add Synthesizer wrapper around KokoroSwift with voice pack support

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

VorleserKit/Package.resolved

@@ -1,6 +1,51 @@
 {
-  "originHash" : "1bf1d418d8d58ea936176af8e96313605ea72a6fbf437f877b8e5d9a5b0d822c",
+  "originHash" : "6130f8afd39b4763c878d68f7965a176b7136eb36f304eaf701123ffb55cbbf7",
   "pins" : [
+    {
+      "identity" : "kokoro-ios",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/mlalma/kokoro-ios.git",
+      "state" : {
+        "revision" : "4d6d1d8ff8cd012014180c9cd4cf0151e7682354",
+        "version" : "1.0.11"
+      }
+    },
+    {
+      "identity" : "misakiswift",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/mlalma/MisakiSwift",
+      "state" : {
+        "revision" : "6835a1ce4a8854075c89f18ff75c74b13ef58e15",
+        "version" : "1.0.6"
+      }
+    },
+    {
+      "identity" : "mlx-swift",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/ml-explore/mlx-swift",
+      "state" : {
+        "revision" : "f58bd2c2b3b84316da69182f436db4219aff30b9",
+        "version" : "0.30.2"
+      }
+    },
+    {
+      "identity" : "mlxutilslibrary",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/mlalma/MLXUtilsLibrary.git",
+      "state" : {
+        "revision" : "41f6cfd5d68b65aa3c65a34efe3b71c371ed915b",
+        "version" : "0.0.6"
+      }
+    },
+    {
+      "identity" : "swift-numerics",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-numerics",
+      "state" : {
+        "revision" : "0c0290ff6b24942dadb83a929ffaaa1481df04a2",
+        "version" : "1.1.1"
+      }
+    },
     {
       "identity" : "swiftsoup",
       "kind" : "remoteSourceControl",

VorleserKit/Package.swift

@@ -11,15 +11,27 @@ let package = Package(
 		.library(name: "VorleserKit", targets: ["VorleserKit"]),
 		.library(name: "BookParser", targets: ["BookParser"]),
 		.library(name: "Storage", targets: ["Storage"]),
+		.library(name: "Synthesizer", targets: ["Synthesizer"]),
 	],
 	dependencies: [
 		.package(url: "https://github.com/weichsel/ZIPFoundation.git", from: "0.9.0"),
 		.package(url: "https://github.com/scinfu/SwiftSoup.git", from: "2.7.0"),
+		.package(url: "https://github.com/mlalma/kokoro-ios.git", exact: "1.0.11"),
+		.package(url: "https://github.com/mlalma/MLXUtilsLibrary.git", exact: "0.0.6"),
+		.package(url: "https://github.com/ml-explore/mlx-swift", exact: "0.30.2"),
 	],
 	targets: [
 		.target(
 			name: "VorleserKit",
-			dependencies: ["Storage"]
+			dependencies: ["Storage", "Synthesizer"]
+		),
+		.target(
+			name: "Synthesizer",
+			dependencies: [
+				.product(name: "KokoroSwift", package: "kokoro-ios"),
+				.product(name: "MLXUtilsLibrary", package: "MLXUtilsLibrary"),
+				.product(name: "MLX", package: "mlx-swift"),
+			]
 		),
 		.target(
 			name: "Storage",

VorleserKit/Sources/Synthesizer/Synthesizer.swift

@@ -0,0 +1,47 @@
+import Foundation
+import KokoroSwift
+import MLX
+import MLXUtilsLibrary
+
+public final class Synthesizer: @unchecked Sendable {
+	private let tts: KokoroTTS
+	private let voiceEmbedding: MLXArray
+	private let language: Language
+	private let voicePack: VoicePack
+
+	public init(voice: VoicePack, modelURL: URL, voicesURL: URL) throws {
+		guard FileManager.default.fileExists(atPath: modelURL.path) else {
+			throw SynthesizerError.modelNotFound(modelURL.path)
+		}
+		guard FileManager.default.fileExists(atPath: voicesURL.path) else {
+			throw SynthesizerError.voicesNotFound(voicesURL.path)
+		}
+
+		self.tts = KokoroTTS(modelPath: modelURL, g2p: .misaki)
+
+		guard let voices = NpyzReader.read(fileFromPath: voicesURL),
+		      let embedding = voices["\(voice.name).npy"] else {
+			throw SynthesizerError.voiceNotAvailable(voice.name)
+		}
+
+		self.voiceEmbedding = embedding
+		self.voicePack = voice
+		self.language = voice.language == .enUS ? .enUS : .enGB
+	}
+
+	public func synthesize(text: String) throws -> [Float] {
+		do {
+			let (samples, _) = try tts.generateAudio(
+				voice: voiceEmbedding,
+				language: language,
+				text: text,
+				speed: 1.0
+			)
+			return samples
+		} catch {
+			throw SynthesizerError.synthesisFailure(text, error)
+		}
+	}
+
+	public static let sampleRate: Double = 24_000
+}

VorleserKit/Sources/Synthesizer/SynthesizerError.swift

@@ -0,0 +1,15 @@
+public enum SynthesizerError: Error, CustomStringConvertible {
+	case modelNotFound(String)
+	case voicesNotFound(String)
+	case voiceNotAvailable(String)
+	case synthesisFailure(String, Error)
+
+	public var description: String {
+		switch self {
+		case .modelNotFound(let path): "kokoro model not found at \(path)"
+		case .voicesNotFound(let path): "voices.npz not found at \(path)"
+		case .voiceNotAvailable(let name): "voice '\(name)' not found in voices.npz"
+		case .synthesisFailure(let text, let error): "synthesis failed for '\(text.prefix(50))...': \(error)"
+		}
+	}
+}

VorleserKit/Sources/Synthesizer/VoicePack.swift

@@ -0,0 +1,21 @@
+import Foundation
+
+public struct VoicePack: Sendable, Identifiable {
+	public let name: String
+	public let displayName: String
+	public let language: Language
+
+	public var id: String { name }
+
+	public enum Language: String, Sendable {
+		case enUS = "en-us"
+		case enGB = "en-gb"
+	}
+
+	/// Curated voices bundled with the app.
+	public static let curated: [VoicePack] = [
+		VoicePack(name: "af_heart", displayName: "Heart", language: .enUS),
+		VoicePack(name: "af_bella", displayName: "Bella", language: .enUS),
+		VoicePack(name: "am_michael", displayName: "Michael", language: .enUS),
+	]
+}