diff --git a/.github/workflows/build-mobile.yml b/.github/workflows/build-mobile.yml
index 1c7158d3..0f35e4c0 100644
--- a/.github/workflows/build-mobile.yml
+++ b/.github/workflows/build-mobile.yml
@@ -45,14 +45,19 @@ jobs:
         working-directory: mobile
         run: dart run flutter_launcher_icons
       
-      # Skip tests for now - mobile app is incomplete (tests exist but lib/ source code is missing)
-      # - name: Run tests
-      #   working-directory: mobile
-      #   run: flutter test
+      - name: Run tests
+        working-directory: mobile
+        run: flutter test
       
       - name: Build APK
         working-directory: mobile
-        run: flutter build apk --release
+        env:
+          OTEL_EXPORTER_OTLP_ENDPOINT: ${{ secrets.OTEL_EXPORTER_OTLP_ENDPOINT }}
+          OTEL_EXPORTER_OTLP_TOKEN: ${{ secrets.OTEL_EXPORTER_OTLP_TOKEN }}
+        run: |
+          flutter build apk --release \
+            --dart-define=OTEL_EXPORTER_OTLP_ENDPOINT="${OTEL_EXPORTER_OTLP_ENDPOINT:-}" \
+            --dart-define=OTEL_EXPORTER_OTLP_TOKEN="${OTEL_EXPORTER_OTLP_TOKEN:-}"
       
       - name: Upload APK
         uses: actions/upload-artifact@v4
@@ -92,43 +97,34 @@ jobs:
           dart run flutter_launcher_icons
           dart run flutter_launcher_icons -f flutter_launcher_icons_ios.yaml
       
-      - name: Configure iOS project for device build without code signing
+      # Simulator build avoids Apple Development Team / provisioning (device ipa still needs signing locally).
+      - name: Run tests
         working-directory: mobile
+        run: flutter test
+      
+      - name: Build iOS (simulator)
+        working-directory: mobile
+        env:
+          OTEL_EXPORTER_OTLP_ENDPOINT: ${{ secrets.OTEL_EXPORTER_OTLP_ENDPOINT }}
+          OTEL_EXPORTER_OTLP_TOKEN: ${{ secrets.OTEL_EXPORTER_OTLP_TOKEN }}
         run: |
-          # Disable code signing requirements in Xcode project
-          sed -i '' 's/DEVELOPMENT_TEAM = .*;/DEVELOPMENT_TEAM = "";/g' ios/Runner.xcodeproj/project.pbxproj
-          sed -i '' 's/CODE_SIGN_IDENTITY = .*;/CODE_SIGN_IDENTITY = "";/g' ios/Runner.xcodeproj/project.pbxproj
-          sed -i '' 's/CODE_SIGN_IDENTITY\[sdk=iphoneos\*\] = .*;/CODE_SIGN_IDENTITY[sdk=iphoneos*] = "";/g' ios/Runner.xcodeproj/project.pbxproj
-          sed -i '' 's/CODE_SIGNING_REQUIRED = .*;/CODE_SIGNING_REQUIRED = NO;/g' ios/Runner.xcodeproj/project.pbxproj
-          sed -i '' 's/CODE_SIGNING_ALLOWED = .*;/CODE_SIGNING_ALLOWED = NO;/g' ios/Runner.xcodeproj/project.pbxproj
-          # Also set for all configurations
-          sed -i '' 's/ProvisioningStyle = Automatic;/ProvisioningStyle = Manual;/g' ios/Runner.xcodeproj/project.pbxproj
-      
-      # Skip tests for now - mobile app is incomplete (tests exist but lib/ source code is missing)
-      # - name: Run tests
-      #   working-directory: mobile
-      #   run: flutter test
-      
-      - name: Build iOS
-        working-directory: mobile
-        run: flutter build ios --release --no-codesign
+          flutter build ios --release --simulator \
+            --dart-define=OTEL_EXPORTER_OTLP_ENDPOINT="${OTEL_EXPORTER_OTLP_ENDPOINT:-}" \
+            --dart-define=OTEL_EXPORTER_OTLP_TOKEN="${OTEL_EXPORTER_OTLP_TOKEN:-}"
       
       - name: Create iOS archive
         if: success()
         working-directory: mobile
         run: |
           mkdir -p dist
-          # Package the built iOS app (IPA would require codesigning, so we'll package the .app)
-          if [ -d "build/ios/iphoneos/Runner.app" ]; then
-            cd build/ios/iphoneos
+          if [ -d "build/ios/iphonesimulator/Runner.app" ]; then
+            cd build/ios/iphonesimulator
             zip -r ../../../dist/TimeTracker-iOS.zip Runner.app
             cd ../../..
           else
-            echo "Warning: Runner.app not found at build/ios/iphoneos/Runner.app"
-            echo "Listing build/ios directory:"
-            ls -la build/ios/ || echo "build/ios directory does not exist"
-            echo "Listing build directory:"
-            ls -la build/ || echo "build directory does not exist"
+            echo "Warning: Runner.app not found at build/ios/iphonesimulator/Runner.app"
+            ls -la build/ios/ || true
+            ls -la build/ || true
           fi
       
       - name: Upload iOS build
diff --git a/.github/workflows/cd-release.yml b/.github/workflows/cd-release.yml
index 2697b877..05662d6b 100644
--- a/.github/workflows/cd-release.yml
+++ b/.github/workflows/cd-release.yml
@@ -960,13 +960,29 @@ jobs:
         working-directory: mobile
         run: dart run flutter_launcher_icons
       
+      - name: Run mobile tests
+        working-directory: mobile
+        run: flutter test
+      
       - name: Build APK
         working-directory: mobile
-        run: flutter build apk --release
+        env:
+          OTEL_EXPORTER_OTLP_ENDPOINT: ${{ secrets.OTEL_EXPORTER_OTLP_ENDPOINT }}
+          OTEL_EXPORTER_OTLP_TOKEN: ${{ secrets.OTEL_EXPORTER_OTLP_TOKEN }}
+        run: |
+          flutter build apk --release \
+            --dart-define=OTEL_EXPORTER_OTLP_ENDPOINT="${OTEL_EXPORTER_OTLP_ENDPOINT:-}" \
+            --dart-define=OTEL_EXPORTER_OTLP_TOKEN="${OTEL_EXPORTER_OTLP_TOKEN:-}"
       
       - name: Build App Bundle
         working-directory: mobile
-        run: flutter build appbundle --release
+        env:
+          OTEL_EXPORTER_OTLP_ENDPOINT: ${{ secrets.OTEL_EXPORTER_OTLP_ENDPOINT }}
+          OTEL_EXPORTER_OTLP_TOKEN: ${{ secrets.OTEL_EXPORTER_OTLP_TOKEN }}
+        run: |
+          flutter build appbundle --release \
+            --dart-define=OTEL_EXPORTER_OTLP_ENDPOINT="${OTEL_EXPORTER_OTLP_ENDPOINT:-}" \
+            --dart-define=OTEL_EXPORTER_OTLP_TOKEN="${OTEL_EXPORTER_OTLP_TOKEN:-}"
         continue-on-error: true
       
       - name: Upload Android APK
@@ -1022,42 +1038,36 @@ jobs:
           dart run flutter_launcher_icons
           dart run flutter_launcher_icons -f flutter_launcher_icons_ios.yaml
       
-      - name: Configure iOS project for device build without code signing
+      - name: Run mobile tests
         working-directory: mobile
-        run: |
-          # Disable code signing requirements in Xcode project
-          sed -i '' 's/DEVELOPMENT_TEAM = .*;/DEVELOPMENT_TEAM = "";/g' ios/Runner.xcodeproj/project.pbxproj
-          sed -i '' 's/CODE_SIGN_IDENTITY = .*;/CODE_SIGN_IDENTITY = "";/g' ios/Runner.xcodeproj/project.pbxproj
-          sed -i '' 's/CODE_SIGN_IDENTITY\[sdk=iphoneos\*\] = .*;/CODE_SIGN_IDENTITY[sdk=iphoneos*] = "";/g' ios/Runner.xcodeproj/project.pbxproj
-          sed -i '' 's/CODE_SIGNING_REQUIRED = .*;/CODE_SIGNING_REQUIRED = NO;/g' ios/Runner.xcodeproj/project.pbxproj
-          sed -i '' 's/CODE_SIGNING_ALLOWED = .*;/CODE_SIGNING_ALLOWED = NO;/g' ios/Runner.xcodeproj/project.pbxproj
-          # Also set for all configurations
-          sed -i '' 's/ProvisioningStyle = Automatic;/ProvisioningStyle = Manual;/g' ios/Runner.xcodeproj/project.pbxproj
+        run: flutter test
       
-      - name: Build iOS (no codesign)
+      - name: Build iOS (simulator)
         working-directory: mobile
-        run: flutter build ios --release --no-codesign
+        env:
+          OTEL_EXPORTER_OTLP_ENDPOINT: ${{ secrets.OTEL_EXPORTER_OTLP_ENDPOINT }}
+          OTEL_EXPORTER_OTLP_TOKEN: ${{ secrets.OTEL_EXPORTER_OTLP_TOKEN }}
+        run: |
+          flutter build ios --release --simulator \
+            --dart-define=OTEL_EXPORTER_OTLP_ENDPOINT="${OTEL_EXPORTER_OTLP_ENDPOINT:-}" \
+            --dart-define=OTEL_EXPORTER_OTLP_TOKEN="${OTEL_EXPORTER_OTLP_TOKEN:-}"
       
       - name: Create iOS archive
         if: success()
         working-directory: mobile
         run: |
           mkdir -p dist
-          # Package the built iOS app (IPA would require codesigning, so we'll package the .app)
-          if [ -d "build/ios/iphoneos/Runner.app" ]; then
-            cd build/ios/iphoneos
+          if [ -d "build/ios/iphonesimulator/Runner.app" ]; then
+            cd build/ios/iphonesimulator
             zip -r ../../../dist/TimeTracker-iOS-${{ needs.determine-version.outputs.version }}.zip Runner.app
             cd ../../..
-            echo "✅ iOS archive created successfully"
+            echo "✅ iOS simulator archive created successfully"
             ls -lh dist/
           else
-            echo "❌ ERROR: Runner.app not found at build/ios/iphoneos/Runner.app"
-            echo "Listing build/ios directory:"
-            ls -la build/ios/ || echo "build/ios directory does not exist"
-            echo "Listing build directory:"
-            ls -la build/ || echo "build directory does not exist"
-            echo "Searching for Runner.app:"
-            find build -name "Runner.app" -type d 2>/dev/null || echo "Runner.app not found anywhere"
+            echo "❌ ERROR: Runner.app not found at build/ios/iphonesimulator/Runner.app"
+            ls -la build/ios/ || true
+            ls -la build/ || true
+            find build -name "Runner.app" -type d 2>/dev/null || true
             exit 1
           fi
       
diff --git a/.gitignore b/.gitignore
index de361c3f..6fbac70e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -131,6 +131,9 @@ dmypy.json
 
 # Application specific
 data/
+# Flutter app source lives under mobile/lib/data/ (do not treat as runtime data dir)
+!mobile/lib/data/
+!mobile/lib/data/**
 logs/
 backups/
 *.db
diff --git a/mobile/lib/core/telemetry/mobile_otel.dart b/mobile/lib/core/telemetry/mobile_otel.dart
new file mode 100644
index 00000000..d4effe70
--- /dev/null
+++ b/mobile/lib/core/telemetry/mobile_otel.dart
@@ -0,0 +1,96 @@
+import 'dart:convert';
+
+import 'package:opentelemetry/api.dart' as otel_api;
+import 'package:opentelemetry/sdk.dart' as otel_sdk;
+import 'package:package_info_plus/package_info_plus.dart';
+
+bool _mobileOtelInitialized = false;
+
+/// OTLP endpoint and token from `--dart-define=OTEL_EXPORTER_OTLP_*` (CI parity with main app).
+/// Values are embedded in release binaries—avoid for untrusted distribution.
+Future<void> initMobileOpenTelemetry() async {
+  const endpoint = String.fromEnvironment('OTEL_EXPORTER_OTLP_ENDPOINT');
+  const token = String.fromEnvironment('OTEL_EXPORTER_OTLP_TOKEN');
+  if (endpoint.isEmpty || token.isEmpty) {
+    return;
+  }
+
+  var base = endpoint.trim();
+  if (base.endsWith('/')) {
+    base = base.substring(0, base.length - 1);
+  }
+  if (base.endsWith('/v1/logs')) {
+    base = base.substring(0, base.length - '/v1/logs'.length);
+  } else {
+    final idx = base.lastIndexOf('/v1/logs');
+    if (idx != -1) {
+      base = base.substring(0, idx);
+    }
+  }
+
+  final traceUri = Uri.parse('$base/v1/traces');
+  final authHeader = buildOtlpAuthHeader(token);
+  final info = await PackageInfo.fromPlatform();
+  final resource = otel_sdk.Resource([
+    otel_api.Attribute.fromString('service.name', 'timetracker-mobile'),
+    otel_api.Attribute.fromString('service.version', info.version),
+  ]);
+
+  final exporter = otel_sdk.CollectorExporter(
+    traceUri,
+    headers: {'Authorization': authHeader},
+  );
+
+  final provider = otel_sdk.TracerProviderBase(
+    resource: resource,
+    processors: [
+      otel_sdk.BatchSpanProcessor(exporter),
+    ],
+  );
+
+  otel_api.registerGlobalTracerProvider(provider);
+  _mobileOtelInitialized = true;
+}
+
+/// Matches [app.telemetry.service._build_otlp_auth_header] (Basic / instance:token).
+String buildOtlpAuthHeader(String token) {
+  final value = token.trim();
+  if (value.toLowerCase().startsWith('basic ')) {
+    return value;
+  }
+  if (value.contains(':')) {
+    final encoded = base64Encode(utf8.encode(value));
+    return 'Basic $encoded';
+  }
+  return 'Basic $value';
+}
+
+/// No-op if OpenTelemetry was not initialized.
+otel_api.Tracer? get mobileTracerOrNull {
+  if (!_mobileOtelInitialized) return null;
+  return otel_api.globalTracerProvider.getTracer('timetracker.mobile');
+}
+
+Future<T> runMobileSpan<T>(
+  String name,
+  Future<T> Function() body, {
+  Map<String, String> attributes = const {},
+}) async {
+  final tracer = mobileTracerOrNull;
+  if (tracer == null) {
+    return body();
+  }
+  final span = tracer.startSpan(name);
+  for (final e in attributes.entries) {
+    span.setAttribute(otel_api.Attribute.fromString(e.key, e.value));
+  }
+  try {
+    return await body();
+  } catch (e, st) {
+    span.setStatus(otel_api.StatusCode.error, e.toString());
+    span.recordException(e, stackTrace: st);
+    rethrow;
+  } finally {
+    span.end();
+  }
+}
diff --git a/mobile/lib/data/api/api_client.dart b/mobile/lib/data/api/api_client.dart
new file mode 100644
index 00000000..bf7bed45
--- /dev/null
+++ b/mobile/lib/data/api/api_client.dart
@@ -0,0 +1,418 @@
+import 'package:dio/dio.dart';
+import 'package:timetracker_mobile/utils/ssl/ssl_utils.dart';
+
+/// HTTP client for TimeTracker `/api/v1` (Bearer token after login).
+class ApiClient {
+  ApiClient({
+    required String baseUrl,
+    Set<String>? trustedInsecureHosts,
+  })  : _trusted = trustedInsecureHosts ?? {},
+        _dio = Dio() {
+    var normalized = baseUrl.trim();
+    if (!normalized.endsWith('/')) {
+      normalized = '$normalized/';
+    }
+    _baseUrl = normalized;
+    _dio.options = BaseOptions(
+      baseUrl: _baseUrl,
+      connectTimeout: const Duration(seconds: 30),
+      receiveTimeout: const Duration(seconds: 60),
+      headers: {'Content-Type': 'application/json'},
+      validateStatus: (_) => true,
+    );
+    configureDioTrustedHosts(_dio, _trusted);
+  }
+
+  final Dio _dio;
+  final Set<String> _trusted;
+  late final String _baseUrl;
+
+  String get baseUrl => _baseUrl;
+
+  Future<void> setAuthToken(String token) async {
+    _dio.options.headers['Authorization'] = 'Bearer $token';
+  }
+
+  Future<Response<dynamic>> validateTokenRaw() {
+    return _dio.get<dynamic>('/api/v1/timer/status');
+  }
+
+  Future<Map<String, dynamic>> getUsersMe() async {
+    final res = await _dio.get<Map<String, dynamic>>('/api/v1/users/me');
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getCurrentUser() async {
+    final me = await getUsersMe();
+    final u = me['user'];
+    if (u is Map<String, dynamic>) return u;
+    if (u is Map) return Map<String, dynamic>.from(u);
+    return {};
+  }
+
+  Future<Map<String, dynamic>> getTimerStatus() async {
+    final res = await _dio.get<Map<String, dynamic>>('/api/v1/timer/status');
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> startTimer({
+    required int projectId,
+    int? taskId,
+    String? notes,
+    int? templateId,
+  }) async {
+    final body = <String, dynamic>{
+      'project_id': projectId,
+      if (taskId != null) 'task_id': taskId,
+      if (notes != null) 'notes': notes,
+      if (templateId != null) 'template_id': templateId,
+    };
+    final res = await _dio.post<Map<String, dynamic>>('/api/v1/timer/start', data: body);
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> stopTimer() async {
+    final res = await _dio.post<Map<String, dynamic>>('/api/v1/timer/stop');
+    final code = res.statusCode ?? 0;
+    if (code >= 200 && code < 300) {
+      return Map<String, dynamic>.from(res.data ?? {});
+    }
+    throw DioException(
+      requestOptions: res.requestOptions,
+      response: res,
+      type: DioExceptionType.badResponse,
+    );
+  }
+
+  Future<Map<String, dynamic>> getTimeEntries({
+    int? projectId,
+    String? startDate,
+    String? endDate,
+    bool? billable,
+    int? page,
+    int? perPage,
+  }) async {
+    final res = await _dio.get<Map<String, dynamic>>(
+      '/api/v1/time-entries',
+      queryParameters: <String, dynamic>{
+        if (projectId != null) 'project_id': projectId,
+        if (startDate != null) 'start_date': startDate,
+        if (endDate != null) 'end_date': endDate,
+        if (billable != null) 'billable': billable.toString(),
+        if (page != null) 'page': page,
+        if (perPage != null) 'per_page': perPage,
+      },
+    );
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getTimeEntry(int entryId) async {
+    final res = await _dio.get<Map<String, dynamic>>('/api/v1/time-entries/$entryId');
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> createTimeEntry({
+    required int projectId,
+    int? taskId,
+    required String startTime,
+    String? endTime,
+    String? notes,
+    String? tags,
+    bool? billable,
+  }) async {
+    final body = <String, dynamic>{
+      'project_id': projectId,
+      'start_time': startTime,
+      if (taskId != null) 'task_id': taskId,
+      if (endTime != null) 'end_time': endTime,
+      if (notes != null) 'notes': notes,
+      if (tags != null) 'tags': tags,
+      if (billable != null) 'billable': billable,
+    };
+    final res = await _dio.post<Map<String, dynamic>>('/api/v1/time-entries', data: body);
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> updateTimeEntry(
+    int entryId, {
+    int? projectId,
+    int? taskId,
+    String? startTime,
+    String? endTime,
+    String? notes,
+    String? tags,
+    bool? billable,
+  }) async {
+    final body = <String, dynamic>{
+      if (projectId != null) 'project_id': projectId,
+      if (taskId != null) 'task_id': taskId,
+      if (startTime != null) 'start_time': startTime,
+      if (endTime != null) 'end_time': endTime,
+      if (notes != null) 'notes': notes,
+      if (tags != null) 'tags': tags,
+      if (billable != null) 'billable': billable,
+    };
+    final res = await _dio.patch<Map<String, dynamic>>('/api/v1/time-entries/$entryId', data: body);
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<void> deleteTimeEntry(int entryId) async {
+    final res = await _dio.delete<Map<String, dynamic>>('/api/v1/time-entries/$entryId');
+    _throwIfError(res);
+  }
+
+  Future<Map<String, dynamic>> getProjects({
+    String? status,
+    int? clientId,
+    int? page,
+    int? perPage,
+  }) async {
+    final res = await _dio.get<Map<String, dynamic>>(
+      '/api/v1/projects',
+      queryParameters: <String, dynamic>{
+        if (status != null) 'status': status,
+        if (clientId != null) 'client_id': clientId,
+        if (page != null) 'page': page,
+        if (perPage != null) 'per_page': perPage,
+      },
+    );
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getProject(int projectId) async {
+    final res = await _dio.get<Map<String, dynamic>>('/api/v1/projects/$projectId');
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getTasks({
+    int? projectId,
+    String? status,
+    int? page,
+    int? perPage,
+  }) async {
+    final res = await _dio.get<Map<String, dynamic>>(
+      '/api/v1/tasks',
+      queryParameters: <String, dynamic>{
+        if (projectId != null) 'project_id': projectId,
+        if (status != null) 'status': status,
+        if (page != null) 'page': page,
+        if (perPage != null) 'per_page': perPage,
+      },
+    );
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getTask(int taskId) async {
+    final res = await _dio.get<Map<String, dynamic>>('/api/v1/tasks/$taskId');
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getClients({
+    String? status,
+    int? page,
+    int? perPage,
+  }) async {
+    final res = await _dio.get<Map<String, dynamic>>(
+      '/api/v1/clients',
+      queryParameters: <String, dynamic>{
+        if (status != null) 'status': status,
+        if (page != null) 'page': page,
+        if (perPage != null) 'per_page': perPage,
+      },
+    );
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getInvoices({
+    int? page,
+    int? perPage,
+    String? status,
+  }) async {
+    final res = await _dio.get<Map<String, dynamic>>(
+      '/api/v1/invoices',
+      queryParameters: <String, dynamic>{
+        if (page != null) 'page': page,
+        if (perPage != null) 'per_page': perPage,
+        if (status != null) 'status': status,
+      },
+    );
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getExpenses({
+    int? page,
+    int? perPage,
+  }) async {
+    final res = await _dio.get<Map<String, dynamic>>(
+      '/api/v1/expenses',
+      queryParameters: <String, dynamic>{
+        if (page != null) 'page': page,
+        if (perPage != null) 'per_page': perPage,
+      },
+    );
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> createExpense(Map<String, dynamic> body) async {
+    final res = await _dio.post<Map<String, dynamic>>('/api/v1/expenses', data: body);
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> createInvoice(Map<String, dynamic> body) async {
+    final res = await _dio.post<Map<String, dynamic>>('/api/v1/invoices', data: body);
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> updateInvoice(int invoiceId, Map<String, dynamic> body) async {
+    final res = await _dio.patch<Map<String, dynamic>>('/api/v1/invoices/$invoiceId', data: body);
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getTimesheetPeriods({
+    String? startDate,
+    String? endDate,
+    String? status,
+  }) async {
+    final res = await _dio.get<Map<String, dynamic>>(
+      '/api/v1/timesheet-periods',
+      queryParameters: <String, dynamic>{
+        if (startDate != null) 'start_date': startDate,
+        if (endDate != null) 'end_date': endDate,
+        if (status != null) 'status': status,
+      },
+    );
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getCapacityReport({
+    required String startDate,
+    required String endDate,
+  }) async {
+    final res = await _dio.get<Map<String, dynamic>>(
+      '/api/v1/reports/capacity',
+      queryParameters: {'start_date': startDate, 'end_date': endDate},
+    );
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getLeaveTypes() async {
+    final res = await _dio.get<Map<String, dynamic>>('/api/v1/time-off/leave-types');
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getTimeOffRequests() async {
+    final res = await _dio.get<Map<String, dynamic>>('/api/v1/time-off/requests');
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<Map<String, dynamic>> getTimeOffBalances() async {
+    final res = await _dio.get<Map<String, dynamic>>('/api/v1/time-off/balances');
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<void> submitTimesheetPeriod(int periodId) async {
+    final res = await _dio.post<Map<String, dynamic>>('/api/v1/timesheet-periods/$periodId/submit');
+    _throwIfError(res);
+  }
+
+  Future<void> approveTimesheetPeriod(int periodId, {String? comment}) async {
+    final res = await _dio.post<Map<String, dynamic>>(
+      '/api/v1/timesheet-periods/$periodId/approve',
+      data: {if (comment != null) 'comment': comment},
+    );
+    _throwIfError(res);
+  }
+
+  Future<void> rejectTimesheetPeriod(int periodId, {String? reason}) async {
+    final r = (reason ?? 'Rejected').trim();
+    final res = await _dio.post<Map<String, dynamic>>(
+      '/api/v1/timesheet-periods/$periodId/reject',
+      data: {'reason': r.isEmpty ? 'Rejected' : r},
+    );
+    _throwIfError(res);
+  }
+
+  Future<void> deleteTimesheetPeriod(int periodId) async {
+    final res = await _dio.delete<Map<String, dynamic>>('/api/v1/timesheet-periods/$periodId');
+    _throwIfError(res);
+  }
+
+  Future<Map<String, dynamic>> createTimeOffRequest({
+    required int leaveTypeId,
+    required String startDate,
+    required String endDate,
+    double? requestedHours,
+    String? comment,
+  }) async {
+    final body = <String, dynamic>{
+      'leave_type_id': leaveTypeId,
+      'start_date': startDate,
+      'end_date': endDate,
+      if (requestedHours != null) 'requested_hours': requestedHours,
+      if (comment != null && comment.isNotEmpty) 'comment': comment,
+    };
+    final res = await _dio.post<Map<String, dynamic>>('/api/v1/time-off/requests', data: body);
+    _throwIfError(res);
+    return Map<String, dynamic>.from(res.data ?? {});
+  }
+
+  Future<void> approveTimeOffRequest(int requestId, {String? comment}) async {
+    final res = await _dio.post<Map<String, dynamic>>(
+      '/api/v1/time-off/requests/$requestId/approve',
+      data: {if (comment != null) 'comment': comment},
+    );
+    _throwIfError(res);
+  }
+
+  Future<void> rejectTimeOffRequest(int requestId, {String? comment}) async {
+    final res = await _dio.post<Map<String, dynamic>>(
+      '/api/v1/time-off/requests/$requestId/reject',
+      data: {if (comment != null) 'comment': comment},
+    );
+    _throwIfError(res);
+  }
+
+  Future<void> deleteTimeOffRequest(int requestId) async {
+    final res = await _dio.delete<Map<String, dynamic>>('/api/v1/time-off/requests/$requestId');
+    _throwIfError(res);
+  }
+
+  void _throwIfError(Response<dynamic> res) {
+    final code = res.statusCode ?? 0;
+    if (code >= 200 && code < 300) return;
+    final data = res.data;
+    String msg = 'HTTP $code';
+    if (data is Map) {
+      final err = data['error'] ?? data['message'];
+      if (err != null) msg = err.toString();
+    }
+    throw DioException(
+      requestOptions: res.requestOptions,
+      response: res,
+      type: DioExceptionType.badResponse,
+      message: msg,
+    );
+  }
+}
diff --git a/mobile/lib/data/models/project.dart b/mobile/lib/data/models/project.dart
new file mode 100644
index 00000000..c825cce7
--- /dev/null
+++ b/mobile/lib/data/models/project.dart
@@ -0,0 +1,47 @@
+class Project {
+  final int id;
+  final String name;
+  final String? client;
+  final String status;
+  final bool billable;
+  final DateTime? createdAt;
+  final DateTime? updatedAt;
+
+  const Project({
+    required this.id,
+    required this.name,
+    this.client,
+    this.status = 'active',
+    this.billable = true,
+    this.createdAt,
+    this.updatedAt,
+  });
+
+  factory Project.fromJson(Map<String, dynamic> json) {
+    return Project(
+      id: (json['id'] as num).toInt(),
+      name: (json['name'] ?? '').toString(),
+      client: json['client']?.toString(),
+      status: (json['status'] ?? 'active').toString(),
+      billable: json['billable'] == true,
+      createdAt: _parseDt(json['created_at']),
+      updatedAt: _parseDt(json['updated_at']),
+    );
+  }
+
+  Map<String, dynamic> toJson() => {
+        'id': id,
+        'name': name,
+        'client': client,
+        'status': status,
+        'billable': billable,
+        'created_at': createdAt?.toIso8601String(),
+        'updated_at': updatedAt?.toIso8601String(),
+      };
+
+  static DateTime? _parseDt(dynamic v) {
+    if (v == null) return null;
+    if (v is DateTime) return v;
+    return DateTime.tryParse(v.toString());
+  }
+}
diff --git a/mobile/lib/data/models/task.dart b/mobile/lib/data/models/task.dart
new file mode 100644
index 00000000..0381bc05
--- /dev/null
+++ b/mobile/lib/data/models/task.dart
@@ -0,0 +1,51 @@
+class Task {
+  final int id;
+  final int projectId;
+  final String name;
+  final String status;
+  final String? priority;
+  final int? createdBy;
+  final DateTime? createdAt;
+  final DateTime? updatedAt;
+
+  const Task({
+    required this.id,
+    required this.projectId,
+    required this.name,
+    this.status = 'todo',
+    this.priority,
+    this.createdBy,
+    this.createdAt,
+    this.updatedAt,
+  });
+
+  factory Task.fromJson(Map<String, dynamic> json) {
+    return Task(
+      id: (json['id'] as num).toInt(),
+      projectId: (json['project_id'] as num?)?.toInt() ?? 0,
+      name: (json['name'] ?? '').toString(),
+      status: (json['status'] ?? 'todo').toString(),
+      priority: json['priority']?.toString(),
+      createdBy: (json['created_by'] as num?)?.toInt(),
+      createdAt: _parseDt(json['created_at']),
+      updatedAt: _parseDt(json['updated_at']),
+    );
+  }
+
+  Map<String, dynamic> toJson() => {
+        'id': id,
+        'project_id': projectId,
+        'name': name,
+        'status': status,
+        'priority': priority,
+        'created_by': createdBy,
+        'created_at': createdAt?.toIso8601String(),
+        'updated_at': updatedAt?.toIso8601String(),
+      };
+
+  static DateTime? _parseDt(dynamic v) {
+    if (v == null) return null;
+    if (v is DateTime) return v;
+    return DateTime.tryParse(v.toString());
+  }
+}
diff --git a/mobile/lib/data/models/time_entry.dart b/mobile/lib/data/models/time_entry.dart
new file mode 100644
index 00000000..7dcf7ce0
--- /dev/null
+++ b/mobile/lib/data/models/time_entry.dart
@@ -0,0 +1,98 @@
+class TimeEntry {
+  final int id;
+  final int userId;
+  final int? projectId;
+  final int? taskId;
+  final DateTime? startTime;
+  final DateTime? endTime;
+  final int? durationSeconds;
+  final String? notes;
+  final String? tags;
+  final String source;
+  final bool billable;
+  final bool paid;
+  final DateTime? createdAt;
+  final DateTime? updatedAt;
+
+  const TimeEntry({
+    required this.id,
+    this.userId = 0,
+    this.projectId,
+    this.taskId,
+    this.startTime,
+    this.endTime,
+    this.durationSeconds,
+    this.notes,
+    this.tags,
+    this.source = 'manual',
+    this.billable = true,
+    this.paid = false,
+    this.createdAt,
+    this.updatedAt,
+  });
+
+  factory TimeEntry.fromJson(Map<String, dynamic> json) {
+    return TimeEntry(
+      id: (json['id'] as num).toInt(),
+      userId: (json['user_id'] as num?)?.toInt() ?? 0,
+      projectId: (json['project_id'] as num?)?.toInt(),
+      taskId: (json['task_id'] as num?)?.toInt(),
+      startTime: _parseDt(json['start_time']),
+      endTime: _parseDt(json['end_time']),
+      durationSeconds: (json['duration_seconds'] as num?)?.toInt(),
+      notes: json['notes']?.toString(),
+      tags: json['tags']?.toString(),
+      source: (json['source'] ?? 'manual').toString(),
+      billable: json['billable'] != false,
+      paid: json['paid'] == true,
+      createdAt: _parseDt(json['created_at']),
+      updatedAt: _parseDt(json['updated_at']),
+    );
+  }
+
+  Map<String, dynamic> toJson() => {
+        'id': id,
+        'user_id': userId,
+        'project_id': projectId,
+        'task_id': taskId,
+        'start_time': startTime?.toIso8601String(),
+        'end_time': endTime?.toIso8601String(),
+        'duration_seconds': durationSeconds,
+        'notes': notes,
+        'tags': tags,
+        'source': source,
+        'billable': billable,
+        'paid': paid,
+        'created_at': createdAt?.toIso8601String(),
+        'updated_at': updatedAt?.toIso8601String(),
+      };
+
+  String get formattedDuration {
+    final secs = durationSeconds;
+    if (secs == null || secs <= 0) {
+      if (startTime != null && endTime != null) {
+        final d = endTime!.difference(startTime!);
+        return _formatSeconds(d.inSeconds);
+      }
+      return '0m';
+    }
+    return _formatSeconds(secs);
+  }
+
+  static String _formatSeconds(int totalSeconds) {
+    final h = totalSeconds ~/ 3600;
+    final m = (totalSeconds % 3600) ~/ 60;
+    if (h > 0) {
+      return m > 0 ? '${h}h ${m}m' : '${h}h';
+    }
+    if (m > 0) return '${m}m';
+    final s = totalSeconds % 60;
+    return '${s}s';
+  }
+
+  static DateTime? _parseDt(dynamic v) {
+    if (v == null) return null;
+    if (v is DateTime) return v;
+    return DateTime.tryParse(v.toString());
+  }
+}
diff --git a/mobile/lib/data/models/time_entry_requirements.dart b/mobile/lib/data/models/time_entry_requirements.dart
new file mode 100644
index 00000000..9cd0d97c
--- /dev/null
+++ b/mobile/lib/data/models/time_entry_requirements.dart
@@ -0,0 +1,25 @@
+import 'package:flutter/foundation.dart';
+
+@immutable
+class TimeEntryRequirements {
+  final bool requireTask;
+  final bool requireDescription;
+  final int descriptionMinLength;
+
+  const TimeEntryRequirements({
+    this.requireTask = false,
+    this.requireDescription = false,
+    this.descriptionMinLength = 0,
+  });
+
+  factory TimeEntryRequirements.fromJson(Map<String, dynamic>? json) {
+    if (json == null || json.isEmpty) {
+      return const TimeEntryRequirements();
+    }
+    return TimeEntryRequirements(
+      requireTask: json['require_task'] == true,
+      requireDescription: json['require_description'] == true,
+      descriptionMinLength: (json['description_min_length'] as num?)?.toInt() ?? 0,
+    );
+  }
+}
diff --git a/mobile/lib/data/models/timer.dart b/mobile/lib/data/models/timer.dart
new file mode 100644
index 00000000..42a551f9
--- /dev/null
+++ b/mobile/lib/data/models/timer.dart
@@ -0,0 +1,55 @@
+import 'package:flutter/foundation.dart';
+
+/// Active timer row from `/api/v1/timer/status` (same fields as server time entry JSON).
+@immutable
+class Timer {
+  final int id;
+  final int userId;
+  final int? projectId;
+  final int? taskId;
+  final DateTime startTime;
+  final String? notes;
+
+  const Timer({
+    required this.id,
+    this.userId = 0,
+    this.projectId,
+    this.taskId,
+    required this.startTime,
+    this.notes,
+  });
+
+  factory Timer.fromJson(Map<String, dynamic> json) {
+    final startRaw = json['start_time'];
+    final start = startRaw is DateTime
+        ? startRaw
+        : DateTime.tryParse(startRaw?.toString() ?? '') ?? DateTime.now();
+    return Timer(
+      id: (json['id'] as num).toInt(),
+      userId: (json['user_id'] as num?)?.toInt() ?? 0,
+      projectId: (json['project_id'] as num?)?.toInt(),
+      taskId: (json['task_id'] as num?)?.toInt(),
+      startTime: start,
+      notes: json['notes']?.toString(),
+    );
+  }
+
+  Map<String, dynamic> toJson() => {
+        'id': id,
+        'user_id': userId,
+        'project_id': projectId,
+        'task_id': taskId,
+        'start_time': startTime.toIso8601String(),
+        'notes': notes,
+      };
+
+  String get formattedElapsed {
+    final d = DateTime.now().difference(startTime);
+    final h = d.inHours;
+    final m = d.inMinutes.remainder(60);
+    final s = d.inSeconds.remainder(60);
+    return '${h.toString().padLeft(2, '0')}:'
+        '${m.toString().padLeft(2, '0')}:'
+        '${s.toString().padLeft(2, '0')}';
+  }
+}
diff --git a/mobile/lib/data/models/user_prefs.dart b/mobile/lib/data/models/user_prefs.dart
new file mode 100644
index 00000000..fa1ea5a5
--- /dev/null
+++ b/mobile/lib/data/models/user_prefs.dart
@@ -0,0 +1,25 @@
+import 'package:flutter/foundation.dart';
+
+@immutable
+class UserPrefs {
+  final String dateFormatKey;
+  final String timeFormatKey;
+  final String timezone;
+
+  const UserPrefs({
+    this.dateFormatKey = 'YYYY-MM-DD',
+    this.timeFormatKey = '24h',
+    this.timezone = 'UTC',
+  });
+
+  factory UserPrefs.fromJson(Map<String, dynamic>? json) {
+    if (json == null || json.isEmpty) {
+      return const UserPrefs();
+    }
+    return UserPrefs(
+      dateFormatKey: (json['date_format'] ?? 'YYYY-MM-DD').toString(),
+      timeFormatKey: (json['time_format'] ?? '24h').toString(),
+      timezone: (json['timezone'] ?? 'UTC').toString(),
+    );
+  }
+}
diff --git a/mobile/lib/data/storage/local_storage.dart b/mobile/lib/data/storage/local_storage.dart
new file mode 100644
index 00000000..9a12ae49
--- /dev/null
+++ b/mobile/lib/data/storage/local_storage.dart
@@ -0,0 +1,88 @@
+import 'dart:convert';
+
+import 'package:hive_flutter/hive_flutter.dart';
+import 'package:timetracker_mobile/data/models/timer.dart' as tt;
+import 'package:timetracker_mobile/data/models/time_entry.dart';
+
+class LocalStorage {
+  LocalStorage._();
+
+  static const _boxName = 'timetracker_local_v1';
+  static const _kTimer = 'timer';
+  static const _kEntries = 'time_entries';
+  static const _kQueue = 'sync_queue';
+
+  static Box<String>? _box;
+
+  static Future<void> init() async {
+    await Hive.initFlutter();
+    _box = await Hive.openBox<String>(_boxName);
+  }
+
+  static Box<String> get _b {
+    final b = _box;
+    if (b == null) {
+      throw StateError('LocalStorage.init() was not called');
+    }
+    return b;
+  }
+
+  static Future<tt.Timer?> getTimer() async {
+    final raw = _b.get(_kTimer);
+    if (raw == null || raw.isEmpty) return null;
+    final map = jsonDecode(raw) as Map<String, dynamic>;
+    return tt.Timer.fromJson(map);
+  }
+
+  static Future<void> saveTimer(tt.Timer timer) async {
+    await _b.put(_kTimer, jsonEncode(timer.toJson()));
+  }
+
+  static Future<void> clearTimer() async {
+    await _b.delete(_kTimer);
+  }
+
+  static Future<List<TimeEntry>> getAllTimeEntries() async {
+    final raw = _b.get(_kEntries);
+    if (raw == null || raw.isEmpty) return [];
+    final list = jsonDecode(raw) as List<dynamic>;
+    return list
+        .map((e) => TimeEntry.fromJson(Map<String, dynamic>.from(e as Map)))
+        .toList();
+  }
+
+  static Future<void> saveTimeEntry(TimeEntry entry) async {
+    final all = await getAllTimeEntries();
+    final idx = all.indexWhere((e) => e.id == entry.id);
+    if (idx >= 0) {
+      all[idx] = entry;
+    } else {
+      all.add(entry);
+    }
+    await _persistEntries(all);
+  }
+
+  static Future<void> deleteTimeEntry(int entryId) async {
+    final all = await getAllTimeEntries();
+    all.removeWhere((e) => e.id == entryId);
+    await _persistEntries(all);
+  }
+
+  static Future<void> _persistEntries(List<TimeEntry> entries) async {
+    await _b.put(
+      _kEntries,
+      jsonEncode(entries.map((e) => e.toJson()).toList()),
+    );
+  }
+
+  static Future<List<Map<String, dynamic>>> getSyncQueue() async {
+    final raw = _b.get(_kQueue);
+    if (raw == null || raw.isEmpty) return [];
+    final list = jsonDecode(raw) as List<dynamic>;
+    return list.map((e) => Map<String, dynamic>.from(e as Map)).toList();
+  }
+
+  static Future<void> setSyncQueue(List<Map<String, dynamic>> queue) async {
+    await _b.put(_kQueue, jsonEncode(queue));
+  }
+}
diff --git a/mobile/lib/data/storage/sync_service.dart b/mobile/lib/data/storage/sync_service.dart
new file mode 100644
index 00000000..9d756786
--- /dev/null
+++ b/mobile/lib/data/storage/sync_service.dart
@@ -0,0 +1,94 @@
+import 'package:timetracker_mobile/data/api/api_client.dart';
+import 'package:timetracker_mobile/data/models/time_entry.dart';
+import 'package:timetracker_mobile/data/storage/local_storage.dart';
+
+class SyncService {
+  SyncService(this._api);
+
+  final ApiClient? _api;
+
+  static Future<void> queueCreateTimeEntry({
+    required int projectId,
+    int? taskId,
+    required String startTime,
+    String? endTime,
+    String? notes,
+    String? tags,
+    bool? billable,
+  }) async {
+    final q = await LocalStorage.getSyncQueue();
+    q.add({
+      'op': 'create_time_entry',
+      'project_id': projectId,
+      if (taskId != null) 'task_id': taskId,
+      'start_time': startTime,
+      if (endTime != null) 'end_time': endTime,
+      if (notes != null) 'notes': notes,
+      if (tags != null) 'tags': tags,
+      if (billable != null) 'billable': billable,
+    });
+    await LocalStorage.setSyncQueue(q);
+  }
+
+  static Future<void> queueDeleteTimeEntry(int entryId) async {
+    final q = await LocalStorage.getSyncQueue();
+    q.add({
+      'op': 'delete_time_entry',
+      'entry_id': entryId,
+    });
+    await LocalStorage.setSyncQueue(q);
+  }
+
+  Future<void> syncAll() async {
+    await processQueue();
+    await syncFromServer();
+  }
+
+  Future<void> processQueue() async {
+    final api = _api;
+    if (api == null) return;
+
+    final q = await LocalStorage.getSyncQueue();
+    final remaining = <Map<String, dynamic>>[];
+
+    for (final op in q) {
+      final type = op['op']?.toString();
+      try {
+        if (type == 'create_time_entry') {
+          await api.createTimeEntry(
+            projectId: (op['project_id'] as num).toInt(),
+            taskId: (op['task_id'] as num?)?.toInt(),
+            startTime: op['start_time'].toString(),
+            endTime: op['end_time']?.toString(),
+            notes: op['notes']?.toString(),
+            tags: op['tags']?.toString(),
+            billable: op['billable'] as bool?,
+          );
+        } else if (type == 'delete_time_entry') {
+          await api.deleteTimeEntry((op['entry_id'] as num).toInt());
+        } else {
+          remaining.add(op);
+        }
+      } catch (_) {
+        remaining.add(op);
+      }
+    }
+
+    await LocalStorage.setSyncQueue(remaining);
+  }
+
+  Future<void> syncFromServer() async {
+    final api = _api;
+    if (api == null) return;
+    try {
+      final res = await api.getTimeEntries(perPage: 200);
+      final raw = res['time_entries'] as List<dynamic>? ?? [];
+      for (final e in raw) {
+        if (e is Map) {
+          final entry = TimeEntry.fromJson(Map<String, dynamic>.from(e));
+          await LocalStorage.saveTimeEntry(entry);
+        }
+      }
+    } catch (_) {}
+  }
+}
diff --git a/mobile/lib/domain/repositories/time_tracking_repository.dart b/mobile/lib/domain/repositories/time_tracking_repository.dart
index 027f421e..9628549a 100644
--- a/mobile/lib/domain/repositories/time_tracking_repository.dart
+++ b/mobile/lib/domain/repositories/time_tracking_repository.dart
@@ -5,6 +5,7 @@ import 'package:timetracker_mobile/data/models/timer.dart';
 import 'package:timetracker_mobile/data/models/time_entry.dart';
 import 'package:timetracker_mobile/data/models/project.dart';
 import 'package:timetracker_mobile/data/models/task.dart';
+import 'package:timetracker_mobile/core/telemetry/mobile_otel.dart';
 import 'package:timetracker_mobile/data/storage/local_storage.dart';
 import 'package:timetracker_mobile/data/storage/sync_service.dart';
 
@@ -94,11 +95,15 @@ class TimeTrackingRepository {
         return timer;
       }
 
-      final response = await apiClient!.startTimer(
-        projectId: projectId,
-        taskId: taskId,
-        notes: notes,
-        templateId: templateId,
+      final response = await runMobileSpan(
+        'mobile.timer.start',
+        () => apiClient!.startTimer(
+          projectId: projectId,
+          taskId: taskId,
+          notes: notes,
+          templateId: templateId,
+        ),
+        attributes: {'project_id': '$projectId'},
       );
       final timer = Timer.fromJson(response['timer'] as Map<String, dynamic>);
       await LocalStorage.saveTimer(timer);
@@ -114,7 +119,10 @@ class TimeTrackingRepository {
       throw Exception('Not connected to server');
     }
     try {
-      final response = await apiClient!.stopTimer();
+      final response = await runMobileSpan(
+        'mobile.timer.stop',
+        () => apiClient!.stopTimer(),
+      );
       final entry = TimeEntry.fromJson(response['time_entry'] as Map<String, dynamic>);
       await LocalStorage.clearTimer();
       return entry;
@@ -334,7 +342,12 @@ class TimeTrackingRepository {
 
   /// Sync pending operations
   Future<void> syncPending() async {
-    await _syncService?.syncAll();
+    await runMobileSpan(
+      'mobile.sync.pending',
+      () async {
+        await _syncService?.syncAll();
+      },
+    );
   }
 
   // ==================== Project Operations ====================
diff --git a/mobile/lib/domain/usecases/sync_usecase.dart b/mobile/lib/domain/usecases/sync_usecase.dart
index 0dc22833..46fd03f1 100644
--- a/mobile/lib/domain/usecases/sync_usecase.dart
+++ b/mobile/lib/domain/usecases/sync_usecase.dart
@@ -1,9 +1,10 @@
 import 'dart:async';
-import '../../core/config/app_config.dart';
-import '../../data/api/api_client.dart';
-import '../../data/local/database/sync_service.dart';
-import '../../utils/auth/auth_service.dart';
+
 import 'package:connectivity_plus/connectivity_plus.dart';
+import 'package:timetracker_mobile/core/config/app_config.dart';
+import 'package:timetracker_mobile/data/api/api_client.dart';
+import 'package:timetracker_mobile/data/storage/sync_service.dart';
+import 'package:timetracker_mobile/utils/auth/auth_service.dart';
 
 class SyncUseCase {
   final Connectivity _connectivity = Connectivity();
@@ -47,13 +48,12 @@ class SyncUseCase {
         return false;
       }
 
-      final apiClient = ApiClient(baseUrl: serverUrl);
+      final trustedHosts = await AppConfig.getTrustedInsecureHosts();
+      final apiClient = ApiClient(baseUrl: serverUrl, trustedInsecureHosts: trustedHosts);
       await apiClient.setAuthToken(token);
 
       final syncService = SyncService(apiClient);
-
-      await syncService.processQueue();
-      await syncService.syncFromServer();
+      await syncService.syncAll();
 
       return true;
     } catch (_) {
diff --git a/mobile/lib/main.dart b/mobile/lib/main.dart
index 04390d39..587f8085 100644
--- a/mobile/lib/main.dart
+++ b/mobile/lib/main.dart
@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:timetracker_mobile/core/constants/app_constants.dart';
+import 'package:timetracker_mobile/core/telemetry/mobile_otel.dart';
 import 'package:timetracker_mobile/core/theme/app_theme.dart';
 import 'package:timetracker_mobile/data/storage/local_storage.dart';
 import 'package:timetracker_mobile/presentation/providers/theme_mode_provider.dart';
@@ -11,6 +12,7 @@ import 'package:timetracker_mobile/presentation/screens/home_screen.dart';
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
   await LocalStorage.init();
+  await initMobileOpenTelemetry();
   runApp(
     const ProviderScope(
       child: TimeTrackerApp(),
diff --git a/mobile/lib/presentation/screens/login_screen.dart b/mobile/lib/presentation/screens/login_screen.dart
index 6c7526d7..1badd40a 100644
--- a/mobile/lib/presentation/screens/login_screen.dart
+++ b/mobile/lib/presentation/screens/login_screen.dart
@@ -5,6 +5,7 @@ import 'package:flutter/services.dart';
 import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 import 'package:timetracker_mobile/core/config/app_config.dart';
 import 'package:timetracker_mobile/core/constants/app_constants.dart';
+import 'package:timetracker_mobile/core/telemetry/mobile_otel.dart';
 import 'package:timetracker_mobile/data/api/api_client.dart';
 import 'package:timetracker_mobile/utils/network/connection_diagnostics.dart';
 import 'package:timetracker_mobile/utils/ssl/certificate_error.dart';
@@ -110,7 +111,10 @@ class _LoginScreenState extends ConsumerState<LoginScreen> {
 
       final apiClient = ApiClient(baseUrl: serverUrl, trustedInsecureHosts: trustedHosts);
       await apiClient.setAuthToken(token);
-      final validationResponse = await apiClient.validateTokenRaw();
+      final validationResponse = await runMobileSpan(
+        'mobile.login.validate_token',
+        () => apiClient.validateTokenRaw(),
+      );
       final status = validationResponse.statusCode;
       if (status != 200) {
         setState(() {
diff --git a/mobile/pubspec.yaml b/mobile/pubspec.yaml
index 1bc47a92..5d7f2161 100644
--- a/mobile/pubspec.yaml
+++ b/mobile/pubspec.yaml
@@ -42,6 +42,9 @@ dependencies:
   package_info_plus: ^8.0.0
   google_fonts: ^8.0.0
 
+  # OpenTelemetry OTLP/HTTP traces (same env names as server: OTEL_EXPORTER_OTLP_* via --dart-define)
+  opentelemetry: ^0.18.11
+
 dev_dependencies:
   flutter_test:
     sdk: flutter