fileEntries,
+                currentOffset: &currentOffset
+            )
+        }
+
+        // Add central directory
+        var centralDirectory = Data()
+        for entry in fileEntries {
+            centralDirectory.append(createCentralDirectoryHeader(entry: entry))
+        }
+
+        // Add end of central directory record
+        let endOfCentralDir = createEndOfCentralDirectoryRecord(
+            fileCount: UInt16(fileEntries.count),
+            centralDirSize: UInt32(centralDirectory.count),
+            centralDirOffset: currentOffset
+        )
+
+        zipData.append(centralDirectory)
+        zipData.append(endOfCentralDir)
+
+        return zipData
+    }
+
+    private func addFileToMinimalZip(
+        filename: String,
+        fileData: Data,
+        zipData: inout Data,
+        fileEntries: inout [(name: String, data: Data, offset: UInt32)],
+        currentOffset: inout UInt32
+    ) throws {
+        let localFileHeader = createLocalFileHeader(
+            filename: filename, fileSize: UInt32(fileData.count))
+
+        fileEntries.append((name: filename, data: fileData, offset: currentOffset))
+
+        zipData.append(localFileHeader)
+        zipData.append(fileData)
+
+        currentOffset += UInt32(localFileHeader.count + fileData.count)
+    }
+
+    private func createLocalFileHeader(filename: String, fileSize: UInt32) -> Data {
+        var header = Data()
+
+        // Local file header signature
+        header.append(Data([0x50, 0x4b, 0x03, 0x04]))
+
+        // Version needed to extract (2.0)
+        header.append(Data([0x14, 0x00]))
+
+        // General purpose bit flag
+        header.append(Data([0x00, 0x00]))
+
+        // Compression method (no compression)
+        header.append(Data([0x00, 0x00]))
+
+        // Last mod file time & date (dummy values)
+        header.append(Data([0x00, 0x00, 0x00, 0x00]))
+
+        // CRC-32 (dummy - we're not compressing)
+        header.append(Data([0x00, 0x00, 0x00, 0x00]))
+
+        // Compressed size
+        withUnsafeBytes(of: fileSize.littleEndian) { header.append(Data($0)) }
+
+        // Uncompressed size
+        withUnsafeBytes(of: fileSize.littleEndian) { header.append(Data($0)) }
+
+        // File name length
+        let filenameData = filename.data(using: .utf8) ?? Data()
+        let filenameLength = UInt16(filenameData.count)
+        withUnsafeBytes(of: filenameLength.littleEndian) { header.append(Data($0)) }
+
+        // Extra field length
+        header.append(Data([0x00, 0x00]))
+
+        // File name
+        header.append(filenameData)
+
+        return header
+    }
+
+    private func createCentralDirectoryHeader(entry: (name: String, data: Data, offset: UInt32))
+        -> Data
+    {
+        var header = Data()
+
+        // Central directory signature
+        header.append(Data([0x50, 0x4b, 0x01, 0x02]))
+
+        // Version made by
+        header.append(Data([0x14, 0x00]))
+
+        // Version needed to extract
+        header.append(Data([0x14, 0x00]))
+
+        // General purpose bit flag
+        header.append(Data([0x00, 0x00]))
+
+        // Compression method
+        header.append(Data([0x00, 0x00]))
+
+        // Last mod file time & date
+        header.append(Data([0x00, 0x00, 0x00, 0x00]))
+
+        // CRC-32
+        header.append(Data([0x00, 0x00, 0x00, 0x00]))
+
+        // Compressed size
+        let compressedSize = UInt32(entry.data.count)
+        withUnsafeBytes(of: compressedSize.littleEndian) { header.append(Data($0)) }
+
+        // Uncompressed size
+        withUnsafeBytes(of: compressedSize.littleEndian) { header.append(Data($0)) }
+
+        // File name length
+        let filenameData = entry.name.data(using: .utf8) ?? Data()
+        let filenameLength = UInt16(filenameData.count)
+        withUnsafeBytes(of: filenameLength.littleEndian) { header.append(Data($0)) }
+
+        // Extra field length
+        header.append(Data([0x00, 0x00]))
+
+        // File comment length
+        header.append(Data([0x00, 0x00]))
+
+        // Disk number start
+        header.append(Data([0x00, 0x00]))
+
+        // Internal file attributes
+        header.append(Data([0x00, 0x00]))
+
+        // External file attributes
+        header.append(Data([0x00, 0x00, 0x00, 0x00]))
+
+        // Relative offset of local header
+        withUnsafeBytes(of: entry.offset.littleEndian) { header.append(Data($0)) }
+
+        // File name
+        header.append(filenameData)
+
+        return header
+    }
+
+    private func createEndOfCentralDirectoryRecord(
+        fileCount: UInt16, centralDirSize: UInt32, centralDirOffset: UInt32
+    ) -> Data {
+        var record = Data()
+
+        // End of central dir signature
+        record.append(Data([0x50, 0x4b, 0x05, 0x06]))
+
+        // Number of this disk
+        record.append(Data([0x00, 0x00]))
+
+        // Number of the disk with the start of the central directory
+        record.append(Data([0x00, 0x00]))
+
+        // Total number of entries in the central directory on this disk
+        withUnsafeBytes(of: fileCount.littleEndian) { record.append(Data($0)) }
+
+        // Total number of entries in the central directory
+        withUnsafeBytes(of: fileCount.littleEndian) { record.append(Data($0)) }
+
+        // Size of the central directory
+        withUnsafeBytes(of: centralDirSize.littleEndian) { record.append(Data($0)) }
+
+        // Offset of start of central directory
+        withUnsafeBytes(of: centralDirOffset.littleEndian) { record.append(Data($0)) }
+
+        // ZIP file comment length
+        record.append(Data([0x00, 0x00]))
+
+        return record
+    }
+
+    func testConnection() async throws {
+        guard isConfigured else {
+            throw SyncError.notConfigured
+        }
+
+        isTesting = true
+        defer { isTesting = false }
+
+        guard let url = URL(string: "\(serverURL)/health") else {
+            throw SyncError.invalidURL
+        }
+
+        var request = URLRequest(url: url)
+        request.httpMethod = "GET"
+        request.setValue("application/json", forHTTPHeaderField: "Accept")
+        request.timeoutInterval = 10
+
+        let (_, response) = try await URLSession.shared.data(for: request)
+
+        guard let httpResponse = response as? HTTPURLResponse else {
+            throw SyncError.invalidResponse
+        }
+
+        guard httpResponse.statusCode == 200 else {
+            throw SyncError.serverError(httpResponse.statusCode)
+        }
+
+        // Connection successful, mark as connected
+        isConnected = true
+        userDefaults.set(true, forKey: Keys.isConnected)
+    }
+
+    func triggerAutoSync(dataManager: ClimbingDataManager) {
+        // Early exit if sync cannot proceed - don't set isSyncing
+        guard isConnected && isConfigured && isAutoSyncEnabled else {
+            // Ensure isSyncing is false when sync is not possible
+            if isSyncing {
+                isSyncing = false
+            }
+            return
+        }
+
+        // Prevent multiple simultaneous syncs
+        guard !isSyncing else {
+            return
+        }
+
+        Task {
+            do {
+                try await syncWithServer(dataManager: dataManager)
+            } catch {
+                await MainActor.run {
+                    self.isSyncing = false
+                }
+            }
+        }
+    }
+
+    func disconnect() {
+        isConnected = false
+        lastSyncTime = nil
+        syncError = nil
+        userDefaults.set(false, forKey: Keys.isConnected)
+        userDefaults.removeObject(forKey: Keys.lastSyncTime)
+    }
+
+    func clearConfiguration() {
+        serverURL = ""
+        authToken = ""
+        lastSyncTime = nil
+        isConnected = false
+        isAutoSyncEnabled = true
+        userDefaults.removeObject(forKey: Keys.lastSyncTime)
+        userDefaults.removeObject(forKey: Keys.isConnected)
+        userDefaults.removeObject(forKey: Keys.autoSyncEnabled)
+    }
+}
+
+enum SyncError: LocalizedError {
+    case notConfigured
+    case notConnected
+    case invalidURL
+    case invalidResponse
+    case unauthorized
+    case badRequest
+    case serverError(Int)
+    case decodingError(Error)
+    case exportFailed
+    case importFailed(Error)
+    case imageNotFound
+    case imageUploadFailed
+
+    var errorDescription: String? {
+        switch self {
+        case .notConfigured:
+            return "Sync server not configured. Please set server URL and auth token."
+        case .notConnected:
+            return "Not connected to sync server. Please test connection first."
+        case .invalidURL:
+            return "Invalid server URL."
+        case .invalidResponse:
+            return "Invalid response from server."
+        case .unauthorized:
+            return "Authentication failed. Check your auth token."
+        case .badRequest:
+            return "Bad request. Check your data format."
+        case .serverError(let code):
+            return "Server error (code \(code))."
+        case .decodingError(let error):
+            return "Failed to decode response: \(error.localizedDescription)"
+        case .exportFailed:
+            return "Failed to export local data."
+        case .importFailed(let error):
+            return "Failed to import data: \(error.localizedDescription)"
+        case .imageNotFound:
+            return "Image not found on server."
+        case .imageUploadFailed:
+            return "Failed to upload image to server."
+        }
+    }
+}

ios/OpenClimb/Utils/DataStateManager.swift

@@ -0,0 +1,85 @@
+//
+//  DataStateManager.swift
+
+import Foundation
+
+/// Manages the overall data state timestamp for sync purposes. This tracks when any data in the
+/// local database was last modified, independent of individual entity timestamps.
+class DataStateManager {
+
+    private let userDefaults = UserDefaults.standard
+
+    private enum Keys {
+        static let lastModified = "openclimb_data_last_modified"
+        static let initialized = "openclimb_data_state_initialized"
+    }
+
+    /// Shared instance for app-wide use
+    static let shared = DataStateManager()
+
+    private init() {
+        // Initialize with current timestamp if this is the first time
+        if !isInitialized() {
+            print("DataStateManager: First time initialization")
+            // Set initial timestamp to a very old date so server data will be considered newer
+            let epochTime = "1970-01-01T00:00:00.000Z"
+            userDefaults.set(epochTime, forKey: Keys.lastModified)
+            markAsInitialized()
+            print("DataStateManager initialized with epoch timestamp: \(epochTime)")
+        } else {
+            print("DataStateManager: Already initialized, current timestamp: \(getLastModified())")
+        }
+    }
+
+    /// Updates the data state timestamp to the current time. Call this whenever any data is modified
+    /// (create, update, delete).
+    func updateDataState() {
+        let now = ISO8601DateFormatter().string(from: Date())
+        userDefaults.set(now, forKey: Keys.lastModified)
+        print("📝 iOS Data state updated to: \(now)")
+    }
+
+    /// Gets the current data state timestamp. This represents when any data was last modified
+    /// locally.
+    func getLastModified() -> String {
+        if let storedTimestamp = userDefaults.string(forKey: Keys.lastModified) {
+            print("📅 iOS DataStateManager returning stored timestamp: \(storedTimestamp)")
+            return storedTimestamp
+        }
+
+        // If no timestamp is stored, return epoch time to indicate very old data
+        // This ensures server data will be considered newer than uninitialized local data
+        let epochTime = "1970-01-01T00:00:00.000Z"
+        print("⚠️ No data state timestamp found - returning epoch time: \(epochTime)")
+        return epochTime
+    }
+
+    /// Sets the data state timestamp to a specific value. Used when importing data from server to
+    /// sync the state.
+    func setLastModified(_ timestamp: String) {
+        userDefaults.set(timestamp, forKey: Keys.lastModified)
+        print("Data state set to: \(timestamp)")
+    }
+
+    /// Resets the data state (for testing or complete data wipe).
+    func reset() {
+        userDefaults.removeObject(forKey: Keys.lastModified)
+        userDefaults.removeObject(forKey: Keys.initialized)
+        print("Data state reset")
+    }
+
+    /// Checks if the data state has been initialized.
+    private func isInitialized() -> Bool {
+        return userDefaults.bool(forKey: Keys.initialized)
+    }
+
+    /// Marks the data state as initialized.
+    private func markAsInitialized() {
+        userDefaults.set(true, forKey: Keys.initialized)
+    }
+
+    /// Gets debug information about the current state.
+    func getDebugInfo() -> String {
+        return "DataState(lastModified=\(getLastModified()), initialized=\(isInitialized()))"
+    }
+}

ios/OpenClimb/Utils/ImageNamingUtils.swift

@@ -0,0 +1,176 @@
+//
+//  ImageNamingUtils.swift
+
+import CryptoKit
+import Foundation
+
+/// Utility for creating consistent image filenames across iOS and Android platforms.
+/// Uses deterministic naming based on problem ID and timestamp to ensure sync compatibility.
+class ImageNamingUtils {
+
+    private static let imageExtension = ".jpg"
+    private static let hashLength = 12  // First 12 chars of SHA-256
+
+    /// Generates a deterministic filename for a problem image.
+    /// Format: "problem_{hash}_{index}.jpg"
+    ///
+    /// - Parameters:
+    ///   - problemId: The ID of the problem this image belongs to
+    ///   - timestamp: ISO8601 timestamp when the image was created
+    ///   - imageIndex: The index of this image for the problem (0, 1, 2, etc.)
+    /// - Returns: A consistent filename that will be the same across platforms
+    static func generateImageFilename(problemId: String, timestamp: String, imageIndex: Int)
+        -> String
+    {
+        // Create a deterministic hash from problemId + timestamp + index
+        let input = "\(problemId)_\(timestamp)_\(imageIndex)"
+        let hash = createHash(from: input)
+
+        return "problem_\(hash)_\(imageIndex)\(imageExtension)"
+    }
+
+    /// Generates a deterministic filename for a problem image using current timestamp.
+    ///
+    /// - Parameters:
+    ///   - problemId: The ID of the problem this image belongs to
+    ///   - imageIndex: The index of this image for the problem (0, 1, 2, etc.)
+    /// - Returns: A consistent filename
+    static func generateImageFilename(problemId: String, imageIndex: Int) -> String {
+        let timestamp = ISO8601DateFormatter().string(from: Date())
+        return generateImageFilename(
+            problemId: problemId, timestamp: timestamp, imageIndex: imageIndex)
+    }
+
+    /// Extracts problem ID from an image filename created by this utility.
+    /// Returns nil if the filename doesn't match our naming convention.
+    ///
+    /// - Parameter filename: The image filename
+    /// - Returns: The hash identifier or nil if not a valid filename
+    static func extractProblemIdFromFilename(_ filename: String) -> String? {
+        guard filename.hasPrefix("problem_") && filename.hasSuffix(imageExtension) else {
+            return nil
+        }
+
+        // Format: problem_{hash}_{index}.jpg
+        let nameWithoutExtension = String(filename.dropLast(imageExtension.count))
+        let parts = nameWithoutExtension.components(separatedBy: "_")
+
+        guard parts.count == 3 && parts[0] == "problem" else {
+            return nil
+        }
+
+        // Return the hash as identifier
+        return parts[1]
+    }
+
+    /// Validates if a filename follows our naming convention.
+    ///
+    /// - Parameter filename: The filename to validate
+    /// - Returns: true if it matches our convention, false otherwise
+    static func isValidImageFilename(_ filename: String) -> Bool {
+        guard filename.hasPrefix("problem_") && filename.hasSuffix(imageExtension) else {
+            return false
+        }
+
+        let nameWithoutExtension = String(filename.dropLast(imageExtension.count))
+        let parts = nameWithoutExtension.components(separatedBy: "_")
+
+        return parts.count == 3 && parts[0] == "problem" && parts[1].count == hashLength
+            && Int(parts[2]) != nil
+    }
+
+    /// Migrates an existing UUID-based filename to our naming convention.
+    /// This is used during sync to rename downloaded images.
+    ///
+    /// - Parameters:
+    ///   - oldFilename: The existing filename (UUID-based)
+    ///   - problemId: The problem ID this image belongs to
+    ///   - imageIndex: The index of this image
+    /// - Returns: The new filename following our convention
+    static func migrateFilename(oldFilename: String, problemId: String, imageIndex: Int) -> String {
+        // If it's already using our convention, keep it
+        if isValidImageFilename(oldFilename) {
+            return oldFilename
+        }
+
+        // Generate new deterministic name
+        // Use current timestamp to maintain some consistency
+        let timestamp = ISO8601DateFormatter().string(from: Date())
+        return generateImageFilename(
+            problemId: problemId, timestamp: timestamp, imageIndex: imageIndex)
+    }
+
+    /// Creates a deterministic hash from input string.
+    /// Uses SHA-256 and takes first 12 characters for filename safety.
+    ///
+    /// - Parameter input: The input string to hash
+    /// - Returns: First 12 characters of SHA-256 hash in lowercase
+    private static func createHash(from input: String) -> String {
+        let inputData = Data(input.utf8)
+        let hashed = SHA256.hash(data: inputData)
+        let hashString = hashed.compactMap { String(format: "%02x", $0) }.joined()
+        return String(hashString.prefix(hashLength))
+    }
+
+    /// Batch renames images for a problem to use our naming convention.
+    /// Returns a mapping of old filename -> new filename.
+    ///
+    /// - Parameters:
+    ///   - problemId: The problem ID
+    ///   - existingFilenames: List of current image filenames for this problem
+    /// - Returns: Dictionary mapping old filename to new filename
+    static func batchRenameForProblem(problemId: String, existingFilenames: [String]) -> [String:
+        String]
+    {
+        var renameMap: [String: String] = [:]
+
+        for (index, oldFilename) in existingFilenames.enumerated() {
+            let newFilename = migrateFilename(
+                oldFilename: oldFilename, problemId: problemId, imageIndex: index)
+            if newFilename != oldFilename {
+                renameMap[oldFilename] = newFilename
+            }
+        }
+
+        return renameMap
+    }
+
+    /// Validates that a collection of filenames follow our naming convention.
+    ///
+    /// - Parameter filenames: Array of filenames to validate
+    /// - Returns: Dictionary with validation results
+    static func validateFilenames(_ filenames: [String]) -> ImageValidationResult {
+        var validImages: [String] = []
+        var invalidImages: [String] = []
+
+        for filename in filenames {
+            if isValidImageFilename(filename) {
+                validImages.append(filename)
+            } else {
+                invalidImages.append(filename)
+            }
+        }
+
+        return ImageValidationResult(
+            totalImages: filenames.count,
+            validImages: validImages,
+            invalidImages: invalidImages
+        )
+    }
+}
+
+/// Result of image filename validation
+struct ImageValidationResult {
+    let totalImages: Int
+    let validImages: [String]
+    let invalidImages: [String]
+
+    var isAllValid: Bool {
+        return invalidImages.isEmpty
+    }
+
+    var validPercentage: Double {
+        guard totalImages > 0 else { return 100.0 }
+        return (Double(validImages.count) / Double(totalImages)) * 100.0
+    }
+}

ios/OpenClimb/Utils/ZipUtils.swift

@@ -1,4 +1,3 @@
-
 import Compression
 import Foundation
 import zlib
@@ -10,7 +9,7 @@ struct ZipUtils {
     private static let METADATA_FILENAME = "metadata.txt"
 
     static func createExportZip(
-        exportData: ClimbDataExport,
+        exportData: ClimbDataBackup,
         referencedImagePaths: Set<String>
     ) throws -> Data {
 
@@ -196,7 +195,7 @@ struct ZipUtils {
     }
 
     private static func createMetadata(
-        exportData: ClimbDataExport,
+        exportData: ClimbDataBackup,
         referencedImagePaths: Set<String>
     ) -> String {
         return """

ios/OpenClimb/ViewModels/ClimbingDataManager.swift

@@ -29,6 +29,12 @@ class ClimbingDataManager: ObservableObject {
     private let decoder = JSONDecoder()
     private var liveActivityObserver: NSObjectProtocol?
 
+    // Sync service for automatic syncing
+    let syncService = SyncService()
+
+    // Published property to propagate sync state changes
+    @Published var isSyncing = false
+
     private enum Keys {
         static let gyms = "openclimb_gyms"
         static let problems = "openclimb_problems"
@@ -64,6 +70,10 @@ class ClimbingDataManager: ObservableObject {
         migrateImagePaths()
         setupLiveActivityNotifications()
 
+        // Keep our published isSyncing in sync with syncService.isSyncing
+        syncService.$isSyncing
+            .assign(to: &$isSyncing)
+
         Task {
             try? await Task.sleep(nanoseconds: 2_000_000_000)
             await performImageMaintenance()
@@ -200,16 +210,24 @@ class ClimbingDataManager: ObservableObject {
     func addGym(_ gym: Gym) {
         gyms.append(gym)
         saveGyms()
+        DataStateManager.shared.updateDataState()
         successMessage = "Gym added successfully"
         clearMessageAfterDelay()
+
+        // Trigger auto-sync if enabled
+        syncService.triggerAutoSync(dataManager: self)
     }
 
     func updateGym(_ gym: Gym) {
         if let index = gyms.firstIndex(where: { $0.id == gym.id }) {
             gyms[index] = gym
             saveGyms()
+            DataStateManager.shared.updateDataState()
             successMessage = "Gym updated successfully"
             clearMessageAfterDelay()
+
+            // Trigger auto-sync if enabled
+            syncService.triggerAutoSync(dataManager: self)
         }
     }
 
@@ -229,8 +247,12 @@ class ClimbingDataManager: ObservableObject {
         // Delete the gym
         gyms.removeAll { $0.id == gym.id }
         saveGyms()
+        DataStateManager.shared.updateDataState()
         successMessage = "Gym deleted successfully"
         clearMessageAfterDelay()
+
+        // Trigger auto-sync if enabled
+        syncService.triggerAutoSync(dataManager: self)
     }
 
     func gym(withId id: UUID) -> Gym? {
@@ -240,16 +262,24 @@ class ClimbingDataManager: ObservableObject {
     func addProblem(_ problem: Problem) {
         problems.append(problem)
         saveProblems()
+        DataStateManager.shared.updateDataState()
         successMessage = "Problem added successfully"
         clearMessageAfterDelay()
+
+        // Trigger auto-sync if enabled
+        syncService.triggerAutoSync(dataManager: self)
     }
 
     func updateProblem(_ problem: Problem) {
         if let index = problems.firstIndex(where: { $0.id == problem.id }) {
             problems[index] = problem
             saveProblems()
+            DataStateManager.shared.updateDataState()
             successMessage = "Problem updated successfully"
             clearMessageAfterDelay()
+
+            // Trigger auto-sync if enabled
+            syncService.triggerAutoSync(dataManager: self)
         }
     }
 
@@ -264,6 +294,10 @@ class ClimbingDataManager: ObservableObject {
         // Delete the problem
         problems.removeAll { $0.id == problem.id }
         saveProblems()
+        DataStateManager.shared.updateDataState()
+
+        // Trigger auto-sync if enabled
+        syncService.triggerAutoSync(dataManager: self)
     }
 
     func problem(withId id: UUID) -> Problem? {
@@ -279,7 +313,7 @@ class ClimbingDataManager: ObservableObject {
     }
 
     func startSession(gymId: UUID, notes: String? = nil) {
-
+        // End any currently active session
         if let currentActive = activeSession {
             endSession(currentActive.id)
         }
@@ -290,6 +324,7 @@ class ClimbingDataManager: ObservableObject {
 
         saveActiveSession()
         saveSessions()
+        DataStateManager.shared.updateDataState()
 
         successMessage = "Session started successfully"
         clearMessageAfterDelay()
@@ -301,6 +336,9 @@ class ClimbingDataManager: ObservableObject {
                     for: newSession, gymName: gym.name)
             }
         }
+
+        // Trigger auto-sync if enabled
+        syncService.triggerAutoSync(dataManager: self)
     }
 
     func endSession(_ sessionId: UUID) {
@@ -317,9 +355,13 @@ class ClimbingDataManager: ObservableObject {
 
             saveActiveSession()
             saveSessions()
+            DataStateManager.shared.updateDataState()
             successMessage = "Session completed successfully"
             clearMessageAfterDelay()
 
+            // Trigger auto-sync if enabled
+            syncService.triggerAutoSync(dataManager: self)
+
             // MARK: - End Live Activity after session ends
             Task {
                 await LiveActivityManager.shared.endLiveActivity()
@@ -337,11 +379,15 @@ class ClimbingDataManager: ObservableObject {
             }
 
             saveSessions()
+            DataStateManager.shared.updateDataState()
             successMessage = "Session updated successfully"
             clearMessageAfterDelay()
 
-            // Update Live Activity when session updates
+            // Update Live Activity when session is updated
             updateLiveActivityForActiveSession()
+
+            // Trigger auto-sync if enabled
+            syncService.triggerAutoSync(dataManager: self)
         }
     }
 
@@ -350,7 +396,7 @@ class ClimbingDataManager: ObservableObject {
         attempts.removeAll { $0.sessionId == session.id }
         saveAttempts()
 
-        // Remove from active session if it's the current one
+        // If this is the active session, clear it
         if activeSession?.id == session.id {
             activeSession = nil
             saveActiveSession()
@@ -359,8 +405,15 @@ class ClimbingDataManager: ObservableObject {
         // Delete the session
         sessions.removeAll { $0.id == session.id }
         saveSessions()
+        DataStateManager.shared.updateDataState()
         successMessage = "Session deleted successfully"
         clearMessageAfterDelay()
+
+        // Update Live Activity when session is deleted
+        updateLiveActivityForActiveSession()
+
+        // Trigger auto-sync if enabled
+        syncService.triggerAutoSync(dataManager: self)
     }
 
     func session(withId id: UUID) -> ClimbSession? {
@@ -380,8 +433,12 @@ class ClimbingDataManager: ObservableObject {
     func addAttempt(_ attempt: Attempt) {
         attempts.append(attempt)
         saveAttempts()
+        DataStateManager.shared.updateDataState()
 
         successMessage = "Attempt logged successfully"
+
+        // Trigger auto-sync if enabled
+        syncService.triggerAutoSync(dataManager: self)
         clearMessageAfterDelay()
 
         // Update Live Activity when new attempt is added
@@ -392,22 +449,30 @@ class ClimbingDataManager: ObservableObject {
         if let index = attempts.firstIndex(where: { $0.id == attempt.id }) {
             attempts[index] = attempt
             saveAttempts()
+            DataStateManager.shared.updateDataState()
             successMessage = "Attempt updated successfully"
             clearMessageAfterDelay()
 
             // Update Live Activity when attempt is updated
             updateLiveActivityForActiveSession()
+
+            // Trigger auto-sync if enabled
+            syncService.triggerAutoSync(dataManager: self)
         }
     }
 
     func deleteAttempt(_ attempt: Attempt) {
         attempts.removeAll { $0.id == attempt.id }
         saveAttempts()
+        DataStateManager.shared.updateDataState()
         successMessage = "Attempt deleted successfully"
         clearMessageAfterDelay()
 
         // Update Live Activity when attempt is deleted
         updateLiveActivityForActiveSession()
+
+        // Trigger auto-sync if enabled
+        syncService.triggerAutoSync(dataManager: self)
     }
 
     func attempts(forSession sessionId: UUID) -> [Attempt] {
@@ -451,7 +516,7 @@ class ClimbingDataManager: ObservableObject {
         return gym(withId: mostUsedGymId)
     }
 
-    func resetAllData() {
+    func resetAllData(showSuccessMessage: Bool = true) {
         gyms.removeAll()
         problems.removeAll()
         sessions.removeAll()
@@ -464,8 +529,12 @@ class ClimbingDataManager: ObservableObject {
         userDefaults.removeObject(forKey: Keys.attempts)
         userDefaults.removeObject(forKey: Keys.activeSession)
 
-        successMessage = "All data has been reset"
-        clearMessageAfterDelay()
+        DataStateManager.shared.reset()
+
+        if showSuccessMessage {
+            successMessage = "All data has been reset"
+            clearMessageAfterDelay()
+        }
     }
 
     func exportData() -> Data? {
@@ -473,13 +542,14 @@ class ClimbingDataManager: ObservableObject {
             let dateFormatter = DateFormatter()
             dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS"
 
-            let exportData = ClimbDataExport(
+            let exportData = ClimbDataBackup(
                 exportedAt: dateFormatter.string(from: Date()),
                 version: "2.0",
-                gyms: gyms.map { AndroidGym(from: $0) },
-                problems: problems.map { AndroidProblem(from: $0) },
-                sessions: sessions.map { AndroidClimbSession(from: $0) },
-                attempts: attempts.map { AndroidAttempt(from: $0) }
+                formatVersion: "2.0",
+                gyms: gyms.map { BackupGym(from: $0) },
+                problems: problems.map { BackupProblem(from: $0) },
+                sessions: sessions.map { BackupClimbSession(from: $0) },
+                attempts: attempts.map { BackupAttempt(from: $0) }
             )
 
             // Collect referenced image paths
@@ -503,7 +573,7 @@ class ClimbingDataManager: ObservableObject {
         }
     }
 
-    func importData(from data: Data) throws {
+    func importData(from data: Data, showSuccessMessage: Bool = true) throws {
         do {
             let importResult = try ZipUtils.extractImportZip(data: data)
 
@@ -529,7 +599,7 @@ class ClimbingDataManager: ObservableObject {
             print("Raw JSON content preview:")
             print(String(decoding: importResult.jsonData.prefix(500), as: UTF8.self) + "...")
 
-            let importData = try decoder.decode(ClimbDataExport.self, from: importResult.jsonData)
+            let importData = try decoder.decode(ClimbDataBackup.self, from: importResult.jsonData)
 
             print("Successfully decoded import data:")
             print("- Gyms: \(importData.gyms.count)")
@@ -539,26 +609,31 @@ class ClimbingDataManager: ObservableObject {
 
             try validateImportData(importData)
 
-            resetAllData()
+            resetAllData(showSuccessMessage: showSuccessMessage)
 
             let updatedProblems = updateProblemImagePaths(
                 problems: importData.problems,
                 imagePathMapping: importResult.imagePathMapping
             )
 
-            self.gyms = importData.gyms.map { $0.toGym() }
-            self.problems = updatedProblems.map { $0.toProblem() }
-            self.sessions = importData.sessions.map { $0.toClimbSession() }
-            self.attempts = importData.attempts.map { $0.toAttempt() }
+            self.gyms = try importData.gyms.map { try $0.toGym() }
+            self.problems = try updatedProblems.map { try $0.toProblem() }
+            self.sessions = try importData.sessions.map { try $0.toClimbSession() }
+            self.attempts = try importData.attempts.map { try $0.toAttempt() }
 
             saveGyms()
             saveProblems()
             saveSessions()
             saveAttempts()
 
-            successMessage =
-                "Data imported successfully with \(importResult.imagePathMapping.count) images"
-            clearMessageAfterDelay()
+            // Update data state to current time since we just imported new data
+            DataStateManager.shared.updateDataState()
+
+            if showSuccessMessage {
+                successMessage =
+                    "Data imported successfully with \(importResult.imagePathMapping.count) images"
+                clearMessageAfterDelay()
+            }
         } catch {
             setError("Import failed: \(error.localizedDescription)")
             throw error
@@ -584,337 +659,6 @@ class ClimbingDataManager: ObservableObject {
     }
 }
 
-struct ClimbDataExport: Codable {
-    let exportedAt: String
-    let version: String
-    let gyms: [AndroidGym]
-    let problems: [AndroidProblem]
-    let sessions: [AndroidClimbSession]
-    let attempts: [AndroidAttempt]
-
-    init(
-        exportedAt: String, version: String = "2.0", gyms: [AndroidGym], problems: [AndroidProblem],
-        sessions: [AndroidClimbSession], attempts: [AndroidAttempt]
-    ) {
-        self.exportedAt = exportedAt
-        self.version = version
-        self.gyms = gyms
-        self.problems = problems
-        self.sessions = sessions
-        self.attempts = attempts
-    }
-}
-
-struct AndroidGym: Codable {
-    let id: String
-    let name: String
-    let location: String?
-    let supportedClimbTypes: [ClimbType]
-    let difficultySystems: [DifficultySystem]
-    let customDifficultyGrades: [String]
-    let notes: String?
-    let createdAt: String
-    let updatedAt: String
-
-    init(from gym: Gym) {
-        self.id = gym.id.uuidString
-        self.name = gym.name
-        self.location = gym.location
-        self.supportedClimbTypes = gym.supportedClimbTypes
-        self.difficultySystems = gym.difficultySystems
-        self.customDifficultyGrades = gym.customDifficultyGrades
-        self.notes = gym.notes
-        let formatter = DateFormatter()
-        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS"
-        self.createdAt = formatter.string(from: gym.createdAt)
-        self.updatedAt = formatter.string(from: gym.updatedAt)
-    }
-
-    init(
-        id: String, name: String, location: String?, supportedClimbTypes: [ClimbType],
-        difficultySystems: [DifficultySystem], customDifficultyGrades: [String] = [],
-        notes: String?, createdAt: String, updatedAt: String
-    ) {
-        self.id = id
-        self.name = name
-        self.location = location
-        self.supportedClimbTypes = supportedClimbTypes
-        self.difficultySystems = difficultySystems
-        self.customDifficultyGrades = customDifficultyGrades
-        self.notes = notes
-        self.createdAt = createdAt
-        self.updatedAt = updatedAt
-    }
-
-    func toGym() -> Gym {
-        let formatter = DateFormatter()
-        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS"
-
-        let gymId = UUID(uuidString: id) ?? UUID()
-        let createdDate = formatter.date(from: createdAt) ?? Date()
-        let updatedDate = formatter.date(from: updatedAt) ?? Date()
-
-        return Gym.fromImport(
-            id: gymId,
-            name: name,
-            location: location,
-            supportedClimbTypes: supportedClimbTypes,
-            difficultySystems: difficultySystems,
-            customDifficultyGrades: customDifficultyGrades,
-            notes: notes,
-            createdAt: createdDate,
-            updatedAt: updatedDate
-        )
-    }
-}
-
-struct AndroidProblem: Codable {
-    let id: String
-    let gymId: String
-    let name: String?
-    let description: String?
-    let climbType: ClimbType
-    let difficulty: DifficultyGrade
-    let tags: [String]
-    let location: String?
-    let imagePaths: [String]?
-    let isActive: Bool
-    let dateSet: String?
-    let notes: String?
-    let createdAt: String
-    let updatedAt: String
-
-    init(from problem: Problem) {
-        self.id = problem.id.uuidString
-        self.gymId = problem.gymId.uuidString
-        self.name = problem.name
-        self.description = problem.description
-        self.climbType = problem.climbType
-        self.difficulty = problem.difficulty
-        self.tags = problem.tags
-        self.location = problem.location
-        self.imagePaths = problem.imagePaths.isEmpty ? nil : problem.imagePaths
-        self.isActive = problem.isActive
-        self.notes = problem.notes
-        let formatter = DateFormatter()
-        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS"
-        self.dateSet = problem.dateSet != nil ? formatter.string(from: problem.dateSet!) : nil
-        self.createdAt = formatter.string(from: problem.createdAt)
-        self.updatedAt = formatter.string(from: problem.updatedAt)
-    }
-
-    init(
-        id: String, gymId: String, name: String?, description: String?, climbType: ClimbType,
-        difficulty: DifficultyGrade, tags: [String] = [],
-        location: String? = nil,
-        imagePaths: [String]? = nil, isActive: Bool = true, dateSet: String? = nil,
-        notes: String? = nil,
-        createdAt: String, updatedAt: String
-    ) {
-        self.id = id
-        self.gymId = gymId
-        self.name = name
-        self.description = description
-        self.climbType = climbType
-        self.difficulty = difficulty
-        self.tags = tags
-        self.location = location
-        self.imagePaths = imagePaths
-        self.isActive = isActive
-        self.dateSet = dateSet
-        self.notes = notes
-        self.createdAt = createdAt
-        self.updatedAt = updatedAt
-    }
-
-    func toProblem() -> Problem {
-        let formatter = DateFormatter()
-        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS"
-
-        let problemId = UUID(uuidString: id) ?? UUID()
-        let preservedGymId = UUID(uuidString: gymId) ?? UUID()
-        let createdDate = formatter.date(from: createdAt) ?? Date()
-        let updatedDate = formatter.date(from: updatedAt) ?? Date()
-
-        return Problem.fromImport(
-            id: problemId,
-            gymId: preservedGymId,
-            name: name,
-            description: description,
-            climbType: climbType,
-            difficulty: difficulty,
-            tags: tags,
-            location: location,
-            imagePaths: imagePaths ?? [],
-            isActive: isActive,
-            dateSet: dateSet != nil ? formatter.date(from: dateSet!) : nil,
-            notes: notes,
-            createdAt: createdDate,
-            updatedAt: updatedDate
-        )
-    }
-
-    func withUpdatedImagePaths(_ newImagePaths: [String]) -> AndroidProblem {
-        return AndroidProblem(
-            id: self.id,
-            gymId: self.gymId,
-            name: self.name,
-            description: self.description,
-            climbType: self.climbType,
-            difficulty: self.difficulty,
-            tags: self.tags,
-            location: self.location,
-            imagePaths: newImagePaths.isEmpty ? nil : newImagePaths,
-            isActive: self.isActive,
-            dateSet: self.dateSet,
-            notes: self.notes,
-            createdAt: self.createdAt,
-            updatedAt: self.updatedAt
-        )
-    }
-}
-
-struct AndroidClimbSession: Codable {
-    let id: String
-    let gymId: String
-    let date: String
-    let startTime: String?
-    let endTime: String?
-    let duration: Int64?
-    let status: SessionStatus
-    let notes: String?
-    let createdAt: String
-    let updatedAt: String
-
-    init(from session: ClimbSession) {
-        self.id = session.id.uuidString
-        self.gymId = session.gymId.uuidString
-        let formatter = DateFormatter()
-        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS"
-        self.date = formatter.string(from: session.date)
-        self.startTime = session.startTime != nil ? formatter.string(from: session.startTime!) : nil
-        self.endTime = session.endTime != nil ? formatter.string(from: session.endTime!) : nil
-        self.duration = session.duration != nil ? Int64(session.duration!) : nil
-        self.status = session.status
-        self.notes = session.notes
-        self.createdAt = formatter.string(from: session.createdAt)
-        self.updatedAt = formatter.string(from: session.updatedAt)
-    }
-
-    init(
-        id: String, gymId: String, date: String, startTime: String?, endTime: String?,
-        duration: Int64?, status: SessionStatus, notes: String? = nil, createdAt: String,
-        updatedAt: String
-    ) {
-        self.id = id
-        self.gymId = gymId
-        self.date = date
-        self.startTime = startTime
-        self.endTime = endTime
-        self.duration = duration
-        self.status = status
-        self.notes = notes
-        self.createdAt = createdAt
-        self.updatedAt = updatedAt
-    }
-
-    func toClimbSession() -> ClimbSession {
-        let formatter = DateFormatter()
-        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS"
-
-        // Preserve original IDs and dates
-        let sessionId = UUID(uuidString: id) ?? UUID()
-        let preservedGymId = UUID(uuidString: gymId) ?? UUID()
-        let sessionDate = formatter.date(from: date) ?? Date()
-        let sessionStartTime = startTime != nil ? formatter.date(from: startTime!) : nil
-        let sessionEndTime = endTime != nil ? formatter.date(from: endTime!) : nil
-        let createdDate = formatter.date(from: createdAt) ?? Date()
-        let updatedDate = formatter.date(from: updatedAt) ?? Date()
-
-        return ClimbSession.fromImport(
-            id: sessionId,
-            gymId: preservedGymId,
-            date: sessionDate,
-            startTime: sessionStartTime,
-            endTime: sessionEndTime,
-            duration: duration != nil ? Int(duration!) : nil,
-            status: status,
-            notes: notes,
-            createdAt: createdDate,
-            updatedAt: updatedDate
-        )
-    }
-}
-
-struct AndroidAttempt: Codable {
-    let id: String
-    let sessionId: String
-    let problemId: String
-    let result: AttemptResult
-    let highestHold: String?
-    let notes: String?
-    let duration: Int64?
-    let restTime: Int64?
-    let timestamp: String
-    let createdAt: String
-
-    init(from attempt: Attempt) {
-        self.id = attempt.id.uuidString
-        self.sessionId = attempt.sessionId.uuidString
-        self.problemId = attempt.problemId.uuidString
-        self.result = attempt.result
-        self.highestHold = attempt.highestHold
-        self.notes = attempt.notes
-        self.duration = attempt.duration != nil ? Int64(attempt.duration!) : nil
-        self.restTime = attempt.restTime != nil ? Int64(attempt.restTime!) : nil
-        let formatter = DateFormatter()
-        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS"
-        self.timestamp = formatter.string(from: attempt.timestamp)
-        self.createdAt = formatter.string(from: attempt.createdAt)
-    }
-
-    init(
-        id: String, sessionId: String, problemId: String, result: AttemptResult,
-        highestHold: String?, notes: String?, duration: Int64?, restTime: Int64?,
-        timestamp: String, createdAt: String
-    ) {
-        self.id = id
-        self.sessionId = sessionId
-        self.problemId = problemId
-        self.result = result
-        self.highestHold = highestHold
-        self.notes = notes
-        self.duration = duration
-        self.restTime = restTime
-        self.timestamp = timestamp
-        self.createdAt = createdAt
-    }
-
-    func toAttempt() -> Attempt {
-        let formatter = DateFormatter()
-        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSSSS"
-
-        let attemptId = UUID(uuidString: id) ?? UUID()
-        let preservedSessionId = UUID(uuidString: sessionId) ?? UUID()
-        let preservedProblemId = UUID(uuidString: problemId) ?? UUID()
-        let attemptTimestamp = formatter.date(from: timestamp) ?? Date()
-        let createdDate = formatter.date(from: createdAt) ?? Date()
-
-        return Attempt.fromImport(
-            id: attemptId,
-            sessionId: preservedSessionId,
-            problemId: preservedProblemId,
-            result: result,
-            highestHold: highestHold,
-            notes: notes,
-            duration: duration != nil ? Int(duration!) : nil,
-            restTime: restTime != nil ? Int(restTime!) : nil,
-            timestamp: attemptTimestamp,
-            createdAt: createdDate
-        )
-    }
-}
-
 extension ClimbingDataManager {
     private func collectReferencedImagePaths() -> Set<String> {
         var imagePaths = Set<String>()
@@ -949,9 +693,9 @@ extension ClimbingDataManager {
     }
 
     private func updateProblemImagePaths(
-        problems: [AndroidProblem],
+        problems: [BackupProblem],
         imagePathMapping: [String: String]
-    ) -> [AndroidProblem] {
+    ) -> [BackupProblem] {
         return problems.map { problem in
             let updatedImagePaths = (problem.imagePaths ?? []).compactMap { oldPath in
                 let fileName = URL(fileURLWithPath: oldPath).lastPathComponent
@@ -1298,7 +1042,7 @@ extension ClimbingDataManager {
         saveAttempts()
     }
 
-    private func validateImportData(_ importData: ClimbDataExport) throws {
+    private func validateImportData(_ importData: ClimbDataBackup) throws {
         if importData.gyms.isEmpty {
             throw NSError(
                 domain: "ImportError", code: 1,

ios/OpenClimb/ViewModels/LiveActivityManager.swift

@@ -130,14 +130,8 @@ final class LiveActivityManager {
             completedProblems: completedProblems
         )
 
-        do {
-            await currentActivity.update(.init(state: updatedContentState, staleDate: nil))
-            print("✅ Live Activity updated successfully")
-        } catch {
-            print("❌ Failed to update Live Activity: \(error)")
-            // If update fails, the activity might have been dismissed
-            self.currentActivity = nil
-        }
+        await currentActivity.update(.init(state: updatedContentState, staleDate: nil))
+        print("✅ Live Activity updated successfully")
     }
 
     /// Call this when a ClimbSession ends to end the Live Activity

ios/OpenClimb/Views/AnalyticsView.swift

@@ -20,6 +20,27 @@ struct AnalyticsView: View {
                 .padding()
             }
             .navigationTitle("Analytics")
+            .toolbar {
+                ToolbarItem(placement: .navigationBarTrailing) {
+                    if dataManager.isSyncing {
+                        HStack(spacing: 2) {
+                            ProgressView()
+                                .progressViewStyle(CircularProgressViewStyle(tint: .blue))
+                                .scaleEffect(0.6)
+                        }
+                        .padding(.horizontal, 6)
+                        .padding(.vertical, 3)
+                        .background(
+                            Circle()
+                                .fill(.regularMaterial)
+                        )
+                        .transition(.scale.combined(with: .opacity))
+                        .animation(
+                            .easeInOut(duration: 0.2), value: dataManager.isSyncing
+                        )
+                    }
+                }
+            }
         }
     }
 }

ios/OpenClimb/Views/GymsView.swift

@@ -15,7 +15,25 @@ struct GymsView: View {
             }
             .navigationTitle("Gyms")
             .toolbar {
-                ToolbarItem(placement: .navigationBarTrailing) {
+                ToolbarItemGroup(placement: .navigationBarTrailing) {
+                    if dataManager.isSyncing {
+                        HStack(spacing: 2) {
+                            ProgressView()
+                                .progressViewStyle(CircularProgressViewStyle(tint: .blue))
+                                .scaleEffect(0.6)
+                        }
+                        .padding(.horizontal, 6)
+                        .padding(.vertical, 3)
+                        .background(
+                            Circle()
+                                .fill(.regularMaterial)
+                        )
+                        .transition(.scale.combined(with: .opacity))
+                        .animation(
+                            .easeInOut(duration: 0.2), value: dataManager.isSyncing
+                        )
+                    }
+
                     Button("Add") {
                         showingAddGym = true
                     }

ios/OpenClimb/Views/LiveActivityDebugView.swift

@@ -1,9 +1,5 @@
 //
 //  LiveActivityDebugView.swift
-//  OpenClimb
-//
-//  Created by Assistant on 2025-09-15.
-//
 
 import SwiftUI
 

ios/OpenClimb/Views/ProblemsView.swift

@@ -62,7 +62,25 @@ struct ProblemsView: View {
             .navigationTitle("Problems")
             .searchable(text: $searchText, prompt: "Search problems...")
             .toolbar {
-                ToolbarItem(placement: .navigationBarTrailing) {
+                ToolbarItemGroup(placement: .navigationBarTrailing) {
+                    if dataManager.isSyncing {
+                        HStack(spacing: 2) {
+                            ProgressView()
+                                .progressViewStyle(CircularProgressViewStyle(tint: .blue))
+                                .scaleEffect(0.6)
+                        }
+                        .padding(.horizontal, 6)
+                        .padding(.vertical, 3)
+                        .background(
+                            Circle()
+                                .fill(.regularMaterial)
+                        )
+                        .transition(.scale.combined(with: .opacity))
+                        .animation(
+                            .easeInOut(duration: 0.2), value: dataManager.isSyncing
+                        )
+                    }
+
                     if !dataManager.gyms.isEmpty {
                         Button("Add") {
                             showingAddProblem = true

ios/OpenClimb/Views/SessionsView.swift

@@ -17,7 +17,25 @@ struct SessionsView: View {
             .navigationTitle("Sessions")
             .navigationBarTitleDisplayMode(.automatic)
             .toolbar {
-                ToolbarItem(placement: .navigationBarTrailing) {
+                ToolbarItemGroup(placement: .navigationBarTrailing) {
+                    if dataManager.isSyncing {
+                        HStack(spacing: 2) {
+                            ProgressView()
+                                .progressViewStyle(CircularProgressViewStyle(tint: .blue))
+                                .scaleEffect(0.6)
+                        }
+                        .padding(.horizontal, 6)
+                        .padding(.vertical, 3)
+                        .background(
+                            Circle()
+                                .fill(.regularMaterial)
+                        )
+                        .transition(.scale.combined(with: .opacity))
+                        .animation(
+                            .easeInOut(duration: 0.2), value: dataManager.isSyncing
+                        )
+                    }
+
                     if dataManager.gyms.isEmpty {
                         EmptyView()
                     } else if dataManager.activeSession == nil {
@@ -168,15 +186,9 @@ struct ActiveSessionBanner: View {
         .onDisappear {
             stopTimer()
         }
-        .background(
-            NavigationLink(
-                destination: SessionDetailView(sessionId: session.id),
-                isActive: $navigateToDetail
-            ) {
-                EmptyView()
-            }
-            .hidden()
-        )
+        .navigationDestination(isPresented: $navigateToDetail) {
+            SessionDetailView(sessionId: session.id)
+        }
     }
 
     private func formatDuration(from start: Date, to end: Date) -> String {

ios/OpenClimb/Views/SettingsView.swift

@@ -12,6 +12,9 @@ struct SettingsView: View {
 
     var body: some View {
         List {
+            SyncSection()
+                .environmentObject(dataManager.syncService)
+
             DataManagementSection(
                 activeSheet: $activeSheet
             )
@@ -19,6 +22,27 @@ struct SettingsView: View {
             AppInfoSection()
         }
         .navigationTitle("Settings")
+        .toolbar {
+            ToolbarItem(placement: .navigationBarTrailing) {
+                if dataManager.isSyncing {
+                    HStack(spacing: 2) {
+                        ProgressView()
+                            .progressViewStyle(CircularProgressViewStyle(tint: .blue))
+                            .scaleEffect(0.6)
+                    }
+                    .padding(.horizontal, 6)
+                    .padding(.vertical, 3)
+                    .background(
+                        Circle()
+                            .fill(.regularMaterial)
+                    )
+                    .transition(.scale.combined(with: .opacity))
+                    .animation(
+                        .easeInOut(duration: 0.2), value: dataManager.isSyncing
+                    )
+                }
+            }
+        }
         .sheet(
             item: Binding<SheetType?>(
                 get: { activeSheet },
@@ -303,6 +327,362 @@ struct ExportDataView: View {
     }
 }
 
+struct SyncSection: View {
+    @EnvironmentObject var syncService: SyncService
+    @EnvironmentObject var dataManager: ClimbingDataManager
+    @State private var showingSyncSettings = false
+    @State private var showingDisconnectAlert = false
+
+    var body: some View {
+        Section("Sync") {
+            // Sync Status
+            HStack {
+                Image(
+                    systemName: syncService.isConnected
+                        ? "checkmark.circle.fill"
+                        : syncService.isConfigured
+                            ? "exclamationmark.triangle.fill"
+                            : "exclamationmark.circle.fill"
+                )
+                .foregroundColor(
+                    syncService.isConnected
+                        ? .green
+                        : syncService.isConfigured
+                            ? .orange
+                            : .red
+                )
+                VStack(alignment: .leading) {
+                    Text("Sync Server")
+                        .font(.headline)
+                    Text(
+                        syncService.isConnected
+                            ? "Connected"
+                            : syncService.isConfigured
+                                ? "Configured - Not tested"
+                                : "Not configured"
+                    )
+                    .font(.caption)
+                    .foregroundColor(.secondary)
+                }
+                Spacer()
+            }
+
+            // Configure Server
+            Button(action: {
+                showingSyncSettings = true
+            }) {
+                HStack {
+                    Image(systemName: "gear")
+                        .foregroundColor(.blue)
+                    Text("Configure Server")
+                    Spacer()
+                    Image(systemName: "chevron.right")
+                        .font(.caption)
+                        .foregroundColor(.secondary)
+                }
+            }
+            .foregroundColor(.primary)
+
+            if syncService.isConfigured {
+
+                // Sync Now - only show if connected
+                if syncService.isConnected {
+                    Button(action: {
+                        performSync()
+                    }) {
+                        HStack {
+                            if syncService.isSyncing {
+                                ProgressView()
+                                    .scaleEffect(0.8)
+                                Text("Syncing...")
+                                    .foregroundColor(.secondary)
+                            } else {
+                                Image(systemName: "arrow.triangle.2.circlepath")
+                                    .foregroundColor(.green)
+                                Text("Sync Now")
+                                Spacer()
+                                if let lastSync = syncService.lastSyncTime {
+                                    Text(
+                                        RelativeDateTimeFormatter().localizedString(
+                                            for: lastSync, relativeTo: Date())
+                                    )
+                                    .font(.caption)
+                                    .foregroundColor(.secondary)
+                                }
+                            }
+                        }
+                    }
+                    .disabled(syncService.isSyncing)
+                    .foregroundColor(.primary)
+                }
+
+                // Auto-sync configuration - always visible for testing
+                HStack {
+                    VStack(alignment: .leading) {
+                        Text("Auto-sync")
+                        Text("Sync automatically on app launch and data changes")
+                            .font(.caption)
+                            .foregroundColor(.secondary)
+                    }
+                    Spacer()
+                    Toggle(
+                        "",
+                        isOn: Binding(
+                            get: { syncService.isAutoSyncEnabled },
+                            set: { syncService.isAutoSyncEnabled = $0 }
+                        )
+                    )
+                    .disabled(!syncService.isConnected)
+                }
+                .foregroundColor(.primary)
+
+                // Disconnect option - only show if connected
+                if syncService.isConnected {
+                    Button(action: {
+                        showingDisconnectAlert = true
+                    }) {
+                        HStack {
+                            Image(systemName: "power")
+                                .foregroundColor(.orange)
+                            Text("Disconnect")
+                            Spacer()
+                        }
+                    }
+                    .foregroundColor(.primary)
+                }
+
+                if let error = syncService.syncError {
+                    Text(error)
+                        .font(.caption)
+                        .foregroundColor(.red)
+                        .padding(.leading, 24)
+                }
+
+            }
+        }
+        .sheet(isPresented: $showingSyncSettings) {
+            SyncSettingsView()
+                .environmentObject(syncService)
+        }
+        .alert("Disconnect from Server", isPresented: $showingDisconnectAlert) {
+            Button("Cancel", role: .cancel) {}
+            Button("Disconnect", role: .destructive) {
+                syncService.disconnect()
+            }
+        } message: {
+            Text(
+                "This will sign you out but keep your server settings. You'll need to test the connection again to sync."
+            )
+        }
+    }
+
+    private func performSync() {
+        Task {
+            do {
+                try await syncService.syncWithServer(dataManager: dataManager)
+            } catch {
+                print("Sync failed: \(error)")
+            }
+        }
+    }
+}
+
+struct SyncSettingsView: View {
+    @EnvironmentObject var syncService: SyncService
+    @Environment(\.dismiss) private var dismiss
+    @State private var serverURL: String = ""
+    @State private var authToken: String = ""
+    @State private var showingDisconnectAlert = false
+    @State private var isTesting = false
+    @State private var showingTestResult = false
+    @State private var testResultMessage = ""
+
+    var body: some View {
+        NavigationView {
+            Form {
+                Section {
+                    TextField("Server URL", text: $serverURL)
+                        .textFieldStyle(.roundedBorder)
+                        .keyboardType(.URL)
+                        .autocapitalization(.none)
+                        .disableAutocorrection(true)
+                        .placeholder(when: serverURL.isEmpty) {
+                            Text("http://your-server:8080")
+                                .foregroundColor(.secondary)
+                        }
+
+                    TextField("Auth Token", text: $authToken)
+                        .textFieldStyle(.roundedBorder)
+                        .autocapitalization(.none)
+                        .disableAutocorrection(true)
+                        .placeholder(when: authToken.isEmpty) {
+                            Text("your-secret-token")
+                                .foregroundColor(.secondary)
+                        }
+                } header: {
+                    Text("Server Configuration")
+                } footer: {
+                    Text(
+                        "Enter your sync server URL and authentication token. You must test the connection before syncing is available."
+                    )
+                }
+
+                Section {
+                    Button(action: {
+                        testConnection()
+                    }) {
+                        HStack {
+                            if isTesting {
+                                ProgressView()
+                                    .scaleEffect(0.8)
+                                Text("Testing...")
+                                    .foregroundColor(.secondary)
+                            } else {
+                                Image(systemName: "network")
+                                    .foregroundColor(.blue)
+                                Text("Test Connection")
+                                Spacer()
+                                if syncService.isConnected {
+                                    Image(systemName: "checkmark.circle.fill")
+                                        .foregroundColor(.green)
+                                }
+                            }
+                        }
+                    }
+                    .disabled(
+                        isTesting
+                            || serverURL.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
+                            || authToken.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
+                    )
+                    .foregroundColor(.primary)
+                } header: {
+                    Text("Connection")
+                } footer: {
+                    Text("Test the connection to verify your server settings before saving.")
+                }
+
+                Section {
+                    Button("Disconnect from Server") {
+                        showingDisconnectAlert = true
+                    }
+                    .foregroundColor(.orange)
+
+                    Button("Clear Configuration") {
+                        syncService.clearConfiguration()
+                        serverURL = ""
+                        authToken = ""
+                    }
+                    .foregroundColor(.red)
+                } footer: {
+                    Text(
+                        "Disconnect will sign you out but keep settings. Clear Configuration removes all sync settings."
+                    )
+                }
+            }
+            .navigationTitle("Sync Settings")
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar {
+                ToolbarItem(placement: .navigationBarLeading) {
+                    Button("Cancel") {
+                        dismiss()
+                    }
+                }
+                ToolbarItem(placement: .navigationBarTrailing) {
+                    Button("Save") {
+                        let newURL = serverURL.trimmingCharacters(in: .whitespacesAndNewlines)
+                        let newToken = authToken.trimmingCharacters(in: .whitespacesAndNewlines)
+
+                        // Mark as disconnected if settings changed
+                        if newURL != syncService.serverURL || newToken != syncService.authToken {
+                            syncService.isConnected = false
+                            UserDefaults.standard.set(false, forKey: "sync_is_connected")
+                        }
+
+                        syncService.serverURL = newURL
+                        syncService.authToken = newToken
+                        dismiss()
+                    }
+                    .fontWeight(.semibold)
+                }
+            }
+        }
+        .onAppear {
+            serverURL = syncService.serverURL
+            authToken = syncService.authToken
+        }
+        .alert("Disconnect from Server", isPresented: $showingDisconnectAlert) {
+            Button("Cancel", role: .cancel) {}
+            Button("Disconnect", role: .destructive) {
+                syncService.disconnect()
+                dismiss()
+            }
+        } message: {
+            Text(
+                "This will sign you out but keep your server settings. You'll need to test the connection again to sync."
+            )
+        }
+        .alert("Connection Test", isPresented: $showingTestResult) {
+            Button("OK") {}
+        } message: {
+            Text(testResultMessage)
+        }
+    }
+
+    private func testConnection() {
+        isTesting = true
+
+        let testURL = serverURL.trimmingCharacters(in: .whitespacesAndNewlines)
+        let testToken = authToken.trimmingCharacters(in: .whitespacesAndNewlines)
+
+        // Store original values in case test fails
+        let originalURL = syncService.serverURL
+        let originalToken = syncService.authToken
+
+        Task {
+            do {
+                // Temporarily set the values for testing
+                syncService.serverURL = testURL
+                syncService.authToken = testToken
+
+                try await syncService.testConnection()
+
+                await MainActor.run {
+                    isTesting = false
+                    testResultMessage =
+                        "Connection successful! You can now save and sync your data."
+                    showingTestResult = true
+                }
+            } catch {
+                // Restore original values if test failed
+                syncService.serverURL = originalURL
+                syncService.authToken = originalToken
+
+                await MainActor.run {
+                    isTesting = false
+                    testResultMessage = "Connection failed: \(error.localizedDescription)"
+                    showingTestResult = true
+                }
+            }
+        }
+    }
+}
+
+// Removed AutoSyncSettingsView - now using simple toggle in main settings
+
+extension View {
+    func placeholder<Content: View>(
+        when shouldShow: Bool,
+        alignment: Alignment = .leading,
+        @ViewBuilder placeholder: () -> Content
+    ) -> some View {
+
+        ZStack(alignment: alignment) {
+            placeholder().opacity(shouldShow ? 1 : 0)
+            self
+        }
+    }
+}
+
 struct ImportDataView: View {
     @EnvironmentObject var dataManager: ClimbingDataManager
     @Environment(\.dismiss) private var dismiss

ios/SessionStatusLive/AppIntent.swift

@@ -1,12 +1,8 @@
 //
 //  AppIntent.swift
-//  SessionStatusLive
-//
-//  Created by Atridad Lahiji on 2025-09-15.
-//
 
-import WidgetKit
 import AppIntents
+import WidgetKit
 
 struct ConfigurationAppIntent: WidgetConfigurationIntent {
     static var title: LocalizedStringResource { "Configuration" }

ios/SessionStatusLive/SessionStatusLive.swift

@@ -1,9 +1,5 @@
 //
 //  SessionStatusLive.swift
-//  SessionStatusLive
-//
-//  Created by Atridad Lahiji on 2025-09-15.
-//
 
 import SwiftUI
 import WidgetKit

ios/SessionStatusLive/SessionStatusLiveBundle.swift

@@ -1,12 +1,8 @@
 //
 //  SessionStatusLiveBundle.swift
-//  SessionStatusLive
-//
-//  Created by Atridad Lahiji on 2025-09-15.
-//
 
-import WidgetKit
 import SwiftUI
+import WidgetKit
 
 @main
 struct SessionStatusLiveBundle: WidgetBundle {

ios/SessionStatusLive/SessionStatusLiveControl.swift

@@ -1,9 +1,5 @@
 //
 //  SessionStatusLiveControl.swift
-//  SessionStatusLive
-//
-//  Created by Atridad Lahiji on 2025-09-15.
-//
 
 import AppIntents
 import SwiftUI
@@ -42,8 +38,9 @@ extension SessionStatusLiveControl {
         }
 
         func currentValue(configuration: TimerConfiguration) async throws -> Value {
-            let isRunning = true // Check if the timer is running
-            return SessionStatusLiveControl.Value(isRunning: isRunning, name: configuration.timerName)
+            let isRunning = true  // Check if the timer is running
+            return SessionStatusLiveControl.Value(
+                isRunning: isRunning, name: configuration.timerName)
         }
     }
 }

ios/SessionStatusLive/SessionStatusLiveLiveActivity.swift

@@ -1,9 +1,5 @@
 //
 //  SessionStatusLiveLiveActivity.swift
-//  SessionStatusLive
-//
-//  Created by Atridad Lahiji on 2025-09-15.
-//
 
 import ActivityKit
 import SwiftUI

sync/.env.example

@@ -0,0 +1,9 @@
+# Required
+AUTH_TOKEN=your-secure-secret-token-here
+IMAGE="git.atri.dad/atridad/openclimb-sync:latest"
+APP_PORT=1337
+ROOT_DIR="./data"
+
+# Optional
+DATA_FILE=/data/data.json
+IMAGES_DIR=/data/images

sync/.gitignore

@@ -0,0 +1,16 @@
+# Binaries
+sync-server
+openclimb-sync
+
+# Go workspace file
+go.work
+
+# Data directory
+data/
+
+# Environment files
+.env
+.env.local
+
+# OS generated files
+.DS_Store

sync/Dockerfile

@@ -0,0 +1,14 @@
+FROM golang:1.25-alpine AS builder
+
+WORKDIR /app
+COPY . .
+RUN CGO_ENABLED=0 GOOS=linux go build -o sync-server .
+
+FROM alpine:latest
+RUN apk --no-cache add ca-certificates
+WORKDIR /root/
+
+COPY --from=builder /app/sync-server .
+
+EXPOSE 8080
+CMD ["./sync-server"]

sync/docker-compose.yml

@@ -0,0 +1,13 @@
+services:
+  openclimb-sync:
+    image: ${IMAGE}
+    ports:
+      - ${APP_PORT}:8080
+    environment:
+      - AUTH_TOKEN=${AUTH_TOKEN}
+      - DATA_FILE=${DATA_FILE}
+      - IMAGES_DIR=${IMAGES_DIR}
+    volumes:
+      - ${ROOT_DIR}:/data
+    restart: unless-stopped
+networks: {}

sync/go.mod

@@ -0,0 +1,3 @@
+module openclimb-sync
+
+go 1.25

sync/main.go

@@ -0,0 +1,358 @@
+package main
+
+import (
+	"crypto/subtle"
+	"encoding/json"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+type ClimbDataBackup struct {
+	ExportedAt    string               `json:"exportedAt"`
+	Version       string               `json:"version"`
+	FormatVersion string               `json:"formatVersion"`
+	Gyms          []BackupGym          `json:"gyms"`
+	Problems      []BackupProblem      `json:"problems"`
+	Sessions      []BackupClimbSession `json:"sessions"`
+	Attempts      []BackupAttempt      `json:"attempts"`
+}
+
+type BackupGym struct {
+	ID                     string   `json:"id"`
+	Name                   string   `json:"name"`
+	Location               *string  `json:"location,omitempty"`
+	SupportedClimbTypes    []string `json:"supportedClimbTypes"`
+	DifficultySystems      []string `json:"difficultySystems"`
+	CustomDifficultyGrades []string `json:"customDifficultyGrades"`
+	Notes                  *string  `json:"notes,omitempty"`
+	CreatedAt              string   `json:"createdAt"`
+	UpdatedAt              string   `json:"updatedAt"`
+}
+
+type BackupProblem struct {
+	ID          string          `json:"id"`
+	GymID       string          `json:"gymId"`
+	Name        *string         `json:"name,omitempty"`
+	Description *string         `json:"description,omitempty"`
+	ClimbType   string          `json:"climbType"`
+	Difficulty  DifficultyGrade `json:"difficulty"`
+	Tags        []string        `json:"tags"`
+	Location    *string         `json:"location,omitempty"`
+	ImagePaths  []string        `json:"imagePaths,omitempty"`
+	IsActive    bool            `json:"isActive"`
+	DateSet     *string         `json:"dateSet,omitempty"`
+	Notes       *string         `json:"notes,omitempty"`
+	CreatedAt   string          `json:"createdAt"`
+	UpdatedAt   string          `json:"updatedAt"`
+}
+
+type DifficultyGrade struct {
+	System       string `json:"system"`
+	Grade        string `json:"grade"`
+	NumericValue int    `json:"numericValue"`
+}
+
+type BackupClimbSession struct {
+	ID        string  `json:"id"`
+	GymID     string  `json:"gymId"`
+	Date      string  `json:"date"`
+	StartTime *string `json:"startTime,omitempty"`
+	EndTime   *string `json:"endTime,omitempty"`
+	Duration  *int64  `json:"duration,omitempty"`
+	Status    string  `json:"status"`
+	Notes     *string `json:"notes,omitempty"`
+	CreatedAt string  `json:"createdAt"`
+	UpdatedAt string  `json:"updatedAt"`
+}
+
+type BackupAttempt struct {
+	ID          string  `json:"id"`
+	SessionID   string  `json:"sessionId"`
+	ProblemID   string  `json:"problemId"`
+	Result      string  `json:"result"`
+	HighestHold *string `json:"highestHold,omitempty"`
+	Notes       *string `json:"notes,omitempty"`
+	Duration    *int64  `json:"duration,omitempty"`
+	RestTime    *int64  `json:"restTime,omitempty"`
+	Timestamp   string  `json:"timestamp"`
+	CreatedAt   string  `json:"createdAt"`
+}
+
+type SyncServer struct {
+	authToken string
+	dataFile  string
+	imagesDir string
+}
+
+func (s *SyncServer) authenticate(r *http.Request) bool {
+	authHeader := r.Header.Get("Authorization")
+	if !strings.HasPrefix(authHeader, "Bearer ") {
+		return false
+	}
+
+	token := strings.TrimPrefix(authHeader, "Bearer ")
+	return subtle.ConstantTimeCompare([]byte(token), []byte(s.authToken)) == 1
+}
+
+func (s *SyncServer) loadData() (*ClimbDataBackup, error) {
+	log.Printf("Loading data from: %s", s.dataFile)
+
+	if _, err := os.Stat(s.dataFile); os.IsNotExist(err) {
+		log.Printf("Data file does not exist, creating empty backup")
+		return &ClimbDataBackup{
+			ExportedAt:    time.Now().UTC().Format(time.RFC3339),
+			Version:       "2.0",
+			FormatVersion: "2.0",
+			Gyms:          []BackupGym{},
+			Problems:      []BackupProblem{},
+			Sessions:      []BackupClimbSession{},
+			Attempts:      []BackupAttempt{},
+		}, nil
+	}
+
+	data, err := os.ReadFile(s.dataFile)
+	if err != nil {
+		log.Printf("Failed to read data file: %v", err)
+		return nil, err
+	}
+
+	log.Printf("Read %d bytes from data file", len(data))
+	log.Printf("File content preview: %s", string(data[:min(200, len(data))]))
+
+	var backup ClimbDataBackup
+	if err := json.Unmarshal(data, &backup); err != nil {
+		log.Printf("Failed to unmarshal JSON: %v", err)
+		return nil, err
+	}
+
+	log.Printf("Loaded backup: gyms=%d, problems=%d, sessions=%d, attempts=%d",
+		len(backup.Gyms), len(backup.Problems), len(backup.Sessions), len(backup.Attempts))
+
+	return &backup, nil
+}
+
+func (s *SyncServer) saveData(backup *ClimbDataBackup) error {
+	backup.ExportedAt = time.Now().UTC().Format(time.RFC3339)
+
+	data, err := json.MarshalIndent(backup, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	dir := filepath.Dir(s.dataFile)
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return err
+	}
+
+	// Ensure images directory exists
+	if err := os.MkdirAll(s.imagesDir, 0755); err != nil {
+		return err
+	}
+
+	return os.WriteFile(s.dataFile, data, 0644)
+}
+
+func (s *SyncServer) handleGet(w http.ResponseWriter, r *http.Request) {
+	if !s.authenticate(r) {
+		log.Printf("Unauthorized access attempt from %s", r.RemoteAddr)
+		http.Error(w, "Unauthorized", http.StatusUnauthorized)
+		return
+	}
+
+	log.Printf("GET /sync request from %s", r.RemoteAddr)
+	backup, err := s.loadData()
+	if err != nil {
+		log.Printf("Failed to load data: %v", err)
+		http.Error(w, "Failed to load data", http.StatusInternalServerError)
+		return
+	}
+
+	log.Printf("Sending data to %s: gyms=%d, problems=%d, sessions=%d, attempts=%d",
+		r.RemoteAddr, len(backup.Gyms), len(backup.Problems), len(backup.Sessions), len(backup.Attempts))
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(backup)
+}
+
+func (s *SyncServer) handlePut(w http.ResponseWriter, r *http.Request) {
+	if !s.authenticate(r) {
+		log.Printf("Unauthorized sync attempt from %s", r.RemoteAddr)
+		http.Error(w, "Unauthorized", http.StatusUnauthorized)
+		return
+	}
+
+	var backup ClimbDataBackup
+	if err := json.NewDecoder(r.Body).Decode(&backup); err != nil {
+		log.Printf("Invalid JSON from %s: %v", r.RemoteAddr, err)
+		http.Error(w, "Invalid JSON", http.StatusBadRequest)
+		return
+	}
+
+	if err := s.saveData(&backup); err != nil {
+		log.Printf("Failed to save data: %v", err)
+		http.Error(w, "Failed to save data", http.StatusInternalServerError)
+		return
+	}
+
+	log.Printf("Data synced by %s", r.RemoteAddr)
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(backup)
+}
+
+func (s *SyncServer) handleHealth(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	json.NewEncoder(w).Encode(map[string]string{
+		"status": "healthy",
+		"time":   time.Now().UTC().Format(time.RFC3339),
+	})
+}
+
+func (s *SyncServer) handleImageUpload(w http.ResponseWriter, r *http.Request) {
+	if !s.authenticate(r) {
+		log.Printf("Unauthorized image upload attempt from %s", r.RemoteAddr)
+		http.Error(w, "Unauthorized", http.StatusUnauthorized)
+		return
+	}
+
+	if r.Method != http.MethodPost {
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	filename := r.URL.Query().Get("filename")
+	if filename == "" {
+		http.Error(w, "Missing filename parameter", http.StatusBadRequest)
+		return
+	}
+
+	imageData, err := io.ReadAll(r.Body)
+	if err != nil {
+		http.Error(w, "Failed to read image data", http.StatusBadRequest)
+		return
+	}
+
+	imagePath := filepath.Join(s.imagesDir, filename)
+	if err := os.WriteFile(imagePath, imageData, 0644); err != nil {
+		log.Printf("Failed to save image %s: %v", filename, err)
+		http.Error(w, "Failed to save image", http.StatusInternalServerError)
+		return
+	}
+
+	log.Printf("Image uploaded: %s (%d bytes) by %s", filename, len(imageData), r.RemoteAddr)
+	w.WriteHeader(http.StatusOK)
+	json.NewEncoder(w).Encode(map[string]string{"status": "uploaded"})
+}
+
+func (s *SyncServer) handleImageDownload(w http.ResponseWriter, r *http.Request) {
+	if !s.authenticate(r) {
+		log.Printf("Unauthorized image download attempt from %s", r.RemoteAddr)
+		http.Error(w, "Unauthorized", http.StatusUnauthorized)
+		return
+	}
+
+	if r.Method != http.MethodGet {
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	filename := r.URL.Query().Get("filename")
+	if filename == "" {
+		http.Error(w, "Missing filename parameter", http.StatusBadRequest)
+		return
+	}
+
+	imagePath := filepath.Join(s.imagesDir, filename)
+	imageData, err := os.ReadFile(imagePath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			http.Error(w, "Image not found", http.StatusNotFound)
+		} else {
+			http.Error(w, "Failed to read image", http.StatusInternalServerError)
+		}
+		return
+	}
+
+	// Set appropriate content type based on file extension
+	ext := filepath.Ext(filename)
+	switch ext {
+	case ".jpg", ".jpeg":
+		w.Header().Set("Content-Type", "image/jpeg")
+	case ".png":
+		w.Header().Set("Content-Type", "image/png")
+	case ".gif":
+		w.Header().Set("Content-Type", "image/gif")
+	case ".webp":
+		w.Header().Set("Content-Type", "image/webp")
+	default:
+		w.Header().Set("Content-Type", "application/octet-stream")
+	}
+
+	w.WriteHeader(http.StatusOK)
+	w.Write(imageData)
+}
+
+func (s *SyncServer) handleSync(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case http.MethodGet:
+		s.handleGet(w, r)
+	case http.MethodPut:
+		s.handlePut(w, r)
+	default:
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+	}
+}
+
+func main() {
+	authToken := os.Getenv("AUTH_TOKEN")
+	if authToken == "" {
+		log.Fatal("AUTH_TOKEN environment variable is required")
+	}
+
+	dataFile := os.Getenv("DATA_FILE")
+	if dataFile == "" {
+		dataFile = "./data/climb_data.json"
+	}
+
+	imagesDir := os.Getenv("IMAGES_DIR")
+	if imagesDir == "" {
+		imagesDir = "./data/images"
+	}
+
+	port := os.Getenv("PORT")
+	if port == "" {
+		port = "8080"
+	}
+
+	server := &SyncServer{
+		authToken: authToken,
+		dataFile:  dataFile,
+		imagesDir: imagesDir,
+	}
+
+	http.HandleFunc("/sync", server.handleSync)
+	http.HandleFunc("/health", server.handleHealth)
+	http.HandleFunc("/images/upload", server.handleImageUpload)
+	http.HandleFunc("/images/download", server.handleImageDownload)
+
+	fmt.Printf("OpenClimb sync server starting on port %s\n", port)
+	fmt.Printf("Data file: %s\n", dataFile)
+	fmt.Printf("Images directory: %s\n", imagesDir)
+	fmt.Printf("Health check available at /health\n")
+	fmt.Printf("Image upload: POST /images/upload?filename=<name>\n")
+	fmt.Printf("Image download: GET /images/download?filename=<name>\n")
+
+	log.Fatal(http.ListenAndServe(":"+port, nil))
+}

sync/version.md

@@ -0,0 +1 @@
+1.0.0