Track Piper model bytes in the worker

piper-worker.js

@@ -1,4 +1,5 @@
 import {TtsSession} from '@mintplex-labs/piper-tts-web';
+import {trackModelDownload} from './piper-download-progress.mjs';
 import {localPiperModelUrl} from './piper-model-routing.mjs';
 import {createOnnxWasmPaths} from './piper-onnx-config.mjs';
 
@@ -8,22 +9,27 @@ const localFetch = self.fetch.bind(self);
 
 // Keep the TTS library's OPFS cache logic, but serve models/config from the
 // same-origin static asset service instead of its built-in external model URL.
-self.fetch = (resource, options) => {
+self.fetch = async (resource, options) => {
   const requestedUrl = resource instanceof Request ? resource.url : String(resource);
   const localModelUrl = localPiperModelUrl(requestedUrl, self.location.origin);
   if (!localModelUrl) return localFetch(resource, options);
   const redirected = resource instanceof Request ? new Request(localModelUrl, resource) : localModelUrl;
-  return localFetch(redirected, options);
+  const response = await localFetch(redirected, options);
+  if (!activeRequestId || !localModelUrl.endsWith('.onnx')) return response;
+  return trackModelDownload(response, {
+    id: activeRequestId,
+    postMessage: message => self.postMessage(message),
+  });
 };
 
 let sessionPromise;
 let inferenceQueue = Promise.resolve();
+let activeRequestId = null;
 
-async function getSession(onProgress) {
+async function getSession() {
   if (!sessionPromise) {
     sessionPromise = TtsSession.create({
       voiceId: VOICE_ID,
-      progress: onProgress,
       wasmPaths: {
         onnxWasm: createOnnxWasmPaths(self.location.origin),
         piperData: `${ASSET_ROOT}/piper/piper_phonemize.data`,
@@ -40,13 +46,17 @@ async function getSession(onProgress) {
 async function synthesizeMessage(event) {
   const {id, text} = event.data || {};
   if (!Number.isSafeInteger(id) || typeof text !== 'string') return;
+  activeRequestId = id;
+  self.postMessage({id, type: 'progress', progress: {stage: 'starting'}});
   try {
-    const session = await getSession(progress => self.postMessage({id, type: 'progress', progress}));
+    const session = await getSession();
     const blob = await session.predict(text);
     const audio = await blob.arrayBuffer();
     self.postMessage({id, type: 'audio', audio}, [audio]);
   } catch (error) {
     self.postMessage({id, type: 'error', error: String(error?.message || error)});
+  } finally {
+    activeRequestId = null;
   }
 }