Add operator hard-negative detection matrix

backend/README.md

@@ -492,6 +492,24 @@ The combined `multi_sample_quality_summary.json` reports per-sample and overall
 best configurations. It is an operator benchmarking command, not a backend API
 or provider import path.
 
+Before promoting any local model as a default, also run the hard-negative
+matrix against the documented background candidates:
+
+```bash
+OPERATOR_SAMPLE_MANIFEST_PATH=storage/operator-data/operator_samples_manifest.json \
+OPERATOR_BACKGROUND_SAMPLE_SLUGS="postel_bos lommel_heide kasterlee_bos" \
+QUALITY_MODEL_ASSET_IDS="geointel-building-yolov8n-expanded160e50-pt geointel-building-yolov8n-tile30-pt yolov8s-building-segmentation-pt" \
+QUALITY_TILE_SIZES="640" \
+QUALITY_TILE_OVERLAPS="64" \
+QUALITY_THRESHOLDS="0.25 0.15 0.05" \
+bash scripts/run_operator_hard_negative_detection_matrix.sh http://192.168.10.150:1202
+```
+
+This path uploads only background rasters, runs configured-YOLO detection and
+counts detections as false-positive pressure. It does not upload reference
+vectors or run QA/QC, so it cannot produce fake precision/recall metrics for
+empty background AOIs.
+
 To inspect the evidence behind a calibration run, export the persisted QA
 evidence bundle: