From 69e30a99478f3381854c57169f949dccdb94f458 Mon Sep 17 00:00:00 2001
From: Javier Cicchelli <javier@rock-n-code.com>
Date: Sat, 4 Jul 2026 13:25:15 +0200
Subject: [PATCH] Improve the recording time with a monotonic clock to avoid
 timer drift on the RecordingViewModel view model in the Recording package
 target.

---
 .gitignore                                    |  1 +
 .../View Models/ContentViewModel.swift        |  8 +--
 .../View Models/RecordingViewModel.swift      | 54 ++++++++++++++++---
 3 files changed, 48 insertions(+), 15 deletions(-)

diff --git a/.gitignore b/.gitignore
index dc447df..81ab3da 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,6 +9,7 @@ xcuserdata/
 ## Build generated
 .build/
 DerivedData/
+Products/
 
 ## Various settings
 *.pbxuser
diff --git a/Apps/Attendi/View Models/ContentViewModel.swift b/Apps/Attendi/View Models/ContentViewModel.swift
index 7f4470e..cc89d41 100644
--- a/Apps/Attendi/View Models/ContentViewModel.swift	
+++ b/Apps/Attendi/View Models/ContentViewModel.swift	
@@ -51,13 +51,7 @@ extension ContentView {
         /// supported equivalent of its current value so the locale picker starts with a valid selection.
         func load() async {
             locales = await SpeechTranscriber.supportedLocales.sorted {
-                name(for: $0) < name(for: $1)
-            }
-
-            if let equivalent = await SpeechTranscriber.supportedLocale(
-                equivalentTo: locale
-            ) {
-                locale = equivalent
+                name(for: $0).localizedStandardCompare(name(for: $1)) == .orderedAscending
             }
         }
         
diff --git a/Packages/Features/Sources/Recording/View Models/RecordingViewModel.swift b/Packages/Features/Sources/Recording/View Models/RecordingViewModel.swift
index 2e0b5a4..bc5c4cf 100644
--- a/Packages/Features/Sources/Recording/View Models/RecordingViewModel.swift	
+++ b/Packages/Features/Sources/Recording/View Models/RecordingViewModel.swift	
@@ -23,6 +23,18 @@ extension RecordingView {
         /// The transcription of the last processed recording, or `nil` when none has been processed yet.
         private(set) var transcription: Transcription?
 
+        /// The recording time accumulated by earlier recording stretches, up to the last pause.
+        @ObservationIgnored
+        private var accumulated: Duration = .zero
+
+        /// The instant the current recording stretch started, or `nil` while not recording.
+        @ObservationIgnored
+        private var anchor: ContinuousClock.Instant?
+
+        /// The clock that measures the recording time.
+        @ObservationIgnored
+        private let clock = ContinuousClock()
+
         /// The binding to the locale of the spoken language to transcribe.
         @ObservationIgnored
         private let locale: Binding<Locale>
@@ -31,7 +43,7 @@ extension RecordingView {
         @ObservationIgnored
         private let recorder: any RecordingService
 
-        /// The task that increments ``elapsedSeconds`` every second while recording.
+        /// The task that updates ``elapsedSeconds`` from the measured recording time once per second while recording.
         @ObservationIgnored
         private var taskTimer: Task<Void, Never>?
 
@@ -180,6 +192,17 @@ extension RecordingView {
 
 private extension RecordingView.Model {
 
+    // MARK: Computed
+
+    /// The time spent recording so far, excluding any time spent paused, as measured by the clock.
+    var elapsed: Duration {
+        guard let anchor else {
+            return accumulated
+        }
+
+        return accumulated + anchor.duration(to: clock.now)
+    }
+
     // MARK: Methods
 
     /// Processes the recorded input: it stops the audio capture, transcribes the captured audio, and publishes the result in ``transcription``;
@@ -200,6 +223,7 @@ private extension RecordingView.Model {
             transcription = nil
         }
 
+        accumulated = .zero
         elapsedSeconds = 0
         state = .notRecording
     }
@@ -223,34 +247,48 @@ private extension RecordingView.Model {
         }
     }
 
-    /// Starts the timer task, which increments ``elapsedSeconds`` once per second until it is cancelled. Any previously running timer task is cancelled first.
+    /// Starts the timer task, which updates ``elapsedSeconds`` from the time measured by the clock on every whole second until it is
+    /// cancelled, so scheduling latency never accumulates as drift. Any previously running timer task is cancelled first.
     ///
-    /// - Parameter shouldRestartTimer: Whether ``elapsedSeconds`` and ``transcription`` should be cleared before the timer starts,
-    /// which is the case for a new recording as opposed to one resuming from a pause.
+    /// - Parameter shouldRestartTimer: Whether the measured recording time, ``elapsedSeconds``, and ``transcription`` should be
+    /// cleared before the timer starts, which is the case for a new recording as opposed to one resuming from a pause.
     func startTimer(
         _ shouldRestartTimer: Bool
     ) {
         if shouldRestartTimer {
+            accumulated = .zero
             elapsedSeconds = 0
             transcription = nil
         }
 
+        anchor = clock.now
+
         taskTimer?.cancel()
         taskTimer = Task { [weak self] in
             while !Task.isCancelled {
-                try? await Task.sleep(for: .seconds(1))
-
                 guard let self, !Task.isCancelled else {
                     return
                 }
 
-                self.elapsedSeconds += 1
+                let elapsed = self.elapsed
+                let seconds = elapsed.components.seconds
+
+                self.elapsedSeconds = Int(seconds)
+
+                try? await Task.sleep(for: .seconds(seconds + 1) - elapsed)
             }
         }
     }
 
-    /// Stops the timer task, if any, keeping ``elapsedSeconds`` at its current value.
+    /// Stops the timer task, if any, folding the current recording stretch into the accumulated recording time so ``elapsedSeconds``
+    /// keeps its value.
     func stopTimer() {
+        if let anchor {
+            accumulated += anchor.duration(to: clock.now)
+
+            self.anchor = nil
+        }
+
         taskTimer?.cancel()
         taskTimer = nil
     }