Harden operator tile background metadata

scripts/README.md

@@ -367,9 +367,40 @@ negative tiles, and records `yolo_tile_dataset_summary.json` with
 `--min-label-visible-ratio` drops labels where only a small clipped fragment of
 the original building bbox is visible inside the tile; this reduces noisy
 tile-edge labels in overlapping-tile datasets. Use `0` for legacy behavior.
+For legacy operator manifests that predate explicit `background_category`, the
+exporter derives the same categories as the split-background evaluator:
+background samples with `reference_feature_count == 0` become
+`pure_empty_negative`, and background samples with one or more reference
+features become `sparse_building_context`.
 It remains operator tooling only: no provider fetch, no API mutation and no
 automatic model training.
 
+For the current AOI1024 baseline, prefer the stricter clean-label profile before
+spending another training run:
+
+```bash
+docker exec -it geointel python3 /app/scripts/export_operator_yolo_tile_dataset.py \
+  --manifest-path /app/storage/operator-data/operator-samples-1024/operator_samples_manifest.json \
+  --output-dir /app/storage/operator-data/yolo-building-aoi1024-cleanpx12vis035 \
+  --tile-size 512 \
+  --stride 256 \
+  --negative-keep-ratio 1.0 \
+  --min-label-px 12 \
+  --min-label-visible-ratio 0.35 \
+  --val-samples turnhout,retie,westerlo,arendonk_heide \
+  --force
+```
+
+Then audit with stricter small-box gates:
+
+```bash
+docker exec -it geointel python3 /app/scripts/audit_operator_yolo_dataset_quality.py \
+  --summary-path /app/storage/operator-data/yolo-building-aoi1024-cleanpx12vis035/yolo_tile_dataset_summary.json \
+  --output-dir /app/artifacts/operator-yolo-dataset-audit/aoi1024-cleanpx12vis035 \
+  --max-small-box-share 0.25 \
+  --min-median-box-area 0.001
+```
+
 Audit the generated tile dataset before spending another long training run:
 
 ```bash