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name: watchos-code-review description: Reviews watchOS code for app lifecycle, complications (ClockKit/WidgetKit), WatchConnectivity, and performance constraints. Use when reviewing code with import WatchKit, WKExtension, WKApplicationDelegate, WCSession, or watchOS-specific patterns.

watchOS Code Review

Quick Reference

Review Checklist

• SwiftUI App protocol used with @WKApplicationDelegateAdaptor for lifecycle events
• scenePhase read from root view (not sheets/modals where it's always .active)
• WKExtendedRuntimeSession started only while app is active (not from background)
• Workout sessions recovered in applicationDidFinishLaunching (not just delegate)
• Background tasks scheduled at least 5 minutes apart; next scheduled before completing current
• URLSessionDownloadTask (not DataTask) used for background network requests
• WidgetKit used instead of ClockKit for watchOS 9+ complications
• Timeline includes future entries (not just current state); gaps avoided
• TimelineEntryRelevance implemented for Smart Stack prioritization
• WCSession delegate set before activate(); singleton pattern used
• isReachable checked before sendMessage; transferUserInfo for critical data
• Received files moved synchronously before delegate callback returns

When to Load References

• Reviewing app lifecycle, background modes, or extended sessions -> lifecycle.md
• Reviewing complications, widgets, or timeline providers -> complications.md
• Reviewing WCSession, iPhone-Watch communication -> connectivity.md
• Reviewing memory, battery, or performance issues -> performance.md

Review Questions

1. Is the app using modern SwiftUI lifecycle with delegate adaptor?
2. Are background tasks completing properly (calling setTaskCompletedWithSnapshot)?
3. Is UI update frequency reduced when isLuminanceReduced is true?
4. Are WatchConnectivity delegate callbacks dispatching to main thread?
5. Is TabView nested within another TabView? (Memory leak on watchOS)