feat: catalog Record dict conversion

hef/catalog.py

@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from dataclasses import dataclass
+from dataclasses import dataclass, asdict, fields
 from typing import Optional
 
 MODES = frozenset({"audio", "video", "av"})
@@ -70,3 +70,20 @@ def validate(record: Record) -> None:
         raise CatalogError("duration_s must be non-negative")
     if record.license in ATTRIBUTION_LICENSES and not record.attribution:
         raise CatalogError(f"license {record.license} requires attribution")
+
+
+def record_to_dict(record: Record) -> dict:
+    """Convert a Record to a plain dict suitable for JSON serialization."""
+    return asdict(record)
+
+
+def record_from_dict(data: dict) -> Record:
+    """Build a Record from a dict, rejecting unknown or missing fields."""
+    known = {f.name for f in fields(Record)}
+    unknown = set(data) - known
+    if unknown:
+        raise CatalogError(f"unknown fields: {sorted(unknown)}")
+    try:
+        return Record(**data)
+    except TypeError as exc:
+        raise CatalogError(str(exc)) from exc