chore: snapshot workflow migration progress

backend/app/domains/materials/library_paths.py

@@ -0,0 +1,51 @@
+from __future__ import annotations
+
+from pathlib import Path
+from typing import Any
+
+from app.config import settings
+
+
+def asset_library_dir() -> Path:
+    return Path(settings.upload_dir) / "asset-libraries"
+
+
+def list_asset_library_blends() -> list[Path]:
+    directory = asset_library_dir()
+    if not directory.is_dir():
+        return []
+
+    return sorted(
+        (path for path in directory.glob("*.blend") if path.is_file()),
+        key=lambda path: (path.stat().st_mtime, path.name),
+        reverse=True,
+    )
+
+
+def resolve_asset_library_blend_path(
+    *,
+    blend_file_path: str | None = None,
+    asset_library_id: Any | None = None,
+) -> str | None:
+    """Resolve the best available .blend path for an asset library.
+
+    Resolution order:
+    1. explicit configured path, when it exists
+    2. canonical uploads/asset-libraries/<id>.blend path
+    3. newest available .blend under uploads/asset-libraries
+    """
+    if blend_file_path:
+        configured = Path(blend_file_path)
+        if configured.is_file():
+            return str(configured)
+
+    if asset_library_id:
+        candidate = asset_library_dir() / f"{asset_library_id}.blend"
+        if candidate.is_file():
+            return str(candidate)
+
+    available = list_asset_library_blends()
+    if available:
+        return str(available[0])
+
+    return None