feat(ml): soft auto-apply — retract auto-tags now below threshold (milestone 139)

Daily scheduled_retract_auto_tags re-scores standing auto-applied tags and drops
the ones the model no longer supports:
- retract_auto_applied_heads: per graduated head, re-score its source='head_auto'
  images (bounded — only the images already carrying the auto-tag, not the whole
  library) and remove ones now < auto_apply_threshold.
- retract_auto_applied_ccip: per source='ccip_auto' character tag, max-cosine the
  image's figure vectors vs that character's prototypes; remove ones now below the
  ccip auto-apply threshold.
Both SKIP operator-confirmed tags (TagPositiveConfirmation) and are SILENT — a low
score isn't proof the tag was wrong, so no hard negative is recorded (that's
reserved for an operator removal). No-op unless the relevant auto-apply switch is
on. New daily beat. sklearn-free tests for both paths + the disabled no-op.

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

backend/app/celery_app.py

@@ -147,6 +147,11 @@ def make_celery() -> Celery:
                 "task": "backend.app.tasks.ml.scheduled_ccip_auto_apply",
                 "schedule": 86400.0,  # no-op unless ccip_auto_apply_enabled
             },
+            "retract-auto-tags-daily": {
+                "task": "backend.app.tasks.ml.scheduled_retract_auto_tags",
+                "schedule": 86400.0,  # soft auto-apply: drop auto-tags now below
+                # their threshold (m139); no-op unless the auto-apply switch is on
+            },
             "snapshot-head-metrics-daily": {
                 "task": "backend.app.tasks.maintenance.snapshot_head_metrics",
                 "schedule": 86400.0,

backend/app/services/ml/character_prototypes.py

@@ -31,9 +31,15 @@ from ...models import (
     MLSettings,
     Tag,
     TagKind,
+    TagPositiveConfirmation,
 )
 from ...models.tag import image_tag
-from .ccip import _FIGURE_KINDS, _hygiene_tagged_images, _single_character_images
+from .ccip import (
+    _FIGURE_KINDS,
+    _hygiene_tagged_images,
+    _l2norm,
+    _single_character_images,
+)
 
 # Deterministic per-tag capping so a rebuild of an UNCHANGED reference set
 # resamples identically (stable prototypes, no churn between refreshes).
@@ -173,3 +179,76 @@ def refresh_character_prototypes(
     settings.ccip_ref_signature = sig
     session.commit()
     return {"skipped": False, "rebuilt": rebuilt, "removed": removed}
+
+
+def retract_auto_applied_ccip(session: Session) -> int:
+    """Soft auto-apply for CCIP character tags (milestone 139): re-score every
+    standing source='ccip_auto' character tag against that character's prototypes
+    and REMOVE the ones whose best figure match is now BELOW
+    ccip_auto_apply_threshold. Skips operator-confirmed tags. SILENT — a low score
+    isn't proof the tag was wrong (that's reserved for an operator removal). No-op
+    unless ccip_auto_apply_enabled. A character with no prototypes yet, or an image
+    with no figure vectors, is left alone (can't judge → keep). Returns
+    n_retracted."""
+    import numpy as np
+
+    settings = session.execute(
+        select(MLSettings).where(MLSettings.id == 1)
+    ).scalar_one()
+    if not settings.ccip_auto_apply_enabled:
+        return 0
+    thr = float(settings.ccip_auto_apply_threshold)
+    pairs = session.execute(
+        select(image_tag.c.image_record_id, image_tag.c.tag_id)
+        .where(image_tag.c.source == "ccip_auto")
+    ).all()
+    if not pairs:
+        return 0
+    confirmed = {
+        (iid, tid) for iid, tid in session.execute(
+            select(
+                TagPositiveConfirmation.image_record_id,
+                TagPositiveConfirmation.tag_id,
+            )
+        ).all()
+    }
+    # Each involved character's normalized prototype matrix, loaded once.
+    proto: dict[int, object] = {}
+    for tid in {tid for _iid, tid in pairs}:
+        vecs = [
+            v for (v,) in session.execute(
+                select(CharacterPrototype.ccip_embedding)
+                .where(CharacterPrototype.tag_id == tid)
+            )
+        ]
+        if vecs:
+            proto[tid] = _l2norm(
+                np.vstack([np.asarray(v, dtype=np.float32) for v in vecs]), np
+            )
+    retracted = 0
+    for iid, tid in pairs:
+        if (iid, tid) in confirmed or tid not in proto:
+            continue                                   # confirmed / no prototypes
+        qvecs = [
+            v for (v,) in session.execute(
+                select(ImageRegion.ccip_embedding)
+                .where(ImageRegion.image_record_id == iid)
+                .where(ImageRegion.kind.in_(_FIGURE_KINDS))
+                .where(ImageRegion.ccip_embedding.is_not(None))
+            )
+        ]
+        if not qvecs:
+            continue                                   # no figure vectors → keep
+        Q = _l2norm(
+            np.vstack([np.asarray(v, dtype=np.float32) for v in qvecs]), np
+        )
+        if float((Q @ proto[tid].T).max()) < thr:
+            session.execute(
+                image_tag.delete()
+                .where(image_tag.c.image_record_id == iid)
+                .where(image_tag.c.tag_id == tid)
+                .where(image_tag.c.source == "ccip_auto")
+            )
+            retracted += 1
+    session.commit()
+    return retracted

backend/app/services/ml/heads.py

@@ -35,6 +35,7 @@ from ...models import (
     Tag,
     TagHead,
     TagKind,
+    TagPositiveConfirmation,
     TagSuggestionRejection,
 )
 from ...models.tag import image_tag
@@ -723,3 +724,64 @@ def auto_apply_sweep(
         for h in range(len(rows))
     ]
     return {"n_applied": sum(applied), "concepts": concepts}
+
+
+def retract_auto_applied_heads(session: Session) -> int:
+    """Soft auto-apply (milestone 139): re-score every standing source='head_auto'
+    tag against its CURRENT head and REMOVE the ones now BELOW the head's
+    auto_apply_threshold — i.e. the head sharpened (or the operator raised the bar)
+    and no longer supports them. Skips operator-confirmed tags
+    (TagPositiveConfirmation). SILENT: a low score isn't proof the tag was wrong,
+    so no hard negative is recorded — that's reserved for an operator removal.
+    No-op unless head_auto_apply_enabled. Only re-scores the images that ALREADY
+    carry the auto-tag (bounded), never the whole library. Returns n_retracted."""
+    import numpy as np
+
+    settings = _settings(session)
+    if not settings.head_auto_apply_enabled:
+        return 0
+    heads = session.execute(
+        select(
+            TagHead.tag_id, TagHead.weights, TagHead.bias,
+            TagHead.auto_apply_threshold,
+        )
+        .where(TagHead.embedding_version == settings.embedder_model_version)
+        .where(TagHead.auto_apply_threshold.is_not(None))
+    ).all()
+    retracted = 0
+    for tag_id, weights, bias, thr in heads:
+        auto_ids = [
+            iid for (iid,) in session.execute(
+                select(image_tag.c.image_record_id)
+                .where(image_tag.c.tag_id == tag_id)
+                .where(image_tag.c.source == "head_auto")
+            )
+        ]
+        if not auto_ids:
+            continue
+        confirmed = {
+            iid for (iid,) in session.execute(
+                select(TagPositiveConfirmation.image_record_id)
+                .where(TagPositiveConfirmation.tag_id == tag_id)
+                .where(TagPositiveConfirmation.image_record_id.in_(auto_ids))
+            )
+        }
+        candidates = [i for i in auto_ids if i not in confirmed]
+        emb = _load_embeddings(session, candidates)
+        cids = [i for i in candidates if i in emb]
+        if not cids:
+            continue
+        Xn = _l2norm(np.vstack([emb[i] for i in cids]).astype(np.float32), np)
+        w = np.asarray(weights, dtype=np.float32)
+        probs = 1.0 / (1.0 + np.exp(-(Xn @ w + float(bias))))
+        below = [cids[k] for k in np.where(probs < float(thr))[0]]
+        for iid in below:
+            session.execute(
+                image_tag.delete()
+                .where(image_tag.c.image_record_id == iid)
+                .where(image_tag.c.tag_id == tag_id)
+                .where(image_tag.c.source == "head_auto")
+            )
+            retracted += 1
+        session.commit()
+    return retracted

backend/app/tasks/ml.py

@@ -592,3 +592,23 @@ def scheduled_ccip_auto_apply() -> str:
                     applied += 1
             session.commit()
         return f"applied={applied}"
+
+
+@celery.task(
+    name="backend.app.tasks.ml.scheduled_retract_auto_tags",
+    soft_time_limit=1800, time_limit=2100,
+)
+def scheduled_retract_auto_tags() -> str:
+    """Soft auto-apply (milestone 139): retract standing head_auto/ccip_auto tags
+    the model no longer supports (score now below the auto-apply threshold),
+    skipping operator-confirmed ones. Silent (no hard negative). No-op unless the
+    respective auto-apply switch is on. Returns 'head=N ccip=M'."""
+    from ..services.ml.character_prototypes import retract_auto_applied_ccip
+    from ..services.ml.heads import retract_auto_applied_heads
+
+    SessionLocal = _sync_session_factory()
+    with SessionLocal() as session:
+        n_head = retract_auto_applied_heads(session)
+    with SessionLocal() as session:
+        n_ccip = retract_auto_applied_ccip(session)
+    return f"head={n_head} ccip={n_ccip}"