evaluate fresh Flemish remediation training

tests/test_experimental_yolo_guards.py

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+from pathlib import Path
+
+import pytest
+
+from scripts.export_experimental_yolo_train_shard import (
+    is_canonical_train_window,
+    validate_experimental_request,
+)
+from scripts.train_experimental_yolo_candidate import validate_paths
+
+
+def test_export_refuses_non_experimental_output(tmp_path: Path) -> None:
+    manifest = tmp_path / "manifest.json"
+    manifest.write_text("{}", encoding="utf-8")
+    with pytest.raises(ValueError, match="output must remain"):
+        validate_experimental_request(manifest, tmp_path / "output")
+
+
+def test_training_refuses_paths_outside_experimental_root(tmp_path: Path) -> None:
+    with pytest.raises(ValueError, match="must remain"):
+        validate_paths(tmp_path / "dataset", tmp_path / "output")
+
+
+def test_train_shard_rejects_near_duplicate_edge_cover_windows() -> None:
+    canonical = {"row_off": 512, "col_off": 0, "height": 512, "width": 512}
+    edge_cover = {"row_off": 513, "col_off": 0, "height": 512, "width": 512}
+    assert is_canonical_train_window(canonical, 512)
+    assert not is_canonical_train_window(edge_cover, 512)