feat(provenance): importer sets image_record.artist_id, stops minting artist tags

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/services/importer.py

@@ -27,10 +27,7 @@ from ..models import (
     ImportSettings,
     Post,
     Source,
-    Tag,
-    TagKind,
 )
-from ..models.tag import image_tag
 from ..utils.paths import derive_subdir, derive_top_level_artist, hash_suffixed_name
 from ..utils.phash import compute_phash, find_similar
 from ..utils.sidecar import find_sidecar, parse_sidecar
@@ -244,7 +241,7 @@ class Importer:
         artist = None
         artist_name = derive_top_level_artist(source, self.import_root)
         if artist_name:
-            artist = self._attach_artist_tag(record.id, artist_name)
+            artist = self._attach_artist(record, artist_name)
 
         # Sidecar provenance (best-effort; never fails the import).
         self._apply_sidecar(record, source, artist)
@@ -266,33 +263,15 @@ class Importer:
             self.session.flush()
         return artist
 
-    def _attach_artist_tag(self, image_id: int, artist_name: str) -> Artist:
-        """Idempotently creates Artist + artist tag, attaches to image.
-        Returns the Artist (sidecar provenance attaches its Source to it)."""
+    def _attach_artist(self, record: ImageRecord, artist_name: str) -> Artist:
+        """Upsert the Artist and set it as the image's canonical artist.
+        Artist-kind tags were retired in FC-2d-vii-c — the Artist row is
+        the single source of truth. Returns the Artist (sidecar
+        provenance attaches its Source to it)."""
         artist = self._upsert_artist(artist_name)
-
-        tag = self.session.execute(
-            select(Tag).where(Tag.name == artist_name).where(Tag.kind == TagKind.artist)
-        ).scalar_one_or_none()
-        if tag is None:
-            tag = Tag(name=artist_name, kind=TagKind.artist)
-            self.session.add(tag)
+        if record.artist_id is None:
+            record.artist_id = artist.id
             self.session.flush()
-
-        # Idempotent association; using a raw insert + on-conflict-do-nothing
-        # is cleaner here than fetching first, but for a sync session we just
-        # check existence.
-        already = self.session.execute(
-            select(image_tag.c.tag_id)
-            .where(image_tag.c.image_record_id == image_id)
-            .where(image_tag.c.tag_id == tag.id)
-        ).scalar_one_or_none()
-        if already is None:
-            self.session.execute(
-                image_tag.insert().values(
-                    image_record_id=image_id, tag_id=tag.id, source="auto",
-                )
-            )
         return artist
 
     @staticmethod
@@ -339,6 +318,9 @@ class Importer:
             )
             return
 
+        if record.artist_id is None:
+            record.artist_id = artist.id
+
         platform = sd.platform or "unknown"
         url = sd.post_url or f"sidecar:{platform}"
         src = self.session.execute(