Performance: reduce memory footprint and idle energy use

AudioType/App/AudioTypeApp.swift

@@ -12,6 +12,7 @@ struct AudioTypeApp: App {
   }
 }
 
+@MainActor
 class AppDelegate: NSObject, NSApplicationDelegate {
   private var statusItem: NSStatusItem!
   private var menuBarController: MenuBarController!
@@ -49,8 +50,8 @@ class AppDelegate: NSObject, NSApplicationDelegate {
 
     // Show onboarding if permissions are missing or no engine is usable
     if !micPermission || !accessibilityPermission || !EngineResolver.anyEngineAvailable {
-      DispatchQueue.main.async {
-        self.showOnboarding()
+      await MainActor.run {
+        showOnboarding()
       }
     } else {
       // All set — start listening for hotkey

AudioType/App/MenuBarController.swift

@@ -17,18 +17,45 @@ extension NSImage {
   }
 }
 
-/// Shared observable for live audio level — drives the recording waveform.
+/// Shared observable for live audio level - drives the recording waveform.
+/// Also carries the overlay text so the hosting view doesn't have to be
+/// rebuilt on every state change.
 class AudioLevelMonitor: ObservableObject {
   static let shared = AudioLevelMonitor()
   @Published var level: Float = 0.0
+  @Published var overlayText: String = "Recording..."
 }
 
 class MenuBarController: NSObject, NSWindowDelegate {
   private weak var statusItem: NSStatusItem?
   private var transcriptionManager: TranscriptionManager
   private var recordingWindow: NSWindow?
+  private var recordingHostingView: NSHostingView<AnyView>?
   private var settingsWindow: NSWindow?
 
+  // Pre-rendered status-bar icons, built once. Calling NSImage.tinted on
+  // every state change re-rasterizes the symbol via lockFocus/unlockFocus
+  // and was a steady source of bitmap allocations.
+  private lazy var idleIcon: NSImage? = {
+    let img = NSImage(
+      systemSymbolName: "waveform.circle.fill", accessibilityDescription: "Ready")
+    img?.isTemplate = true
+    return img
+  }()
+  private lazy var recordingIcon: NSImage? = {
+    NSImage(systemSymbolName: "waveform.circle.fill", accessibilityDescription: "Recording")?
+      .tinted(with: AudioTypeTheme.nsRecordingRed)
+  }()
+  private lazy var processingIcon: NSImage? = {
+    NSImage(systemSymbolName: "ellipsis.circle.fill", accessibilityDescription: "Processing")?
+      .tinted(with: AudioTypeTheme.nsAmber)
+  }()
+  private lazy var errorIcon: NSImage? = {
+    NSImage(
+      systemSymbolName: "exclamationmark.triangle.fill", accessibilityDescription: "Error")?
+      .tinted(with: .systemRed)
+  }()
+
   init(transcriptionManager: TranscriptionManager) {
     self.transcriptionManager = transcriptionManager
     super.init()
@@ -50,6 +77,10 @@ class MenuBarController: NSObject, NSWindowDelegate {
     )
   }
 
+  deinit {
+    NotificationCenter.default.removeObserver(self)
+  }
+
   func setupStatusItem(_ statusItem: NSStatusItem) {
     self.statusItem = statusItem
 
@@ -106,38 +137,24 @@ class MenuBarController: NSObject, NSWindowDelegate {
 
     switch state {
     case .idle:
-      let img = NSImage(
-        systemSymbolName: "waveform.circle.fill", accessibilityDescription: "Ready")
-      img?.isTemplate = true
-      button.image = img
+      button.image = idleIcon
       AudioLevelMonitor.shared.level = 0
       hideRecordingIndicator()
       updateStatusMenuItem("Ready")
 
     case .recording:
-      // Tinted coral/red — non-template so the color shows through
-      if let base = NSImage(
-        systemSymbolName: "waveform.circle.fill", accessibilityDescription: "Recording") {
-        button.image = base.tinted(with: AudioTypeTheme.nsRecordingRed)
-      }
+      button.image = recordingIcon
       showRecordingIndicator()
       updateStatusMenuItem("Recording...")
 
     case .processing:
-      // Tinted amber — "I'm thinking"
-      if let base = NSImage(
-        systemSymbolName: "ellipsis.circle.fill", accessibilityDescription: "Processing") {
-        button.image = base.tinted(with: AudioTypeTheme.nsAmber)
-      }
+      button.image = processingIcon
       AudioLevelMonitor.shared.level = 0
       updateRecordingIndicator(text: "Processing...")
       updateStatusMenuItem("Processing...")
 
     case .error(let message):
-      let img = NSImage(
-        systemSymbolName: "exclamationmark.triangle.fill", accessibilityDescription: "Error")
-      img?.isTemplate = false
-      button.image = img?.tinted(with: .systemRed)
+      button.image = errorIcon
       hideRecordingIndicator()
       updateStatusMenuItem("Error: \(message)")
     }
@@ -175,22 +192,27 @@ class MenuBarController: NSObject, NSWindowDelegate {
       recordingWindow = window
     }
 
-    let hostingView = NSHostingView(
-      rootView: RecordingOverlay(text: "Recording...")
-        .environmentObject(AudioLevelMonitor.shared))
-    hostingView.frame = NSRect(x: 0, y: 0, width: 180, height: 50)
-    recordingWindow?.contentView = hostingView
+    // Build the hosting view once; subsequent updates just mutate the
+    // observable state. Re-creating NSHostingView on every state change
+    // was leaking the SwiftUI graph and Metal layers.
+    if recordingHostingView == nil {
+      let hosting = NSHostingView(
+        rootView: AnyView(
+          RecordingOverlay()
+            .environmentObject(AudioLevelMonitor.shared)
+        )
+      )
+      hosting.frame = NSRect(x: 0, y: 0, width: 180, height: 50)
+      recordingHostingView = hosting
+      recordingWindow?.contentView = hosting
+    }
+
+    AudioLevelMonitor.shared.overlayText = "Recording..."
     recordingWindow?.orderFront(nil)
   }
 
   private func updateRecordingIndicator(text: String) {
-    if let window = recordingWindow {
-      let hostingView = NSHostingView(
-        rootView: RecordingOverlay(text: text)
-          .environmentObject(AudioLevelMonitor.shared))
-      hostingView.frame = NSRect(x: 0, y: 0, width: 180, height: 50)
-      window.contentView = hostingView
-    }
+    AudioLevelMonitor.shared.overlayText = text
   }
 
   private func hideRecordingIndicator() {

AudioType/App/TranscriptionManager.swift

@@ -32,6 +32,11 @@ class TranscriptionManager: ObservableObject {
   private var hotKeyManager: HotKeyManager?
   private var textInserter: TextInserter?
 
+  /// Active transcription task. Held so a new recording can cancel any
+  /// in-flight transcription from a previous one (e.g. user re-triggers
+  /// the hotkey while the network call is still pending).
+  private var transcriptionTask: Task<Void, Never>?
+
   private let logger = Logger(subsystem: "com.audiotype", category: "TranscriptionManager")
 
   private init() {}
@@ -60,7 +65,7 @@ class TranscriptionManager: ObservableObject {
 
     if !EngineResolver.anyEngineAvailable {
       logger.warning("No transcription engine available")
-      setState(.error("No engine available — add a cloud API key or enable Apple Speech"))
+      setState(.error("No engine available - add a cloud API key or enable Apple Speech"))
     } else {
       logger.info("Transcription engine ready: \(engine.displayName)")
     }
@@ -85,15 +90,15 @@ class TranscriptionManager: ObservableObject {
     audioRecorder = nil
   }
 
-  /// Called when the user saves an API key or changes engine preference — re-evaluate.
+  /// Called when the user saves an API key or changes engine preference - re-evaluate.
   func onEngineConfigChanged() {
     let engine = EngineResolver.resolve()
     activeEngineName = engine.displayName
     if EngineResolver.anyEngineAvailable {
       setState(.idle)
       logger.info("Engine config changed, active engine: \(engine.displayName)")
     } else {
-      setState(.error("No engine available — add a cloud API key or enable Apple Speech"))
+      setState(.error("No engine available - add a cloud API key or enable Apple Speech"))
     }
   }
 
@@ -111,21 +116,37 @@ class TranscriptionManager: ObservableObject {
     }
   }
 
+  /// Engine resolved at recording start and reused for the matching
+  /// transcription. Keeps Keychain / availability checks out of the
+  /// post-stop hot path and ensures the engine identity doesn't change
+  /// mid-recording if the user edits settings.
+  private var activeEngine: TranscriptionEngine?
+
   private func startRecording() {
     guard state == .idle else {
       logger.warning("Cannot start recording: not in idle state")
       return
     }
 
     guard EngineResolver.anyEngineAvailable else {
-      setState(.error("No engine available — add a cloud API key or enable Apple Speech"))
+      setState(.error("No engine available - add a cloud API key or enable Apple Speech"))
       return
     }
 
+    // Cancel any still-pending transcription from a previous recording so
+    // we don't insert stale text into the user's new context.
+    transcriptionTask?.cancel()
+    transcriptionTask = nil
+
+    // Resolve the engine once, up front. transcribeAndInsert will reuse it.
+    let engine = EngineResolver.resolve()
+    activeEngine = engine
+    activeEngineName = engine.displayName
+
     do {
       try audioRecorder?.startRecording()
       setState(.recording)
-      logger.info("Recording started")
+      logger.info("Recording started with engine: \(engine.displayName)")
     } catch {
       logger.error("Failed to start recording: \(error.localizedDescription)")
       setState(.error("Failed to start recording"))
@@ -144,21 +165,22 @@ class TranscriptionManager: ObservableObject {
       return
     }
 
+    // Take the engine resolved at startRecording. Falls back to a fresh
+    // resolution defensively if somehow nil.
+    let engine = activeEngine ?? EngineResolver.resolve()
+    activeEngine = nil
+
     logger.info("Recording stopped, captured \(samples.count) samples")
     setState(.processing)
 
-    // Transcribe in background
-    Task.detached { [weak self] in
-      await self?.transcribeAndInsert(samples: samples)
+    // Transcribe in background. Hold the task so the next recording can
+    // cancel it if it's still pending.
+    transcriptionTask = Task.detached { [weak self] in
+      await self?.transcribeAndInsert(samples: samples, engine: engine)
     }
   }
 
-  private func transcribeAndInsert(samples: [Float]) async {
-    let engine = EngineResolver.resolve()
-
-    await MainActor.run {
-      self.activeEngineName = engine.displayName
-    }
+  private func transcribeAndInsert(samples: [Float], engine: TranscriptionEngine) async {
 
     let startTime = CFAbsoluteTimeGetCurrent()