feat(downloads): auto-heal patreon campaign-ID failures via resolver retry

backend/app/tasks/downloads.py

@@ -3,6 +3,7 @@
 import asyncio
 import logging
 import re
+from dataclasses import dataclass
 from datetime import datetime, timedelta
 from typing import Optional
 
@@ -19,6 +20,7 @@ from app.models.download import Download, DownloadStatus, ErrorType as DBErrorTy
 from app.models.setting import Setting, DEFAULT_SETTINGS
 from app.services.gallery_dl import GalleryDLService, SourceConfig, DownloadResult
 from app.services.credential_manager import CredentialManager
+from app.services.patreon_resolver import resolve_campaign_id
 from app.events import publish_event
 
 logger = logging.getLogger(__name__)
@@ -113,6 +115,71 @@ def _extract_vanity_from_url(url: str) -> Optional[str]:
     return m.group(1) if m else None
 
 
+@dataclass
+class _DownloadAttempt:
+    """Result of executing a download, possibly with a retry after campaign-ID resolution."""
+    dl_result: DownloadResult
+    resolved_campaign_id: Optional[str]
+
+
+async def _execute_download_with_retry(
+    *,
+    gdl_service,
+    platform: str,
+    source_url: str,
+    source_metadata: dict,
+    subscription_name: str,
+    source_config,
+    cookies_path: Optional[str],
+    auth_token: Optional[str],
+) -> _DownloadAttempt:
+    """Run the download once, auto-heal Patreon campaign-ID failures with one retry.
+
+    Returns a _DownloadAttempt wrapping:
+      - the final DownloadResult (retry's result if we retried, else the first)
+      - resolved_campaign_id: the newly-resolved ID (if we resolved one this call), else None
+
+    The caller is responsible for persisting resolved_campaign_id into source.metadata_.
+    """
+    effective_url = _effective_patreon_url(platform, source_url, source_metadata)
+    dl_result = await gdl_service.download(
+        url=effective_url,
+        subscription_name=subscription_name,
+        platform=platform,
+        source_config=source_config,
+        cookies_path=cookies_path,
+        auth_token=auth_token,
+    )
+
+    # Only retry if: patreon + campaign-ID failure + no cached id + extractable vanity
+    if (
+        platform == "patreon"
+        and not dl_result.success
+        and "patreon_campaign_id" not in (source_metadata or {})
+        and _looks_like_campaign_id_failure(dl_result)
+    ):
+        vanity = _extract_vanity_from_url(source_url)
+        if vanity:
+            logger.info(
+                f"Attempting campaign-ID resolution for {subscription_name}/patreon ({vanity})"
+            )
+            campaign_id = await resolve_campaign_id(vanity, cookies_path)
+            if campaign_id:
+                retry_result = await gdl_service.download(
+                    url=f"https://www.patreon.com/id:{campaign_id}",
+                    subscription_name=subscription_name,
+                    platform=platform,
+                    source_config=source_config,
+                    cookies_path=cookies_path,
+                    auth_token=auth_token,
+                )
+                return _DownloadAttempt(
+                    dl_result=retry_result, resolved_campaign_id=campaign_id
+                )
+
+    return _DownloadAttempt(dl_result=dl_result, resolved_campaign_id=None)
+
+
 async def _download_source_async(source_id: int, download_id: int = None) -> dict:
     """Async implementation of source download.
 
@@ -255,17 +322,22 @@ async def _download_source_async(source_id: int, download_id: int = None) -> dic
     source_config = SourceConfig.from_dict(source_metadata)
     dl_result = None
     dl_error = None
+    resolved_campaign_id: Optional[str] = None
 
     try:
         gdl_service = GalleryDLService(rate_limit=db_rate_limit)
-        dl_result = await gdl_service.download(
-            url=source_url,
-            subscription_name=subscription_name,
+        attempt = await _execute_download_with_retry(
+            gdl_service=gdl_service,
             platform=source_platform,
+            source_url=source_url,
+            source_metadata=source_metadata,
+            subscription_name=subscription_name,
             source_config=source_config,
             cookies_path=cookies_path,
             auth_token=auth_token,
         )
+        dl_result = attempt.dl_result
+        resolved_campaign_id = attempt.resolved_campaign_id
     except Exception as e:
         logger.exception(f"Unexpected error downloading {subscription_name}/{source_platform}: {e}")
         dl_error = e
@@ -287,6 +359,13 @@ async def _download_source_async(source_id: int, download_id: int = None) -> dic
                 logger.error(f"Could not re-fetch download {actual_download_id} or source {source_id} for result update")
                 return {"source_id": source_id, "status": "error", "error": "Lost DB records"}
 
+            # Persist resolved campaign ID (if the retry hook resolved one this run)
+            if resolved_campaign_id:
+                source.metadata_ = {
+                    **(source.metadata_ or {}),
+                    "patreon_campaign_id": resolved_campaign_id,
+                }
+
             if dl_error:
                 download.status = DownloadStatus.FAILED
                 download.error_type = DBErrorType.UNKNOWN_ERROR