feat(captions): add caption history tracking and improve transcription

Add descriptive change tracking for all caption settings in the history
popover. Improve transcription performance with .all compute options,
higher concurrency, and monotonic progress reporting.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jkuri

Reframed/Editor/History.swift

@@ -219,6 +219,16 @@ final class History {
       changes.append("Camera background set to \(describeCameraBackground(new.cameraBackgroundStyle))")
     }
 
+    if old.captionSettings != new.captionSettings || old.captionSegments != new.captionSegments {
+      describeCaptionChanges(
+        from: old.captionSettings,
+        to: new.captionSettings,
+        oldSegments: old.captionSegments,
+        newSegments: new.captionSegments,
+        into: &changes
+      )
+    }
+
     if old.videoRegions != new.videoRegions {
       let oldCount = old.videoRegions?.count ?? 0
       let newCount = new.videoRegions?.count ?? 0
@@ -239,6 +249,9 @@ final class History {
         changes.append("Animation settings updated")
       }
       if old.cameraLayout != new.cameraLayout { changes.append("Camera layout updated") }
+      if old.captionSettings != new.captionSettings || old.captionSegments != new.captionSegments {
+        changes.append("Caption settings updated")
+      }
     }
 
     if changes.isEmpty {
@@ -382,6 +395,76 @@ final class History {
     }
   }
 
+  private static func describeCaptionChanges(
+    from old: CaptionSettingsData?,
+    to new: CaptionSettingsData?,
+    oldSegments: [CaptionSegment]?,
+    newSegments: [CaptionSegment]?,
+    into changes: inout [String]
+  ) {
+    let oldSegs = oldSegments ?? []
+    let newSegs = newSegments ?? []
+    if oldSegs.isEmpty && !newSegs.isEmpty {
+      changes.append("Captions generated (\(newSegs.count) segments)")
+      return
+    }
+    if !oldSegs.isEmpty && newSegs.isEmpty {
+      changes.append("Captions cleared")
+      return
+    }
+    if oldSegs != newSegs && !oldSegs.isEmpty && !newSegs.isEmpty {
+      if oldSegs.count != newSegs.count {
+        changes.append("Caption segments updated (\(newSegs.count) segments)")
+      } else {
+        changes.append("Caption segments edited")
+      }
+    }
+
+    if old?.enabled != new?.enabled {
+      let enabled = new?.enabled ?? true
+      changes.append(enabled ? "Captions enabled" : "Captions disabled")
+    }
+    if old?.fontSize != new?.fontSize {
+      changes.append("Caption font size set to \(Int(new?.fontSize ?? 48))px")
+    }
+    if old?.fontWeight != new?.fontWeight {
+      let weight = new?.fontWeight ?? .bold
+      changes.append("Caption font weight set to \(weight.label)")
+    }
+    if old?.position != new?.position {
+      let pos = new?.position ?? .bottom
+      changes.append("Caption position set to \(pos.label.lowercased())")
+    }
+    if old?.textColor != new?.textColor {
+      changes.append("Caption text color updated")
+    }
+    if old?.backgroundColor != new?.backgroundColor {
+      changes.append("Caption background color updated")
+    }
+    if old?.backgroundOpacity != new?.backgroundOpacity {
+      changes.append("Caption background opacity set to \(Int((new?.backgroundOpacity ?? 0.6) * 100))%")
+    }
+    if old?.showBackground != new?.showBackground {
+      let show = new?.showBackground ?? true
+      changes.append(show ? "Caption background enabled" : "Caption background disabled")
+    }
+    if old?.maxWordsPerLine != new?.maxWordsPerLine {
+      changes.append("Caption words per line set to \(new?.maxWordsPerLine ?? 6)")
+    }
+    if old?.model != new?.model {
+      let modelName = WhisperModel(rawValue: new?.model ?? "")?.shortLabel ?? "unknown"
+      changes.append("Caption model set to \(modelName)")
+    }
+    if old?.language != new?.language {
+      let lang = new?.language ?? .auto
+      changes.append("Caption language set to \(lang.label)")
+    }
+    if old?.audioSource != new?.audioSource {
+      let source = new?.audioSource ?? .microphone
+      changes.append("Caption audio source set to \(source.label)")
+    }
+  }
+
   private static func describeAudioChanges(
     from old: AudioSettingsData?,
     to new: AudioSettingsData?,

Reframed/Utilities/TranscriptionService.swift

@@ -23,10 +23,10 @@ enum TranscriptionService {
     let modelsBase = FileManager.default.homeDirectoryForCurrentUser
       .appendingPathComponent(".reframed")
     let computeOptions = ModelComputeOptions(
-      melCompute: .cpuAndGPU,
-      audioEncoderCompute: .cpuAndNeuralEngine,
-      textDecoderCompute: .cpuAndNeuralEngine,
-      prefillCompute: .cpuAndGPU
+      melCompute: .all,
+      audioEncoderCompute: .all,
+      textDecoderCompute: .all,
+      prefillCompute: .all
     )
     let config = WhisperKitConfig(
       downloadBase: modelsBase,
@@ -41,8 +41,10 @@ enum TranscriptionService {
 
     await onProgress?(0.15)
 
+    let workerCount = max(16, ProcessInfo.processInfo.activeProcessorCount)
     var options = DecodingOptions(
       wordTimestamps: true,
+      concurrentWorkerCount: workerCount,
       chunkingStrategy: .vad
     )
     if let language {
@@ -51,11 +53,15 @@ enum TranscriptionService {
 
     let progressCallback = onProgress
     let expectedWindows = totalWindows
+    nonisolated(unsafe) var highWaterMark: Double = 0.15
     let callback: TranscriptionCallback = { (progress: TranscriptionProgress) -> Bool? in
       let windowProgress = Double(progress.windowId + 1) / Double(expectedWindows)
-      let overall = 0.15 + windowProgress * 0.8
+      let overall = min(0.15 + windowProgress * 0.8, 0.95)
+      guard overall > highWaterMark else { return nil }
+      highWaterMark = overall
+      let value = overall
       Task { @MainActor in
-        progressCallback?(min(overall, 0.95))
+        progressCallback?(value)
       }
       return nil
     }