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| """Fetch the model weights from the Hugging Face model repo and verify their SHA-256. | |
| Weights are never committed to git. The Docker image downloads them at build time; | |
| a local run downloads them on first start if models/ does not already have them. | |
| python -m serve.weights # download (if needed) and verify | |
| """ | |
| from __future__ import annotations | |
| import hashlib | |
| import shutil | |
| import tempfile | |
| import urllib.request | |
| from pathlib import Path | |
| from serve.config import Settings | |
| def sha256_of(path: Path) -> str: | |
| h = hashlib.sha256() | |
| with path.open("rb") as f: | |
| for chunk in iter(lambda: f.read(1 << 20), b""): | |
| h.update(chunk) | |
| return h.hexdigest() | |
| def ensure_model(path: Path, url: str, expected_sha256: str | None) -> Path: | |
| """Return path to a verified model file, downloading it if missing.""" | |
| path = Path(path) | |
| if path.exists(): | |
| if not expected_sha256 or sha256_of(path) == expected_sha256: | |
| return path | |
| raise RuntimeError(f"{path} exists but its SHA-256 does not match the expected model.") | |
| path.parent.mkdir(parents=True, exist_ok=True) | |
| with tempfile.NamedTemporaryFile(dir=path.parent, delete=False, suffix=".part") as tmp: | |
| tmp_path = Path(tmp.name) | |
| with urllib.request.urlopen(url, timeout=120) as resp: | |
| shutil.copyfileobj(resp, tmp) | |
| digest = sha256_of(tmp_path) | |
| if expected_sha256 and digest != expected_sha256: | |
| tmp_path.unlink(missing_ok=True) | |
| raise RuntimeError(f"Downloaded model SHA-256 {digest} != expected {expected_sha256} ({url})") | |
| tmp_path.replace(path) | |
| return path | |
| if __name__ == "__main__": | |
| s = Settings() | |
| p = ensure_model(s.model_path, s.model_url, s.model_sha256) | |
| print(f"Model ready: {p} ({p.stat().st_size / 2**20:.1f} MB, sha256 {sha256_of(p)[:12]}...)") | |