diff --git a/ios/App/App.xcodeproj/project.pbxproj b/ios/App/App.xcodeproj/project.pbxproj
index 1cb1c67..f4e2a3f 100644
--- a/ios/App/App.xcodeproj/project.pbxproj
+++ b/ios/App/App.xcodeproj/project.pbxproj
@@ -20,6 +20,7 @@
 		50B271D11FEDC1A000F3C39B /* public in Resources */ = {isa = PBXBuildFile; fileRef = 50B271D01FEDC1A000F3C39B /* public */; };
 		543A7005429A43F54C0EC61B /* CoachWatchApp.swift in Sources */ = {isa = PBXBuildFile; fileRef = F6BEAEF6F6274D61CAF22636 /* CoachWatchApp.swift */; };
 		88F28EB12FBB330E00E8306E /* CoachWorkoutObserver.swift in Sources */ = {isa = PBXBuildFile; fileRef = 88F28EB02FBB330E00E8306E /* CoachWorkoutObserver.swift */; };
+		B06AB24B350B221F38D99E17 /* ConnectivityManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = A420239FC6D065C8A599B61C /* ConnectivityManager.swift */; };
 		C0AC4A07811751FB78AA0001 /* CoachAuth.swift in Sources */ = {isa = PBXBuildFile; fileRef = C0AC4A07811751FB78AA0002 /* CoachAuth.swift */; };
 		D1BD5B1990CF3F2B9C5D0001 /* CoachWorkoutKit.swift in Sources */ = {isa = PBXBuildFile; fileRef = D1BD5B1990CF3F2B9C5D0002 /* CoachWorkoutKit.swift */; };
 		E2CE6C2AA1DF4F3CAD6E0001 /* MainViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = E2CE6C2AA1DF4F3CAD6E0002 /* MainViewController.swift */; };
@@ -67,6 +68,7 @@
 		88F28EB02FBB330E00E8306E /* CoachWorkoutObserver.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CoachWorkoutObserver.swift; sourceTree = "<group>"; };
 		8A06CDFF5B4F7852B6329862 /* ContentView.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; path = ContentView.swift; sourceTree = "<group>"; };
 		958DCC722DB07C7200EA8C5F /* debug.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; name = debug.xcconfig; path = ../debug.xcconfig; sourceTree = SOURCE_ROOT; };
+		A420239FC6D065C8A599B61C /* ConnectivityManager.swift */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = sourcecode.swift; path = ConnectivityManager.swift; sourceTree = "<group>"; };
 		C0AC4A07811751FB78AA0002 /* CoachAuth.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CoachAuth.swift; sourceTree = "<group>"; };
 		D09B589FA572B2C14E8CD835 /* CoachWatch.entitlements */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.plist.entitlements; path = CoachWatch.entitlements; sourceTree = "<group>"; };
 		D1BD5B1990CF3F2B9C5D0002 /* CoachWorkoutKit.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CoachWorkoutKit.swift; sourceTree = "<group>"; };
@@ -151,6 +153,7 @@
 				8A06CDFF5B4F7852B6329862 /* ContentView.swift */,
 				82122ACF7E5A608AD1D55D24 /* Info.plist */,
 				D09B589FA572B2C14E8CD835 /* CoachWatch.entitlements */,
+				A420239FC6D065C8A599B61C /* ConnectivityManager.swift */,
 			);
 			name = CoachWatch;
 			path = CoachWatch;
@@ -287,6 +290,7 @@
 			files = (
 				543A7005429A43F54C0EC61B /* CoachWatchApp.swift in Sources */,
 				290D0F17978B7EF3DDB3A792 /* ContentView.swift in Sources */,
+				B06AB24B350B221F38D99E17 /* ConnectivityManager.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
diff --git a/ios/App/CoachWatch/ConnectivityManager.swift b/ios/App/CoachWatch/ConnectivityManager.swift
new file mode 100644
index 0000000..6e32f3f
--- /dev/null
+++ b/ios/App/CoachWatch/ConnectivityManager.swift
@@ -0,0 +1,76 @@
+import Foundation
+import WatchConnectivity
+
+/// Envoie les samples de séance vers l'iPhone.
+/// - `sendMessage` quand l'iPhone est joignable (temps réel)
+/// - sinon buffer + `transferUserInfo` (livraison différée garantie)
+final class ConnectivityManager: NSObject, ObservableObject {
+    static let shared = ConnectivityManager()
+
+    @Published private(set) var isReachable = false
+
+    private let queue = DispatchQueue(label: "ch.hypnotruck.coach.connectivity")
+    private var buffer: [[String: Any]] = []
+
+    private override init() {
+        super.init()
+        guard WCSession.isSupported() else { return }
+        let session = WCSession.default
+        session.delegate = self
+        session.activate()
+    }
+
+    func sendSample(_ payload: [String: Any]) {
+        queue.async {
+            let session = WCSession.default
+            guard session.activationState == .activated else {
+                self.buffer.append(payload)
+                return
+            }
+            if session.isReachable {
+                session.sendMessage(payload, replyHandler: nil) { [weak self] _ in
+                    // échec d'envoi temps réel -> bascule en livraison différée
+                    self?.queue.async {
+                        self?.buffer.append(payload)
+                        self?.flushLocked()
+                    }
+                }
+            } else {
+                self.buffer.append(payload)
+                self.flushLocked()
+            }
+        }
+    }
+
+    /// À appeler sur `queue` uniquement.
+    private func flushLocked() {
+        guard !buffer.isEmpty else { return }
+        let session = WCSession.default
+        guard session.activationState == .activated else { return }
+        session.transferUserInfo(["samples": buffer])
+        buffer.removeAll()
+    }
+
+    private func updateReachable(_ value: Bool) {
+        DispatchQueue.main.async { [weak self] in self?.isReachable = value }
+    }
+}
+
+extension ConnectivityManager: WCSessionDelegate {
+    func session(_ session: WCSession,
+                 activationDidCompleteWith activationState: WCSessionActivationState,
+                 error: Error?) {
+        updateReachable(session.isReachable)
+        if activationState == .activated {
+            queue.async { [weak self] in self?.flushLocked() }
+        }
+    }
+
+    func sessionReachabilityDidChange(_ session: WCSession) {
+        let reachable = session.isReachable
+        updateReachable(reachable)
+        if reachable {
+            queue.async { [weak self] in self?.flushLocked() }
+        }
+    }
+}