From 33efba8bf52cf33303a1cec5aecaa1778aad7aeb Mon Sep 17 00:00:00 2001
From: Bryan Van Deusen <bryan.vandeusen@fabledsword.com>
Date: Sat, 16 May 2026 13:38:27 -0400
Subject: [PATCH] feat(tags): merge repoints allowlist, embedding, aliases,
 fandom children

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 backend/app/services/tag_service.py | 36 +++++++++--
 tests/test_tag_merge.py             | 98 ++++++++++++++++++++++++++++-
 2 files changed, 129 insertions(+), 5 deletions(-)

diff --git a/backend/app/services/tag_service.py b/backend/app/services/tag_service.py
index e79df6c..e2d1310 100644
--- a/backend/app/services/tag_service.py
+++ b/backend/app/services/tag_service.py
@@ -368,18 +368,46 @@ class TagService:
         )
 
     async def _repoint_allowlist(self, src: int, tgt: int) -> None:
-        pass
+        tgt_has = await self.session.scalar(
+            select(exists().where(TagAllowlist.tag_id == tgt))
+        )
+        if tgt_has:
+            await self.session.execute(
+                text("DELETE FROM tag_allowlist WHERE tag_id = :src"),
+                {"src": src},
+            )
+        else:
+            await self.session.execute(
+                update(TagAllowlist)
+                .where(TagAllowlist.tag_id == src)
+                .values(tag_id=tgt)
+            )
 
     async def _repoint_embedding(self, src: int) -> None:
-        pass
+        await self.session.execute(
+            text(
+                "DELETE FROM tag_reference_embedding WHERE tag_id = :src"
+            ),
+            {"src": src},
+        )
 
     async def _repoint_aliases(self, src: int, tgt: int) -> None:
-        pass
+        from ..models.tag_alias import TagAlias
+
+        await self.session.execute(
+            update(TagAlias)
+            .where(TagAlias.canonical_tag_id == src)
+            .values(canonical_tag_id=tgt)
+        )
 
     async def _repoint_fandom_children(
         self, src: int, tgt: int, src_kind: TagKind
     ) -> None:
-        pass
+        if src_kind != TagKind.fandom:
+            return
+        await self.session.execute(
+            update(Tag).where(Tag.fandom_id == src).values(fandom_id=tgt)
+        )
 
     async def _create_protective_aliases(
         self, src_name: str, src_kind: TagKind, tgt: int
diff --git a/tests/test_tag_merge.py b/tests/test_tag_merge.py
index b9d0c2f..c5e70df 100644
--- a/tests/test_tag_merge.py
+++ b/tests/test_tag_merge.py
@@ -1,5 +1,5 @@
 import pytest
-from sqlalchemy import select
+from sqlalchemy import func, select
 
 from backend.app.models import Tag, TagKind, image_tag
 from backend.app.models.tag_allowlist import TagAllowlist
@@ -206,3 +206,99 @@ async def test_merge_dedups_suggestion_rejections(db):
             )
         )
     ).first() is None
+
+
+@pytest.mark.asyncio
+async def test_merge_allowlist_target_has_keeps_target_threshold(db):
+    svc = TagService(db)
+    a = await svc.find_or_create("SrcAL", TagKind.general)
+    b = await svc.find_or_create("TgtAL", TagKind.general)
+    db.add(TagAllowlist(tag_id=a.id, min_confidence=0.5))
+    db.add(TagAllowlist(tag_id=b.id, min_confidence=0.9))
+    await db.flush()
+    await svc.merge(a.id, b.id)
+    rows = (await db.execute(select(TagAllowlist))).scalars().all()
+    assert len(rows) == 1
+    assert rows[0].tag_id == b.id
+    assert rows[0].min_confidence == 0.9
+
+
+@pytest.mark.asyncio
+async def test_merge_allowlist_source_only_moves_to_target(db):
+    svc = TagService(db)
+    a = await svc.find_or_create("SrcAL2", TagKind.general)
+    b = await svc.find_or_create("TgtAL2", TagKind.general)
+    db.add(TagAllowlist(tag_id=a.id, min_confidence=0.42))
+    await db.flush()
+    await svc.merge(a.id, b.id)
+    rows = (await db.execute(select(TagAllowlist))).scalars().all()
+    assert len(rows) == 1
+    assert rows[0].tag_id == b.id
+    assert rows[0].min_confidence == 0.42
+
+
+@pytest.mark.asyncio
+async def test_merge_deletes_source_embedding(db):
+    from backend.app.models.tag_reference_embedding import (
+        TagReferenceEmbedding,
+    )
+
+    svc = TagService(db)
+    a = await svc.find_or_create("SrcEmb", TagKind.general)
+    b = await svc.find_or_create("TgtEmb", TagKind.general)
+    db.add(
+        TagReferenceEmbedding(
+            tag_id=a.id,
+            embedding=[0.0] * 1152,
+            reference_count=1,
+            model_version="v",
+        )
+    )
+    await db.flush()
+    await svc.merge(a.id, b.id)
+    db.expire_all()  # merge() uses Core DML; drop stale identity-map state
+    remaining = await db.scalar(
+        select(func.count())
+        .select_from(TagReferenceEmbedding)
+        .where(TagReferenceEmbedding.tag_id == a.id)
+    )
+    assert remaining == 0
+
+
+@pytest.mark.asyncio
+async def test_merge_repoints_existing_aliases(db):
+    from backend.app.models.tag_alias import TagAlias
+
+    svc = TagService(db)
+    a = await svc.find_or_create("SrcAlias", TagKind.general)
+    b = await svc.find_or_create("TgtAlias", TagKind.general)
+    db.add(
+        TagAlias(
+            alias_string="oldpred",
+            alias_category="general",
+            canonical_tag_id=a.id,
+        )
+    )
+    await db.flush()
+    await svc.merge(a.id, b.id)
+    db.expire_all()  # merge() uses Core DML; drop stale identity-map state
+    al = (
+        await db.execute(
+            select(TagAlias).where(TagAlias.alias_string == "oldpred")
+        )
+    ).scalar_one()
+    assert al.canonical_tag_id == b.id
+
+
+@pytest.mark.asyncio
+async def test_merge_fandom_reparents_children(db):
+    svc = TagService(db)
+    f_src = await svc.find_or_create("FandomSrc", TagKind.fandom)
+    f_tgt = await svc.find_or_create("FandomTgt", TagKind.fandom)
+    child = await svc.find_or_create(
+        "ChildChar", TagKind.character, fandom_id=f_src.id
+    )
+    await svc.merge(f_src.id, f_tgt.id)
+    db.expire_all()  # merge() uses Core DML; drop stale identity-map state
+    refreshed = await db.get(Tag, child.id)
+    assert refreshed.fandom_id == f_tgt.id