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/downloader.py

@@ -17,8 +17,10 @@ import aiohttp
 from collections import deque
 from dataclasses import dataclass
 from datetime import datetime, timedelta
+from email.utils import parsedate_to_datetime
 from typing import Optional, Dict, Tuple, Callable, Union, Awaitable
 from ..services.settings_manager import get_settings_manager
+from .errors import RateLimitError
 
 logger = logging.getLogger(__name__)
 
@@ -587,6 +589,19 @@ class Downloader:
                     return False, "Access forbidden"
                 elif response.status == 404:
                     return False, "Resource not found"
+                elif response.status == 429:
+                    retry_after = self._extract_retry_after(response.headers)
+                    error_msg = "Request rate limited"
+                    logger.warning(
+                        "Rate limit encountered for %s %s; retry_after=%s",
+                        method,
+                        url,
+                        retry_after,
+                    )
+                    return False, RateLimitError(
+                        error_msg,
+                        retry_after=retry_after,
+                    )
                 else:
                     return False, f"Request failed with status {response.status}"
                     
@@ -608,6 +623,38 @@ class Downloader:
         await self._create_session()
         logger.info("HTTP session refreshed due to settings change")
 
+    @staticmethod
+    def _extract_retry_after(headers) -> Optional[float]:
+        """Parse the Retry-After header into seconds."""
+        if not headers:
+            return None
+
+        header_value = headers.get("Retry-After")
+        if not header_value:
+            return None
+
+        header_value = header_value.strip()
+        if not header_value:
+            return None
+
+        if header_value.isdigit():
+            try:
+                seconds = float(header_value)
+            except ValueError:
+                return None
+            return max(0.0, seconds)
+
+        try:
+            retry_datetime = parsedate_to_datetime(header_value)
+        except (TypeError, ValueError):
+            return None
+
+        if retry_datetime.tzinfo is None:
+            return None
+
+        delta = retry_datetime - datetime.now(tz=retry_datetime.tzinfo)
+        return max(0.0, delta.total_seconds())
+
 
 # Global instance accessor
 async def get_downloader() -> Downloader: