refactor(ml): remove the dead per-tag centroid subsystem (#1189)

The v2 pivot replaced per-tag SigLIP centroids with learned heads + CCIP.
Centroids were still recomputed (on every tag merge + a daily beat) but NOTHING
read them — suggestions come from heads+CCIP and apply_allowlist_tags applies
via Camie predictions, not centroids. Pure dead wiring; remove it.

Removed: CentroidService, recompute_centroid/recompute_centroids tasks, the
daily beat, POST /api/ml/recompute-centroids, the recompute-on-merge trigger,
the tag_reference_embedding table + model, the centroid_similarity_threshold +
min_reference_images settings (migration 0066), the CentroidRecomputeCard +
its store action + MaintenancePanel tile, and the centroid slider in
MLThresholdSliders. _keep_as_alias drops its vestigial has-centroid branch (the
allowlist branch already covers "could re-emit"); tag merge no longer clears a
table that no longer exists.

NOT touched (still live, parallel to heads): the Camie tagger, ImagePrediction,
and the allowlist bulk-apply — accepting a suggestion still allowlists + applies
it across the library. The tag-eval "centroid" baseline metric is unrelated
(in-memory) and stays. (image_record.centroid_scores JSON column also remains —
separate legacy field, its own micro-cleanup.)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ttrj5P7upUTueSfoJcxEqa

alembic/versions/0066_drop_centroids.py

@@ -0,0 +1,57 @@
+"""drop the dead per-tag centroid subsystem (#1189 cleanup)
+
+The v2 pivot replaced per-tag SigLIP centroids with learned heads + CCIP.
+Nothing read the centroids anymore — they were recomputed (on merge + a daily
+beat) but never consumed for suggestions or auto-apply. Remove the storage +
+its two now-unused settings columns. (The recompute tasks, beat, endpoint,
+service, and UI card are removed in the same change.)
+
+Revision ID: 0066
+Revises: 0065
+Create Date: 2026-06-30
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0066"
+down_revision: Union[str, None] = "0065"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.drop_table("tag_reference_embedding")
+    op.drop_column("ml_settings", "centroid_similarity_threshold")
+    op.drop_column("ml_settings", "min_reference_images")
+
+
+def downgrade() -> None:
+    op.add_column(
+        "ml_settings",
+        sa.Column(
+            "min_reference_images", sa.Integer(), nullable=False,
+            server_default="5",
+        ),
+    )
+    op.add_column(
+        "ml_settings",
+        sa.Column(
+            "centroid_similarity_threshold", sa.Float(), nullable=False,
+            server_default="0.55",
+        ),
+    )
+    op.create_table(
+        "tag_reference_embedding",
+        sa.Column("tag_id", sa.Integer(), nullable=False),
+        sa.Column("embedding", sa.LargeBinary(), nullable=False),
+        sa.Column("reference_count", sa.Integer(), nullable=False),
+        sa.Column("model_version", sa.String(length=128), nullable=False),
+        sa.Column(
+            "updated_at", sa.DateTime(timezone=True),
+            server_default=sa.func.now(), nullable=False,
+        ),
+        sa.ForeignKeyConstraint(["tag_id"], ["tag.id"], ondelete="CASCADE"),
+        sa.PrimaryKeyConstraint("tag_id"),
+    )

backend/app/api/ml_admin.py

@@ -1,4 +1,4 @@
-"""ML admin API: settings, backfill trigger, centroid recompute trigger."""
+"""ML admin API: settings + backfill trigger."""
 
 from quart import Blueprint, jsonify, request
 
@@ -11,8 +11,6 @@ ml_admin_bp = Blueprint("ml_admin", __name__, url_prefix="/api/ml")
 _EDITABLE = (
     "suggestion_threshold_character",
     "suggestion_threshold_general",
-    "centroid_similarity_threshold",
-    "min_reference_images",
     "tagger_store_floor",
     "video_frame_interval_seconds",
     "video_max_frames",
@@ -41,8 +39,6 @@ async def get_settings():
         {
             "suggestion_threshold_character": s.suggestion_threshold_character,
             "suggestion_threshold_general": s.suggestion_threshold_general,
-            "centroid_similarity_threshold": s.centroid_similarity_threshold,
-            "min_reference_images": s.min_reference_images,
             "tagger_store_floor": s.tagger_store_floor,
             "video_frame_interval_seconds": s.video_frame_interval_seconds,
             "video_max_frames": s.video_max_frames,
@@ -142,11 +138,3 @@ async def trigger_backfill():
 
     r = backfill.delay()
     return jsonify({"celery_task_id": r.id}), 202
-
-
-@ml_admin_bp.route("/recompute-centroids", methods=["POST"])
-async def trigger_recompute():
-    from ..tasks.ml import recompute_centroids
-
-    r = recompute_centroids.delay()
-    return jsonify({"celery_task_id": r.id}), 202

backend/app/api/tags.py

@@ -304,12 +304,6 @@ async def merge_tag(source_id: int):
         from ..tasks.ml import apply_allowlist_tags
 
         apply_allowlist_tags.delay(tag_id=result.target_id)
-    # Tag merge invalidates the target's centroid (the merged-in source
-    # tag's images now contribute to it). Daily list_drifted catches it
-    # within 24h, but eager recompute closes the suggestion-quality dip
-    # in the meantime. Audit 2026-06-02.
-    from ..tasks.ml import recompute_centroid
-    recompute_centroid.delay(result.target_id)
     return jsonify(
         {
             "target": {

backend/app/celery_app.py

@@ -101,10 +101,6 @@ def make_celery() -> Celery:
                 "task": "backend.app.tasks.ml.backfill",
                 "schedule": 86400.0,
             },
-            "recompute-centroids-daily": {
-                "task": "backend.app.tasks.ml.recompute_centroids",
-                "schedule": 86400.0,
-            },
             "apply-allowlist-sweep-daily": {
                 "task": "backend.app.tasks.ml.apply_allowlist_tags",
                 "schedule": 86400.0,

backend/app/models/__init__.py

@@ -38,7 +38,6 @@ from .tag_allowlist import TagAllowlist
 from .tag_eval_run import TagEvalRun
 from .tag_head import TagHead
 from .tag_positive_confirmation import TagPositiveConfirmation
-from .tag_reference_embedding import TagReferenceEmbedding
 from .tag_suggestion_rejection import TagSuggestionRejection
 from .task_run import TaskRun
 
@@ -83,7 +82,6 @@ __all__ = [
     "TagEvalRun",
     "TagHead",
     "TagPositiveConfirmation",
-    "TagReferenceEmbedding",
     "TagSuggestionRejection",
     "TaskRun",
 ]

backend/app/models/ml_settings.py

@@ -33,21 +33,14 @@ class MLSettings(Base):
     suggestion_threshold_general: Mapped[float] = mapped_column(
         Float, nullable=False, default=0.70
     )
-    centroid_similarity_threshold: Mapped[float] = mapped_column(
-        Float, nullable=False, default=0.55
-    )
     # Ingest floor: tagger predictions below this confidence are not stored
-    # (tagger.Tagger.infer). Default 0.70 — the suggestion path already
-    # filters at 0.70 and the centroid/learned path covers low-confidence
-    # preferred tags, so the sub-0.70 tail is redundant weight (it had
-    # bloated image_record's TOAST to ~100 GB; plan-task #764). Operator-
-    # tunable via Settings → ML; must stay ≤ the suggestion thresholds.
+    # (tagger.Tagger.infer). Default 0.70 — the suggestion path already filters
+    # there, so the sub-0.70 tail is redundant weight (it had bloated
+    # image_record's TOAST to ~100 GB; plan-task #764). Operator-tunable via
+    # Settings → ML; must stay ≤ the suggestion thresholds.
     tagger_store_floor: Mapped[float] = mapped_column(
         Float, nullable=False, default=0.70
     )
-    min_reference_images: Mapped[int] = mapped_column(
-        Integer, nullable=False, default=5
-    )
     # Video tagging (#747). Sample one frame every N seconds (fixed CADENCE, not a
     # fixed count) so a tag's frame-presence reflects real screen time regardless
     # of video length; cap the total so a long video can't explode into hundreds

backend/app/models/tag_reference_embedding.py

@@ -1,23 +0,0 @@
-"""TagReferenceEmbedding — per-tag centroid (mean SigLIP embedding of members)."""
-
-from datetime import datetime
-
-from pgvector.sqlalchemy import Vector
-from sqlalchemy import DateTime, ForeignKey, Integer, String, func
-from sqlalchemy.orm import Mapped, mapped_column
-
-from .base import Base
-
-
-class TagReferenceEmbedding(Base):
-    __tablename__ = "tag_reference_embedding"
-
-    tag_id: Mapped[int] = mapped_column(
-        ForeignKey("tag.id", ondelete="CASCADE"), primary_key=True
-    )
-    embedding: Mapped[list[float]] = mapped_column(Vector(1152), nullable=False)
-    reference_count: Mapped[int] = mapped_column(Integer, nullable=False)
-    model_version: Mapped[str] = mapped_column(String(128), nullable=False)
-    updated_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), nullable=False, server_default=func.now()
-    )

backend/app/services/ml/centroids.py

@@ -1,163 +0,0 @@
-"""Tag centroids: the mean SigLIP embedding of a tag's member images.
-
-Powers centroid-augmented suggestions (a tag whose centroid is close to an
-image's embedding becomes a suggestion even if Camie didn't predict it).
-"""
-
-from dataclasses import dataclass
-
-import numpy as np
-from sqlalchemy import func, select
-from sqlalchemy.dialects.postgresql import insert
-from sqlalchemy.ext.asyncio import AsyncSession
-
-from ...models import (
-    ImageRecord,
-    MLSettings,
-    Tag,
-    TagKind,
-    TagReferenceEmbedding,
-)
-from ...models.tag import image_tag
-
-ELIGIBLE_KINDS = {
-    TagKind.character,
-    TagKind.fandom,
-    TagKind.general,
-    TagKind.series,
-}
-
-
-@dataclass(frozen=True)
-class CentroidHit:
-    tag_id: int
-    similarity: float
-
-
-class CentroidService:
-    def __init__(self, session: AsyncSession):
-        self.session = session
-
-    async def _min_reference_images(self) -> int:
-        return (
-            await self.session.execute(
-                select(MLSettings.min_reference_images).where(MLSettings.id == 1)
-            )
-        ).scalar_one()
-
-    async def _model_version(self) -> str:
-        """Audit 2026-06-02: SigLIP model-version stamp comes from the
-        DB row, not the env constant. tag_and_embed (tasks/ml.py:110)
-        already reads from MLSettings.embedder_model_version, so by
-        sourcing centroid stamps + drift checks from the same row, we
-        eliminate the silent-drift case the audit flagged. env
-        SIGLIP_MODEL_VERSION still drives which model embedder.py
-        loads at runtime; the version stamp is purely the operator-
-        controlled identifier."""
-        return (
-            await self.session.execute(
-                select(MLSettings.embedder_model_version).where(MLSettings.id == 1)
-            )
-        ).scalar_one()
-
-    async def recompute_for_tag(self, tag_id: int) -> bool:
-        """Recompute one tag's centroid. Returns True if a centroid was
-        written, False if skipped (ineligible kind or too few members)."""
-        tag = await self.session.get(Tag, tag_id)
-        if tag is None or tag.kind not in ELIGIBLE_KINDS:
-            return False
-
-        min_refs = await self._min_reference_images()
-
-        stmt = (
-            select(ImageRecord.siglip_embedding)
-            .join(image_tag, image_tag.c.image_record_id == ImageRecord.id)
-            .where(image_tag.c.tag_id == tag_id)
-            .where(ImageRecord.siglip_embedding.is_not(None))
-        )
-        embeddings = [
-            np.array(e, dtype=np.float32)
-            for e in (await self.session.execute(stmt)).scalars().all()
-        ]
-        if len(embeddings) < min_refs:
-            return False
-
-        centroid = np.mean(np.stack(embeddings), axis=0).astype(np.float32)
-        model_version = await self._model_version()
-
-        stmt = insert(TagReferenceEmbedding).values(
-            tag_id=tag_id,
-            embedding=centroid.tolist(),
-            reference_count=len(embeddings),
-            model_version=model_version,
-        )
-        stmt = stmt.on_conflict_do_update(
-            index_elements=["tag_id"],
-            set_={
-                "embedding": centroid.tolist(),
-                "reference_count": len(embeddings),
-                "model_version": model_version,
-                "updated_at": func.now(),
-            },
-        )
-        await self.session.execute(stmt)
-        return True
-
-    async def list_drifted(self) -> list[int]:
-        """Tag ids whose centroid is stale: member count != reference_count,
-        OR no centroid row, OR centroid built on a different SigLIP version.
-        Only considers eligible-kind tags with embeddings present."""
-        current_model_version = await self._model_version()
-        member_counts = (
-            select(
-                image_tag.c.tag_id.label("tag_id"),
-                func.count(image_tag.c.image_record_id).label("members"),
-            )
-            .join(ImageRecord, ImageRecord.id == image_tag.c.image_record_id)
-            .where(ImageRecord.siglip_embedding.is_not(None))
-            .group_by(image_tag.c.tag_id)
-            .subquery()
-        )
-        stmt = (
-            select(Tag.id)
-            .join(member_counts, member_counts.c.tag_id == Tag.id)
-            .outerjoin(
-                TagReferenceEmbedding,
-                TagReferenceEmbedding.tag_id == Tag.id,
-            )
-            .where(Tag.kind.in_(ELIGIBLE_KINDS))
-            .where(
-                (TagReferenceEmbedding.tag_id.is_(None))
-                | (
-                    TagReferenceEmbedding.reference_count
-                    != member_counts.c.members
-                )
-                | (TagReferenceEmbedding.model_version != current_model_version)
-            )
-        )
-        return list((await self.session.execute(stmt)).scalars().all())
-
-    async def find_similar_tags(
-        self, image_id: int, limit: int = 20
-    ) -> list[CentroidHit]:
-        """Cosine similarity between an image's embedding and stored
-        centroids. Returns top-`limit` by similarity DESC. pgvector's
-        cosine_distance gives 1 - cosine_similarity."""
-        img = await self.session.get(ImageRecord, image_id)
-        if img is None or img.siglip_embedding is None:
-            return []
-        emb = img.siglip_embedding
-        distance = TagReferenceEmbedding.embedding.cosine_distance(emb)
-        stmt = (
-            select(
-                TagReferenceEmbedding.tag_id,
-                (1 - distance).label("similarity"),
-            )
-            .order_by(distance.asc())
-            .limit(limit)
-        )
-        rows = (await self.session.execute(stmt)).all()
-        return [
-            CentroidHit(tag_id=r.tag_id, similarity=float(r.similarity))
-            for r in rows
-        ]

backend/app/services/tag_service.py

@@ -11,7 +11,6 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from ..models import HeadMetric, Tag, TagHead, TagKind, image_tag
 from ..models.tag_allowlist import TagAllowlist
-from ..models.tag_reference_embedding import TagReferenceEmbedding
 from .db_helpers import get_or_create
 from .tag_query import fandom_join_alias, tag_columns
 
@@ -304,10 +303,10 @@ class TagService:
 
     async def _keep_as_alias(self, tag_id: int) -> bool:
         """A merged-away tag's old name must survive as an alias iff the ML
-        pipeline has ever applied it OR could re-emit it (allowlisted / has
-        a centroid) — otherwise the proactive apply_allowlist_tags worker
-        would silently regenerate it. Purely-manual, ML-unknown tags are
-        deleted outright (no DB bloat)."""
+        pipeline has ever applied it OR could re-emit it (allowlisted) —
+        otherwise the proactive apply_allowlist_tags worker would silently
+        regenerate it. Purely-manual, ML-unknown tags are deleted outright (no
+        DB bloat)."""
         is_machine = await self.session.scalar(
             select(
                 exists().where(
@@ -325,14 +324,7 @@ class TagService:
         allowlisted = await self.session.scalar(
             select(exists().where(TagAllowlist.tag_id == tag_id))
         )
-        if allowlisted:
-            return True
-        has_centroid = await self.session.scalar(
-            select(
-                exists().where(TagReferenceEmbedding.tag_id == tag_id)
-            )
-        )
-        return bool(has_centroid)
+        return bool(allowlisted)
 
     async def rename(self, tag_id: int, new_name: str) -> Tag:
         """Rename a tag. Raises TagMergeConflict if the new name collides
@@ -573,7 +565,6 @@ class TagService:
         merged_count = await self._repoint_image_tags(source_id, target_id)
         await self._repoint_rejections(source_id, target_id)
         await self._repoint_allowlist(source_id, target_id)
-        await self._repoint_embedding(source_id)
         await self._repoint_aliases(source_id, target_id)
         await self._repoint_fandom_children(
             source_id, target_id, source_kind
@@ -655,13 +646,6 @@ class TagService:
                 .values(tag_id=tgt)
             )
 
-    async def _repoint_embedding(self, src: int) -> None:
-        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:
         from ..models.tag_alias import TagAlias

backend/app/tasks/ml.py

@@ -1,9 +1,9 @@
-"""ML Celery tasks: per-image inference, backfill discovery, centroid
-recompute, allowlist auto-apply, model self-heal.
+"""ML Celery tasks: per-image inference, backfill discovery, head training,
+allowlist auto-apply, model self-heal.
 
-All run on the ml-worker (queue 'ml') except recompute_centroids and
-apply_allowlist_tags sweeps which are 'maintenance' lane. Sync sessions
-(Celery workers are sync processes), same pattern as FC-2a tasks.
+All run on the ml-worker (queue 'ml') except apply_allowlist_tags sweeps which
+are 'maintenance' lane. Sync sessions (Celery workers are sync processes), same
+pattern as FC-2a tasks.
 """
 
 import logging
@@ -487,59 +487,6 @@ def _confidence_for_tag(session, tag, preds: dict) -> float | None:
     return best
 
 
-@celery.task(name="backend.app.tasks.ml.recompute_centroid", bind=True)
-def recompute_centroid(self, tag_id: int) -> bool:
-    import asyncio
-
-    from ..services.ml.centroids import CentroidService
-    from ._async_session import async_session_factory
-
-    async def _run() -> bool:
-        # Per-task NullPool engine bound to THIS asyncio.run loop — the shared
-        # process-wide engine reuses connections across loops and raises
-        # "Future attached to a different loop" on every call after the first.
-        async_factory, async_engine = async_session_factory()
-        try:
-            async with async_factory() as session:
-                svc = CentroidService(session)
-                result = await svc.recompute_for_tag(tag_id)
-                await session.commit()
-                return result
-        finally:
-            await async_engine.dispose()
-
-    return asyncio.run(_run())
-
-
-@celery.task(
-    name="backend.app.tasks.ml.recompute_centroids",
-    bind=True,
-    # Audit 2026-06-02 — drifted-centroid rebuild over potentially
-    # hundreds of tags.
-    soft_time_limit=1800, time_limit=2100,
-)
-def recompute_centroids(self) -> int:
-    """Daily: find drifted centroids, enqueue recompute_centroid for each."""
-    import asyncio
-
-    from ..services.ml.centroids import CentroidService
-    from ._async_session import async_session_factory
-
-    async def _list() -> list[int]:
-        # Per-task NullPool engine bound to this loop (see recompute_centroid).
-        async_factory, async_engine = async_session_factory()
-        try:
-            async with async_factory() as session:
-                return await CentroidService(session).list_drifted()
-        finally:
-            await async_engine.dispose()
-
-    drifted = asyncio.run(_list())
-    for tid in drifted:
-        recompute_centroid.delay(tid)
-    return len(drifted)
-
-
 @celery.task(
     name="backend.app.tasks.ml.tag_eval_run",
     bind=True,

frontend/src/components/settings/CentroidRecomputeCard.vue

@@ -1,36 +0,0 @@
-<template>
-  <MaintenanceTile
-    icon="mdi-vector-triangle"
-    title="Tag centroids"
-    blurb="Rebuild SigLIP centroids for similarity suggestions."
-    :open="busy"
-  >
-      <p class="text-body-2 mb-3">
-        Rebuild the per-tag SigLIP centroids that power similarity-based
-        suggestions. Runs nightly automatically; trigger manually after a
-        large tagging session.
-      </p>
-      <v-btn color="primary" rounded="pill" :loading="busy" @click="run">
-        <v-icon start>mdi-vector-triangle</v-icon> Recompute centroids
-      </v-btn>
-      <span v-if="done" class="ml-3 text-caption">Enqueued.</span>
-      <QueueStatusBar queue="ml" queue-label="ML" />
-  </MaintenanceTile>
-</template>
-
-<script setup>
-import { toast } from '../../utils/toast.js'
-import { ref } from 'vue'
-import { useMLStore } from '../../stores/ml.js'
-import MaintenanceTile from '../common/MaintenanceTile.vue'
-import QueueStatusBar from './QueueStatusBar.vue'
-const store = useMLStore()
-const busy = ref(false)
-const done = ref(false)
-async function run() {
-  busy.value = true
-  try { await store.triggerRecomputeCentroids(); done.value = true }
-  catch (e) { toast({ text: e.message, type: 'error' }) }
-  finally { busy.value = false }
-}
-</script>

frontend/src/components/settings/MLThresholdSliders.vue

@@ -28,8 +28,7 @@
           <div class="text-caption fc-muted mt-1">
             Tagger predictions below this confidence aren't stored — raising it
             keeps the image library lean. Suggestions can't be shown below the
-            floor; lower-confidence tags you actually want still surface through
-            the learned centroid path.
+            floor.
           </div>
         </v-col>
       </v-row>
@@ -84,8 +83,7 @@ const store = useMLStore()
 // tagger store floor (nothing below the floor is stored to surface).
 const fields = [
   { key: 'suggestion_threshold_character', label: 'Character', floorMin: true },
-  { key: 'suggestion_threshold_general', label: 'General', floorMin: true },
-  { key: 'centroid_similarity_threshold', label: 'Centroid similarity' }
+  { key: 'suggestion_threshold_general', label: 'General', floorMin: true }
 ]
 const local = reactive({})
 watch(() => store.settings, (s) => { if (s) Object.assign(local, s) }, { immediate: true })

frontend/src/components/settings/MaintenancePanel.vue

@@ -1,9 +1,8 @@
 <template>
   <div class="fc-maint">
     <p class="fc-muted text-body-2 mb-5">
-      One-off backfills, tagging config and storage tools. The ML backfill and
-      centroid recompute also run nightly; the allowlist auto-applies accepted
-      tags. Click a tile to open it.
+      One-off backfills, tagging config and storage tools. The ML backfill runs
+      nightly; the allowlist auto-applies accepted tags. Click a tile to open it.
     </p>
 
     <section class="fc-section">
@@ -11,7 +10,6 @@
       <p class="fc-section__hint">Re-run tagging, thumbnails, extraction and DB upkeep.</p>
       <div class="fc-tile-grid">
         <MLBackfillCard />
-        <CentroidRecomputeCard />
         <ThumbnailBackfillCard />
         <ArchiveReextractCard />
         <MissingFileRepairCard />
@@ -48,7 +46,6 @@
 import { onMounted, onUnmounted } from 'vue'
 
 import MLBackfillCard from './MLBackfillCard.vue'
-import CentroidRecomputeCard from './CentroidRecomputeCard.vue'
 import ThumbnailBackfillCard from './ThumbnailBackfillCard.vue'
 import ArchiveReextractCard from './ArchiveReextractCard.vue'
 import MissingFileRepairCard from './MissingFileRepairCard.vue'

frontend/src/stores/ml.js

@@ -22,12 +22,8 @@ export const useMLStore = defineStore('ml', () => {
     await api.post('/api/ml/backfill')
   }
 
-  async function triggerRecomputeCentroids() {
-    await api.post('/api/ml/recompute-centroids')
-  }
-
   return {
     settings, loading, error,
-    loadSettings, patchSettings, triggerBackfill, triggerRecomputeCentroids
+    loadSettings, patchSettings, triggerBackfill
   }
 })

tests/test_api_ml_admin.py

@@ -107,11 +107,9 @@ async def test_video_min_tag_frames_above_max_rejected(client):
 
 
 @pytest.mark.asyncio
-async def test_backfill_and_recompute_trigger(client):
+async def test_backfill_trigger(client):
     r1 = await client.post("/api/ml/backfill")
     assert r1.status_code == 202
-    r2 = await client.post("/api/ml/recompute-centroids")
-    assert r2.status_code == 202
 
 
 @pytest.mark.asyncio

tests/test_migration_0003.py

@@ -6,7 +6,6 @@ from backend.app.models import (
     MLSettings,
     TagAlias,
     TagAllowlist,
-    TagReferenceEmbedding,
     TagSuggestionRejection,
 )
 
@@ -16,7 +15,6 @@ def test_new_tables_registered():
         "tag_allowlist",
         "tag_suggestion_rejection",
         "tag_alias",
-        "tag_reference_embedding",
         "ml_settings",
     }
     assert expected.issubset(Base.metadata.tables.keys())
@@ -42,12 +40,6 @@ def test_ml_settings_singleton_constraint():
     assert "ck_ml_settings_singleton" in names
 
 
-def test_tag_reference_embedding_has_vector():
-    cols = {c.name for c in TagReferenceEmbedding.__table__.columns}
-    assert "embedding" in cols
-    assert "reference_count" in cols
-
-
 def test_tag_allowlist_confidence_check():
     names = {c.name for c in TagAllowlist.__table__.constraints}
     assert "ck_tag_allowlist_confidence_range" in names

tests/test_ml_artist_retired.py

@@ -8,12 +8,6 @@ def test_artist_not_surfaced():
     assert "artist" not in SURFACED_CATEGORIES
 
 
-def test_artist_not_centroid_eligible():
-    from backend.app.models import TagKind
-    from backend.app.services.ml.centroids import ELIGIBLE_KINDS
-    assert TagKind.artist not in ELIGIBLE_KINDS
-
-
 def test_artist_not_head_eligible():
     # Tagging-v2: suggestions come from heads, and heads are only trained for
     # general/character concepts — so 'artist' (and any other kind) can't surface.

tests/test_ml_centroids.py

@@ -1,112 +0,0 @@
-import numpy as np
-import pytest
-
-from backend.app.models import ImageRecord, TagKind
-from backend.app.models.tag import image_tag
-from backend.app.services.ml.centroids import CentroidService
-from backend.app.services.tag_service import TagService
-
-pytestmark = pytest.mark.integration
-
-
-def _img(sha: str, embedding: list[float] | None) -> ImageRecord:
-    return ImageRecord(
-        path=f"/images/{sha}.jpg",
-        sha256=sha,
-        size_bytes=1,
-        mime="image/jpeg",
-        width=1,
-        height=1,
-        origin="imported_filesystem",
-        integrity_status="unknown",
-        siglip_embedding=embedding,
-    )
-
-
-async def _attach(db, image_id: int, tag_id: int):
-    await db.execute(
-        image_tag.insert().values(
-            image_record_id=image_id, tag_id=tag_id, source="manual"
-        )
-    )
-
-
-@pytest.mark.asyncio
-async def test_recompute_skips_too_few_members(db):
-    tags = TagService(db)
-    tag = await tags.find_or_create("Lonely", TagKind.character)
-    img = _img("a" * 64, [0.1] * 1152)
-    db.add(img)
-    await db.flush()
-    await _attach(db, img.id, tag.id)
-
-    svc = CentroidService(db)
-    assert await svc.recompute_for_tag(tag.id) is False
-
-
-@pytest.mark.asyncio
-async def test_recompute_writes_centroid(db):
-    tags = TagService(db)
-    tag = await tags.find_or_create("Popular", TagKind.character)
-    for i in range(5):
-        img = _img(f"{i:064d}", [float(i)] * 1152)
-        db.add(img)
-        await db.flush()
-        await _attach(db, img.id, tag.id)
-
-    svc = CentroidService(db)
-    assert await svc.recompute_for_tag(tag.id) is True
-
-    from backend.app.models import TagReferenceEmbedding
-    cen = await db.get(TagReferenceEmbedding, tag.id)
-    assert cen is not None
-    assert cen.reference_count == 5
-    assert abs(np.array(cen.embedding)[0] - 2.0) < 1e-4
-
-
-@pytest.mark.asyncio
-async def test_recompute_skips_ineligible_kind(db):
-    tags = TagService(db)
-    tag = await tags.find_or_create("somearchive", TagKind.archive)
-    for i in range(5):
-        img = _img(f"arch{i:060d}", [1.0] * 1152)
-        db.add(img)
-        await db.flush()
-        await _attach(db, img.id, tag.id)
-    svc = CentroidService(db)
-    assert await svc.recompute_for_tag(tag.id) is False
-
-
-@pytest.mark.asyncio
-async def test_list_drifted_includes_uncomputed(db):
-    tags = TagService(db)
-    tag = await tags.find_or_create("Drifty", TagKind.character)
-    for i in range(5):
-        img = _img(f"d{i:063d}", [0.5] * 1152)
-        db.add(img)
-        await db.flush()
-        await _attach(db, img.id, tag.id)
-    svc = CentroidService(db)
-    drifted = await svc.list_drifted()
-    assert tag.id in drifted
-
-
-@pytest.mark.asyncio
-async def test_find_similar_tags(db):
-    tags = TagService(db)
-    tag = await tags.find_or_create("SimTag", TagKind.character)
-    for i in range(5):
-        img = _img(f"s{i:063d}", [1.0] * 1152)
-        db.add(img)
-        await db.flush()
-        await _attach(db, img.id, tag.id)
-    svc = CentroidService(db)
-    await svc.recompute_for_tag(tag.id)
-
-    query_img = _img("q" * 64, [1.0] * 1152)
-    db.add(query_img)
-    await db.flush()
-    hits = await svc.find_similar_tags(query_img.id, limit=10)
-    assert any(h.tag_id == tag.id for h in hits)
-    sim = next(h.similarity for h in hits if h.tag_id == tag.id)
-    assert sim > 0.99

tests/test_tag_merge.py

@@ -279,34 +279,6 @@ async def test_merge_allowlist_source_only_moves_to_target(db):
     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