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FabledCurator/backend/app/services/ml/heads.py
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chore: retire the tag-eval harness — it proved the heads system, job done (operator-approved)
The head-vs-centroid eval (#1130) existed to prove the 'frozen embedding +
trained head' spine; the operator accepted the tagging system and dropped the
harness. Removed per rule 22: TagEvalCard + store, /api/tag_eval blueprint,
tag_eval_run ml task, recover-stalled-tag-eval-runs sweep + beat entry,
TagEvalRun model + table (migration 0073), and its tests.

The eval's data loaders + metric helpers were NOT eval-specific — the nightly
heads trainer runs on them — so they moved verbatim to
services/ml/training_data.py (heads.py import updated; behavior unchanged).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CDgx8bQS5YrGRK76v8HUnM
2026-07-02 12:41:24 -04:00

503 lines
19 KiB
Python

"""Production heads: train + score the per-concept classifiers (#114).
The eval harness (#1130) proved the spine, then retired 2026-07-02 once the
tagging system was accepted; this is the production form.
- TRAIN (sync, ml worker — needs scikit-learn): for every general/character tag
with enough labelled positives, fit a logistic-regression head on the FROZEN
SigLIP embeddings (positives + negatives = rejections + sampled unlabeled),
derive an honest suggest threshold + earned-auto-apply point from CROSS-
VALIDATED scores, and upsert a TagHead row. Uses the eval-proven data loaders
+ metric helpers (training_data.py) so heads match the measured numbers.
- SCORE (async, API worker — numpy via pgvector, NO scikit-learn): score one
image's embedding against all current heads → the suggestions the rail shows,
REPLACING Camie predictions + per-tag centroids.
scikit-learn is imported lazily inside the train path so the API worker can still
import this module to enqueue training + to score (scoring needs only numpy).
"""
from __future__ import annotations
import logging
from datetime import UTC, datetime
from typing import Any
from sqlalchemy import delete, func, select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import Session
from ...models import (
HeadAutoApplyRun,
HeadTrainingRun,
ImageRecord,
ImageRegion,
MLSettings,
Tag,
TagHead,
TagKind,
TagSuggestionRejection,
)
from ...models.tag import image_tag
from .training_data import (
_auto_apply_point,
_ids_with_tag,
_l2norm,
_load_embeddings,
_metrics_from_scores,
_rejected_ids,
_safe_folds,
_sample_unlabeled,
)
log = logging.getLogger(__name__)
DEFAULT_NEG_RATIO = 3
DEFAULT_CV_FOLDS = 5
MIN_POSITIVES_FLOOR = 8 # hard floor; settings.head_min_positives can raise it
_UNLABELED_POOL = 4000
_EXAMPLES_MIN = 8 # need at least this many embedded +/- to fit a head
# Only these tag kinds get heads (the surfaced suggestion categories).
_HEAD_KINDS = (TagKind.general, TagKind.character)
# tag.kind -> the suggestion category the rail groups under.
_CATEGORY = {TagKind.general: "general", TagKind.character: "character"}
class HeadTrainingAlreadyRunning(Exception):
"""Raised by start_head_training_run when a run is already in flight."""
def start_head_training_run(session: Session, params: dict[str, Any]) -> int:
"""Create a HeadTrainingRun (status='running') + dispatch the ml-queue task.
Returns the run id. One training run at a time (light guard)."""
existing = session.execute(
select(HeadTrainingRun.id).where(HeadTrainingRun.status == "running")
).scalar_one_or_none()
if existing is not None:
raise HeadTrainingAlreadyRunning(existing)
norm = _normalize_params(session, params)
run = HeadTrainingRun(
params=norm, status="running", last_progress_at=datetime.now(UTC)
)
session.add(run)
session.flush()
run_id = run.id
from ...tasks.ml import train_heads as _task
_task.delay(run_id)
return run_id
def _settings(session: Session) -> MLSettings:
return session.execute(
select(MLSettings).where(MLSettings.id == 1)
).scalar_one()
def _normalize_params(session: Session, params: dict[str, Any] | None) -> dict[str, Any]:
params = params or {}
s = _settings(session)
try:
min_pos = max(MIN_POSITIVES_FLOOR, int(params.get("min_positives", s.head_min_positives)))
except (TypeError, ValueError):
min_pos = max(MIN_POSITIVES_FLOOR, s.head_min_positives)
try:
neg_ratio = max(1, int(params.get("neg_ratio", DEFAULT_NEG_RATIO)))
except (TypeError, ValueError):
neg_ratio = DEFAULT_NEG_RATIO
try:
cv_folds = max(2, int(params.get("cv_folds", DEFAULT_CV_FOLDS)))
except (TypeError, ValueError):
cv_folds = DEFAULT_CV_FOLDS
try:
precision_target = min(max(float(params.get("precision_target", s.head_auto_apply_precision)), 0.5), 0.999)
except (TypeError, ValueError):
precision_target = s.head_auto_apply_precision
return {
"min_positives": min_pos,
"neg_ratio": neg_ratio,
"cv_folds": cv_folds,
"precision_target": round(precision_target, 4),
}
def _embedder_version(session: Session) -> str:
return _settings(session).embedder_model_version
def _eligible_tag_ids(session: Session, min_pos: int) -> list[int]:
"""Concept tags (general/character) with >= min_pos labelled images — the
set that gets a head. Counts all sources; source-aware filtering (#1133) is
a separate, optional refinement."""
rows = session.execute(
select(Tag.id)
.join(image_tag, image_tag.c.tag_id == Tag.id)
.where(Tag.kind.in_(_HEAD_KINDS))
.group_by(Tag.id)
.having(func.count(image_tag.c.image_record_id) >= min_pos)
).all()
return [r[0] for r in rows]
def train_all_heads(
session: Session, params: dict[str, Any], run: HeadTrainingRun | None = None
) -> dict[str, int]:
"""(Re)train a head for every eligible concept; prune heads whose tag is no
longer eligible. Commits per head so a SIGKILL leaves trained heads durable
(training is idempotent). Returns {n_trained, n_skipped}."""
import numpy as np
cfg = _normalize_params(session, params)
embedding_version = _embedder_version(session)
eligible = _eligible_tag_ids(session, cfg["min_positives"])
eligible_set = set(eligible)
trained = 0
skipped = 0
for i, tag_id in enumerate(eligible):
try:
ok = train_head(session, tag_id, embedding_version, cfg, np)
except Exception:
log.exception("train_head failed for tag %d", tag_id)
ok = False
session.commit()
trained += int(ok)
skipped += int(not ok)
if run is not None and i % 10 == 0:
run.last_progress_at = datetime.now(UTC)
session.commit()
# Retire heads whose concept dropped out of the eligible set (lost its
# positives, or the tag was re-kinded) so stale heads can't keep suggesting.
if eligible_set:
session.execute(delete(TagHead).where(TagHead.tag_id.not_in(eligible_set)))
else:
session.execute(delete(TagHead))
session.commit()
return {"n_trained": trained, "n_skipped": skipped}
def train_head(
session: Session, tag_id: int, embedding_version: str, cfg: dict, np
) -> bool:
"""Fit + upsert one head. Returns True if a head was written, False if the
concept had too few usable examples to train (the row is then removed)."""
from sklearn.linear_model import LogisticRegression
from sklearn.model_selection import StratifiedKFold, cross_val_predict
pos_ids = _ids_with_tag(session, tag_id)
if len(pos_ids) < cfg["min_positives"]:
session.execute(delete(TagHead).where(TagHead.tag_id == tag_id))
return False
pos_set = set(pos_ids)
rejected = [i for i in _rejected_ids(session, tag_id) if i not in pos_set]
want_neg = max(len(pos_ids) * cfg["neg_ratio"], _EXAMPLES_MIN * 4)
sampled = _sample_unlabeled(
session, pos_set | set(rejected), min(_UNLABELED_POOL, want_neg)
)
neg_ids = rejected + [i for i in sampled if i not in pos_set]
emb = _load_embeddings(session, pos_ids + neg_ids)
pos = [emb[i] for i in pos_ids if i in emb]
neg = [emb[i] for i in neg_ids if i in emb]
if len(pos) < _EXAMPLES_MIN or len(neg) < _EXAMPLES_MIN:
session.execute(delete(TagHead).where(TagHead.tag_id == tag_id))
return False
X = np.vstack(pos + neg).astype(np.float32)
y = np.array([1] * len(pos) + [0] * len(neg))
Xn = _l2norm(X, np)
clf = LogisticRegression(max_iter=1000, class_weight="balanced")
cv = StratifiedKFold(
n_splits=_safe_folds(y, cfg["cv_folds"], np), shuffle=True, random_state=0
)
# Honest thresholds from out-of-fold scores; deployable weights from a final
# fit on ALL the data.
cv_probs = cross_val_predict(clf, Xn, y, cv=cv, method="predict_proba")[:, 1]
metrics = _metrics_from_scores(y, cv_probs, np)
auto = _auto_apply_point(y, cv_probs, cfg["precision_target"], np)
clf.fit(Xn, y)
head = session.get(TagHead, tag_id)
if head is None:
head = TagHead(tag_id=tag_id)
session.add(head)
head.embedding_version = embedding_version
head.weights = clf.coef_[0].astype(np.float32).tolist()
head.bias = float(clf.intercept_[0])
head.suggest_threshold = float(metrics["threshold"])
head.auto_apply_threshold = float(auto["threshold"]) if auto else None
head.n_pos = len(pos)
head.n_neg = len(neg)
head.ap = float(metrics["ap"])
head.precision_cv = float(metrics["precision"])
head.recall = float(metrics["recall"])
head.trained_at = datetime.now(UTC)
head.metrics = {"f1": metrics["f1"], "auto_apply": auto}
return True
# --- Scoring (async, API worker) -----------------------------------------
# Score one image against every current head to produce the rail's suggestions.
# A tiny in-process cache holds the stacked weight matrix keyed on (count,
# max(trained_at)) so a retrain invalidates it without per-request weight loads.
_HEADS_CACHE: dict[str, Any] = {"key": None, "heads": None}
async def _current_heads(session: AsyncSession, embedding_version: str):
"""Stacked (W, b, thresholds, tag_id/name/category) for heads matching the
current embedding, cached until the next retrain."""
import numpy as np
sig = (
await session.execute(
select(func.count(), func.max(TagHead.trained_at)).where(
TagHead.embedding_version == embedding_version
)
)
).one()
key = f"{embedding_version}:{sig[0]}:{sig[1].isoformat() if sig[1] else '-'}"
cached = _HEADS_CACHE.get("heads")
if cached is not None and _HEADS_CACHE.get("key") == key:
return cached
rows = (
await session.execute(
select(
TagHead.tag_id, Tag.name, Tag.kind,
TagHead.weights, TagHead.bias,
TagHead.suggest_threshold, TagHead.auto_apply_threshold,
)
.join(Tag, Tag.id == TagHead.tag_id)
.where(TagHead.embedding_version == embedding_version)
)
).all()
if not rows:
loaded = {"W": None, "rows": []}
else:
W = np.vstack([np.asarray(r.weights, dtype=np.float32) for r in rows])
b = np.asarray([r.bias for r in rows], dtype=np.float32)
thr = np.asarray([r.suggest_threshold for r in rows], dtype=np.float32)
meta = [
{
"tag_id": r.tag_id,
"name": r.name,
"category": _CATEGORY.get(r.kind, "general"),
"auto_apply_threshold": r.auto_apply_threshold,
}
for r in rows
]
loaded = {"W": W, "b": b, "thr": thr, "meta": meta}
_HEADS_CACHE["key"] = key
_HEADS_CACHE["heads"] = loaded
return loaded
async def score_image(
session: AsyncSession, image_id: int, threshold_override: float | None = None,
) -> list[dict]:
"""Suggestions for one image from the trained heads: [{tag_id, name,
category, score}], ranked. A concept surfaces when its score clears the
head's own suggest_threshold — or, when threshold_override is given (the
typed-dropdown "show everything" mode), that flat floor instead (0 → every
head). Empty if the image has no embedding or no heads exist yet.
MAX-OVER-BAG: the image is scored as a BAG of embeddings — the whole-image
vector PLUS every concept-region crop the agent embedded (same model
version) — and each head takes its MAX score across the bag. A small/local
concept (glasses, a stomach bulge) that the whole-image vector washes out
can still surface from the crop where it dominates. The whole-image vector is
always in the bag, so this can never score lower than whole-image alone."""
import numpy as np
img = await session.get(ImageRecord, image_id)
if img is None:
return []
settings = await _settings_async(session)
cur_version = settings.embedder_model_version
heads = await _current_heads(session, cur_version)
if heads["W"] is None:
return []
# Only embeddings in the CURRENT model's space enter the bag. Mid model-swap
# (#1190), an image still carrying the OLD-version whole-image vector is
# skipped rather than scored by heads trained in a different space; a legacy
# NULL version is treated as current (those predate per-row stamping).
bag = []
if img.siglip_embedding is not None and img.siglip_model_version in (
cur_version, None,
):
bag.append(np.asarray(img.siglip_embedding, dtype=np.float32))
region_vecs = (
await session.execute(
select(ImageRegion.siglip_embedding)
.where(ImageRegion.image_record_id == image_id)
.where(ImageRegion.siglip_embedding.is_not(None))
.where(ImageRegion.embedding_version == cur_version)
)
).all()
for (vec,) in region_vecs:
if vec is not None:
bag.append(np.asarray(vec, dtype=np.float32))
if not bag:
return []
X = np.vstack(bag) # (B, D)
norms = np.linalg.norm(X, axis=1, keepdims=True)
norms[norms == 0] = 1.0
Xn = X / norms
Z = Xn @ heads["W"].T + heads["b"] # (B, H)
probs = (1.0 / (1.0 + np.exp(-Z))).max(axis=0) # (H,) best over the bag
out = []
for i, p in enumerate(probs):
cut = threshold_override if threshold_override is not None else heads["thr"][i]
if p >= cut:
m = heads["meta"][i]
out.append({
"tag_id": m["tag_id"],
"name": m["name"],
"category": m["category"],
"score": float(p),
})
out.sort(key=lambda d: d["score"], reverse=True)
return out
async def _settings_async(session: AsyncSession) -> MLSettings:
return (
await session.execute(select(MLSettings).where(MLSettings.id == 1))
).scalar_one()
# --- Earned auto-apply (sync, ml worker) ---------------------------------
# A graduated head can apply its tag to images it scores above the head's
# auto_apply_threshold, without a human. Gated by a master switch + a support
# floor so a precise-looking but under-supported head can't spray tags.
_AUTO_APPLY_CHUNK = 5000
class HeadAutoApplyAlreadyRunning(Exception):
"""Raised when an auto-apply sweep is already in flight."""
class HeadAutoApplyDisabled(Exception):
"""Raised when a real (non-dry-run) sweep is requested but the master
switch (head_auto_apply_enabled) is off."""
def start_head_auto_apply_run(session: Session, params: dict[str, Any]) -> int:
"""Create a HeadAutoApplyRun + dispatch the ml-queue sweep. dry_run previews
(writes nothing); a real sweep needs the master switch on. One run at a time."""
dry_run = bool((params or {}).get("dry_run", False))
existing = session.execute(
select(HeadAutoApplyRun.id).where(HeadAutoApplyRun.status == "running")
).scalar_one_or_none()
if existing is not None:
raise HeadAutoApplyAlreadyRunning(existing)
if not dry_run and not _settings(session).head_auto_apply_enabled:
raise HeadAutoApplyDisabled()
run = HeadAutoApplyRun(
dry_run=dry_run, params={"dry_run": dry_run}, status="running",
last_progress_at=datetime.now(UTC),
)
session.add(run)
session.flush()
run_id = run.id
from ...tasks.ml import apply_head_tags as _task
_task.delay(run_id)
return run_id
def _auto_apply_heads(session: Session, embedding_version: str, min_pos: int):
"""Eligible heads to fire: graduated (auto_apply_threshold set), enough
support, current embedding. Returns the row list (tag_id/name/weights/...)."""
return session.execute(
select(
TagHead.tag_id, Tag.name, TagHead.weights, TagHead.bias,
TagHead.auto_apply_threshold,
)
.join(Tag, Tag.id == TagHead.tag_id)
.where(TagHead.embedding_version == embedding_version)
.where(TagHead.auto_apply_threshold.is_not(None))
.where(TagHead.n_pos >= min_pos)
).all()
def auto_apply_sweep(
session: Session, run: HeadAutoApplyRun, dry_run: bool
) -> dict[str, Any]:
"""Score every embedded image against the eligible heads and apply (or, for
dry_run, just count) each head's tag where score >= its auto_apply_threshold
and the tag isn't already applied or rejected on that image. Streams
embeddings in chunks; commits per chunk on a real run. Returns
{n_applied, concepts:[{tag_id,name,applied,scanned,threshold}]}."""
import numpy as np
from sqlalchemy.dialects.postgresql import insert as pg_insert
settings = _settings(session)
rows = _auto_apply_heads(
session, settings.embedder_model_version,
settings.head_auto_apply_min_positives,
)
if not rows:
return {"n_applied": 0, "concepts": []}
W = np.vstack([np.asarray(r.weights, dtype=np.float32) for r in rows])
b = np.asarray([r.bias for r in rows], dtype=np.float32)
thr = np.asarray([r.auto_apply_threshold for r in rows], dtype=np.float32)
tag_ids = [r.tag_id for r in rows]
names = [r.name for r in rows]
# Skip images that already carry, or have rejected, each tag.
skip = {tid: set() for tid in tag_ids}
for tid in tag_ids:
for (iid,) in session.execute(
select(image_tag.c.image_record_id).where(image_tag.c.tag_id == tid)
):
skip[tid].add(iid)
for (iid,) in session.execute(
select(TagSuggestionRejection.image_record_id).where(
TagSuggestionRejection.tag_id == tid
)
):
skip[tid].add(iid)
applied = [0] * len(rows)
scanned = 0
all_ids = list(session.execute(
select(ImageRecord.id).where(ImageRecord.siglip_embedding.is_not(None))
).scalars())
for start in range(0, len(all_ids), _AUTO_APPLY_CHUNK):
chunk = all_ids[start:start + _AUTO_APPLY_CHUNK]
emb = _load_embeddings(session, chunk)
cids = [i for i in chunk if i in emb]
if not cids:
continue
Xn = _l2norm(np.vstack([emb[i] for i in cids]).astype(np.float32), np)
probs = 1.0 / (1.0 + np.exp(-(Xn @ W.T + b))) # (N, H)
scanned += len(cids)
for h in range(len(rows)):
tid = tag_ids[h]
for idx in np.where(probs[:, h] >= thr[h])[0]:
iid = cids[int(idx)]
if iid in skip[tid]:
continue
skip[tid].add(iid)
applied[h] += 1
if not dry_run:
session.execute(
pg_insert(image_tag)
.values(image_record_id=iid, tag_id=tid, source="head_auto")
.on_conflict_do_nothing()
)
if not dry_run:
session.commit()
run.last_progress_at = datetime.now(UTC)
session.commit()
concepts = [
{"tag_id": tag_ids[h], "name": names[h], "applied": applied[h],
"scanned": scanned, "threshold": float(thr[h])}
for h in range(len(rows))
]
return {"n_applied": sum(applied), "concepts": concepts}