Spread capped failure samples across weak contexts

backend/tests/test_failure_driven_yolo_sampling.py

@@ -279,6 +279,42 @@ def test_region_cap_rotates_repeats_between_sampling_rounds() -> None:
     assert second_metadata["sampling_round"] == 2
 
 
+def test_region_cap_preserves_failed_context_positive_before_hard_negative() -> None:
+    manifest = {"samples": [
+        {"sample_slug": "target", "split": "train", "region": "flanders", "context": "industrial"},
+        {"sample_slug": "negative", "split": "train", "region": "flanders", "context": "industrial-hard-negative"},
+        {"sample_slug": "wa", "split": "train", "region": "wallonia", "context": "rural-town"},
+        {"sample_slug": "br", "split": "train", "region": "brussels", "context": "dense-urban"},
+    ]}
+    summary = {"tiles": [
+        {"sample_slug": "target", "split": "train", "label_count": 2, "image_path": "/tmp/target.png"},
+        {"sample_slug": "negative", "split": "train", "label_count": 0, "image_path": "/tmp/negative.png"},
+        {"sample_slug": "wa", "split": "train", "label_count": 1, "image_path": "/tmp/wa.png"},
+        {"sample_slug": "br", "split": "train", "label_count": 1, "image_path": "/tmp/br.png"},
+    ]}
+    assessment = {
+        "status": "continue_training_loop",
+        "gates": {"min_region_f1": .45, "min_region_precision": .5, "min_region_recall": .4,
+                  "max_pure_empty_false_positives": 0},
+        "calibration": {
+            "regions": {
+                "flanders": {"f1": .2, "precision": .2, "recall": .3},
+                "wallonia": {"f1": .6, "precision": .6, "recall": .6},
+                "brussels": {"f1": .6, "precision": .6, "recall": .6},
+            },
+            "samples": {"target": {"f1": .2, "precision": .2, "recall": .3}},
+        },
+    }
+
+    paths, metadata = MODULE.build_sampling(
+        summary=summary, manifest=manifest, assessment=assessment, max_region_share=.65,
+    )
+
+    assert paths.count(str(Path("/tmp/target.png").resolve())) == 2
+    assert paths.count(str(Path("/tmp/negative.png").resolve())) == 1
+    assert metadata["priority_positive_repeat_count"] == 4
+
+
 def test_precision_guard_band_keeps_near_gate_region_stabilized() -> None:
     manifest = {"samples": [
         {"sample_slug": "wa-positive", "split": "train", "region": "wallonia", "context": "rural-town"},