iOS setup

1. App Group. Apple Developer portal → Identifiers → App Groups → create group.com.example.app. In Xcode add the App Groups capability with that group to both the app target and the widget extension target.
2. Swift package. Add https://github.com/vaazh-studios/widgetbridge to both targets (the app needs it for the reloader, the extension for the reader).
3. Kotlin side (shared code):

   val bridge = iosWidgetBridge(WidgetBridgeConfig(schemaVersion = 1, iosAppGroup = "group.com.example.app"), QuoteFeed.serializer())
   

4. App target, once at launch (AppDelegate or your @main init):

   WidgetBridgeReloader.start()
   

   It observes the notification the Kotlin side posts after a publish and calls WidgetCenter.shared.reloadAllTimelines(). WidgetKit is Swift-only, so this hop is unavoidable.
5. Widget extension, in the TimelineProvider:

   let reader = WidgetFeedReader(appGroup: "group.com.example.app", schemaVersion: 1)
   let feed = reader?.read(QuoteFeed.self)
   let image = feed?.assetURL("q1.jpg").flatMap { UIImage(contentsOfFile: $0.path) }
   

   Your QuoteFeed is a plain Decodable mirroring the Kotlin @Serializable class.

The extension never imports the Kotlin framework. Storage is <App Group container>/widgetbridge. Simulator note: App Group containers work on the simulator without a paid team, but the entitlement must be present on both targets.