TEMP: on-screen diagnostic overlay for the watch hang

Records recent ExerciseProgressView lifecycle/mutation events (init count, page changes, bridge updates, phase starts) and shows them as a green overlay so they can be read off a frozen screen on-device. To be reverted once the hang is diagnosed.

Workouts Watch App/Views/ExerciseProgressView.swift

@@ -8,6 +8,18 @@
 import SwiftUI
 import WatchKit
 
+// DIAGNOSTIC (temporary): records recent lifecycle/mutation events so the on-screen
+// overlay can show what ran right before a freeze. Remove once the hang is solved.
+enum PVDiag {
+    nonisolated(unsafe) static var initCount = 0
+    nonisolated(unsafe) static var lines: [String] = []
+    static func add(_ s: String) {
+        print("⌚️PV \(s)")
+        lines.append(s)
+        if lines.count > 7 { lines.removeFirst(lines.count - 7) }
+    }
+}
+
 /// Runs a single exercise as a horizontally-paged flow, mirroring the iPhone's:
 ///
 ///   [Ready] → Work₁ → Rest₁ → Work₂ → … → Workₙ → Finish
@@ -71,6 +83,8 @@ struct ExerciseProgressView: View {
         let completed = min(max(0, log?.currentStateIndex ?? 0), sets - 1)
         let resume = ready ? 0 : base + completed * 2
         _currentPage = State(initialValue: debugInitialPage ?? resume)
+        PVDiag.initCount += 1
+        PVDiag.add("init: ready=\(ready) page=\(debugInitialPage ?? resume) sets=\(sets) duration=\(LoadType(rawValue: log?.loadType ?? -1) == .duration)")
     }
 
     private var log: WorkoutLogDocument? {
@@ -152,6 +166,20 @@ struct ExerciseProgressView: View {
                     .padding(.bottom, 2)
             }
         }
+        // DIAGNOSTIC overlay (temporary): shows recent events; readable off a frozen screen.
+        .overlay(alignment: .top) {
+            VStack(alignment: .leading, spacing: 0) {
+                Text("init#\(PVDiag.initCount)").bold()
+                ForEach(Array(PVDiag.lines.enumerated()), id: \.offset) { _, line in
+                    Text(line)
+                }
+            }
+            .font(.system(size: 8, design: .monospaced))
+            .foregroundStyle(.green)
+            .frame(maxWidth: .infinity, alignment: .leading)
+            .background(.black.opacity(0.65))
+            .allowsHitTesting(false)
+        }
         .toolbar {
             ToolbarItem(placement: .cancellationAction) {
                 Button {
@@ -166,6 +194,7 @@ struct ExerciseProgressView: View {
             Button("Continue", role: .cancel) { }
         }
         .onChange(of: currentPage) { _, newPage in
+            PVDiag.add("currentPage -> \(newPage)")
             // Swiping all the way back to the Ready page wipes the run; any other page
             // records forward progress.
             if showsReady && newPage == 0 {
@@ -264,6 +293,7 @@ struct ExerciseProgressView: View {
 
     /// Flip a not-yet-started exercise to in-progress the moment the user taps Start.
     private func beginExercise() {
+        PVDiag.add("beginExercise -> onChange (bridge.update)")
         guard let i = doc.logs.firstIndex(where: { $0.id == logID }) else { return }
         guard doc.logs[i].status == WorkoutStatus.notStarted.rawValue else { return }
         doc.logs[i].status = WorkoutStatus.inProgress.rawValue
@@ -307,6 +337,7 @@ struct ExerciseProgressView: View {
         guard let i = doc.logs.firstIndex(where: { $0.id == logID }) else { return }
         guard reached > doc.logs[i].currentStateIndex else { return }
 
+        PVDiag.add("recordProgress reached=\(reached) -> onChange (bridge.update)")
         doc.logs[i].currentStateIndex = reached
         doc.logs[i].status = WorkoutStatus.inProgress.rawValue
         doc.logs[i].completed = false
@@ -324,6 +355,7 @@ struct ExerciseProgressView: View {
         guard log.currentStateIndex != 0
                 || log.status != WorkoutStatus.notStarted.rawValue
                 || log.completed else { return }
+        PVDiag.add("resetExercise -> onChange (bridge.update)")
         doc.logs[i].currentStateIndex = 0
         doc.logs[i].status = WorkoutStatus.notStarted.rawValue
         doc.logs[i].completed = false
@@ -548,6 +580,7 @@ private struct WorkPhaseView: View {
     }
 
     private func restart() {
+        PVDiag.add("work.restart set=\(setNumber) (beep)")
         startDate = Date()
         WorkoutHaptic.start.play()
     }
@@ -591,6 +624,7 @@ private struct CountdownPhaseView: View {
     }
 
     private func start() {
+        PVDiag.add("countdown.start '\(header)' seconds=\(seconds) (beep)")
         startDate = Date()
         endDate = startDate.addingTimeInterval(Double(max(1, seconds)))
         lastPingSecond = Int.max
@@ -606,6 +640,7 @@ private struct CountdownPhaseView: View {
         if remaining <= 0 {
             // Time's up — final cue and slide on. If the wrist was down the timer may have
             // stalled; this then fires on the first tick once the app gets runtime again.
+            PVDiag.add("countdown.finished '\(header)' -> advance")
             didFinish = true
             WorkoutHaptic.stop.play()
             onFinished()