feat: add voice playback settings with 4-provider support (#608)

Add WebSpeech, OpenAI TTS, Custom endpoint, and Edge TTS providers.

Co-authored-by: Hermes Agent <noreply@nousresearch.com>

packages/server/src/services/hermes/tts.ts

@@ -12,6 +12,9 @@ const FIXED_PITCH = '+12Hz'
 export interface TtsOptions {
   text: string
   lang?: string
+  voice?: string
+  rate?: string
+  pitch?: string
 }
 
 export async function edgeTts(opts: TtsOptions): Promise<Buffer> {
@@ -20,9 +23,9 @@ export async function edgeTts(opts: TtsOptions): Promise<Buffer> {
 
   try {
     const tts = new EdgeTTS({
-      voice: FIXED_VOICE,
-      rate: FIXED_RATE,
-      pitch: FIXED_PITCH,
+      voice: opts.voice || FIXED_VOICE,
+      rate: opts.rate || FIXED_RATE,
+      pitch: opts.pitch || FIXED_PITCH,
       timeout: 15000,
     })
 
@@ -35,7 +38,41 @@ export async function edgeTts(opts: TtsOptions): Promise<Buffer> {
 }
 
 export async function textToSpeech(opts: TtsOptions): Promise<{ audio: Buffer; engine: string }> {
+  const voice = opts.voice || FIXED_VOICE
+  const rate = opts.rate || FIXED_RATE
+  const pitch = opts.pitch || FIXED_PITCH
   const audio = await edgeTts(opts)
-  logger.debug({ engine: 'edge', voice: FIXED_VOICE, rate: FIXED_RATE, pitch: FIXED_PITCH }, 'TTS generated via Edge')
+  logger.debug({ engine: 'edge', voice, rate, pitch }, 'TTS generated via Edge')
   return { audio, engine: 'edge' }
 }
+
+/**
+ * Convert speed multiplier (0.5-2.0) to Edge TTS rate string.
+ * Edge TTS rate format: "+/-NN%"
+ */
+export function speedToEdgeRate(speed: number): string {
+  const percent = Math.round((speed - 1) * 100)
+  return percent >= 0 ? `+${percent}%` : `${percent}%`
+}
+
+/**
+ * Convert OpenAI TTS request to internal TtsOptions.
+ * OpenAI format: { model, input, voice, speed }
+ */
+export interface OpenaiTtsRequest {
+  model?: string
+  input: string
+  voice?: string
+  speed?: number
+}
+
+export async function openaiCompatibleTts(
+  body: OpenaiTtsRequest,
+): Promise<{ audio: Buffer; engine: string }> {
+  return textToSpeech({
+    text: body.input,
+    voice: body.voice || FIXED_VOICE,
+    rate: body.speed ? speedToEdgeRate(body.speed) : FIXED_RATE,
+    pitch: FIXED_PITCH,
+  })
+}