backend/app/services/tag_directory_service.py

@@ -55,21 +55,20 @@ class TagDirectoryService:
         fandom = aliased(Tag)
         member = aliased(Tag)
         # image_count aggregates the tag's images INCLUDING, for a fandom, every
-        # image carrying one of its characters (member.fandom_id == Tag.id) — the
-        # member subquery is empty for non-fandom tags, so they stay direct-only.
-        # DISTINCT so an image with both the fandom and ≥1 of its characters
-        # counts once; a correlated scalar subquery keeps it 1 row per tag with
-        # no group_by (the fandom self-join below is 1:1).
+        # image carrying one of its characters. `member` is the tag actually on
+        # the image; an image counts for the outer Tag if that applied tag IS the
+        # Tag (direct) OR is a character whose fandom_id is the Tag (the fandom
+        # leg). Both legs correlate the OUTER Tag.id at a SINGLE level — a nested
+        # `tag_id IN (SELECT ... WHERE member.fandom_id == Tag.id)` does NOT
+        # correlate and silently counts every fandom-character globally (~every
+        # tag collapses to the same inflated number). DISTINCT so an image with
+        # the fandom AND ≥1 of its characters counts once; a correlated scalar
+        # subquery keeps it 1 row per tag with no group_by.
         count_col = (
             select(func.count(image_tag.c.image_record_id.distinct()))
-            .where(
-                or_(
-                    image_tag.c.tag_id == Tag.id,
-                    image_tag.c.tag_id.in_(
-                        select(member.id).where(member.fandom_id == Tag.id)
-                    ),
-                )
-            )
+            .select_from(image_tag)
+            .join(member, member.id == image_tag.c.tag_id)
+            .where(or_(image_tag.c.tag_id == Tag.id, member.fandom_id == Tag.id))
             .correlate(Tag)
             .scalar_subquery()
             .label("image_count")

tests/test_tag_directory_service.py

@@ -47,20 +47,35 @@ async def test_directory_fandom_counts_and_previews_via_characters(db):
     char = Tag(name="Ichigo", kind=TagKind.character, fandom_id=fandom.id)
     db.add(char)
     await db.flush()
+    # A SECOND, unrelated fandom + character + image. The count for "Bleach"
+    # must NOT pick this up — guards against the count's fandom leg failing to
+    # correlate the outer tag and counting EVERY fandom-character globally
+    # (which inflates every card to the same number).
+    other_fandom = Tag(name="Naruto", kind=TagKind.fandom)
+    db.add(other_fandom)
+    await db.flush()
+    other_char = Tag(name="Sasuke", kind=TagKind.character, fandom_id=other_fandom.id)
+    db.add(other_char)
+    await db.flush()
     # img0: character only; img1: fandom direct; img2: BOTH (dedup → counts once)
     img0, img1, img2 = await _img(db, 0), await _img(db, 1), await _img(db, 2)
+    other_img = await _img(db, 3)
     await db.execute(image_tag.insert().values([
         {"image_record_id": img0.id, "tag_id": char.id, "source": "manual"},
         {"image_record_id": img1.id, "tag_id": fandom.id, "source": "manual"},
         {"image_record_id": img2.id, "tag_id": char.id, "source": "manual"},
         {"image_record_id": img2.id, "tag_id": fandom.id, "source": "manual"},
+        {"image_record_id": other_img.id, "tag_id": other_char.id, "source": "manual"},
     ]))
     await db.flush()
     svc = TagDirectoryService(db)
     page = await svc.list_tags(kind="fandom", q=None, cursor=None, limit=10)
     card = next(c for c in page.cards if c["name"] == "Bleach")
-    assert card["image_count"] == 3
+    assert card["image_count"] == 3  # NOT 4 — Naruto's image must be excluded
     assert len(card["preview_thumbnails"]) == 3
+    # The unrelated fandom counts only its own one image.
+    other = next(c for c in page.cards if c["name"] == "Naruto")
+    assert other["image_count"] == 1
 
 
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