Serialize multi-sample manifest path

backend/tests/test_sprint178_mol_operational_pack.py

@@ -98,6 +98,7 @@ def test_real_data_matrix_propagates_project_region_and_persisted_area() -> None
     assert 'project_region="Mol, Kempen"' in multi
     assert 'REAL_PROJECT_REGION="${project_region}"' in multi
     assert 'manifest_path = Path(sys.argv[3])' in multi
+    assert '"operator_sample_manifest_path": str(manifest_path)' in multi
 
 
 def test_mol_operational_runner_uses_real_positive_qa_and_background_paths() -> None:

scripts/run_multi_sample_detection_quality_matrix.sh

@@ -217,7 +217,7 @@ best_by_sample = {
 summary = {
     "generated_at": datetime.now(timezone.utc).isoformat(),
     "base_url": base_url,
-    "operator_sample_manifest_path": manifest_path,
+    "operator_sample_manifest_path": str(manifest_path),
     "sample_count": len(sample_summaries),
     "run_count": len(flat_items),
     "best_overall_by_score": best("quality_score"),