feat(artist): resolve patreon + subscribestar display names at add-time (#130 step 5)

Parity with pixiv (operator ask): the extension add now resolves the real
display name for our other native platforms too, not just the URL handle.
patreon_resolver.resolve_display_name reads the campaigns API's
attributes.name; SubscribeStarClient.resolve_display_name pulls the creator
name off the profile page (og:title, else the <title> stripped of the
SubscribeStar suffix). extension_service._resolve_artist_name dispatches per
platform (pixiv=token, patreon/subscribestar=cookies via get_cookies_path),
best-effort in an executor, falling back to the readable URL handle on any
failure. Still all curator core — the extension is unchanged (sends only the
URL). gallery-dl platforms keep the handle (readable, no native client).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CDgx8bQS5YrGRK76v8HUnM

backend/app/services/extension_service.py

@@ -8,6 +8,7 @@ and returns a JSON-shaped dict for the API layer.
 
 from __future__ import annotations
 
+import logging
 import re
 
 from sqlalchemy import select
@@ -18,6 +19,8 @@ from ..utils.slug import slugify
 from .db_helpers import get_or_create
 from .source_service import BACKFILL_MAX_CHUNKS
 
+log = logging.getLogger(__name__)
+
 
 class UnknownPlatformError(Exception):
     """URL didn't match any platform pattern."""
@@ -82,9 +85,9 @@ class ExtensionService:
             )).scalar_one()
             return self._shape(existing, artist, created_source=False, created_artist=False)
 
-        # New source → name the artist properly. Pixiv's URL yields only the
-        # numeric id, so resolve the real display name via the app API.
-        name = await self._resolve_artist_name(platform, raw_slug)
+        # New source → name the artist properly by resolving the real display
+        # name from the platform (falls back to the URL handle).
+        name = await self._resolve_artist_name(platform, raw_slug, url)
         artist, created_artist = await self._find_or_create_artist(name)
         source, created_source = await self._find_or_create_source(
             artist_id=artist.id, platform=platform, url=url,
@@ -110,25 +113,48 @@ class ExtensionService:
             "created_artist": created_artist,
         }
 
-    async def _resolve_artist_name(self, platform: str, raw_slug: str) -> str:
-        """A human display name for a new artist. Pixiv's URL carries only the
-        numeric user id, so resolve the real name via the app API (curator holds
-        the OAuth token); every other platform's URL handle is already readable.
-        Falls back to raw_slug on any failure (no token, API error)."""
-        if platform != "pixiv" or self._crypto is None:
+    async def _resolve_artist_name(
+        self, platform: str, raw_slug: str, url: str
+    ) -> str:
+        """The real display name for a new artist, resolved from the platform at
+        add-time (#130). Our native platforms each have a name source — pixiv the
+        app API (token), patreon the campaigns API, subscribestar the profile
+        page (both cookies). Other platforms (and any failure — no credential,
+        network error) fall back to the URL handle, which is already readable.
+        The resolvers are sync, so they run in an executor."""
+        if self._crypto is None or platform not in ("pixiv", "patreon", "subscribestar"):
             return raw_slug
         import asyncio
 
         from .credential_service import CredentialService
-        from .pixiv_client import PixivClient
-
-        token = await CredentialService(self.session, self._crypto).get_token("pixiv")
-        if not token:
-            return raw_slug
+        cred = CredentialService(self.session, self._crypto)
         loop = asyncio.get_running_loop()
-        name = await loop.run_in_executor(
-            None, PixivClient(token).resolve_display_name, raw_slug
-        )
+        try:
+            if platform == "pixiv":
+                token = await cred.get_token("pixiv")
+                if not token:
+                    return raw_slug
+                from .pixiv_client import PixivClient
+                name = await loop.run_in_executor(
+                    None, PixivClient(token).resolve_display_name, raw_slug
+                )
+            elif platform == "patreon":
+                cookies = await cred.get_cookies_path("patreon")
+                from .patreon_resolver import resolve_display_name
+                name = await loop.run_in_executor(
+                    None, resolve_display_name, raw_slug,
+                    str(cookies) if cookies else None,
+                )
+            else:  # subscribestar
+                cookies = await cred.get_cookies_path("subscribestar")
+                from .subscribestar_client import SubscribeStarClient
+                client = SubscribeStarClient(str(cookies) if cookies else None)
+                name = await loop.run_in_executor(
+                    None, client.resolve_display_name, url
+                )
+        except Exception as exc:      # resolution is best-effort — never block the add
+            log.warning("artist display-name resolution failed (%s): %s", platform, exc)
+            return raw_slug
         return name or raw_slug
 
     async def probe(self, url: str) -> dict: