Fix 440 MB leak from re-evaluated .tabItem labels

ContentView declared an @EnvironmentObject it never read, so every
SystemMonitor publish (3 s by default) re-evaluated its body. On macOS
the AppKit tab bridge permanently retains the AnyView(Label(...)) behind
each .tabItem, leaking ~6 KB per tick — 519 MB after three days of
uptime, >90% of the process footprint.

Keep the TabView shells free of observable dependencies:

- ContentView: drop the unused @EnvironmentObject, so the body is
  evaluated exactly once.
- SettingsView: split the shell from its two tabs, which now own the
  AppSettings observation (dragging a threshold slider leaked 2 labels
  per step).
- PerformanceView: drop the write-only selection binding (3 labels per
  sub-tab switch).

Two smaller wins while in here:

- GPUMonitor leaked one io_object per GPU poll: leaving a
  `defer { release; IOIteratorNext }` loop via break/return hands back an
  object nobody releases. Replaced with firstMatch(in:), and removed a
  never-released iterator in getAppleSiliconChipName.
- MetricsStore re-encoded the whole 20k-sample history to JSON every
  30 s; saveEvery 10 -> 40 (~2 min). flush() on quit and on background
  is unchanged.

Measured over 10 minutes (~200 refresh cycles): footprint 86-123 MB with
no upward trend, leaked Label views pinned at 4 — the tab items
themselves. Was 519 MB and climbing ~170 MB/day. 55/55 unit tests pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

TopManager/Services/GPUMonitor.swift

@@ -86,14 +86,8 @@ final class GPUMonitor {
     }
 
     private static func getAppleSiliconChipName() -> String? {
-        let matchingDict = IOServiceMatching("IOPlatformExpertDevice")
-        var service: io_service_t = 0
-
-        guard IOServiceGetMatchingServices(kIOMainPortDefault, matchingDict, &service) == KERN_SUCCESS else {
-            return nil
-        }
-
         let platformExpert = IOServiceGetMatchingService(kIOMainPortDefault, IOServiceMatching("IOPlatformExpertDevice"))
+        guard platformExpert != 0 else { return nil }
         defer { IOObjectRelease(platformExpert) }
 
         if let modelData = IORegistryEntryCreateCFProperty(
@@ -125,6 +119,25 @@ final class GPUMonitor {
         }
     }
 
+    /// Walks an `io_iterator_t` and returns the first non-`nil` value `body`
+    /// produces, releasing **every** object it pulled out of the iterator.
+    ///
+    /// The obvious `while` + `defer { release; next() }` shape leaks one
+    /// `io_object_t` whenever the loop is left with `break`/`return`, because
+    /// the deferred `IOIteratorNext` hands back an object nobody releases. At a
+    /// GPU poll every few seconds that leaks tens of thousands of mach port
+    /// rights per day.
+    private static func firstMatch<T>(in iterator: io_iterator_t, _ body: (io_service_t) -> T?) -> T? {
+        var result: T?
+        while result == nil {
+            let service = IOIteratorNext(iterator)
+            guard service != 0 else { break }
+            result = body(service)
+            IOObjectRelease(service)
+        }
+        return result
+    }
+
     private func fetchAppleSiliconGPUInfo() -> GPUInfo? {
         // Apple Silicon uses unified memory - get memory pressure instead
         let totalMemory = ProcessInfo.processInfo.physicalMemory
@@ -139,19 +152,13 @@ final class GPUMonitor {
         if IOServiceGetMatchingServices(kIOMainPortDefault, matchingDict, &iterator) == KERN_SUCCESS {
             defer { IOObjectRelease(iterator) }
 
-            var service = IOIteratorNext(iterator)
-            while service != 0 {
-                defer {
-                    IOObjectRelease(service)
-                    service = IOIteratorNext(iterator)
-                }
-
-                if let props = IORegistryEntryCreateCFProperty(
+            _ = Self.firstMatch(in: iterator) { service -> Bool? in
+                guard let props = IORegistryEntryCreateCFProperty(
                     service,
                     "PerformanceStatistics" as CFString,
                     kCFAllocatorDefault,
                     0
-                )?.takeRetainedValue() as? [String: Any] {
+                )?.takeRetainedValue() as? [String: Any] else { return nil }
 
                 // Try various keys for GPU memory on Apple Silicon
                 if let inUse = props["In use system memory"] as? UInt64 {
@@ -169,8 +176,7 @@ final class GPUMonitor {
                     utilizationPercent = Double(util)
                 }
 
-                    break
-                }
+                return true
             }
         }
 
@@ -194,13 +200,7 @@ final class GPUMonitor {
         }
         defer { IOObjectRelease(iterator) }
 
-        var service = IOIteratorNext(iterator)
-        while service != 0 {
-            defer {
-                IOObjectRelease(service)
-                service = IOIteratorNext(iterator)
-            }
-
+        return Self.firstMatch(in: iterator) { service -> GPUInfo? in
             var name = "GPU"
             if let modelData = IORegistryEntryCreateCFProperty(
                 service,
@@ -246,8 +246,8 @@ final class GPUMonitor {
                     isUnifiedMemory: false
                 )
             }
-        }
 
             return nil
         }
     }
+}

TopManager/Services/MetricsStore.swift

@@ -107,10 +107,16 @@ final class MetricsStore {
     private var unsaved = 0
     private let ioQueue = DispatchQueue(label: "com.topmanager.metricsstore.io", qos: .utility)
 
+    /// - Note: `saveEvery` is deliberately coarse. Every save re-encodes the
+    ///   *whole* history (up to `maxCount` samples), which costs a few hundred
+    ///   thousand transient allocations; at the old cadence of 10 that ran twice
+    ///   a minute and kept the malloc small zone needlessly dirty. 40 samples is
+    ///   ~2 minutes at the default 3 s refresh, and `flush()` still runs on quit
+    ///   and when the app goes to the background.
     init(fileURL: URL? = nil,
          maxAge: TimeInterval = 24 * 60 * 60,
          maxCount: Int = 20_000,
-         saveEvery: Int = 10) {
+         saveEvery: Int = 40) {
         self.fileURL = fileURL ?? Self.defaultFileURL()
         self.maxAge = maxAge
         self.maxCount = maxCount

TopManager/Views/ContentView.swift

@@ -1,8 +1,15 @@
 import SwiftUI
 
+/// The main window's tab shell.
+///
+/// IMPORTANT: this view must stay free of any observable dependency
+/// (`@EnvironmentObject`, `@StateObject`, `@State`, …). On macOS, every
+/// re-evaluation of a body containing `.tabItem` permanently retains the
+/// wrapped `AnyView(Label(…))` inside the AppKit tab bridge, so a body that
+/// re-runs on the monitor's refresh cadence leaks ~6 KB per tick (≈440 MB over
+/// three days). With no stored properties SwiftUI evaluates this body exactly
+/// once. The tab *contents* observe `SystemMonitor` themselves.
 struct ContentView: View {
-    @EnvironmentObject var monitor: SystemMonitor
-
     var body: some View {
         TabView {
             ProcessView()

TopManager/Views/Performance/PerformanceView.swift

@@ -1,28 +1,26 @@
 import SwiftUI
 import Charts
 
+/// Sub-tab shell for the Performance tab. The selection is left to SwiftUI on
+/// purpose: an explicit `@State` binding would re-evaluate this body — and so
+/// leak its `.tabItem` labels — on every tab switch. See `ContentView`.
 struct PerformanceView: View {
-    @State private var selectedTab = 0
-
     var body: some View {
-        TabView(selection: $selectedTab) {
+        TabView {
             CPUTabView()
                 .tabItem {
                     Label("CPU", systemImage: "cpu")
                 }
-                .tag(0)
 
             MemoryTabView()
                 .tabItem {
                     Label("Memory", systemImage: "memorychip")
                 }
-                .tag(1)
 
             NetworkTabView()
                 .tabItem {
                     Label("Network", systemImage: "network")
                 }
-                .tag(2)
         }
     }
 }

TopManager/Views/SettingsView.swift

@@ -1,20 +1,26 @@
 import SwiftUI
 
+/// Settings window shell. Like `ContentView`, it deliberately observes nothing:
+/// a body containing `.tabItem` leaks its `AnyView(Label(…))` on every
+/// re-evaluation, and dragging a threshold slider re-publishes `AppSettings`
+/// on every step. The tabs below own the observation instead.
 struct SettingsView: View {
-    @EnvironmentObject var settings: AppSettings
-
     var body: some View {
         TabView {
-            generalTab
+            GeneralSettingsTab()
                 .tabItem { Label("General", systemImage: "gearshape") }
-            alertsTab
+            AlertSettingsTab()
                 .tabItem { Label("Alerts", systemImage: "bell") }
         }
         .frame(width: 440, height: 340)
         .padding()
     }
+}
 
-    private var generalTab: some View {
+private struct GeneralSettingsTab: View {
+    @EnvironmentObject var settings: AppSettings
+
+    var body: some View {
         Form {
             Section {
                 Toggle("Launch at login", isOn: $settings.launchAtLogin)
@@ -41,8 +47,12 @@ struct SettingsView: View {
         }
         .formStyle(.grouped)
     }
+}
 
-    private var alertsTab: some View {
+private struct AlertSettingsTab: View {
+    @EnvironmentObject var settings: AppSettings
+
+    var body: some View {
         Form {
             Section {
                 Toggle("Enable notifications", isOn: $settings.notificationsEnabled)