fix: isolate system audio converter callbacks

Meetingnotes.xcodeproj/project.pbxproj

@@ -276,7 +276,7 @@
 				CODE_SIGN_IDENTITY = "Apple Development";
 				CODE_SIGN_STYLE = Automatic;
 				COMBINE_HIDPI_IMAGES = YES;
-				CURRENT_PROJECT_VERSION = 20;
+				CURRENT_PROJECT_VERSION = 21;
 				DEVELOPMENT_ASSET_PATHS = "\"meetingnotes/Preview Content\"";
 				DEVELOPMENT_TEAM = G9LVHZAJNX;
 				ENABLE_HARDENED_RUNTIME = YES;
@@ -290,7 +290,7 @@
 					"@executable_path/../Frameworks",
 				);
 				MACOSX_DEPLOYMENT_TARGET = 15.0;
-				MARKETING_VERSION = 1.1.8;
+				MARKETING_VERSION = 1.1.9;
 				ONLY_ACTIVE_ARCH = NO;
 				OTHER_SWIFT_FLAGS = "$(inherited) -D ENABLE_TCC_SPI";
 				PRODUCT_BUNDLE_IDENTIFIER = net.jamesbone.meetingnotes;
@@ -312,7 +312,7 @@
 				CODE_SIGN_IDENTITY = "Apple Development";
 				CODE_SIGN_STYLE = Automatic;
 				COMBINE_HIDPI_IMAGES = YES;
-				CURRENT_PROJECT_VERSION = 20;
+				CURRENT_PROJECT_VERSION = 21;
 				DEVELOPMENT_ASSET_PATHS = "\"meetingnotes/Preview Content\"";
 				DEVELOPMENT_TEAM = G9LVHZAJNX;
 				ENABLE_HARDENED_RUNTIME = YES;
@@ -326,7 +326,7 @@
 					"@executable_path/../Frameworks",
 				);
 				MACOSX_DEPLOYMENT_TARGET = 15.0;
-				MARKETING_VERSION = 1.1.8;
+				MARKETING_VERSION = 1.1.9;
 				ONLY_ACTIVE_ARCH = YES;
 				OTHER_SWIFT_FLAGS = "$(inherited) -D ENABLE_TCC_SPI";
 				PRODUCT_BUNDLE_IDENTIFIER = net.jamesbone.meetingnotes;

meetingnotes/Managers/AudioManager.swift

@@ -302,14 +302,14 @@ final class AudioManager: NSObject, ObservableObject {
     private func startTapIO(_ tap: ProcessTap) throws {
         guard var description = tap.tapStreamDescription,
               let inputFormat = AVAudioFormat(streamDescription: &description),
-              let targetFormat = systemAudioFile?.processingFormat,
+              let targetFormat = systemAudioFile?.processingFormat else {
-              let converter = AVAudioConverter(from: inputFormat, to: targetFormat) else {
             throw NSError(domain: "AudioManager", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unsupported system audio format"])
         }
         try tap.run(on: tapQueue) { [weak self] _, inputData, _, _, _ in
-            guard let self else { return }
+            guard let self,
+                  let converter = AVAudioConverter(from: inputFormat, to: targetFormat) else { return }
             self.processAudioBuffer(
-                { AVAudioPCMBuffer(pcmFormat: inputFormat, bufferListNoCopy: inputData, deallocator: nil) },
+                { self.copyAudioBuffer(from: inputData, format: inputFormat) },
                 converter: converter,
                 targetFormat: targetFormat,
                 source: .system
@@ -319,6 +319,42 @@ final class AudioManager: NSObject, ObservableObject {
             Task { await self.restartSystemAudioTap() }
         }
     }
+
+    private func copyAudioBuffer(
+        from inputData: UnsafePointer<AudioBufferList>,
+        format: AVAudioFormat
+    ) -> AVAudioPCMBuffer? {
+        guard let borrowedBuffer = AVAudioPCMBuffer(
+            pcmFormat: format,
+            bufferListNoCopy: inputData,
+            deallocator: nil
+        ), borrowedBuffer.frameLength > 0,
+        let ownedBuffer = AVAudioPCMBuffer(
+            pcmFormat: format,
+            frameCapacity: borrowedBuffer.frameLength
+        ) else { return nil }
+
+        ownedBuffer.frameLength = borrowedBuffer.frameLength
+        let sourceBuffers = UnsafeMutableAudioBufferListPointer(
+            UnsafeMutablePointer(mutating: inputData)
+        )
+        let destinationBuffers = UnsafeMutableAudioBufferListPointer(
+            ownedBuffer.mutableAudioBufferList
+        )
+        guard sourceBuffers.count == destinationBuffers.count else { return nil }
+
+        for index in 0..<sourceBuffers.count {
+            let source = sourceBuffers[index]
+            let destination = destinationBuffers[index]
+            let byteCount = Int(source.mDataByteSize)
+            guard byteCount <= Int(destination.mDataByteSize),
+                  let sourceData = source.mData,
+                  let destinationData = destination.mData else { return nil }
+            memcpy(destinationData, sourceData, byteCount)
+            destinationBuffers[index].mDataByteSize = source.mDataByteSize
+        }
+        return ownedBuffer
+    }
     
     private func processAudioBuffer(
         _ inputBufferProvider: () -> AVAudioPCMBuffer?,
@@ -326,8 +362,8 @@ final class AudioManager: NSObject, ObservableObject {
         targetFormat: AVAudioFormat,
         source: AudioSource
     ) {
-        // Keep callback-owned buffers alive until conversion finishes. Teardown
+        // The system callback copies its borrowed Core Audio memory while this
-        // takes this same lock before invalidating the Core Audio process tap.
+        // lock prevents teardown, then conversion operates on the owned copy.
         audioFileLock.lock()
         defer { audioFileLock.unlock() }
         guard isAcceptingAudio,