# Watch Connectivity

Use Watch Connectivity to keep Clerk auth state in sync between an iOS app and its companion watchOS app. This lets users sign in on either device and have the session automatically propagate.

> This guide is for **companion watch apps** that pair with an iPhone app. **Standalone watch apps** (no companion iOS app) must authenticate separately and do not use Watch Connectivity sync.

## Enable Watch Connectivity sync

1. ### Confirm a companion watch app

   Watch Connectivity only works when your watchOS target is a **companion** to the iOS app. Make sure your iOS app target is paired with a watchOS target in Xcode. For Apple’s guidance on setting up a companion watch app, see [Setting up a watchOS project](https://developer.apple.com/documentation/watchos-apps/setting-up-a-watchos-project).
2. ### Configure Clerk in both apps

   Use the same publishable key in both apps and enable watch sync in `Clerk.Options`:

   **iOS app**

   ```swift
   import ClerkKit
   import SwiftUI

   @main
   struct WatchConnectivityExampleApp: App {
     init() {
       // Configure Clerk with Watch Connectivity sync enabled
       let options = Clerk.Options(
         watchConnectivityEnabled: true
       )

       Clerk.configure(
         publishableKey: "YOUR_PUBLISHABLE_KEY",
         options: options
       )
     }

     var body: some Scene {
       WindowGroup {
         ContentView()
           .environment(Clerk.shared)
       }
     }
   }
   ```

   **watchOS app**

   ```swift
   import ClerkKit
   import SwiftUI

   @main
   struct WatchConnectivityExampleWatchApp: App {
     init() {
       // Configure Clerk with Watch Connectivity sync enabled
       let options = Clerk.Options(
         watchConnectivityEnabled: true
       )

       Clerk.configure(
         publishableKey: "YOUR_PUBLISHABLE_KEY",
         options: options
       )
     }

     var body: some Scene {
       WindowGroup {
         ContentView()
           .environment(Clerk.shared)
       }
     }
   }
   ```
3. ### Simulator setup (optional)

   For simulator testing, make sure your iPhone simulator is paired with a watchOS simulator in **Xcode > Window > Devices and Simulators**.
4. ### Install and run

   1. Build and run the iOS app first (this installs the companion watch app).
   2. Then run the watchOS app.
   3. Sign in on either device to verify the session syncs.

   > If you see "WCSession counterpart app not installed", install the iOS app first.

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