Add hard-negative balanced YOLO tile export

CHANGELOG.md

@@ -7,6 +7,18 @@
 
 # Changelog
 
+## Sprint 133 Hard-negative-balanced YOLO candidate (2026-07-07)
+
+- Added `--background-negative-repeat` / `OPERATOR_YOLO_BACKGROUND_NEGATIVE_REPEAT` support to `scripts/export_operator_yolo_tile_dataset.py` so train-split background-candidate negative tiles can be repeated deterministically without duplicating validation tiles.
+- Added exported tile provenance fields `sample_role`, `repeat_index` and `is_repeated_background_negative` plus regression coverage in `backend/tests/test_sprint130_operator_yolo_tile_dataset.py`.
+- Live Tower export produced `/app/storage/operator-data/yolo-building-tile-hardneg160r8` with tile size `160`, stride `80`, background repeat `8`, 864 tiles, 260 positive tiles, 604 negative tiles, 11213 labels, 756 train tiles and 108 validation tiles.
+- Live Tower 40-epoch CPU training produced `/app/models/geointel-building-yolov8n-hardneg160r8e40.pt`; the model catalog exposes it as `geointel-building-yolov8n-hardneg160r8e40-pt` with SHA256 `7a77bd9f68e4c3927ffc8a8cd978a81067b02f42cffe77ada5334b5f8dbb6b50`.
+- Live YOLO preflight loaded the model successfully with `status=ready`, `model_load_ok=true`, `manifest_valid=true`, `tile_paths_exist=true`, `will_download_models=false` and `will_run_inference=false`.
+- Live 60-run dense QA matrix showed `geointel-building-yolov8n-expanded160e50-pt` remains the better dense-AOI candidate; hardneg160r8e40 underperformed it on Geel, Mol, Turnhout and Retie.
+- Live 36-run background matrix showed hardneg160r8e40 materially reduced false-positive pressure: Kasterlee-bos dropped from expanded160e50's 38/46/76 detections to 5/9/25 at thresholds `0.25`/`0.15`/`0.05`, and Postel-bos/Lommel-heide stayed at 0 detections across all thresholds.
+- Decision: hardneg160r8e40 is useful evidence for a low-false-positive training direction, but it should not become the V1 default because dense-AOI recall/F1 regressed. The next model pass should combine stronger positive coverage with hard-negative balancing or test a stronger aerial-building architecture.
+- No Training Studio UI, API contract change, provider fetching, model auto-provisioning, fake detections or app-side model training behavior was introduced.
+
 ## Sprint 132 Operator hard-negative detection matrix (2026-07-07)
 
 - Added `scripts/run_operator_hard_negative_detection_matrix.sh` to score configured-YOLO false-positive pressure on documented background-candidate operator AOIs without uploading reference vectors or running QA/QC.

backend/tests/test_sprint130_operator_yolo_tile_dataset.py

@@ -64,6 +64,7 @@ def test_operator_yolo_tile_dataset_export_help_does_not_require_gis_dependencie
     assert "--tile-size" in result.stdout
     assert "--stride" in result.stdout
     assert "--negative-keep-ratio" in result.stdout
+    assert "--background-negative-repeat" in result.stdout
 
 
 def test_iter_tile_windows_covers_edges_without_duplicates() -> None:
@@ -93,3 +94,32 @@ def test_negative_tile_keep_is_deterministic_and_ratio_bound() -> None:
     assert 1 <= sum(first) <= 25
     assert all(all_kept)
     assert not any(none_kept)
+
+
+def test_background_negative_repeat_only_applies_to_training_background_tiles() -> None:
+    module = load_tile_exporter()
+
+    assert module.background_negative_repeat_count(
+        is_negative=True,
+        sample_role="background_candidate",
+        split="train",
+        background_negative_repeat=4,
+    ) == 4
+    assert module.background_negative_repeat_count(
+        is_negative=True,
+        sample_role="background_candidate",
+        split="val",
+        background_negative_repeat=4,
+    ) == 1
+    assert module.background_negative_repeat_count(
+        is_negative=False,
+        sample_role="background_candidate",
+        split="train",
+        background_negative_repeat=4,
+    ) == 1
+    assert module.background_negative_repeat_count(
+        is_negative=True,
+        sample_role="reference",
+        split="train",
+        background_negative_repeat=4,
+    ) == 1

docs/CODEX_EXECUTION_LOG.md

@@ -1,3 +1,57 @@
+## Sprint 133 Hard-negative-balanced YOLO candidate (2026-07-07)
+
+Changed:
+- Hardened `scripts/export_operator_yolo_tile_dataset.py` with deterministic train-only background-negative repetition through `--background-negative-repeat` and `OPERATOR_YOLO_BACKGROUND_NEGATIVE_REPEAT`.
+- Background-negative repetition applies only when `is_negative=true`, `sample_role=background_candidate` and `split=train`; validation tiles, positive tiles and normal reference samples are not duplicated.
+- Added tile-level provenance fields `sample_role`, `repeat_index` and `is_repeated_background_negative`.
+- Added regression coverage in `backend/tests/test_sprint130_operator_yolo_tile_dataset.py`.
+- Updated `scripts/README.md`, `docs/TODO.md`, `docs/CODEX_EXECUTION_LOG.md` and `CHANGELOG.md`.
+
+Tested:
+- RED: `python -m pytest backend\tests\test_sprint130_operator_yolo_tile_dataset.py -q` failed before `--background-negative-repeat` and `background_negative_repeat_count` existed.
+- `python -m pytest backend\tests\test_sprint130_operator_yolo_tile_dataset.py -q` passed.
+- `python -m py_compile scripts\export_operator_yolo_tile_dataset.py` passed.
+- `python scripts\export_operator_yolo_tile_dataset.py --help` passed.
+- Live Tower hard-negative-balanced tile export passed:
+  - dataset: `/app/storage/operator-data/yolo-building-tile-hardneg160r8`
+  - source samples: 10
+  - tile size: `160`
+  - stride: `80`
+  - negative keep ratio: `1.0`
+  - background negative repeat: `8`
+  - exported tiles: `864`
+  - positive tiles: `260`
+  - negative tiles: `604`
+  - labels: `11213`
+  - train tiles: `756`
+  - validation tiles: `108`
+- Live Tower 40-epoch CPU training passed:
+  - output model: `/app/models/geointel-building-yolov8n-hardneg160r8e40.pt`
+  - catalog asset: `geointel-building-yolov8n-hardneg160r8e40-pt`
+  - SHA256: `7a77bd9f68e4c3927ffc8a8cd978a81067b02f42cffe77ada5334b5f8dbb6b50`
+  - final validation: precision `0.403`, recall `0.378`, mAP50 `0.301`, mAP50-95 `0.0944`
+- Live API preflight passed for `geointel-building-yolov8n-hardneg160r8e40-pt` with `status=ready`, `model_load_ok=true`, `manifest_valid=true`, `tile_paths_exist=true`, `will_download_models=false` and `will_run_inference=false`.
+- Live 60-run multi-sample QA matrix completed:
+  - output: `/mnt/user/appdata/geointel/artifacts/detection-quality-matrix/multi-sample/hardneg160r8e40-live/multi_sample_quality_summary.json`
+  - command compared `geointel-building-yolov8n-hardneg160r8e40-pt`, `geointel-building-yolov8n-expanded160e50-pt`, `geointel-building-yolov8n-tile30-pt` and `yolov8s-building-segmentation-pt` over Geel, Mol, Turnhout, Retie and Kasterlee-bos with tile `640`, overlap `64`, thresholds `0.25`/`0.15`/`0.05`.
+  - best overall score and recall remained Geel with `geointel-building-yolov8n-expanded160e50-pt`, precision `0.30333333333333334`, recall `0.14748784440842788`, F1 `0.1984732824427481`.
+  - hardneg160r8e40 dense F1 lagged expanded160e50 on Geel (`0.14394765539803708` vs `0.1984732824427481`), Mol (`0.11572700296735906` vs `0.1651651651651652`), Turnhout (`0.14911463187325258` vs `0.1938490214352283`) and Retie (`0.10538116591928251` vs `0.1569506726457399`).
+- Live 36-run hard-negative matrix completed:
+  - output: `/mnt/user/appdata/geointel/artifacts/detection-hard-negatives/hardneg160r8e40-live/hard_negative_matrix_summary.json`
+  - Postel-bos: hardneg160r8e40 produced 0/0/0 detections at thresholds `0.25`/`0.15`/`0.05`; expanded160e50 produced 0/0/1.
+  - Lommel-heide: hardneg160r8e40 produced 0/0/0 detections; expanded160e50 produced 0/0/10.
+  - Kasterlee-bos: hardneg160r8e40 produced 5/9/25 detections; expanded160e50 produced 38/46/76.
+
+Open:
+- None for the hard-negative-balanced tile export contract itself.
+
+Limitations:
+- `geointel-building-yolov8n-hardneg160r8e40-pt` reduced false-positive pressure but regressed dense-AOI recall/F1. It should not become the V1 default.
+- This remains operator tooling only. It does not add Training Studio, browser training controls, provider fetching, fake detections, model auto-provisioning or API contract changes.
+
+Next recommended pass:
+- Train or import a materially stronger aerial/Kempen building model candidate, then benchmark it against the same dense QA and hard-negative matrices before changing default model selection.
+
 ## Sprint 132 Operator hard-negative detection matrix (2026-07-07)
 
 Changed:

docs/TODO.md

@@ -106,7 +106,7 @@ This file now starts with the current implementation status. Older preparation/b
 - [x] Calibrate confidence, IoU and model selection against additional local orthophoto/reference samples beyond Geel/Mol/Turnhout.
 - [x] Add negative/background AOIs to the operator sample corpus and train an expanded local tile-level YOLO candidate.
 - [x] Add a hard-negative model-quality pass with sparse/background AOIs and explicit false-positive scoring.
-- [ ] Train a hard-negative-balanced YOLO candidate and rerun dense QA plus background false-positive matrices.
+- [x] Train a hard-negative-balanced YOLO candidate and rerun dense QA plus background false-positive matrices.
 - [ ] Find or train a materially stronger aerial/Kempen building model candidate; `geointel-building-yolov8n-expanded160e50-pt` is the best current dense-AOI candidate but still too weak and too noisy for a V1 default.
 
 ## Sprint 8 status

scripts/README.md

@@ -328,6 +328,27 @@ negative tiles, and records `yolo_tile_dataset_summary.json` with
 It remains operator tooling only: no provider fetch, no API mutation and no
 automatic model training.
 
+For hard-negative-balanced experiments, repeat only train-split negative tiles
+from samples marked `sample_role=background_candidate`:
+
+```bash
+docker exec -it geointel python3 /app/scripts/export_operator_yolo_tile_dataset.py \
+  --manifest-path /app/storage/operator-data/operator_samples_manifest.json \
+  --output-dir /app/storage/operator-data/yolo-building-tile-hardneg160r8 \
+  --tile-size 160 \
+  --stride 80 \
+  --negative-keep-ratio 1.0 \
+  --background-negative-repeat 8 \
+  --val-samples turnhout,retie,kasterlee_bos \
+  --force
+```
+
+The repeat option can also be set with
+`OPERATOR_YOLO_BACKGROUND_NEGATIVE_REPEAT`. It does not duplicate validation
+tiles, positive tiles or normal reference-sample negatives. Repeated background
+tiles receive deterministic `_hnXX` filenames and tile metadata records
+`sample_role`, `repeat_index` and `is_repeated_background_negative`.
+
 Train against the tile dataset by pointing the existing wrapper at the tile
 output directory:
 
@@ -388,6 +409,13 @@ was clean on Postel-bos and Lommel-heide at thresholds `0.25` and `0.15`, but
 produced 38 detections on Kasterlee-bos even at `0.25`. That blocks it from
 becoming a V1 default until a hard-negative-balanced candidate improves.
 
+The hard-negative-balanced `geointel-building-yolov8n-hardneg160r8e40-pt`
+candidate reduced Kasterlee-bos false-positive pressure to 5/9/25 detections
+at thresholds `0.25`/`0.15`/`0.05` and stayed at 0 detections on Postel-bos and
+Lommel-heide across all tested thresholds. It also regressed dense-AOI F1
+against `geointel-building-yolov8n-expanded160e50-pt`, so it is useful model
+quality evidence but not a V1 default.
+
 Export calibration QA evidence for visual review:
 
 ```bash

scripts/export_operator_yolo_tile_dataset.py

@@ -78,6 +78,12 @@ def parse_args() -> argparse.Namespace:
         default=float(os.environ.get("OPERATOR_YOLO_MIN_LABEL_PX", "4")),
         help="Minimum clipped box width/height in pixels before a tile label is kept.",
     )
+    parser.add_argument(
+        "--background-negative-repeat",
+        type=int,
+        default=int(os.environ.get("OPERATOR_YOLO_BACKGROUND_NEGATIVE_REPEAT", "1")),
+        help="Repeat kept train/background negative tiles this many times for hard-negative balancing.",
+    )
     parser.add_argument("--force", action="store_true", help="Remove and recreate output-dir before exporting.")
     return parser.parse_args()
 
@@ -134,6 +140,22 @@ def keep_negative_tile(sample_slug: str, tile_index: int, negative_keep_ratio: f
     return bucket < negative_keep_ratio
 
 
+def background_negative_repeat_count(
+    *,
+    is_negative: bool,
+    sample_role: str,
+    split: str,
+    background_negative_repeat: int,
+) -> int:
+    if not is_negative:
+        return 1
+    if split != "train":
+        return 1
+    if sample_role != "background_candidate":
+        return 1
+    return max(1, background_negative_repeat)
+
+
 def resolve_manifest_path(raw: str, manifest_path: Path) -> Path:
     path = Path(raw)
     if path.exists():
@@ -274,8 +296,10 @@ def export_sample_tiles(
     stride: int,
     negative_keep_ratio: float,
     min_label_px: float,
+    background_negative_repeat: int,
 ) -> list[dict[str, Any]]:
     sample_slug = str(sample["sample_slug"])
+    sample_role = str(sample.get("sample_role") or "reference")
     split = "val" if sample_slug.lower() in val_slugs else "train"
     raster_path = resolve_manifest_path(str(sample["raster_path"]), manifest_path)
     reference_path = resolve_manifest_path(str(sample["reference_path"]), manifest_path)
@@ -302,31 +326,43 @@ def export_sample_tiles(
                     }
                 )
                 continue
-            tile_name = f"{sample_slug}_{tile_index:04d}_r{tile_window.row_off}_c{tile_window.col_off}"
-            image_path = output_dir / "images" / split / f"{tile_name}.png"
-            label_path = output_dir / "labels" / split / f"{tile_name}.txt"
-            image_path.parent.mkdir(parents=True, exist_ok=True)
-            label_path.parent.mkdir(parents=True, exist_ok=True)
-            Image.fromarray(image_array_from_raster_window(dataset, tile_window)).save(image_path)
-            label_path.write_text("\n".join(labels) + ("\n" if labels else ""), encoding="utf-8")
-            exported.append(
-                {
-                    "sample_slug": sample_slug,
-                    "split": split,
-                    "tile_index": tile_index,
-                    "kept": True,
-                    "image_path": str(image_path),
-                    "label_path": str(label_path),
-                    "label_count": len(labels),
-                    "is_negative": is_negative,
-                    "window": {
-                        "row_off": tile_window.row_off,
-                        "col_off": tile_window.col_off,
-                        "height": tile_window.height,
-                        "width": tile_window.width,
-                    },
-                }
+            repeats = background_negative_repeat_count(
+                is_negative=is_negative,
+                sample_role=sample_role,
+                split=split,
+                background_negative_repeat=background_negative_repeat,
             )
+            image_array = image_array_from_raster_window(dataset, tile_window)
+            for repeat_index in range(repeats):
+                repeat_suffix = f"_hn{repeat_index + 1:02d}" if repeats > 1 else ""
+                tile_name = f"{sample_slug}_{tile_index:04d}_r{tile_window.row_off}_c{tile_window.col_off}{repeat_suffix}"
+                image_path = output_dir / "images" / split / f"{tile_name}.png"
+                label_path = output_dir / "labels" / split / f"{tile_name}.txt"
+                image_path.parent.mkdir(parents=True, exist_ok=True)
+                label_path.parent.mkdir(parents=True, exist_ok=True)
+                Image.fromarray(image_array).save(image_path)
+                label_path.write_text("\n".join(labels) + ("\n" if labels else ""), encoding="utf-8")
+                exported.append(
+                    {
+                        "sample_slug": sample_slug,
+                        "sample_role": sample_role,
+                        "split": split,
+                        "tile_index": tile_index,
+                        "repeat_index": repeat_index,
+                        "kept": True,
+                        "image_path": str(image_path),
+                        "label_path": str(label_path),
+                        "label_count": len(labels),
+                        "is_negative": is_negative,
+                        "is_repeated_background_negative": repeats > 1,
+                        "window": {
+                            "row_off": tile_window.row_off,
+                            "col_off": tile_window.col_off,
+                            "height": tile_window.height,
+                            "width": tile_window.width,
+                        },
+                    }
+                )
     return exported
 
 
@@ -355,6 +391,7 @@ def main() -> int:
                 stride=args.stride,
                 negative_keep_ratio=args.negative_keep_ratio,
                 min_label_px=args.min_label_px,
+                background_negative_repeat=args.background_negative_repeat,
             )
         )
 
@@ -375,6 +412,7 @@ def main() -> int:
         "tile_size": args.tile_size,
         "stride": args.stride,
         "negative_keep_ratio": args.negative_keep_ratio,
+        "background_negative_repeat": args.background_negative_repeat,
         "min_label_px": args.min_label_px,
         "source_sample_count": len(samples),
         "tile_count": len(kept_tiles),