Add static Piper asset service

scripts/build-assets.mjs

@@ -0,0 +1,67 @@
+import {createHash} from 'node:crypto';
+import {createWriteStream} from 'node:fs';
+import {cp, mkdir, readdir, rm, stat, rename, unlink} from 'node:fs/promises';
+import {join} from 'node:path';
+import {Readable, Transform} from 'node:stream';
+import {pipeline} from 'node:stream/promises';
+import {assetPrefix, requiredOnnxFiles, voiceFiles, voiceRepository, voiceRevision} from './assets.mjs';
+
+const root = process.cwd();
+const output = join(root, 'public', 'static', assetPrefix);
+const onnxSource = join(root, 'node_modules', 'onnxruntime-web', 'dist');
+const piperSource = join(root, 'node_modules', '@diffusionstudio', 'piper-wasm', 'build');
+
+async function downloadVoiceFile(file) {
+  const destination = join(output, 'voices', file.path);
+  const temporary = `${destination}.part`;
+  await mkdir(join(destination, '..'), {recursive: true});
+  const response = await fetch(`${voiceRepository}/${voiceRevision}/${file.path}`);
+  if (!response.ok || !response.body) throw new Error(`Unable to download ${file.path}: HTTP ${response.status}`);
+  const sha256 = createHash('sha256');
+  const sha1 = createHash('sha1').update(Buffer.from(`blob ${file.size}\0`));
+  let size = 0;
+  const verify = new Transform({
+    transform(chunk, _encoding, callback) {
+      size += chunk.length;
+      sha256.update(chunk);
+      sha1.update(chunk);
+      callback(null, chunk);
+    },
+  });
+  try {
+    await pipeline(Readable.fromWeb(response.body), verify, createWriteStream(temporary));
+    if (size !== file.size || (file.sha256 && sha256.digest('hex') !== file.sha256) ||
+        (file.gitBlobSha1 && sha1.digest('hex') !== file.gitBlobSha1)) {
+      throw new Error(`Integrity check failed for ${file.path} (${size} bytes)`);
+    }
+    await rename(temporary, destination);
+  } catch (error) {
+    await unlink(temporary).catch(() => {});
+    throw error;
+  }
+}
+
+await rm(join(root, 'public', 'static'), {recursive: true, force: true});
+await mkdir(join(output, 'onnx'), {recursive: true});
+await mkdir(join(output, 'piper'), {recursive: true});
+for (const file of voiceFiles) await downloadVoiceFile(file);
+await cp(join(root, 'PIPER_VOICE_NOTICES.txt'), join(output, 'voices', 'ATTRIBUTION.txt'));
+
+const onnxFiles = (await readdir(onnxSource)).filter(name => name.endsWith('.wasm') || name.endsWith('.mjs'));
+for (const file of requiredOnnxFiles) {
+  if (!onnxFiles.includes(file)) throw new Error(`Missing ONNX Runtime asset: ${file}`);
+}
+for (const file of onnxFiles) await cp(join(onnxSource, file), join(output, 'onnx', file));
+
+for (const file of ['piper_phonemize.wasm', 'piper_phonemize.data']) {
+  const source = join(piperSource, file);
+  const fileStat = await stat(source).catch(() => null);
+  if (!fileStat?.isFile() || fileStat.size === 0) throw new Error(`Missing Piper runtime file: ${file}`);
+  await cp(source, join(output, 'piper', file));
+}
+
+for (const file of voiceFiles) {
+  const downloaded = join(output, 'voices', file.path);
+  if ((await stat(downloaded)).size !== file.size) throw new Error(`Missing verified voice file: ${file.path}`);
+}
+console.log(`Static Piper assets prepared at ${output}`);