Add bounded dictation state and persistent offline Redux worker

scripts/fetch-model.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+"""Explicit setup only: fetch the pinned ~178 MB Redux weights; never used by runtime."""
+import argparse
+import hashlib
+import os
+from pathlib import Path
+import sys
+import tempfile
+import urllib.request
+
+sys.path.insert(0, str(Path(__file__).resolve().parents[1] / "python"))
+from frameyap.model_files import FILES, REVISION
+
+
+def matches(path, size, digest):
+    if not path.is_file() or path.is_symlink() or path.stat().st_size != size:
+        return False
+    with path.open("rb") as stream:
+        return hashlib.file_digest(stream, "sha256").hexdigest() == digest
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--destination", type=Path, required=True)
+    args = parser.parse_args()
+    dest = args.destination.expanduser().absolute()
+    if dest.is_symlink():
+        parser.error("destination must not be a symlink")
+    dest.mkdir(mode=0o700, parents=True, exist_ok=True)
+    for name, (size, digest) in FILES.items():
+        target = dest / name
+        if matches(target, size, digest):
+            continue
+        if target.exists() or target.is_symlink():
+            parser.error(f"existing mismatched file: {target}; move it aside explicitly")
+        url = f"https://huggingface.co/moondream/parakeet-redux/resolve/{REVISION}/{name}"
+        fd, temp = tempfile.mkstemp(prefix=".download-", dir=dest)
+        try:
+            with os.fdopen(fd, "wb") as output, urllib.request.urlopen(url, timeout=60) as source:
+                total = 0
+                while chunk := source.read(1024 * 1024):
+                    total += len(chunk)
+                    if total > size:
+                        raise ValueError("download exceeded pinned size")
+                    output.write(chunk)
+            if not matches(Path(temp), size, digest):
+                raise ValueError(f"pinned SHA-256/size mismatch: {name}")
+            os.replace(temp, target)
+        finally:
+            Path(temp).unlink(missing_ok=True)
+    print(f"Pinned Redux {REVISION} verified in {dest}")
+    print("Model attribution: moondream/parakeet-redux, CC-BY-4.0; see downloaded README.md.")
+
+
+if __name__ == "__main__":
+    main()