chore: snapshot workflow migration progress

backend/app/api/routers/cad.py

@@ -13,6 +13,9 @@ from sqlalchemy import select
 from sqlalchemy.orm import selectinload
 
 from app.database import get_db
+from app.core.render_paths import resolve_result_path
+from app.config import settings
+from app.domains.media.models import MediaAsset, MediaAssetType
 from app.models.cad_file import CadFile, ProcessingStatus
 from app.models.order import Order
 from app.models.order_item import OrderItem
@@ -191,6 +194,38 @@ async def _get_cad_file(cad_id: uuid.UUID, db: AsyncSession) -> CadFile:
     return cad
 
 
+async def _resolve_gltf_path(cad: CadFile, db: AsyncSession) -> Path | None:
+    """Resolve the best available GLTF/GLB path for a CAD file.
+
+    Prefer the legacy cad_files.gltf_path for compatibility, but fall back to
+    the canonical media_assets.gltf_geometry record written by the newer export
+    pipeline.
+    """
+    if cad.gltf_path:
+        legacy_path = resolve_result_path(cad.gltf_path) or Path(cad.gltf_path)
+        if legacy_path.exists():
+            return legacy_path
+
+    asset_result = await db.execute(
+        select(MediaAsset)
+        .where(
+            MediaAsset.cad_file_id == cad.id,
+            MediaAsset.asset_type == MediaAssetType.gltf_geometry,
+            MediaAsset.is_archived == False,  # noqa: E712
+        )
+        .order_by(MediaAsset.created_at.desc())
+    )
+    asset = asset_result.scalars().first()
+    if asset and asset.storage_key:
+        asset_path = resolve_result_path(asset.storage_key)
+        if asset_path is None:
+            asset_path = Path(settings.upload_dir) / asset.storage_key.lstrip("/")
+        if asset_path.exists():
+            return asset_path
+
+    return None
+
+
 @router.get("/{id}/thumbnail")
 async def get_thumbnail(
     id: uuid.UUID,
@@ -228,20 +263,13 @@ async def get_model(
 ):
     """Serve the glTF file for a CAD file."""
     cad = await _get_cad_file(id, db)
-
-    if not cad.gltf_path:
+    gltf_path = await _resolve_gltf_path(cad, db)
+    if gltf_path is None:
         raise HTTPException(
             status_code=404,
             detail="glTF model not yet generated for this CAD file",
         )
 
-    gltf_path = Path(cad.gltf_path)
-    if not gltf_path.exists():
-        raise HTTPException(
-            status_code=404,
-            detail="glTF file missing from storage",
-        )
-
     # glTF files may be either .gltf (JSON) or .glb (binary)
     suffix = gltf_path.suffix.lower()
     if suffix == ".glb":