feat(civitai): add rate limiting support and error handling

- Add RateLimitError import and _make_request wrapper method to handle rate limiting
- Update API methods to use _make_request wrapper instead of direct downloader calls
- Add explicit RateLimitError handling in API methods to properly propagate rate limit errors
- Add _extract_retry_after method to parse Retry-After headers
- Improve error handling by surfacing rate limit information to callers

These changes ensure that rate limiting from the Civitai API is properly detected and handled, allowing callers to implement appropriate backoff strategies when rate limits are encountered.

py/services/metadata_sync_service.py

@@ -10,6 +10,7 @@ from typing import Any, Awaitable, Callable, Dict, Iterable, Optional
 
 from ..services.settings_manager import SettingsManager
 from ..utils.model_utils import determine_base_model
+from .errors import RateLimitError
 
 logger = logging.getLogger(__name__)
 
@@ -205,6 +206,9 @@ class MetadataSyncService:
             for provider_name, provider in provider_attempts:
                 try:
                     civitai_metadata_candidate, error = await provider.get_model_by_hash(sha256)
+                except RateLimitError as exc:
+                    exc.provider = exc.provider or (provider_name or provider.__class__.__name__)
+                    raise
                 except Exception as exc:  # pragma: no cover - defensive logging
                     logger.error("Provider %s failed for hash %s: %s", provider_name, sha256, exc)
                     civitai_metadata_candidate, error = None, str(exc)
@@ -299,6 +303,16 @@ class MetadataSyncService:
             error_msg = f"Error fetching metadata - Missing key: {exc} in model_data={model_data}"
             logger.error(error_msg)
             return False, error_msg
+        except RateLimitError as exc:
+            provider_label = exc.provider or "metadata provider"
+            wait_hint = (
+                f"; retry after approximately {int(exc.retry_after)}s"
+                if exc.retry_after and exc.retry_after > 0
+                else ""
+            )
+            error_msg = f"Rate limited by {provider_label}{wait_hint}"
+            logger.warning(error_msg)
+            return False, error_msg
         except Exception as exc:  # pragma: no cover - error path
             error_msg = f"Error fetching metadata: {exc}"
             logger.error(error_msg, exc_info=True)