feat(system-tags): process vs chrome groups + WIP provisional auto-apply (#1464)

Backend for the system-tag behavior refactor (milestone #157). editor screenshot
moves from chrome (hidden) to the PROCESS group (shown, like wip); wip+editor gain
provisional auto-apply so they stop needing endless manual identification —
without a runaway loop.

- tag.py: split PRESENTATION_SYSTEM_TAGS → CHROME_SYSTEM_TAGS (banner) +
  PROCESS_SYSTEM_TAGS (wip, editor screenshot).
- heads.py: generalize presentation_auto_apply_sweep → system_tag_auto_apply_sweep
  (mode chrome|process). Same Guard 1 (skip human/confirmed) + Guard 2 (ring-loud
  conflict → PresentationReview). process mode uses source 'process_auto' and does
  NOT hide (hide is a gallery-query effect of group membership).
- training_data._AUTO_SOURCES += 'process_auto' → the head never trains on its own
  auto-applied output; only wip_title/manual train it (the runaway break).
- ml_settings: process_auto_apply_enabled (OFF, opt-in) + threshold + conflict
  threshold. presentation_review.mode ('chrome'|'process'). Migration 0086.
- gallery_service: default-hide reads CHROME only (editor now shows); Explore
  neighbors exclude the whole PROCESS group.
- tasks/ml + celery beat: scheduled_process_auto_apply (daily, opt-in); prune
  covers both modes.
- api: ml_admin process_* CRUD+validation; hidden-review returns mode.
- tests: rename chrome sweep calls; new test_process_auto_apply (apply, guards,
  mode flag, no-self-train); gallery test asserts editor now visible.

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

backend/app/models/ml_settings.py

@@ -85,12 +85,14 @@ class MLSettings(Base):
         Float, nullable=False, default=0.95
     )
     # -- Presentation chrome auto-hide (#141) -------------------------------
-    # banner / editor screenshot auto-apply on the sweep with their OWN flat
-    # threshold (decoupled from content-head graduation). Hiding is consequential
-    # so it runs HIGH. `wip` is never auto-applied. When an image would be
-    # auto-hidden but ALSO scores >= presentation_conflict_threshold on a content
-    # head, it's still hidden but flagged for review (PresentationReview) instead
-    # of buried silently. ON by default (opt-out); every auto-tag is reversible.
+    # `banner` (chrome — clusters on UI, not content) auto-applies on the sweep
+    # with its OWN flat threshold (decoupled from content-head graduation) and is
+    # HIDDEN from the gallery. Hiding is consequential so it runs HIGH. When an
+    # image would be auto-hidden but ALSO scores >= presentation_conflict_threshold
+    # on a content head, it's still hidden but flagged for review
+    # (PresentationReview, mode='chrome') instead of buried silently. ON by default
+    # (opt-out); every auto-tag is reversible. NOTE (#1464): `wip` + `editor
+    # screenshot` are no longer chrome — they went to the PROCESS path below.
     presentation_auto_apply_enabled: Mapped[bool] = mapped_column(
         Boolean, nullable=False, default=True
     )
@@ -100,6 +102,26 @@ class MLSettings(Base):
     presentation_conflict_threshold: Mapped[float] = mapped_column(
         Float, nullable=False, default=0.50
     )
+    # -- Process auto-apply (#1464) ----------------------------------------
+    # `wip` / `editor screenshot` are PROCESS art — unfinished pieces + program
+    # screenshots that must stay OUT of head/CCIP training but, unlike chrome,
+    # remain VISIBLE in the gallery (operator 2026-07-12). They auto-apply on the
+    # sweep with their OWN flat threshold and a PROVISIONAL source (`process_auto`,
+    # in training_data._AUTO_SOURCES) so the head NEVER trains on its own output —
+    # it learns only from title (`wip_title`) + manual labels, which breaks the
+    # runaway loop. When a process tag would be applied but the image ALSO scores
+    # >= process_conflict_threshold on a content head, it's flagged for review
+    # (PresentationReview, mode='process') rather than silently marked. OFF by
+    # default — a new whole-library auto-tagger is opt-in; every auto-tag reversible.
+    process_auto_apply_enabled: Mapped[bool] = mapped_column(
+        Boolean, nullable=False, default=False
+    )
+    process_auto_apply_threshold: Mapped[float] = mapped_column(
+        Float, nullable=False, default=0.90
+    )
+    process_conflict_threshold: Mapped[float] = mapped_column(
+        Float, nullable=False, default=0.50
+    )
     # Default = SigLIP 2 (so400m, 512px) for new installs (migration 0069);
     # existing libraries keep their stored value until the operator re-embeds.
     embedder_model_version: Mapped[str] = mapped_column(