Add configurable speech voice settings

.env.example

@@ -1,2 +1,7 @@
 EXPO_PUBLIC_OLLAMA_BASE_URL=http://localhost:11434
 EXPO_PUBLIC_OLLAMA_MODEL=llama3.2
+EXPO_PUBLIC_SPEECH_LANGUAGE=en-US
+EXPO_PUBLIC_SPEECH_RATE=0.85
+EXPO_PUBLIC_SPEECH_PITCH=1
+# Optional iOS voice identifier. Leave empty to use the first matching iPhone voice.
+# EXPO_PUBLIC_SPEECH_VOICE=com.apple.voice.compact.en-US.Samantha

src/config/speech.ts

@@ -0,0 +1,6 @@
+export const speechConfig = {
+  language: process.env.EXPO_PUBLIC_SPEECH_LANGUAGE ?? 'en-US',
+  preferredVoice: process.env.EXPO_PUBLIC_SPEECH_VOICE,
+  pitch: Number(process.env.EXPO_PUBLIC_SPEECH_PITCH ?? 1),
+  rate: Number(process.env.EXPO_PUBLIC_SPEECH_RATE ?? 0.85),
+};

src/services/speechService.ts

@@ -1,11 +1,19 @@
 import * as Speech from 'expo-speech';
 
-export function speakText(text: string) {
+import { speechConfig } from '../config/speech';
+
+let cachedVoice: string | undefined;
+
+export async function speakText(text: string) {
   Speech.stop();
+
+  const voice = await getPreferredVoice();
+
   Speech.speak(stripThinkingBlocks(text), {
-    language: 'en-US',
+    language: speechConfig.language,
-    pitch: 1,
+    pitch: speechConfig.pitch,
-    rate: 0.9,
+    rate: speechConfig.rate,
+    voice,
   });
 }
 
@@ -16,3 +24,20 @@ export function stopSpeaking() {
 function stripThinkingBlocks(text: string) {
   return text.replace(/<think>[\s\S]*?<\/think>/gi, '').trim();
 }
+
+async function getPreferredVoice() {
+  if (cachedVoice) {
+    return cachedVoice;
+  }
+
+  if (speechConfig.preferredVoice) {
+    cachedVoice = speechConfig.preferredVoice;
+    return cachedVoice;
+  }
+
+  const voices = await Speech.getAvailableVoicesAsync();
+  const matchingVoice = voices.find((voice) => voice.language === speechConfig.language);
+  cachedVoice = matchingVoice?.identifier;
+
+  return cachedVoice;
+}