Keep the iPhone screen awake for the whole app session

Move the idle-timer disable out of ExerciseView/ExerciseProgressView and
up to the app scene, re-asserting it whenever the scene becomes active
(iOS clears the flag on background). A propped-up phone now stays lit for
the entire workout, not just while an exercise is open.

Claude-Session: https://claude.ai/code/session_01SCv7zvGFcKy47KSTnTLxRe

CHANGELOG.md

@@ -10,7 +10,7 @@ Tapping an exercise on iPhone now opens a paged workout run — the same Ready
 
 The exercise detail and edit screen moved behind an Edit swipe on the trailing edge; the leading swipe still completes a set.
 
-The iPhone screen now stays awake while an exercise is open, so it no longer sleeps mid-set.
+The iPhone screen now stays awake the whole time the app is open, so a propped-up phone never sleeps during a workout.
 
 The Apple Watch is now a focused workout runner: it opens on the active workout's exercises (or prompts you to start one on iPhone) and lists every in-progress workout at the root.
 

Workouts/Views/WorkoutLogs/ExerciseProgressView.swift

@@ -181,8 +181,6 @@ struct ExerciseProgressView: View {
             }
         }
         .onAppear {
-            // Keep the screen lit while logging — a mid-workout sleep is annoying.
-            UIApplication.shared.isIdleTimerDisabled = true
             guard !didRestorePage else { return }
             if startsResumed {
                 // Resume on the first unfinished set. A paged TabView can settle on page 0
@@ -199,9 +197,6 @@ struct ExerciseProgressView: View {
                 didRestorePage = true
             }
         }
-        .onDisappear {
-            UIApplication.shared.isIdleTimerDisabled = false
-        }
     }
 
     /// Move to the resume page without animation, only if we're not already there

Workouts/Views/WorkoutLogs/ExerciseView.swift

@@ -10,7 +10,6 @@
 import SwiftUI
 import SwiftData
 import Charts
-import UIKit
 
 struct ExerciseView: View {
     @Environment(SyncEngine.self) private var sync
@@ -68,13 +67,10 @@ struct ExerciseView: View {
         .onAppear {
             refreshDocIfNeeded()
             progress = log?.currentStateIndex ?? 0
-            // Keep the screen lit while logging sets — a mid-workout sleep is annoying.
-            UIApplication.shared.isIdleTimerDisabled = true
             // Take over this run: the watch parks and locks it while we're editing here.
             services.watchBridge.setEditingWorkout(workout.id)
         }
         .onDisappear {
-            UIApplication.shared.isIdleTimerDisabled = false
             services.watchBridge.setEditingWorkout(nil)
         }
         // Reflect external changes (e.g. a set completed on the watch) live. Each edit

Workouts/WorkoutsApp.swift

@@ -7,10 +7,12 @@
 
 import SwiftUI
 import SwiftData
+import UIKit
 
 @main
 struct WorkoutsApp: App {
     @State private var services = AppServices()
+    @Environment(\.scenePhase) private var scenePhase
 
     var body: some Scene {
         WindowGroup {
@@ -24,6 +26,12 @@ struct WorkoutsApp: App {
             root
             #endif
         }
+        // Keep the screen lit for the whole app, not just while logging — the phone is
+        // often propped up across the room during a workout. iOS clears this flag when
+        // the app is backgrounded, so re-assert it each time the scene becomes active.
+        .onChange(of: scenePhase, initial: true) { _, phase in
+            UIApplication.shared.isIdleTimerDisabled = (phase == .active)
+        }
     }
 
     private var root: some View {