feat: core types, time, rng, model fetch

Co-Authored-By: Claude Haiku 5.5 <[email protected]>

scripts/fetch-models.ts

@@ -0,0 +1,60 @@
+// Downloads model files into models/ and verifies their sha256.
+// Files already present with a matching hash are skipped.
+import { join } from "node:path";
+
+interface ModelFile {
+  path: string; // relative to repo root
+  url: string;
+  sha256: string;
+}
+
+export const MODELS: ModelFile[] = [
+  {
+    path: "models/demucs/htdemucs_6s.onnx",
+    url: "https://huggingface.co/Kani95/htdemucs-6s-ort/resolve/main/htdemucs_6s.onnx",
+    sha256: "35cb61d4d35173ff1d16df7393f41f05651ffdfe13d3c10e06abc26708bd6933",
+  },
+  {
+    path: "models/basic-pitch/nmp.onnx",
+    url: "https://github.com/spotify/basic-pitch/raw/main/basic_pitch/saved_models/icassp_2022/nmp.onnx",
+    sha256: "2c3c1d144bfa61ad236e92e169c13535c880469a12a047d4e73451f2c059a0ec",
+  },
+];
+
+const ROOT = join(import.meta.dir, "..");
+
+async function sha256Of(file: string): Promise<string> {
+  const hasher = new Bun.CryptoHasher("sha256");
+  hasher.update(new Uint8Array(await Bun.file(file).arrayBuffer()));
+  return hasher.digest("hex");
+}
+
+export async function fetchModels(root = ROOT): Promise<void> {
+  for (const m of MODELS) {
+    const dest = join(root, m.path);
+    if (await Bun.file(dest).exists()) {
+      const have = await sha256Of(dest);
+      if (have === m.sha256) {
+        console.log(`ok       ${m.path}`);
+        continue;
+      }
+      console.log(`mismatch ${m.path} (have ${have}), re-downloading`);
+    }
+    console.log(`fetch    ${m.url}`);
+    const res = await fetch(m.url, { redirect: "follow" });
+    if (!res.ok) throw new Error(`download failed for ${m.url}: HTTP ${res.status}`);
+    const bytes = new Uint8Array(await res.arrayBuffer());
+    const hasher = new Bun.CryptoHasher("sha256");
+    hasher.update(bytes);
+    const got = hasher.digest("hex");
+    if (got !== m.sha256) {
+      throw new Error(`sha256 mismatch for ${m.path}: expected ${m.sha256}, got ${got}`);
+    }
+    await Bun.write(dest, bytes);
+    console.log(`saved    ${m.path}`);
+  }
+}
+
+if (import.meta.main) {
+  await fetchModels();
+}