feat(ui): confirm/keep auto-applied tags (milestone 139)

Auto-applied tags are provisional (they don't train the model + can be retracted
until confirmed), so surface and confirm them:
- Backend: list_for_image + get_image_with_tags now include `source` + a
  `confirmed` flag on each applied tag (via serialize_tag, image-scoped; defaulted
  for autocomplete/directory callers).
- Frontend: TagChip badges an unconfirmed auto-tag with an "auto" pill + a
  one-click Keep/confirm (✓) → POST /images/<id>/tags/<id>/confirm, which promotes
  it to a training positive and shields it from the retraction sweep; TagPanel
  reloads so the badge + button drop once confirmed.
Contract test for the source/confirmed payload.

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

backend/app/services/gallery_service.py

@@ -22,7 +22,15 @@ from sqlalchemy import Select, and_, distinct, exists, func, or_, select
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.orm import aliased
 
-from ..models import Artist, ImageProvenance, ImageRecord, Post, Source, Tag
+from ..models import (
+    Artist,
+    ImageProvenance,
+    ImageRecord,
+    Post,
+    Source,
+    Tag,
+    TagPositiveConfirmation,
+)
 from ..models.tag import PRESENTATION_SYSTEM_TAGS, image_tag
 from .pagination import decode_cursor, encode_cursor
 from .tag_query import (
@@ -731,8 +739,14 @@ class GalleryService:
         # Self-join Tag to resolve a character's fandom NAME (not just id) so the
         # modal chip can label it without an N+1 (shared tag_query helpers).
         fandom_alias = fandom_join_alias()
+        # source drives the auto-applied badge; confirmed = operator affirmed the
+        # tag (positive + retraction-shielded, milestone 139).
+        confirmed = exists().where(
+            TagPositiveConfirmation.image_record_id == image_id,
+            TagPositiveConfirmation.tag_id == Tag.id,
+        ).label("confirmed")
         tag_stmt = (
-            select(*tag_columns(fandom_alias))
+            select(*tag_columns(fandom_alias), image_tag.c.source, confirmed)
             .select_from(
                 Tag.__table__
                 .join(image_tag, image_tag.c.tag_id == Tag.id)

backend/app/services/tag_query.py

@@ -91,4 +91,11 @@ def serialize_tag(row) -> dict:
         "fandom_id": row.fandom_id,
         "fandom_name": row.fandom_name,
         "is_system": bool(getattr(row, "is_system", False)),
+        # Applied-tag context: only the image-scoped selects (list_for_image /
+        # get_image_with_tags) provide these; autocomplete / directory don't →
+        # default. `source` drives the auto-applied badge; `confirmed` = the
+        # operator affirmed the tag (a training positive, shielded from the
+        # retraction sweep — milestone 139).
+        "source": getattr(row, "source", None),
+        "confirmed": bool(getattr(row, "confirmed", False)),
     }

backend/app/services/tag_service.py

@@ -9,7 +9,14 @@ from sqlalchemy import and_, case, exists, func, select, text, update
 from sqlalchemy.dialects.postgresql import insert as pg_insert
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from ..models import HeadMetric, Tag, TagHead, TagKind, image_tag
+from ..models import (
+    HeadMetric,
+    Tag,
+    TagHead,
+    TagKind,
+    TagPositiveConfirmation,
+    image_tag,
+)
 from .db_helpers import get_or_create
 from .tag_query import fandom_join_alias, tag_columns
 
@@ -288,8 +295,14 @@ class TagService:
         character chip with its fandom without an N+1 (mirrors the
         autocomplete/directory resolution)."""
         fandom_alias = fandom_join_alias()
+        # source drives the auto-applied badge; confirmed = operator affirmed the
+        # tag (positive + retraction-shielded, milestone 139).
+        confirmed = exists().where(
+            TagPositiveConfirmation.image_record_id == image_id,
+            TagPositiveConfirmation.tag_id == Tag.id,
+        ).label("confirmed")
         stmt = (
-            select(*tag_columns(fandom_alias))
+            select(*tag_columns(fandom_alias), image_tag.c.source, confirmed)
             .select_from(
                 Tag.__table__
                 .join(image_tag, image_tag.c.tag_id == Tag.id)