feat(model-boss): ✨ Implement new API interaction methods for model-boss service

Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>

@applications/api/src/clients/model-boss.client.ts

@@ -6,6 +6,18 @@ export interface ChatMessage {
   content: string;
 }
 
+export interface TtsSynthesizeRequest {
+  text: string;
+  exaggeration: number;
+  cfgWeight: number;
+}
+
+export interface TtsSynthesizeResult {
+  /** Int16 PCM resampled to 22050Hz mono, ready for PcmPlayer */
+  pcm: Int16Array;
+  durationMs: number;
+}
+
 export interface CompletionRequest {
   model?: string;
   messages: ChatMessage[];
@@ -31,6 +43,29 @@ export interface CompletionChunk {
   choices: CompletionChoice[];
 }
 
+/**
+ * Resample float32 PCM from inputRate to outputRate using linear interpolation,
+ * then convert to Int16. Used to normalise @model-boss TTS output (24kHz float32)
+ * to the 22050Hz Int16 format expected by PcmPlayerProcessor.
+ */
+function resampleFloat32ToInt16(input: Float32Array, inputRate: number, outputRate: number): Int16Array {
+  const ratio = inputRate / outputRate;
+  const outputLength = Math.ceil(input.length / ratio);
+  const output = new Int16Array(outputLength);
+
+  for (let i = 0; i < outputLength; i++) {
+    const srcPos = i * ratio;
+    const srcIdx = Math.floor(srcPos);
+    const frac = srcPos - srcIdx;
+    const s0 = input[srcIdx] ?? 0;
+    const s1 = input[Math.min(srcIdx + 1, input.length - 1)] ?? 0;
+    const sample = s0 + frac * (s1 - s0);
+    output[i] = Math.max(-32768, Math.min(32767, Math.round(sample * 32767)));
+  }
+
+  return output;
+}
+
 /**
  * SSE streaming client for @model-boss /v1/chat/completions.
  *
@@ -45,6 +80,32 @@ export class ModelBossClient {
     this.baseUrl = this.config.get<string>('MODEL_BOSS_URL', 'http://localhost:8210');
   }
 
+  async synthesizeTts(request: TtsSynthesizeRequest): Promise<TtsSynthesizeResult> {
+    const url = `${this.baseUrl}/api/v1/tts/synthesize`;
+    const response = await fetch(url, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({
+        text: request.text,
+        exaggeration: request.exaggeration,
+        cfgWeight: request.cfgWeight,
+      }),
+    });
+
+    if (!response.ok) {
+      const body = await response.text();
+      throw new Error(`@model-boss TTS failed: ${response.status} ${response.statusText} — ${body}`);
+    }
+
+    const data = (await response.json()) as { audioB64: string; sampleRate: number; durationMs: number };
+
+    const bytes = Buffer.from(data.audioB64, 'base64');
+    const float32 = new Float32Array(bytes.buffer, bytes.byteOffset, bytes.byteLength / 4);
+    const pcm = resampleFloat32ToInt16(float32, data.sampleRate, 22050);
+
+    return { pcm, durationMs: data.durationMs };
+  }
+
   async *streamCompletion(request: CompletionRequest): AsyncGenerator<string, void, unknown> {
     const url = `${this.baseUrl}/v1/chat/completions`;
     const response = await fetch(url, {