Park the Watch run while iPhone edits an exercise or split

Publish an exclusive-edit lock (editingWorkoutID / editingSplitID) in the
phone→watch application context. While the phone has a workout's exercise
(ExerciseView) or a split (SplitDetailView) open in an editor, the watch pops
out of that run, blocks re-entry, and shows it as "Editing on iPhone" — so the
two devices never drive the same run at once and the watch can't clobber the
phone's edit with a stale optimistic write. The lock clears when the editor
closes; absent keys in the latest-wins context mean "not editing".

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

Workouts/Connectivity/PhoneConnectivityBridge.swift

@@ -14,6 +14,14 @@ final class PhoneConnectivityBridge: NSObject {
     private let syncEngine: SyncEngine
     private var session: WCSession?
 
+    /// Exclusive-edit lock published to the watch. While the phone has a workout's
+    /// exercise (or a split) open in an editor, the watch parks any matching run and
+    /// blocks re-entry — so the two devices never drive the same run at once. Included in
+    /// every `pushAll` (the latest-wins context replaces wholesale, so a push that omitted
+    /// them would clear the lock prematurely).
+    private(set) var editingWorkoutID: String?
+    private(set) var editingSplitID: String?
+
     private var context: ModelContext { container.mainContext }
 
     init(container: ModelContainer, syncEngine: SyncEngine) {
@@ -48,11 +56,30 @@ final class PhoneConnectivityBridge: NSObject {
             splits: splits.map(SplitDocument.init(from:)),
             workouts: workouts.map(WorkoutDocument.init(from:)),
             restSeconds: restSeconds,
-            doneCountdownSeconds: doneCountdownSeconds
+            doneCountdownSeconds: doneCountdownSeconds,
+            editingWorkoutID: editingWorkoutID,
+            editingSplitID: editingSplitID
         )
         try? session.updateApplicationContext(payload)
     }
 
+    /// Mark (or clear, with `nil`) the workout currently open in a phone exercise editor.
+    /// The watch parks that run and blocks re-entry until it clears. Pushes immediately so
+    /// the lock takes effect without waiting on a cache change.
+    func setEditingWorkout(_ id: String?) {
+        guard editingWorkoutID != id else { return }
+        editingWorkoutID = id
+        pushAll()
+    }
+
+    /// Mark (or clear, with `nil`) the split currently open in a phone editor. The watch
+    /// parks any active run sourced from that split (matched by `splitID`).
+    func setEditingSplit(_ id: String?) {
+        guard editingSplitID != id else { return }
+        editingSplitID = id
+        pushAll()
+    }
+
     /// Parse the (non-Sendable) WC dictionary in the nonisolated delegate context,
     /// then hop to the MainActor with only Sendable values.
     nonisolated private func route(_ dict: [String: Any]) {

Workouts/Views/Splits/SplitDetailView.swift

@@ -12,6 +12,7 @@ import SwiftData
 
 struct SplitDetailView: View {
     @Environment(SyncEngine.self) private var sync
+    @Environment(AppServices.self) private var services
     @Environment(\.dismiss) private var dismiss
 
     var split: Split
@@ -109,6 +110,11 @@ struct SplitDetailView: View {
         } message: { item in
             Text("Remove \"\(item.name)\" from this split?")
         }
+        // Editing this split (or any of its exercises, all reached from here) parks any
+        // active watch run sourced from it — matched by splitID — so the watch can't keep
+        // performing an exercise whose plan we're reconfiguring.
+        .onAppear { services.watchBridge.setEditingSplit(split.id) }
+        .onDisappear { services.watchBridge.setEditingSplit(nil) }
     }
 
     private func moveExercises(from source: IndexSet, to destination: Int) {

Workouts/Views/WorkoutLogs/ExerciseView.swift

@@ -14,6 +14,7 @@ import UIKit
 
 struct ExerciseView: View {
     @Environment(SyncEngine.self) private var sync
+    @Environment(AppServices.self) private var services
     @Environment(\.dismiss) private var dismiss
 
     let workout: Workout
@@ -69,9 +70,12 @@ struct ExerciseView: View {
             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
         // rewrites the whole workout file, so the cache always holds the latest — pulling