fix(download): accept newer CivitAI file types for primary file selection

Downloads failed with "No suitable file found in metadata" for models whose
only file uses newer CivitAI file types (e.g. 'Enhancement LoRA' for
Anima/AIR image-editing LoRAs) because the primary-file allowlist only
covered legacy types.

- unify the weights-type allowlist as MODEL_WEIGHT_FILE_TYPES
  (py/utils/constants.py) and apply it across download, recipe and
  metadata-refresh lookups
- mirror CivitAI's getPrimaryFile() semantics: prefer weights-type primary,
  fall back to weights files, then trust CivitAI's primary flag (excluding
  non-downloadable artifacts like Config/Archive/Workflow)
- mirror the allowlist in the frontend via shared isModelWeightFile() helper
- add regression tests for the Enhancement LoRA primary-file download,
  primary-flag fallback and weights-over-non-weights-primary preference

py/services/civitai_client.py

@@ -21,6 +21,7 @@ from .model_metadata_provider import (
 from .downloader import get_downloader
 from .errors import RateLimitError, ResourceNotFoundError
 from ..utils.civitai_utils import resolve_license_payload
+from ..utils.constants import MODEL_WEIGHT_FILE_TYPES
 
 logger = logging.getLogger(__name__)
 
@@ -538,10 +539,16 @@ class CivitaiClient:
         return model_versions[0]
 
     def _extract_primary_model_hash(self, version_entry: Dict[str, Any]) -> Optional[str]:
+        # Prefer the generic "Model" file (most reliable version identity);
+        # fall back to any other weights-type primary.
         for file_info in version_entry.get("files", []):
             if file_info.get("type") == "Model" and file_info.get("primary"):
-                hashes = file_info.get("hashes", {})
-                model_hash = hashes.get("SHA256")
+                model_hash = (file_info.get("hashes", {}) or {}).get("SHA256")
+                if model_hash:
+                    return model_hash
+        for file_info in version_entry.get("files", []):
+            if file_info.get("type") in MODEL_WEIGHT_FILE_TYPES and file_info.get("primary"):
+                model_hash = (file_info.get("hashes", {}) or {}).get("SHA256")
                 if model_hash:
                     return model_hash
         return None

py/services/download_manager.py

@@ -18,6 +18,7 @@ from ..utils.models import LoraMetadata, CheckpointMetadata, EmbeddingMetadata
 from ..utils.constants import (
     CARD_PREVIEW_WIDTH,
     DIFFUSION_MODEL_BASE_MODELS,
+    MODEL_WEIGHT_FILE_TYPES,
     SUPPORTED_DOWNLOAD_SKIP_BASE_MODELS,
     VALID_LORA_TYPES,
 )
@@ -46,6 +47,11 @@ CIVITAI_DOWNLOAD_URL_PREFIXES = (
 )
 
 
+# File types that are never the intended download target even when CivitAI
+# marks them primary — configs/archives/workflows are auxiliary artifacts.
+NON_DOWNLOADABLE_PRIMARY_TYPES = ("Config", "Archive", "Workflow", "Training Data")
+
+
 class DownloadManager:
     _instance = None
     _lock = asyncio.Lock()
@@ -1500,7 +1506,7 @@ class DownloadManager:
                             f
                             for f in files
                             if f.get("primary")
-                            and f.get("type") in ("Model", "Negative", "Diffusion Model", "UNet")
+                            and f.get("type") in MODEL_WEIGHT_FILE_TYPES
                         ),
                         None,
                     )
@@ -1540,21 +1546,52 @@ class DownloadManager:
             # Fallback to primary file if no match found
             if not file_info:
                 logger.debug("[download] Looking for primary file as fallback")
+                # Prefer a weights-type file CivitAI marked primary; then any
+                # weights-type file (providers without primary flags, e.g.
+                # civarchive); then trust CivitAI's primary flag regardless of
+                # type — newer types like 'Enhancement LoRA' are valid primary
+                # files. Weights files are preferred over non-weights primary
+                # files so a Config/Archive primary never replaces a Model.
                 file_info = next(
                     (
                         f
                         for f in files
-                        if f.get("primary") and f.get("type") in ("Model", "Negative", "Diffusion Model", "UNet")
+                        if f.get("primary") and f.get("type") in MODEL_WEIGHT_FILE_TYPES
                     ),
                     None,
                 )
                 if file_info:
                     logger.debug(
-                        "[download] Fallback primary file selected: id=%s, name=%s",
+                        "[download] Fallback primary file selected (primary + weights): id=%s, name=%s",
                         file_info.get("id"), file_info.get("name"),
                     )
                 else:
-                    logger.debug("[download] No primary file found in fallback lookup")
+                    file_info = next(
+                        (f for f in files if f.get("type") in MODEL_WEIGHT_FILE_TYPES),
+                        None,
+                    )
+                    if file_info:
+                        logger.debug(
+                            "[download] Fallback primary file selected (weights type, no primary flag): id=%s, name=%s",
+                            file_info.get("id"), file_info.get("name"),
+                        )
+                    else:
+                        file_info = next(
+                            (
+                                f
+                                for f in files
+                                if f.get("primary")
+                                and f.get("type") not in NON_DOWNLOADABLE_PRIMARY_TYPES
+                            ),
+                            None,
+                        )
+                        if file_info:
+                            logger.debug(
+                                "[download] Fallback primary file selected (trusting CivitAI primary flag): id=%s, name=%s, type=%s",
+                                file_info.get("id"), file_info.get("name"), file_info.get("type"),
+                            )
+                        else:
+                            logger.debug("[download] No primary file found in fallback lookup")
 
             if not file_info:
                 return {"success": False, "error": "No suitable file found in metadata"}