Perf/reduce main thread load

GooseSwift/ActivitySessionModel.swift

@@ -14,6 +14,16 @@ final class ActivitySessionModel: ObservableObject {
   @Published private(set) var maxHeartRate: Int?
   @Published private(set) var zoneDurations: [Int: TimeInterval] = [:]
 
+  // Private backing stores updated at full 60 Hz sample rate.
+  // @Published properties are only flushed at uiPublishInterval to avoid
+  // driving a SwiftUI re-render on every sample tick.
+  private var _elapsed: TimeInterval = 0
+  private var _averageHeartRate: Int?
+  private var _maxHeartRate: Int?
+  private var _zoneDurations: [Int: TimeInterval] = [:]
+  private var lastPublishedAt: Date = .distantPast
+  private static let uiPublishInterval: TimeInterval = 1.0 / 4.0
+
   private var lastTick: Date?
   private var heartRateWeightedTotal: Double = 0
   private var heartRateMeasuredSeconds: TimeInterval = 0
@@ -71,6 +81,7 @@ final class ActivitySessionModel: ObservableObject {
       return
     }
     tick(now: now, heartRate: heartRate)
+    flushToUI(now: now)  // ensure latest samples are visible before pausing
     isPaused = true
     lastTick = nil
     timer?.invalidate()
@@ -82,6 +93,7 @@ final class ActivitySessionModel: ObservableObject {
       return
     }
     tick(now: now, heartRate: heartRate)
+    flushToUI(now: now)  // flush final sample before clearing state
     isActive = false
     isPaused = false
     endedAt = now
@@ -97,18 +109,31 @@ final class ActivitySessionModel: ObservableObject {
     }
     let previousTick = lastTick ?? now
     let delta = max(0, now.timeIntervalSince(previousTick))
-    elapsed += delta
+    _elapsed += delta
     lastTick = now
 
-    guard delta > 0, let heartRate else {
-      return
+    if delta > 0, let heartRate {
+      let zoneID = HeartRateZone.zoneID(for: heartRate)
+      _zoneDurations[zoneID, default: 0] += delta
+      heartRateWeightedTotal += Double(heartRate) * delta
+      heartRateMeasuredSeconds += delta
+      _averageHeartRate = Int((heartRateWeightedTotal / max(heartRateMeasuredSeconds, 1)).rounded())
+      _maxHeartRate = max(_maxHeartRate ?? heartRate, heartRate)
+    }
+
+    if now.timeIntervalSince(lastPublishedAt) >= Self.uiPublishInterval {
+      flushToUI(now: now)
     }
-    let zoneID = HeartRateZone.zoneID(for: heartRate)
-    zoneDurations[zoneID, default: 0] += delta
-    heartRateWeightedTotal += Double(heartRate) * delta
-    heartRateMeasuredSeconds += delta
-    averageHeartRate = Int((heartRateWeightedTotal / max(heartRateMeasuredSeconds, 1)).rounded())
-    maxHeartRate = max(maxHeartRate ?? heartRate, heartRate)
+  }
+
+  // Copies backing-store values into the @Published properties in a single
+  // synchronous block so SwiftUI coalesces them into one re-render.
+  private func flushToUI(now: Date) {
+    lastPublishedAt = now
+    elapsed = _elapsed
+    averageHeartRate = _averageHeartRate
+    maxHeartRate = _maxHeartRate
+    zoneDurations = _zoneDurations
   }
 
   private func scheduleTimer() {
@@ -130,13 +155,18 @@ final class ActivitySessionModel: ObservableObject {
     if !keepingSelection {
       selectedActivity = .run
     }
+    _elapsed = 0
+    _averageHeartRate = nil
+    _maxHeartRate = nil
+    _zoneDurations = [:]
+    heartRateWeightedTotal = 0
+    heartRateMeasuredSeconds = 0
+    lastTick = nil
+    lastPublishedAt = .distantPast
     elapsed = 0
     averageHeartRate = nil
     maxHeartRate = nil
     zoneDurations = [:]
-    heartRateWeightedTotal = 0
-    heartRateMeasuredSeconds = 0
-    lastTick = nil
     startedAt = nil
     endedAt = nil
     isActive = false

GooseSwift/GooseAppModel+Lifecycle.swift

@@ -73,8 +73,14 @@ extension GooseAppModel {
   }
 
   func applyHeartRateTimelineSnapshot(_ snapshot: HeartRateTimelineSnapshot) {
-    heartRateHourlyRanges = snapshot.ranges
-    heartRateStorageStatus = snapshot.status
+    // Equality guard: the pipeline fires every 1 s; avoid a spurious objectWillChange
+    // (and full-view re-render of all GooseAppModel observers) when the data is unchanged.
+    if snapshot.ranges != heartRateHourlyRanges {
+      heartRateHourlyRanges = snapshot.ranges
+    }
+    if snapshot.status != heartRateStorageStatus {
+      heartRateStorageStatus = snapshot.status
+    }
   }
 
   func handleBLEConnectionStateChange(_ state: String) {

GooseSwift/GooseAppModel+PacketPublishing.swift

@@ -666,7 +666,10 @@ extension GooseAppModel {
     }
 
     movementPacketValidation.ingest(sample)
-    movementPacketValidationStatus = movementPacketValidation.statusSummary
+    let newValidationStatus = movementPacketValidation.statusSummary
+    if newValidationStatus != movementPacketValidationStatus {
+      movementPacketValidationStatus = newValidationStatus
+    }
     ble.record(
       level: .debug,
       source: "activity.detect",
@@ -703,6 +706,9 @@ extension GooseAppModel {
     for event in events {
       switch event {
       case .status(let status):
+        // Guard prevents @Published objectWillChange from firing when the status string
+        // repeats unchanged across consecutive movement packets.
+        guard status != activityDetectionStatus else { break }
         activityDetectionStatus = status
       case .primeGPS(let reason):
         activityDetectionStatus = "Movement detected; priming GPS"

GooseSwift/GooseMessageStore.swift

@@ -47,10 +47,10 @@ final class GooseMessageStore: ObservableObject {
       return
     }
 
-    messages.insert(contentsOf: pendingMessages.reversed(), at: 0)
+    // Concatenation is O(n+k); insert-at-0 with shift is also O(n) but forces a copy of the
+    // entire backing store. Using + avoids mutating the existing buffer in-place.
+    let merged = pendingMessages.reversed() + messages
     pendingMessages.removeAll(keepingCapacity: true)
-    if messages.count > maximumMessages {
-      messages.removeLast(messages.count - maximumMessages)
-    }
+    messages = merged.count > maximumMessages ? Array(merged.prefix(maximumMessages)) : Array(merged)
   }
 }

GooseSwift/HomeDashboardView.swift

@@ -11,24 +11,26 @@ struct HomeDashboardView: View {
   @State private var selectedHealthMonitorTrend: HealthMetricSnapshot?
 
   var body: some View {
+    // Compute once per render — avoids calling healthStore.landingSnapshots(…) 9× per body pass.
+    let cached = landingSnapshots
     ScrollView {
       LazyVStack(alignment: .leading, spacing: 18) {
         HomeDailyScoreCard(
-          scores: scoreSnapshots,
+          scores: scoreSnapshots(using: cached),
           actionSummary: dailyActionSummary,
           coachTip: CoachTipFactory.homeTip(healthStore: healthStore, appModel: model),
           openScore: openHealth,
           openCoach: openCoach
         )
 
         HomeStressEnergySection(
-          stress: landingSnapshot(for: .stress),
-          energy: landingSnapshot(for: .energyBank),
+          stress: landingSnapshot(for: .stress, in: cached),
+          energy: landingSnapshot(for: .energyBank, in: cached),
           openStress: { openHealth(.stress) }
         )
 
         HomeCardioLoadWidget(
-          snapshot: landingSnapshot(for: .cardioLoad),
+          snapshot: landingSnapshot(for: .cardioLoad, in: cached),
           days: healthStore.cardioLoadWeeklyPoints()
         ) {
           showingCardioLoadSheet = true
@@ -41,9 +43,9 @@ struct HomeDashboardView: View {
         )
 
         HomeTimelineSection(
-          sleep: homeSnapshot(for: .sleep),
-          activity: homeSnapshot(for: .strain),
-          recovery: homeSnapshot(for: .recovery),
+          sleep: homeSnapshot(for: .sleep, in: cached),
+          activity: homeSnapshot(for: .strain, in: cached),
+          recovery: homeSnapshot(for: .recovery, in: cached),
           activities: model.homeActivityTimelineItems,
           openSleep: { openHealth(.sleep) },
           openActivity: { openHealth(.strain) },
@@ -100,10 +102,11 @@ struct HomeDashboardView: View {
       model.refreshActivityTimeline(for: newValue)
     }
     .sheet(isPresented: $showingScoreDatePicker) {
+      let cached = landingSnapshots
       ScoreDatePickerSheet(
         title: "Daily Scores",
         routes: [.sleep, .recovery, .strain],
-        snapshots: scorePickerSnapshots,
+        snapshots: scorePickerSnapshots(using: cached),
         selectedDate: $selectedDate
       )
     }
@@ -115,19 +118,19 @@ struct HomeDashboardView: View {
     }
   }
 
-  private var scoreSnapshots: [HealthMetricSnapshot] {
+  private func scoreSnapshots(using cached: [HealthMetricSnapshot]) -> [HealthMetricSnapshot] {
     [
-      datedHomeSnapshot(for: .sleep),
-      datedHomeSnapshot(for: .recovery),
-      datedHomeSnapshot(for: .strain),
+      datedHomeSnapshot(for: .sleep, in: cached),
+      datedHomeSnapshot(for: .recovery, in: cached),
+      datedHomeSnapshot(for: .strain, in: cached),
     ]
   }
 
-  private var scorePickerSnapshots: [HealthMetricSnapshot] {
+  private func scorePickerSnapshots(using cached: [HealthMetricSnapshot]) -> [HealthMetricSnapshot] {
     [
-      homeSnapshot(for: .sleep),
-      homeSnapshot(for: .recovery),
-      homeSnapshot(for: .strain),
+      homeSnapshot(for: .sleep, in: cached),
+      homeSnapshot(for: .recovery, in: cached),
+      homeSnapshot(for: .strain, in: cached),
     ]
   }
 
@@ -165,12 +168,12 @@ struct HomeDashboardView: View {
     )
   }
 
-  private func landingSnapshot(for route: HealthRoute) -> HealthMetricSnapshot {
-    landingSnapshots.first { $0.route == route } ?? healthStore.snapshot(for: route)
+  private func landingSnapshot(for route: HealthRoute, in snapshots: [HealthMetricSnapshot]) -> HealthMetricSnapshot {
+    snapshots.first { $0.route == route } ?? healthStore.snapshot(for: route)
   }
 
-  private func homeSnapshot(for route: HealthRoute) -> HealthMetricSnapshot {
-    let snapshot = landingSnapshot(for: route)
+  private func homeSnapshot(for route: HealthRoute, in snapshots: [HealthMetricSnapshot]) -> HealthMetricSnapshot {
+    let snapshot = landingSnapshot(for: route, in: snapshots)
     guard route == .strain, snapshot.unit != "%" else {
       return snapshot
     }
@@ -193,8 +196,8 @@ struct HomeDashboardView: View {
     )
   }
 
-  private func datedHomeSnapshot(for route: HealthRoute) -> HealthMetricSnapshot {
-    ScoreDateTimeline.datedSnapshot(from: homeSnapshot(for: route), date: selectedDate)
+  private func datedHomeSnapshot(for route: HealthRoute, in snapshots: [HealthMetricSnapshot]) -> HealthMetricSnapshot {
+    ScoreDateTimeline.datedSnapshot(from: homeSnapshot(for: route, in: snapshots), date: selectedDate)
   }
 
   private func openHealth(_ route: HealthRoute) {