feat(subscribestar): flip dispatch to the native ingester (#893, Step 5)

SubscribeStar now downloads + verifies through the native core ingester instead
of gallery-dl — the go-live switch for milestone #71.

- download_backends: subscribestar added to NATIVE_INGESTER_PLATFORMS; a
  _NATIVE_INGESTERS registry + _resolve_native_campaign_id make _run_native_ingester
  / preview_source / verify_source_credential platform-aware. SubscribeStar's
  campaign_id IS the creator URL (no resolver); Patreon still resolves the vanity.
  preview now catches the shared NativeIngestError (covers both platforms).
- platform_lock: subscribestar serialized (one paced walk at a time).
- gallery_dl: subscribestar entry removed from PLATFORM_DEFAULTS (rule 22 — no
  fallback once native works).
- frontend SourceActions: isPatreon → isNative (patreon|subscribestar) so the
  recover/recapture actions show for subscribestar; download_service's
  cursor/mode/post_first + the preview endpoint already key on
  uses_native_ingester, so backfill/recovery/recapture/preview light up for free.
- tests: download_backends (subscribestar native), platform_lock (serialized),
  and three gallery-dl-sample tests repointed to hentaifoundry (api_credentials
  verify, gallery_dl_service skip-value, api_sources arm-no-preflight).

post_is_gated stays best-effort (can't cause junk downloads); not gating this.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/services/download_backends.py

@@ -24,13 +24,22 @@ import asyncio
 from pathlib import Path
 
 from .gallery_dl import DownloadResult, ErrorType
+from .native_ingest_common import NativeIngestError
 from .patreon_ingester import PatreonIngester
 from .patreon_resolver import extract_vanity, resolve_campaign_id_for_source
+from .subscribestar_ingester import SubscribeStarIngester
 
 # Platforms whose download + verify go through the native ingester rather than
-# gallery-dl. gallery-dl still serves every other platform (subscribestar,
-# hentaifoundry, discord, pixiv, deviantart) unchanged.
-NATIVE_INGESTER_PLATFORMS = frozenset({"patreon"})
+# gallery-dl. gallery-dl still serves the rest (hentaifoundry, discord, pixiv,
+# deviantart) until they migrate too.
+NATIVE_INGESTER_PLATFORMS = frozenset({"patreon", "subscribestar"})
+
+# Native ingester classes keyed by platform (uniform constructor signature, so
+# _run_native_ingester / preview build whichever the source needs).
+_NATIVE_INGESTERS = {
+    "patreon": PatreonIngester,
+    "subscribestar": SubscribeStarIngester,
+}
 
 # Mirrors patreon_resolver._CAMPAIGNS_URL — surfaced in resolution-failure
 # messages so the operator sees the exact lookup endpoint that was hit.
@@ -81,22 +90,36 @@ async def run_download(
     return result, None
 
 
+async def _resolve_native_campaign_id(
+    platform: str, url: str, cookies_path: str | None, overrides: dict,
+) -> tuple[str | None, str | None]:
+    """`(campaign_id, resolved_campaign_id)` for a native source. SubscribeStar's
+    feed id IS the creator URL (no lookup → resolved None). Patreon resolves the
+    campaign id from the vanity URL (resolved non-None when a lookup actually ran,
+    so phase 3 caches it)."""
+    if platform == "subscribestar":
+        return url, None
+    return await resolve_campaign_id_for_source(url, cookies_path, overrides)
+
+
 async def _run_native_ingester(
     ctx: dict, source_config, mode: str | None, gdl, sync_session_factory,
 ) -> tuple[DownloadResult, str | None]:
-    """Patreon (today the only native platform): resolve the campaign id, then run
-    the native ingester in a worker thread (it is sync requests/subprocess).
+    """Run the native ingester for a native platform in a worker thread (sync
+    requests/subprocess). Patreon resolves a campaign id from the vanity URL;
+    SubscribeStar's feed id is the creator URL itself. A campaign id we cannot
+    resolve is a loud NOT_FOUND — never a silent empty success.
 
-    `resolved_campaign_id` is non-None only when we had to look it up from the
-    vanity URL this run, so phase 3 caches it the way the old gallery-dl retry
-    did. A campaign id we cannot resolve is a loud NOT_FOUND — never a silent
-    empty success.
+    `resolved_campaign_id` is non-None only when a lookup ran this call, so phase
+    3 caches it the way the old gallery-dl retry did.
     """
+    platform = ctx["platform"]
     overrides = ctx["config_overrides"] or {}
-    campaign_id, resolved_campaign_id = await resolve_campaign_id_for_source(
-        ctx["url"], ctx["cookies_path"], overrides
+    campaign_id, resolved_campaign_id = await _resolve_native_campaign_id(
+        platform, ctx["url"], ctx["cookies_path"], overrides
     )
     if not campaign_id:
+        # Only reachable for Patreon (SubscribeStar's campaign id is the URL).
         url = ctx["url"]
         vanity = extract_vanity(url)
         return (
@@ -104,7 +127,7 @@ async def _run_native_ingester(
                 success=False,
                 url=url,
                 artist_slug=ctx["artist_slug"],
-                platform="patreon",
+                platform=platform,
                 error_type=ErrorType.NOT_FOUND,
                 error_message=(
                     f"Could not resolve Patreon campaign id. source_url={url!r}; "
@@ -127,7 +150,7 @@ async def _run_native_ingester(
         if source_config.sleep_request is not None
         else max(0.5, rate_limit / 4)
     )
-    ingester = PatreonIngester(
+    ingester = _NATIVE_INGESTERS[platform](
         images_root=gdl.images_root,
         cookies_path=ctx["cookies_path"],
         session_factory=sync_session_factory,
@@ -174,10 +197,8 @@ async def preview_source(
     """
     import asyncio
 
-    from .patreon_client import PatreonAPIError
-
-    campaign_id, _ = await resolve_campaign_id_for_source(
-        url, cookies_path, config_overrides or {}
+    campaign_id, _ = await _resolve_native_campaign_id(
+        platform, url, cookies_path, config_overrides or {}
     )
     if not campaign_id:
         vanity = extract_vanity(url)
@@ -188,7 +209,7 @@ async def preview_source(
                 "(cookies expired, or the creator moved/renamed?)."
             )
         }
-    ingester = PatreonIngester(
+    ingester = _NATIVE_INGESTERS[platform](
         images_root=images_root,
         cookies_path=cookies_path,
         session_factory=sync_session_factory,
@@ -199,7 +220,7 @@ async def preview_source(
             None,
             lambda: ingester.preview(source_id, campaign_id, page_limit=page_limit),
         )
-    except PatreonAPIError as exc:
+    except NativeIngestError as exc:
         return {"error": f"Couldn't preview: {exc}"}
     return result
 
@@ -221,7 +242,12 @@ async def verify_source_credential(
     """
     if uses_native_ingester(platform):
         # Native ingester platforms verify via their own lightweight auth probe
-        # (resolve campaign id + one authenticated API page). Patreon today.
+        # (one authenticated feed fetch). SubscribeStar's probe takes the creator
+        # URL directly; Patreon's resolves the campaign id first.
+        if platform == "subscribestar":
+            from .subscribestar_ingester import verify_subscribestar_credential
+
+            return await verify_subscribestar_credential(url, cookies_path, config_overrides)
         from .patreon_ingester import verify_patreon_credential
 
         return await verify_patreon_credential(url, cookies_path, config_overrides)

backend/app/services/gallery_dl.py

@@ -298,11 +298,8 @@ class GalleryDLService:
     # removed at the plan-#697 cutover — it now uses the native ingester
     # (services/patreon_ingester.py), not gallery-dl.
     PLATFORM_DEFAULTS = {
-        "subscribestar": {
-            "content_types": ["all"],
-            "directory": ["{date:%Y-%m-%d}_{id}_{title[:40]}"],
-            "filename": "{num:>02}_{filename}.{extension}",
-        },
+        # subscribestar removed — it's a native-ingester platform now (#71); the
+        # remaining entries are the gallery-dl platforms not yet migrated.
         "hentaifoundry": {
             "content_types": ["all"],
             "directory": [],

backend/app/services/platform_lock.py

@@ -21,9 +21,10 @@ from ..config import get_config
 log = logging.getLogger(__name__)
 
 # Platforms walked one-at-a-time. gallery-dl platforms are intentionally NOT
-# here: each runs as a self-pacing subprocess and they're lower-volume. Add a
-# platform here to cap it to a single concurrent walk.
-SERIALIZED_PLATFORMS = frozenset({"patreon"})
+# here: each runs as a self-pacing subprocess and they're lower-volume. The
+# native-ingester platforms are serialized (one paced scrape/API walk at a time).
+# Add a platform here to cap it to a single concurrent walk.
+SERIALIZED_PLATFORMS = frozenset({"patreon", "subscribestar"})
 
 _LOCK_PREFIX = "fc:download_lock:"