feat(ia): wave 1 — Import tab dissolves, Maintenance regroups by system, one extension home

Settings IA per the approved A3 design (the old layout was the two-app merge
fossilized):
- Import tab retired: ImportTriggerPanel + ImportTaskList deleted (manual
  /import scans stay API-level; imports arrive via downloads/extension, heal
  via the Layer-2 auto-refetch sweep, and show in Activity). ImportFiltersForm
  moves to Maintenance → 'Ingestion & filters' and loads its own settings; the
  import store shrinks to settings-only (no remaining consumers of the
  scan/task-list machinery). Overview's pending banner now points at Activity.
- Maintenance regrouped: Ingestion & filters / GPU agent & embeddings
  (GpuAgent, Failed processing, CPU embedding backfill) / Tagging (sliders,
  Heads, Aliases) / Library health (MissingFiles, Thumbnails, DB, Archive
  re-extract demoted last) / Storage.
- One extension home: BrowserExtensionCard moves from Settings → Overview to
  Subscriptions → Settings, above the API key bar it authenticates.
- Single-color import filter WIRED: skip_single_color/threshold existed since
  FC-2 but nothing read them (the audit module's docstring said as much) —
  now enforced on both import paths via the audit's canonical predicate
  (tolerance 30, matching the Cleanup card default; animated images exempt
  like the transparency check). Default stays off; test added.
- Dead weight: PlaceholderView (zero refs) and the permanently-disabled
  'Export failed logs (CSV — v2)' menu stub deleted; stale docs fixed
  (celery queue docstring, threshold comment citing retired tasks, ml
  package docstring, HeadsCard 'replaces Camie' blurb).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CDgx8bQS5YrGRK76v8HUnM

backend/app/celery_app.py

@@ -7,7 +7,7 @@ Queues:
   download    — gallery-dl tasks (FC-3)
   scan        — periodic source checks (FC-3) — kept separate so long imports
                 don't starve the scheduler
-  maintenance — pHash recomputation, centroid rebuild, etc. (FC-2/FC-3)
+  maintenance — recovery sweeps, pHash backfill, GPU-queue coordination, etc.
   default     — anything not explicitly routed
 """
 

backend/app/services/audits/single_color.py

@@ -1,8 +1,9 @@
 """Single-color audit: matches images where one color dominates beyond
-the threshold (within the given Euclidean RGB tolerance). The first
-canonical implementation — the import-side filter (SkipReason.single_color)
-was never wired; FC-Cleanup's audit module is the source of truth and a
-future spec can adopt it on the import path too.
+the threshold (within the given Euclidean RGB tolerance). The canonical
+predicate for BOTH surfaces: FC-Cleanup's retroactive audit and — since
+2026-07-02 — the import-side filter (Importer._single_color_hit /
+SkipReason.single_color), so what the audit flags and what the import
+skips can never disagree.
 """
 
 from PIL import Image

backend/app/services/importer.py

@@ -44,6 +44,7 @@ from ..utils.sidecar import find_sidecar, parse_sidecar
 from ..utils.slug import slugify
 from .archive_extractor import extract_archive, is_archive
 from .attachment_store import AttachmentStore
+from .audits import single_color
 from .link_extract import extract_external_links
 from .thumbnailer import Thumbnailer
 
@@ -790,6 +791,13 @@ class Importer:
                         error=f"{pct:.2%} transparent",
                     )
 
+            if self.settings.skip_single_color and self._single_color_hit(source):
+                return ImportResult(
+                    status="skipped", skip_reason=SkipReason.single_color,
+                    error=(f"one color dominates >"
+                           f"{self.settings.single_color_threshold:.0%}"),
+                )
+
         # Artist anchored to the attribution path (folder→artist), resolved
         # UP-FRONT so the enrich-on-duplicate branches link provenance with the
         # right artist even when the sidecar carries none — which is now the norm
@@ -1123,6 +1131,13 @@ class Importer:
                         status="skipped", skip_reason=SkipReason.too_transparent,
                         error=f"{pct:.2%} transparent",
                     )
+
+            if self.settings.skip_single_color and self._single_color_hit(path):
+                return ImportResult(
+                    status="skipped", skip_reason=SkipReason.single_color,
+                    error=(f"one color dominates >"
+                           f"{self.settings.single_color_threshold:.0%}"),
+                )
         else:
             # Best-effort probe for dims + duration so downloaded videos can dedup
             # (#871). LENIENT: unlike _import_media this path does not reject on a
@@ -1538,6 +1553,33 @@ class Importer:
                 # Benign orphan; the DB swap already committed. Don't undo it.
                 pass
 
+    # Matches the Cleanup audit card's default tolerance: the import-side
+    # filter and the retroactive audit must agree on what "single color" MEANS
+    # (Euclidean RGB distance to the dominant color); only the match threshold
+    # is operator-tunable per surface.
+    _SINGLE_COLOR_TOLERANCE = 30
+
+    def _single_color_hit(self, source: Path) -> bool:
+        """True when one color dominates beyond the configured threshold — the
+        same canonical predicate the Cleanup audit runs (audits.single_color,
+        whose docstring anticipated this adoption; the skip_single_color
+        setting existed but was never wired until 2026-07-02). Never raises:
+        unreadable files were already rejected by verify() upstream, and a
+        residual decode error just declines to match (the import proceeds)."""
+        try:
+            with Image.open(source) as im:
+                if getattr(im, "is_animated", False):
+                    # Frame 0 only would misjudge animations; skip like the
+                    # transparency check does.
+                    return False
+                return single_color.evaluate(
+                    im,
+                    threshold=self.settings.single_color_threshold,
+                    tolerance=self._SINGLE_COLOR_TOLERANCE,
+                )
+        except Exception:
+            return False
+
     def _transparency_pct(self, source: Path) -> float:
         """Fraction of fully-transparent pixels in the image. 0.0 if no alpha.
 

backend/app/services/ml/__init__.py

@@ -1 +1,3 @@
-"""ML pipeline services: tagger, embedder, suggestions, centroids, allowlist, aliases."""
+"""ML pipeline services: embedders, heads (the learning suggester), suggestions,
+GPU-job queue + failure triage, CCIP characters, crops/regions, allowlist and
+aliases."""

backend/app/tasks/maintenance.py

@@ -139,10 +139,9 @@ QUEUE_STUCK_THRESHOLD_MINUTES: dict[str, int] = {
     "download": 30,
     # Audit 2026-06-02 — maintenance/scan queues run tasks that
     # legitimately exceed the 5-min default (verify_integrity at 70m
-    # hard, scan_directory at 70m hard, apply_allowlist_tags /
-    # recompute_centroids / backfill_phash at 35m hard). 75 min lives
-    # above the longest of those and the per-task overrides below
-    # cover the outliers (backups, library audit).
+    # hard, scan_directory at 70m hard, backfill_phash at 35m hard).
+    # 75 min lives above the longest of those and the per-task
+    # overrides below cover the outliers (backups, library audit).
     "maintenance": 75,
     "scan": 75,
 }