fix(aliases): store modal alias under raw model key + make aliases visible/manageable

The headline bug: aliases created from the modal NEVER resolved. Create
sent the normalized display name ('Sword', 'Uchiha Sasuke') while
resolution keys on the raw booru model key ('sword', 'uchiha_sasuke',
case-sensitive) — so the mapping was stored under a key nothing looks up,
and the prediction kept reappearing unaliased. The raw key wasn't even in
the /suggestions response, so the modal couldn't send it.

- Suggestion now carries raw_name (the model key an alias must use) and
  via_alias (surfaced via an operator alias); both serialized by the API.
- Modal alias-create sends raw_name, not display_name (the fix). Aliased
  suggestions show an 'alias' badge and a 'Remove alias' action; 'Treat as
  alias for…' is hidden for centroid hits (no model key) and already-aliased
  rows.
- Tag-side management: TagCard ⋮ → 'Aliases…' opens a dialog listing the
  model keys that fold into a tag, with remove (GET /api/tags/<id>/aliases +
  AliasService.list_for_tag). Creation stays in the modal suggestion flow.

Tests: full API round-trip locking the raw-key contract (raw_name exposed →
alias authored with it → resolves + via_alias on a later image);
list_for_tag (service + API); via_alias/raw_name on the existing service
suggestion tests. No migration.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/app/api/suggestions.py

@@ -37,6 +37,11 @@ async def get_suggestions(image_id: int):
                         "score": round(s.score, 4),
                         "source": s.source,
                         "creates_new_tag": s.creates_new_tag,
+                        # raw model key (alias is stored under this) + whether an
+                        # operator alias produced this suggestion — drive the
+                        # modal's "Treat as alias"/"Remove alias" affordances.
+                        "raw_name": s.raw_name,
+                        "via_alias": s.via_alias,
                     }
                     for s in items
                 ]

backend/app/api/tags.py

@@ -8,6 +8,7 @@ from ..extensions import get_session
 from ..models import Tag, TagKind
 from ..models.tag_allowlist import TagAllowlist
 from ..services.bulk_tag_service import BulkTagService
+from ..services.ml.aliases import AliasService
 from ..services.series_match_service import SeriesMatchService
 from ..services.series_service import SeriesError, SeriesService
 from ..services.tag_directory_service import TagDirectoryService
@@ -200,6 +201,25 @@ async def get_tag(tag_id: int):
         )
 
 
+@tags_bp.route("/tags/<int:tag_id>/aliases", methods=["GET"])
+async def list_tag_aliases(tag_id: int):
+    """Model keys that fold into this tag (tag-side alias view). Remove via the
+    shared DELETE /api/aliases/<string>/<category>."""
+    async with get_session() as session:
+        if await session.get(Tag, tag_id) is None:
+            return jsonify({"error": "tag not found"}), 404
+        rows = await AliasService(session).list_for_tag(tag_id)
+    return jsonify(
+        [
+            {
+                "alias_string": r.alias_string,
+                "alias_category": r.alias_category,
+            }
+            for r in rows
+        ]
+    )
+
+
 @tags_bp.route("/tags/<int:tag_id>", methods=["PATCH"])
 async def update_tag(tag_id: int):
     """Rename and/or re-fandom a tag. Body may carry `name` and/or

backend/app/services/ml/aliases.py

@@ -81,6 +81,31 @@ class AliasService:
             .where(TagAlias.alias_category == alias_category)
         )
 
+    async def list_for_tag(self, canonical_tag_id: int) -> Sequence[AliasRow]:
+        """Aliases that resolve TO this tag — drives the tag-side 'Aliases'
+        view (see/remove the model keys that fold into a tag)."""
+        stmt = (
+            select(
+                TagAlias.alias_string,
+                TagAlias.alias_category,
+                TagAlias.canonical_tag_id,
+                Tag.name,
+            )
+            .join(Tag, Tag.id == TagAlias.canonical_tag_id)
+            .where(TagAlias.canonical_tag_id == canonical_tag_id)
+            .order_by(TagAlias.alias_string.asc())
+        )
+        rows = (await self.session.execute(stmt)).all()
+        return [
+            AliasRow(
+                alias_string=r[0],
+                alias_category=r[1],
+                canonical_tag_id=r[2],
+                canonical_tag_name=r[3],
+            )
+            for r in rows
+        ]
+
     async def list_all(self) -> Sequence[AliasRow]:
         stmt = (
             select(

backend/app/services/ml/suggestions.py

@@ -31,6 +31,14 @@ class Suggestion:
     score: float
     source: str  # 'tagger' | 'centroid' | 'both'
     creates_new_tag: bool
+    # raw_name = the booru model vocab key behind this suggestion. It's the key
+    # an alias MUST be stored under (resolution looks up the raw key), so the
+    # modal needs it to author an alias correctly. None for centroid-only hits
+    # (no underlying prediction → nothing to alias).
+    raw_name: str | None = None
+    # via_alias = this suggestion was surfaced because an operator alias remapped
+    # the raw prediction to this canonical tag. Lets the UI mark it + offer undo.
+    via_alias: bool = False
 
 
 @dataclass
@@ -161,6 +169,11 @@ class SuggestionService:
                     if existing.source != sug.source
                     else existing.source,
                     creates_new_tag=existing.creates_new_tag,
+                    # Keep the alias identity from `existing`: the tagger pass
+                    # (which carries raw_name / via_alias) runs before centroid
+                    # augmentation, so it's always the first writer for a key.
+                    raw_name=existing.raw_name,
+                    via_alias=existing.via_alias,
                 )
 
         for raw, display, category, conf in candidates:
@@ -177,6 +190,8 @@ class SuggestionService:
                         score=conf,
                         source="tagger",
                         creates_new_tag=False,
+                        raw_name=raw,
+                        via_alias=True,
                     ),
                 )
             else:
@@ -208,6 +223,8 @@ class SuggestionService:
                             score=conf,
                             source="tagger",
                             creates_new_tag=False,
+                            raw_name=raw,
+                            via_alias=False,
                         ),
                     )
                 else:
@@ -220,6 +237,8 @@ class SuggestionService:
                             score=conf,
                             source="tagger",
                             creates_new_tag=True,
+                            raw_name=raw,
+                            via_alias=False,
                         ),
                     )