potential split between CLI and core library

Package.swift

@@ -8,7 +8,37 @@ let package = Package(
   platforms: [
     .macOS("14.2")
   ],
+  products: [
+    // Library that can be imported by other packages
+    .library(
+      name: "AudioTeeCore",
+      targets: ["AudioTeeCore"]
+    ),
+    // CLI executable
+    .executable(
+      name: "audiotee",
+      targets: ["AudioTeeCLI"]
+    )
+  ],
   targets: [
-    .executableTarget(name: "audiotee")
+    // Core library with all business logic
+    .target(
+      name: "AudioTeeCore",
+      path: "Sources/AudioTeeCore"
+    ),
+    
+    // CLI executable that uses the library
+    .executableTarget(
+      name: "AudioTeeCLI",
+      dependencies: ["AudioTeeCore"],
+      path: "Sources/AudioTeeCLI"
+    ),
+    
+    // Tests for the library
+    .testTarget(
+      name: "AudioTeeCoreTests",
+      dependencies: ["AudioTeeCore"],
+      path: "Tests/AudioTeeCoreTests"
+    )
   ]
-)
+)

Sources/AudioTeeCLI/AudioTee.swift

@@ -1,3 +1,4 @@
+import AudioTeeCore
 import CoreAudio
 import Foundation
 

Sources/AudioTeeCLI/main.swift

@@ -1,3 +1,4 @@
+import AudioTeeCore
 import AudioToolbox
 import Foundation
 

Sources/AudioTeeCore/Core/AudioRecorder.swift

@@ -10,7 +10,7 @@ public class AudioRecorder {
   private var outputHandler: AudioOutputHandler
   private var converter: AudioFormatConverter?
 
-  init(
+  public init(
     deviceID: AudioObjectID, outputHandler: AudioOutputHandler, convertToSampleRate: Double? = nil,
     chunkDuration: Double = 0.2
   ) {
@@ -51,7 +51,7 @@ public class AudioRecorder {
     }
   }
 
-  func startRecording() {
+  public func startRecording() {
     Logger.debug("Starting audio recording")
 
     // Log format info and send metadata for final format
@@ -112,7 +112,7 @@ public class AudioRecorder {
     return noErr
   }
 
-  func stopRecording() {
+  public func stopRecording() {
     processAudioBuffer()
     outputHandler.handleStreamStop()
     cleanupIOProc()

Sources/AudioTeeCore/Core/AudioTapManager.swift

@@ -3,10 +3,12 @@ import AudioToolbox
 import CoreAudio
 import Foundation
 
-class AudioTapManager {
+public class AudioTapManager {
   private var tapID: AudioObjectID?
   private var deviceID: AudioObjectID?
 
+  public init() {}
+  
   deinit {
     Logger.debug("Cleaning up audio tap manager")
 
@@ -22,7 +24,7 @@ class AudioTapManager {
   }
 
   /// Sets up the audio tap and aggregate device
-  func setupAudioTap(with config: TapConfiguration) throws {
+  public func setupAudioTap(with config: TapConfiguration) throws {
     Logger.debug("Setting up audio tap manager")
 
     tapID = try createSystemAudioTap(with: config)
@@ -38,7 +40,7 @@ class AudioTapManager {
   }
 
   /// Returns the aggregate device ID for recording
-  func getDeviceID() -> AudioObjectID? {
+  public func getDeviceID() -> AudioObjectID? {
     return deviceID
   }
 

Sources/AudioTeeCore/Output/BinaryOutputHandler.swift

@@ -1,6 +1,8 @@
 import Foundation
 
 public class BinaryAudioOutputHandler: AudioOutputHandler {
+  public init() {}
+  
   public func handleAudioPacket(_ packet: AudioPacket) {
     // TODO: should we use a DispatchQueue instead of writing directly?
     // Write raw binary audio data directly to stdout

Tests/AudioTeeCoreTests/AudioPacketTests.swift

@@ -0,0 +1,30 @@
+import XCTest
+@testable import AudioTeeCore
+
+final class AudioPacketTests: XCTestCase {
+  func testPacketCreation() {
+    let timestamp = Date()
+    let duration = 1.0
+    let data = Data([0x01, 0x02, 0x03, 0x04])
+    
+    let packet = AudioPacket(
+      timestamp: timestamp,
+      duration: duration,
+      data: data
+    )
+    
+    XCTAssertEqual(packet.timestamp, timestamp)
+    XCTAssertEqual(packet.duration, duration)
+    XCTAssertEqual(packet.data, data)
+  }
+  
+  func testPacketDataSize() {
+    let packet = AudioPacket(
+      timestamp: Date(),
+      duration: 0.5,
+      data: Data(repeating: 0xFF, count: 1024)
+    )
+    
+    XCTAssertEqual(packet.data.count, 1024)
+  }
+}