feat(lab): bind M4.8 regression to reference graph

tests/test_m48_object_quality_api.py

@@ -92,7 +92,10 @@ def _fixture(
             "identity_sha256": "a" * 64,
             "created_at_utc": "2026-08-23T20:00:00Z",
             "identity": {
-                "source": {"source_session_id": "recorded-session"},
+                "source": {
+                    "source_session_id": "recorded-session",
+                    "m47_lab_result_id": f"m47-reference-graph-lab-{'c' * 64}",
+                },
                 "freeze": {"prediction_rows_sha256": "8" * 64},
             },
         },
@@ -1101,6 +1104,9 @@ def test_m48_small_static_regression_is_separate_read_only_assisted_evidence(
     assert summary.json()["experiment_id"] == (
         "m48-small-static-passage-regression/v1"
     )
+    assert summary.json()["reference_graph_lab_result_id"] == (
+        f"m47-reference-graph-lab-{'c' * 64}"
+    )
     assert summary.json()["independent_truth"] is False
     assert summary.json()["metrics"]["worker_missed_anchor_count"] == 1
 
@@ -1110,6 +1116,7 @@ def test_m48_small_static_regression_is_separate_read_only_assisted_evidence(
     assert catalog.status_code == 200
     assert catalog.json()["case_count"] == 1
     assert catalog.json()["cases"][0]["outcome"] == "missed-assisted-anchor"
+    assert catalog.json()["cases"][0]["anchor_extent_xyxy"] == [0.2, 0.2, 0.3, 0.4]
 
     case = client.get(
         f"/api/v1/laboratory/m48/regressions/small-static/{result_id}/cases/{anchor_id}"