diff --git a/android/app/build.gradle.kts b/android/app/build.gradle.kts
index 9994ece..694f359 100644
--- a/android/app/build.gradle.kts
+++ b/android/app/build.gradle.kts
@@ -1,5 +1,6 @@
 plugins {
     id("com.android.application")
+    id("org.jetbrains.kotlin.android")
     // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
     id("dev.flutter.flutter-gradle-plugin")
 }
@@ -40,3 +41,7 @@ kotlin {
 flutter {
     source = "../.."
 }
+
+dependencies {
+    implementation("com.google.android.gms:play-services-wearable:19.0.0")
+}
diff --git a/android/app/src/main/AndroidManifest.xml b/android/app/src/main/AndroidManifest.xml
index 00d050e..43248fa 100644
--- a/android/app/src/main/AndroidManifest.xml
+++ b/android/app/src/main/AndroidManifest.xml
@@ -1,5 +1,9 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
     <uses-permission android:name="android.permission.INTERNET"/>
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_CONNECTED_DEVICE"/>
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC"/>
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS"/>
 
     <application
         android:label="GameTime"
@@ -33,6 +37,22 @@
         <meta-data
             android:name="flutterEmbedding"
             android:value="2" />
+        <service
+            android:name=".watch.WatchCompanionForegroundService"
+            android:exported="false"
+            android:foregroundServiceType="connectedDevice|dataSync" />
+        <service
+            android:name=".watch.PhoneWatchBridgeListenerService"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="com.google.android.gms.wearable.MESSAGE_RECEIVED" />
+                <action android:name="com.google.android.gms.wearable.CAPABILITY_CHANGED" />
+                <data
+                    android:host="*"
+                    android:pathPrefix="/gametime"
+                    android:scheme="wear" />
+            </intent-filter>
+        </service>
     </application>
     <!-- Required to query activities that can process text, see:
          https://developer.android.com/training/package-visibility and
diff --git a/android/app/src/main/kotlin/com/gametime/app/MainActivity.kt b/android/app/src/main/kotlin/com/gametime/app/MainActivity.kt
index e9ef322..4a55248 100644
--- a/android/app/src/main/kotlin/com/gametime/app/MainActivity.kt
+++ b/android/app/src/main/kotlin/com/gametime/app/MainActivity.kt
@@ -1,5 +1,12 @@
 package com.gametime.app
 
+import com.gametime.app.watch.WatchBridgePlugin
 import io.flutter.embedding.android.FlutterActivity
+import io.flutter.embedding.engine.FlutterEngine
 
-class MainActivity : FlutterActivity()
+class MainActivity : FlutterActivity() {
+    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
+        super.configureFlutterEngine(flutterEngine)
+        WatchBridgePlugin.register(flutterEngine, applicationContext)
+    }
+}
diff --git a/android/app/src/main/kotlin/com/gametime/app/watch/PhoneWatchBridgeListenerService.kt b/android/app/src/main/kotlin/com/gametime/app/watch/PhoneWatchBridgeListenerService.kt
new file mode 100644
index 0000000..d995c1d
--- /dev/null
+++ b/android/app/src/main/kotlin/com/gametime/app/watch/PhoneWatchBridgeListenerService.kt
@@ -0,0 +1,63 @@
+package com.gametime.app.watch
+
+import com.google.android.gms.wearable.CapabilityInfo
+import com.google.android.gms.wearable.MessageEvent
+import com.google.android.gms.wearable.Wearable
+import com.google.android.gms.wearable.WearableListenerService
+import org.json.JSONObject
+import java.nio.charset.StandardCharsets
+
+class PhoneWatchBridgeListenerService : WearableListenerService() {
+    override fun onMessageReceived(messageEvent: MessageEvent) {
+        if (messageEvent.path != WatchBridgePlugin.COMMAND_PATH) {
+            return
+        }
+        val payload = JSONObject(String(messageEvent.data, StandardCharsets.UTF_8))
+        val command = payload.toMap()
+        val delivered = WatchBridgePlugin.emitCommand(command, messageEvent.sourceNodeId)
+        if (!delivered) {
+            sendPhoneBusyAck(command, messageEvent.sourceNodeId)
+        }
+    }
+
+    override fun onCapabilityChanged(capabilityInfo: CapabilityInfo) {
+        if (capabilityInfo.name != WatchBridgePlugin.WATCH_CAPABILITY) {
+            return
+        }
+        WatchBridgePlugin.emitConnection(
+            isReachable = capabilityInfo.nodes.isNotEmpty(),
+            requestsResync = capabilityInfo.nodes.isNotEmpty(),
+        )
+    }
+
+    override fun onCreate() {
+        super.onCreate()
+        WatchBridgePlugin.requestCapabilityRefresh(applicationContext)
+    }
+
+    private fun sendPhoneBusyAck(command: Map<String, Any?>, sourceNodeId: String) {
+        val ack = JSONObject(
+            mapOf(
+                "schemaVersion" to (command["schemaVersion"] ?: 1),
+                "commandId" to command["commandId"],
+                "sessionId" to command["sessionId"],
+                "expectedRevision" to command["expectedRevision"],
+                "status" to "rejectedPhoneBusy",
+                "ackedAtEpochMs" to System.currentTimeMillis(),
+            ),
+        ).toString().toByteArray(StandardCharsets.UTF_8)
+        Wearable.getMessageClient(this)
+            .sendMessage(sourceNodeId, WatchBridgePlugin.ACK_PATH, ack)
+    }
+}
+
+private fun JSONObject.toMap(): Map<String, Any?> {
+    val output = linkedMapOf<String, Any?>()
+    val keys = keys()
+    while (keys.hasNext()) {
+        val key = keys.next()
+        val value = get(key)
+        output[key] = if (value == JSONObject.NULL) null else value
+    }
+    return output
+}
diff --git a/android/app/src/main/kotlin/com/gametime/app/watch/WatchBridgePlugin.kt b/android/app/src/main/kotlin/com/gametime/app/watch/WatchBridgePlugin.kt
new file mode 100644
index 0000000..02aa3f4
--- /dev/null
+++ b/android/app/src/main/kotlin/com/gametime/app/watch/WatchBridgePlugin.kt
@@ -0,0 +1,214 @@
+package com.gametime.app.watch
+
+import android.content.Context
+import android.content.Intent
+import com.google.android.gms.wearable.CapabilityClient
+import com.google.android.gms.wearable.PutDataMapRequest
+import com.google.android.gms.wearable.Wearable
+import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.plugin.common.EventChannel
+import io.flutter.plugin.common.MethodCall
+import io.flutter.plugin.common.MethodChannel
+import org.json.JSONObject
+import java.nio.charset.StandardCharsets
+import java.util.concurrent.ConcurrentHashMap
+
+object WatchBridgePlugin {
+    private const val METHOD_CHANNEL = "gametime.watch_bridge/methods"
+    private const val COMMAND_CHANNEL = "gametime.watch_bridge/commands"
+    private const val CONNECTION_CHANNEL = "gametime.watch_bridge/connection"
+
+    const val COMMAND_PATH = "/gametime/watch/command"
+    const val ACK_PATH = "/gametime/phone/ack"
+    const val STATE_PATH = "/gametime/phone/projection"
+    const val WATCH_CAPABILITY = "gametime_watch_companion"
+
+    private val pendingCommandNodes = ConcurrentHashMap<String, String>()
+    private var appContext: Context? = null
+    private var commandSink: EventChannel.EventSink? = null
+    private var connectionSink: EventChannel.EventSink? = null
+
+    fun register(flutterEngine: FlutterEngine, context: Context) {
+        appContext = context.applicationContext
+        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, METHOD_CHANNEL)
+            .setMethodCallHandler(::handleMethodCall)
+        EventChannel(flutterEngine.dartExecutor.binaryMessenger, COMMAND_CHANNEL)
+            .setStreamHandler(
+                object : EventChannel.StreamHandler {
+                    override fun onListen(arguments: Any?, events: EventChannel.EventSink?) {
+                        commandSink = events
+                    }
+
+                    override fun onCancel(arguments: Any?) {
+                        commandSink = null
+                    }
+                },
+            )
+        EventChannel(flutterEngine.dartExecutor.binaryMessenger, CONNECTION_CHANNEL)
+            .setStreamHandler(
+                object : EventChannel.StreamHandler {
+                    override fun onListen(arguments: Any?, events: EventChannel.EventSink?) {
+                        connectionSink = events
+                        requestCapabilityRefresh(context.applicationContext)
+                    }
+
+                    override fun onCancel(arguments: Any?) {
+                        connectionSink = null
+                    }
+                },
+            )
+    }
+
+    fun emitCommand(payload: Map<String, Any?>, sourceNodeId: String): Boolean {
+        val sink = commandSink ?: return false
+        val commandId = payload["commandId"] as? String
+        if (commandId != null) {
+            pendingCommandNodes[commandId] = sourceNodeId
+        }
+        sink.success(payload)
+        return true
+    }
+
+    fun emitConnection(isReachable: Boolean, requestsResync: Boolean) {
+        connectionSink?.success(
+            mapOf(
+                "isReachable" to isReachable,
+                "requestsResync" to requestsResync,
+            ),
+        )
+    }
+
+    private fun handleMethodCall(call: MethodCall, result: MethodChannel.Result) {
+        val context = appContext
+        if (context == null) {
+            result.error("watch_bridge_unavailable", "Application context unavailable.", null)
+            return
+        }
+        when (call.method) {
+            "publishProjection" -> publishProjection(context, call.arguments, result)
+            "sendCommandAck" -> sendCommandAck(context, call.arguments, result)
+            "requestCapabilityRefresh" -> {
+                requestCapabilityRefresh(context)
+                result.success(null)
+            }
+            "startForegroundService" -> {
+                startForegroundService(context)
+                result.success(null)
+            }
+            "stopForegroundService" -> {
+                context.stopService(Intent(context, WatchCompanionForegroundService::class.java))
+                result.success(null)
+            }
+            else -> result.notImplemented()
+        }
+    }
+
+    private fun publishProjection(
+        context: Context,
+        arguments: Any?,
+        result: MethodChannel.Result,
+    ) {
+        val map = arguments as? Map<*, *>
+        if (map == null) {
+            result.error("invalid_projection", "Projection payload must be a map.", null)
+            return
+        }
+        val projectionJson = JSONObject(map).toString()
+        val request = PutDataMapRequest.create(STATE_PATH).apply {
+            dataMap.putString("projectionJson", projectionJson)
+            dataMap.putInt("schemaVersion", (map["schemaVersion"] as? Number)?.toInt() ?: 1)
+            dataMap.putInt("revision", (map["revision"] as? Number)?.toInt() ?: 0)
+            dataMap.putLong(
+                "projectedAtEpochMs",
+                (map["projectedAtEpochMs"] as? Number)?.toLong() ?: 0L,
+            )
+        }.asPutDataRequest().setUrgent()
+        Wearable.getDataClient(context).putDataItem(request)
+            .addOnSuccessListener { result.success(null) }
+            .addOnFailureListener { error ->
+                result.error("publish_projection_failed", error.message, null)
+            }
+    }
+
+    private fun sendCommandAck(
+        context: Context,
+        arguments: Any?,
+        result: MethodChannel.Result,
+    ) {
+        val map = arguments as? Map<*, *>
+        if (map == null) {
+            result.error("invalid_ack", "Ack payload must be a map.", null)
+            return
+        }
+        val commandId = map["commandId"] as? String
+        val targetNode = commandId?.let { pendingCommandNodes.remove(it) }
+        val payload = JSONObject(map).toString().toByteArray(StandardCharsets.UTF_8)
+        if (targetNode != null) {
+            sendMessage(context, targetNode, payload, result)
+            return
+        }
+        Wearable.getCapabilityClient(context)
+            .getCapability(WATCH_CAPABILITY, CapabilityClient.FILTER_REACHABLE)
+            .addOnSuccessListener { capability ->
+                val nodes = capability.nodes.toList()
+                if (nodes.isEmpty()) {
+                    result.success(null)
+                    return@addOnSuccessListener
+                }
+                var remaining = nodes.size
+                var failed = false
+                for (node in nodes) {
+                    Wearable.getMessageClient(context)
+                        .sendMessage(node.id, ACK_PATH, payload)
+                        .addOnSuccessListener {
+                            remaining -= 1
+                            if (remaining == 0 && !failed) result.success(null)
+                        }
+                        .addOnFailureListener { error ->
+                            failed = true
+                            result.error("send_ack_failed", error.message, null)
+                        }
+                }
+            }
+            .addOnFailureListener { error ->
+                result.error("capability_lookup_failed", error.message, null)
+            }
+    }
+
+    private fun sendMessage(
+        context: Context,
+        nodeId: String,
+        payload: ByteArray,
+        result: MethodChannel.Result,
+    ) {
+        Wearable.getMessageClient(context)
+            .sendMessage(nodeId, ACK_PATH, payload)
+            .addOnSuccessListener { result.success(null) }
+            .addOnFailureListener { error ->
+                result.error("send_ack_failed", error.message, null)
+            }
+    }
+
+    fun requestCapabilityRefresh(context: Context) {
+        Wearable.getCapabilityClient(context)
+            .getCapability(WATCH_CAPABILITY, CapabilityClient.FILTER_REACHABLE)
+            .addOnSuccessListener { capability ->
+                emitConnection(
+                    isReachable = capability.nodes.isNotEmpty(),
+                    requestsResync = capability.nodes.isNotEmpty(),
+                )
+            }
+            .addOnFailureListener {
+                emitConnection(isReachable = false, requestsResync = false)
+            }
+    }
+
+    private fun startForegroundService(context: Context) {
+        val intent = Intent(context, WatchCompanionForegroundService::class.java)
+        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
+            context.startForegroundService(intent)
+        } else {
+            context.startService(intent)
+        }
+    }
+}
diff --git a/android/app/src/main/kotlin/com/gametime/app/watch/WatchCompanionForegroundService.kt b/android/app/src/main/kotlin/com/gametime/app/watch/WatchCompanionForegroundService.kt
new file mode 100644
index 0000000..ef5db54
--- /dev/null
+++ b/android/app/src/main/kotlin/com/gametime/app/watch/WatchCompanionForegroundService.kt
@@ -0,0 +1,58 @@
+package com.gametime.app.watch
+
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.Service
+import android.content.Intent
+import android.os.Build
+import android.os.IBinder
+import com.gametime.app.R
+
+class WatchCompanionForegroundService : Service() {
+    override fun onCreate() {
+        super.onCreate()
+        ensureNotificationChannel()
+        startForeground(NOTIFICATION_ID, notification())
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        return START_STICKY
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    private fun notification(): Notification {
+        val builder = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            Notification.Builder(this, CHANNEL_ID)
+        } else {
+            @Suppress("DEPRECATION")
+            Notification.Builder(this)
+        }
+        return builder
+            .setSmallIcon(R.mipmap.ic_launcher)
+            .setContentTitle("GameTime")
+            .setContentText("Séance en cours")
+            .setOngoing(true)
+            .setCategory(Notification.CATEGORY_SERVICE)
+            .build()
+    }
+
+    private fun ensureNotificationChannel() {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
+            return
+        }
+        val manager = getSystemService(NotificationManager::class.java)
+        val channel = NotificationChannel(
+            CHANNEL_ID,
+            "Synchronisation montre",
+            NotificationManager.IMPORTANCE_LOW,
+        )
+        manager.createNotificationChannel(channel)
+    }
+
+    private companion object {
+        const val CHANNEL_ID = "gametime_watch_companion"
+        const val NOTIFICATION_ID = 91
+    }
+}
diff --git a/android/app/src/main/res/values/wear.xml b/android/app/src/main/res/values/wear.xml
new file mode 100644
index 0000000..9842987
--- /dev/null
+++ b/android/app/src/main/res/values/wear.xml
@@ -0,0 +1,5 @@
+<resources>
+    <string-array name="android_wear_capabilities">
+        <item>gametime_phone_companion</item>
+    </string-array>
+</resources>
diff --git a/lib/application/app_bootstrap.dart b/lib/application/app_bootstrap.dart
index d9c8096..3f9227f 100644
--- a/lib/application/app_bootstrap.dart
+++ b/lib/application/app_bootstrap.dart
@@ -1,6 +1,7 @@
 import '../infrastructure/local/local.dart';
 import '../infrastructure/remote/remote.dart';
 import '../infrastructure/security/security.dart';
+import '../infrastructure/watch_bridge/watch_bridge.dart';
 import 'application.dart';
 
 abstract interface class AppDependencies {
@@ -33,6 +34,7 @@ final class AppBootstrap implements AppDependencies {
     required this.activeExerciseStepUseCases,
     required this.watchCompanionProjectionUseCases,
     required this.watchCompanionCommandHandler,
+    required this.watchWearDataLayerAdapter,
     required this.closeWorkoutSessionUseCase,
     required this.workoutHistoryUseCases,
     required this.progressionStatsUseCase,
@@ -61,6 +63,7 @@ final class AppBootstrap implements AppDependencies {
   final ActiveExerciseStepUseCases activeExerciseStepUseCases;
   final WatchCompanionProjectionUseCases watchCompanionProjectionUseCases;
   final WatchCompanionCommandHandler watchCompanionCommandHandler;
+  final WatchWearDataLayerAdapter watchWearDataLayerAdapter;
   @override
   final CloseWorkoutSessionUseCase closeWorkoutSessionUseCase;
   @override
@@ -126,6 +129,18 @@ final class AppBootstrap implements AppDependencies {
       ids: ids,
       originDeviceId: originDeviceId,
     );
+    final watchCompanionCommandHandler = WatchCompanionCommandHandler(
+      sessionRepository: activeSessionRepository,
+      activeSessionUseCases: activeWorkoutSessionUseCases,
+      stepUseCases: activeExerciseStepUseCases,
+      projectionSource: watchCompanionProjectionUseCases,
+    );
+    final watchWearDataLayerAdapter = WatchWearDataLayerAdapter(
+      nativeChannel: const MethodChannelWatchBridgeNativeChannel(),
+      commandIngress: watchCompanionCommandHandler,
+      projectionSource: watchCompanionProjectionUseCases,
+    );
+    await watchWearDataLayerAdapter.start();
     await SeedStarterContentUseCase(
       seedStateRepository: starterSeedRepository,
       contentRepository: starterSeedRepository,
@@ -184,12 +199,8 @@ final class AppBootstrap implements AppDependencies {
       activeWorkoutSessionUseCases: activeWorkoutSessionUseCases,
       activeExerciseStepUseCases: activeExerciseStepUseCases,
       watchCompanionProjectionUseCases: watchCompanionProjectionUseCases,
-      watchCompanionCommandHandler: WatchCompanionCommandHandler(
-        sessionRepository: activeSessionRepository,
-        activeSessionUseCases: activeWorkoutSessionUseCases,
-        stepUseCases: activeExerciseStepUseCases,
-        projectionSource: watchCompanionProjectionUseCases,
-      ),
+      watchCompanionCommandHandler: watchCompanionCommandHandler,
+      watchWearDataLayerAdapter: watchWearDataLayerAdapter,
       closeWorkoutSessionUseCase: CloseWorkoutSessionUseCase(
         sessionRepository: activeSessionRepository,
         historyRepository: historyRepository,
@@ -243,5 +254,9 @@ final class AppBootstrap implements AppDependencies {
     );
   }
 
-  Future<void> dispose() => database.close();
+  Future<void> dispose() async {
+    await watchWearDataLayerAdapter.stop();
+    await watchCompanionProjectionUseCases.dispose();
+    await database.close();
+  }
 }
diff --git a/lib/infrastructure/infrastructure.dart b/lib/infrastructure/infrastructure.dart
index b8732f3..7a27f39 100644
--- a/lib/infrastructure/infrastructure.dart
+++ b/lib/infrastructure/infrastructure.dart
@@ -7,3 +7,4 @@ library;
 export 'local/local.dart';
 export 'remote/remote.dart';
 export 'security/security.dart';
+export 'watch_bridge/watch_bridge.dart';
diff --git a/lib/infrastructure/watch_bridge/native_watch_bridge_channel.dart b/lib/infrastructure/watch_bridge/native_watch_bridge_channel.dart
new file mode 100644
index 0000000..22738e1
--- /dev/null
+++ b/lib/infrastructure/watch_bridge/native_watch_bridge_channel.dart
@@ -0,0 +1,137 @@
+import 'dart:async';
+
+import 'package:flutter/services.dart';
+import 'package:watch_bridge_contract/watch_bridge_contract.dart';
+
+final class WatchBridgeConnectionEvent {
+  const WatchBridgeConnectionEvent({
+    required this.isReachable,
+    this.requestsResync = false,
+  });
+
+  final bool isReachable;
+  final bool requestsResync;
+}
+
+abstract interface class WatchBridgeNativeChannel {
+  Stream<WatchCommandEnvelope> get commands;
+
+  Stream<WatchBridgeConnectionEvent> get connectionEvents;
+
+  Future<void> publishProjection(WatchSessionProjection projection);
+
+  Future<void> sendCommandAck(
+    WatchCommandEnvelope command,
+    WatchCommandAck ack, {
+    int? revisionAtAck,
+  });
+
+  Future<void> requestCapabilityRefresh();
+
+  Future<void> startForegroundService();
+
+  Future<void> stopForegroundService();
+}
+
+final class MethodChannelWatchBridgeNativeChannel
+    implements WatchBridgeNativeChannel {
+  const MethodChannelWatchBridgeNativeChannel({
+    MethodChannel methodChannel = const MethodChannel(_methodChannelName),
+    EventChannel commandChannel = const EventChannel(_commandChannelName),
+    EventChannel connectionChannel = const EventChannel(_connectionChannelName),
+  }) : _methodChannel = methodChannel,
+       _commandChannel = commandChannel,
+       _connectionChannel = connectionChannel;
+
+  static const _methodChannelName = 'gametime.watch_bridge/methods';
+  static const _commandChannelName = 'gametime.watch_bridge/commands';
+  static const _connectionChannelName = 'gametime.watch_bridge/connection';
+
+  final MethodChannel _methodChannel;
+  final EventChannel _commandChannel;
+  final EventChannel _connectionChannel;
+
+  @override
+  Stream<WatchCommandEnvelope> get commands {
+    return _commandChannel
+        .receiveBroadcastStream()
+        .where((event) {
+          return event is Map;
+        })
+        .map((event) {
+          return WatchCommandEnvelope.fromJson(_stringObjectMap(event));
+        });
+  }
+
+  @override
+  Stream<WatchBridgeConnectionEvent> get connectionEvents {
+    return _connectionChannel
+        .receiveBroadcastStream()
+        .where((event) {
+          return event is Map;
+        })
+        .map((event) {
+          final json = _stringObjectMap(event);
+          return WatchBridgeConnectionEvent(
+            isReachable: json['isReachable'] == true,
+            requestsResync: json['requestsResync'] == true,
+          );
+        });
+  }
+
+  @override
+  Future<void> publishProjection(WatchSessionProjection projection) {
+    return _invokeIgnoringMissingPlugin(
+      'publishProjection',
+      projection.toJson(),
+    );
+  }
+
+  @override
+  Future<void> requestCapabilityRefresh() {
+    return _invokeIgnoringMissingPlugin('requestCapabilityRefresh');
+  }
+
+  @override
+  Future<void> sendCommandAck(
+    WatchCommandEnvelope command,
+    WatchCommandAck ack, {
+    int? revisionAtAck,
+  }) {
+    return _invokeIgnoringMissingPlugin('sendCommandAck', {
+      'schemaVersion': watchBridgeSchemaVersion,
+      'commandId': command.commandId,
+      'sessionId': command.sessionId,
+      'expectedRevision': command.expectedRevision,
+      'status': ack.name,
+      'revisionAtAck': revisionAtAck,
+      'ackedAtEpochMs': DateTime.now().toUtc().millisecondsSinceEpoch,
+    });
+  }
+
+  @override
+  Future<void> startForegroundService() {
+    return _invokeIgnoringMissingPlugin('startForegroundService');
+  }
+
+  @override
+  Future<void> stopForegroundService() {
+    return _invokeIgnoringMissingPlugin('stopForegroundService');
+  }
+
+  Future<void> _invokeIgnoringMissingPlugin(
+    String method, [
+    Object? arguments,
+  ]) {
+    return _methodChannel
+        .invokeMethod<void>(method, arguments)
+        .onError<MissingPluginException>((_, _) {});
+  }
+}
+
+Map<String, Object?> _stringObjectMap(Object? value) {
+  if (value is Map) {
+    return value.map((key, value) => MapEntry(key.toString(), value));
+  }
+  return const {};
+}
diff --git a/lib/infrastructure/watch_bridge/watch_bridge.dart b/lib/infrastructure/watch_bridge/watch_bridge.dart
new file mode 100644
index 0000000..96a3711
--- /dev/null
+++ b/lib/infrastructure/watch_bridge/watch_bridge.dart
@@ -0,0 +1,2 @@
+export 'native_watch_bridge_channel.dart';
+export 'wear_data_layer_adapter.dart';
diff --git a/lib/infrastructure/watch_bridge/wear_data_layer_adapter.dart b/lib/infrastructure/watch_bridge/wear_data_layer_adapter.dart
new file mode 100644
index 0000000..9f06fbf
--- /dev/null
+++ b/lib/infrastructure/watch_bridge/wear_data_layer_adapter.dart
@@ -0,0 +1,183 @@
+import 'dart:async';
+
+import 'package:watch_bridge_contract/watch_bridge_contract.dart';
+
+import '../../application/watch_companion_use_cases.dart';
+import 'native_watch_bridge_channel.dart';
+
+final class WatchWearDataLayerAdapter implements WatchProjectionPublisher {
+  WatchWearDataLayerAdapter({
+    required WatchBridgeNativeChannel nativeChannel,
+    required WatchCommandIngress commandIngress,
+    required WatchProjectionSource projectionSource,
+    Duration heartbeatInterval = const Duration(seconds: 5),
+  }) : _nativeChannel = nativeChannel,
+       _commandIngress = commandIngress,
+       _projectionSource = projectionSource,
+       _heartbeatInterval = heartbeatInterval;
+
+  final WatchBridgeNativeChannel _nativeChannel;
+  final WatchCommandIngress _commandIngress;
+  final WatchProjectionSource _projectionSource;
+  final Duration _heartbeatInterval;
+  final _commandAcks = <_WatchAdapterCommandKey, WatchCommandAck>{};
+  final _subscriptions = <StreamSubscription<dynamic>>[];
+  Future<void> _commandTail = Future<void>.value();
+  Timer? _heartbeatTimer;
+  WatchSessionProjection? _latestProjection;
+  bool _started = false;
+  bool _foregroundActive = false;
+
+  Future<void> start() async {
+    if (_started) {
+      return;
+    }
+    _started = true;
+    _subscriptions.add(
+      _projectionSource.projections.listen((projection) {
+        unawaited(publish(projection));
+      }),
+    );
+    _subscriptions.add(
+      _nativeChannel.commands.listen((command) {
+        unawaited(_enqueueCommand(command));
+      }),
+    );
+    _subscriptions.add(
+      _nativeChannel.connectionEvents.listen((event) {
+        if (event.isReachable || event.requestsResync) {
+          unawaited(_projectionSource.emitCurrentProjection());
+        }
+      }),
+    );
+    await _projectionSource.emitCurrentProjection();
+    await _nativeChannel.requestCapabilityRefresh();
+  }
+
+  Future<void> stop() async {
+    _heartbeatTimer?.cancel();
+    _heartbeatTimer = null;
+    for (final subscription in _subscriptions) {
+      await subscription.cancel();
+    }
+    _subscriptions.clear();
+    _started = false;
+  }
+
+  @override
+  Future<void> publish(WatchSessionProjection projection) async {
+    _latestProjection = projection;
+    await _nativeChannel.publishProjection(projection);
+    await _syncForegroundService(projection);
+    _syncHeartbeat(projection);
+  }
+
+  Future<void> _enqueueCommand(WatchCommandEnvelope command) {
+    final run = _commandTail.then(
+      (_) => _handleCommand(command),
+      onError: (_) => _handleCommand(command),
+    );
+    _commandTail = run.then((_) {}, onError: (_) {});
+    return run;
+  }
+
+  Future<void> _handleCommand(WatchCommandEnvelope command) async {
+    final key = _WatchAdapterCommandKey(command);
+    final cachedAck = _commandAcks[key];
+    if (cachedAck != null) {
+      await _sendAck(command, WatchCommandAck.acceptedNoOp);
+      return;
+    }
+    final ack = await _commandIngress.dispatch(command);
+    if (ack == WatchCommandAck.accepted ||
+        ack == WatchCommandAck.acceptedNoOp) {
+      _rememberAck(key, ack);
+    }
+    await _sendAck(command, ack);
+  }
+
+  Future<void> _sendAck(
+    WatchCommandEnvelope command,
+    WatchCommandAck ack,
+  ) async {
+    int? revisionAtAck;
+    try {
+      revisionAtAck = (await _projectionSource.currentProjection()).revision;
+    } on Exception {
+      revisionAtAck = _latestProjection?.revision;
+    }
+    await _nativeChannel.sendCommandAck(
+      command,
+      ack,
+      revisionAtAck: revisionAtAck,
+    );
+  }
+
+  void _rememberAck(_WatchAdapterCommandKey key, WatchCommandAck ack) {
+    _commandAcks[key] = ack;
+    if (_commandAcks.length <= 128) {
+      return;
+    }
+    _commandAcks.remove(_commandAcks.keys.first);
+  }
+
+  Future<void> _syncForegroundService(WatchSessionProjection projection) async {
+    final shouldRun =
+        projection.phase != WatchSessionPhase.noActiveSession &&
+        projection.deviceSessionId.isNotEmpty;
+    if (shouldRun == _foregroundActive) {
+      return;
+    }
+    _foregroundActive = shouldRun;
+    if (shouldRun) {
+      await _nativeChannel.startForegroundService();
+    } else {
+      await _nativeChannel.stopForegroundService();
+    }
+  }
+
+  void _syncHeartbeat(WatchSessionProjection projection) {
+    if (!_hasRunningTimer(projection)) {
+      _heartbeatTimer?.cancel();
+      _heartbeatTimer = null;
+      return;
+    }
+    _heartbeatTimer ??= Timer.periodic(_heartbeatInterval, (_) {
+      unawaited(_projectionSource.emitCurrentProjection());
+    });
+  }
+}
+
+bool _hasRunningTimer(WatchSessionProjection projection) {
+  final timers = [
+    if (projection.dominantTimer != null) projection.dominantTimer!,
+    ...projection.secondaryTimers,
+  ];
+  return timers.any((timer) => timer.runState == WatchTimerRunState.running);
+}
+
+final class _WatchAdapterCommandKey {
+  _WatchAdapterCommandKey(WatchCommandEnvelope command)
+    : sessionId = command.sessionId,
+      expectedRevision = command.expectedRevision,
+      commandId = command.commandId,
+      type = command.type;
+
+  final String sessionId;
+  final int expectedRevision;
+  final String commandId;
+  final WatchCommandType type;
+
+  @override
+  bool operator ==(Object other) {
+    return identical(this, other) ||
+        other is _WatchAdapterCommandKey &&
+            sessionId == other.sessionId &&
+            expectedRevision == other.expectedRevision &&
+            commandId == other.commandId &&
+            type == other.type;
+  }
+
+  @override
+  int get hashCode => Object.hash(sessionId, expectedRevision, commandId, type);
+}
diff --git a/test/infrastructure/watch_bridge/wear_data_layer_adapter_test.dart b/test/infrastructure/watch_bridge/wear_data_layer_adapter_test.dart
new file mode 100644
index 0000000..f3d4794
--- /dev/null
+++ b/test/infrastructure/watch_bridge/wear_data_layer_adapter_test.dart
@@ -0,0 +1,319 @@
+import 'dart:async';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:gametime/application/application.dart';
+import 'package:gametime/infrastructure/infrastructure.dart';
+import 'package:watch_bridge_contract/watch_bridge_contract.dart';
+
+void main() {
+  test('publishes every projection revision from the source stream', () async {
+    final native = _FakeWatchBridgeNativeChannel();
+    final source = _FakeProjectionSource(_projection(revision: 0));
+    final adapter = _adapter(native: native, source: source);
+    await adapter.start();
+    native.published.clear();
+
+    source.emit(_projection(revision: 1));
+    source.emit(_projection(revision: 2));
+    await Future<void>.delayed(Duration.zero);
+
+    expect(native.published.map((projection) => projection.revision), [1, 2]);
+    await adapter.stop();
+  });
+
+  test('heartbeats while a timer is running', () async {
+    final native = _FakeWatchBridgeNativeChannel();
+    final source = _FakeProjectionSource(_runningProjection(revision: 1));
+    final adapter = _adapter(
+      native: native,
+      source: source,
+      heartbeatInterval: const Duration(milliseconds: 10),
+    );
+    await adapter.start();
+    native.published.clear();
+    source.emitCount = 0;
+
+    await adapter.publish(_runningProjection(revision: 1));
+    await Future<void>.delayed(const Duration(milliseconds: 35));
+
+    expect(source.emitCount, greaterThanOrEqualTo(1));
+    expect(native.published.length, greaterThanOrEqualTo(2));
+    await adapter.stop();
+  });
+
+  test('dispatches watch command and sends ack back to native layer', () async {
+    final native = _FakeWatchBridgeNativeChannel();
+    final ingress = _FakeCommandIngress();
+    final source = _FakeProjectionSource(_projection(revision: 0));
+    final adapter = _adapter(native: native, ingress: ingress, source: source);
+    await adapter.start();
+
+    native.emitCommand(_command(WatchCommandType.pauseSession));
+    await Future<void>.delayed(Duration.zero);
+
+    expect(ingress.commands.single.type, WatchCommandType.pauseSession);
+    expect(native.acks.single.ack, WatchCommandAck.accepted);
+    expect(native.acks.single.revisionAtAck, 1);
+    await adapter.stop();
+  });
+
+  test('deduplicates retry before dispatching to ingress again', () async {
+    final native = _FakeWatchBridgeNativeChannel();
+    final ingress = _FakeCommandIngress();
+    final source = _FakeProjectionSource(_projection(revision: 0));
+    final adapter = _adapter(native: native, ingress: ingress, source: source);
+    await adapter.start();
+    final command = _command(WatchCommandType.skipCurrentSet);
+
+    native.emitCommand(command);
+    native.emitCommand(command);
+    await Future<void>.delayed(Duration.zero);
+
+    expect(ingress.commands, hasLength(1));
+    expect(native.acks.map((ack) => ack.ack), [
+      WatchCommandAck.accepted,
+      WatchCommandAck.acceptedNoOp,
+    ]);
+    await adapter.stop();
+  });
+
+  test('emits a full resync when a watch node reconnects', () async {
+    final native = _FakeWatchBridgeNativeChannel();
+    final source = _FakeProjectionSource(_projection(revision: 3));
+    final adapter = _adapter(native: native, source: source);
+    await adapter.start();
+    native.published.clear();
+    source.emitCount = 0;
+
+    native.emitConnection(
+      const WatchBridgeConnectionEvent(isReachable: true, requestsResync: true),
+    );
+    await Future<void>.delayed(Duration.zero);
+
+    expect(source.emitCount, 1);
+    expect(native.published.single.revision, 5);
+    await adapter.stop();
+  });
+
+  test('processes commands sequentially in receive order', () async {
+    final native = _FakeWatchBridgeNativeChannel();
+    final ingress = _BlockingCommandIngress();
+    final source = _FakeProjectionSource(_projection(revision: 0));
+    final adapter = _adapter(native: native, ingress: ingress, source: source);
+    await adapter.start();
+
+    native.emitCommand(_command(WatchCommandType.skipCurrentStep, id: 'first'));
+    native.emitCommand(_command(WatchCommandType.skipCurrentSet, id: 'second'));
+    await Future<void>.delayed(Duration.zero);
+
+    expect(ingress.started, ['first']);
+    ingress.completeNext();
+    await Future<void>.delayed(Duration.zero);
+
+    expect(ingress.started, ['first', 'second']);
+    ingress.completeNext();
+    await Future<void>.delayed(Duration.zero);
+
+    expect(native.acks.map((ack) => ack.command.commandId), [
+      'first',
+      'second',
+    ]);
+    await adapter.stop();
+  });
+}
+
+WatchWearDataLayerAdapter _adapter({
+  required _FakeWatchBridgeNativeChannel native,
+  WatchCommandIngress? ingress,
+  required _FakeProjectionSource source,
+  Duration heartbeatInterval = const Duration(seconds: 5),
+}) {
+  return WatchWearDataLayerAdapter(
+    nativeChannel: native,
+    commandIngress: ingress ?? _FakeCommandIngress(),
+    projectionSource: source,
+    heartbeatInterval: heartbeatInterval,
+  );
+}
+
+WatchCommandEnvelope _command(
+  WatchCommandType type, {
+  String id = 'command-1',
+}) {
+  return WatchCommandEnvelope(
+    commandId: id,
+    type: type,
+    sessionId: 'session-1',
+    expectedRevision: 1,
+    sentAtEpochMs: _now.millisecondsSinceEpoch,
+  );
+}
+
+WatchSessionProjection _projection({required int revision}) {
+  return WatchSessionProjection(
+    deviceSessionId: 'session-1',
+    revision: revision,
+    projectedAtEpochMs: _now.millisecondsSinceEpoch,
+    phase: WatchSessionPhase.ready,
+    phoneReachable: true,
+    seriesIndex: 1,
+    seriesTotal: 2,
+    exerciseName: 'Squat',
+    primaryAction: WatchPrimaryAction.startCurrentExercise,
+  );
+}
+
+WatchSessionProjection _runningProjection({required int revision}) {
+  return WatchSessionProjection(
+    deviceSessionId: 'session-1',
+    revision: revision,
+    projectedAtEpochMs: _now.millisecondsSinceEpoch,
+    phase: WatchSessionPhase.running,
+    phoneReachable: true,
+    seriesIndex: 1,
+    seriesTotal: 2,
+    exerciseName: 'Squat',
+    primaryAction: WatchPrimaryAction.pauseSession,
+    dominantTimer: WatchTimerProjection(
+      kind: WatchTimerKind.step,
+      label: 'Chrono étape',
+      displayMode: WatchTimerDisplayMode.countdown,
+      runState: WatchTimerRunState.running,
+      referenceEpochMs: _now.millisecondsSinceEpoch,
+      accumulatedMs: 0,
+      startedAtEpochMs: _now.millisecondsSinceEpoch,
+      targetMs: 30000,
+    ),
+  );
+}
+
+final _now = DateTime.utc(2026, 7, 25, 12);
+
+final class _FakeProjectionSource implements WatchProjectionSource {
+  _FakeProjectionSource(this.current);
+
+  WatchSessionProjection current;
+  var emitCount = 0;
+  final _controller = StreamController<WatchSessionProjection>.broadcast();
+
+  @override
+  Stream<WatchSessionProjection> get projections => _controller.stream;
+
+  void emit(WatchSessionProjection projection) {
+    current = projection;
+    _controller.add(projection);
+  }
+
+  @override
+  Future<WatchSessionProjection> currentProjection() async => current;
+
+  @override
+  Future<WatchSessionProjection> emitCurrentProjection() async {
+    emitCount += 1;
+    current = WatchSessionProjection(
+      deviceSessionId: current.deviceSessionId,
+      revision: current.revision + 1,
+      projectedAtEpochMs: current.projectedAtEpochMs,
+      phase: current.phase,
+      phoneReachable: current.phoneReachable,
+      seriesIndex: current.seriesIndex,
+      seriesTotal: current.seriesTotal,
+      exerciseName: current.exerciseName,
+      dominantTimer: current.dominantTimer,
+      secondaryTimers: current.secondaryTimers,
+      primaryAction: current.primaryAction,
+      secondaryActions: current.secondaryActions,
+    );
+    _controller.add(current);
+    return current;
+  }
+}
+
+final class _FakeCommandIngress implements WatchCommandIngress {
+  final commands = <WatchCommandEnvelope>[];
+
+  @override
+  Future<WatchCommandAck> dispatch(WatchCommandEnvelope command) async {
+    commands.add(command);
+    return WatchCommandAck.accepted;
+  }
+}
+
+final class _BlockingCommandIngress implements WatchCommandIngress {
+  final started = <String>[];
+  final _pending = <Completer<WatchCommandAck>>[];
+
+  @override
+  Future<WatchCommandAck> dispatch(WatchCommandEnvelope command) {
+    started.add(command.commandId);
+    final completer = Completer<WatchCommandAck>();
+    _pending.add(completer);
+    return completer.future;
+  }
+
+  void completeNext() {
+    _pending.removeAt(0).complete(WatchCommandAck.accepted);
+  }
+}
+
+final class _FakeWatchBridgeNativeChannel implements WatchBridgeNativeChannel {
+  final published = <WatchSessionProjection>[];
+  final acks = <_SentAck>[];
+  final _commands = StreamController<WatchCommandEnvelope>.broadcast();
+  final _connections = StreamController<WatchBridgeConnectionEvent>.broadcast();
+  var capabilityRefreshCount = 0;
+  var foregroundStartCount = 0;
+  var foregroundStopCount = 0;
+
+  @override
+  Stream<WatchCommandEnvelope> get commands => _commands.stream;
+
+  @override
+  Stream<WatchBridgeConnectionEvent> get connectionEvents =>
+      _connections.stream;
+
+  void emitCommand(WatchCommandEnvelope command) {
+    _commands.add(command);
+  }
+
+  void emitConnection(WatchBridgeConnectionEvent event) {
+    _connections.add(event);
+  }
+
+  @override
+  Future<void> publishProjection(WatchSessionProjection projection) async {
+    published.add(projection);
+  }
+
+  @override
+  Future<void> requestCapabilityRefresh() async {
+    capabilityRefreshCount += 1;
+  }
+
+  @override
+  Future<void> sendCommandAck(
+    WatchCommandEnvelope command,
+    WatchCommandAck ack, {
+    int? revisionAtAck,
+  }) async {
+    acks.add(_SentAck(command, ack, revisionAtAck));
+  }
+
+  @override
+  Future<void> startForegroundService() async {
+    foregroundStartCount += 1;
+  }
+
+  @override
+  Future<void> stopForegroundService() async {
+    foregroundStopCount += 1;
+  }
+}
+
+final class _SentAck {
+  const _SentAck(this.command, this.ack, this.revisionAtAck);
+
+  final WatchCommandEnvelope command;
+  final WatchCommandAck ack;
+  final int? revisionAtAck;
+}