diff --git a/experiments/summarize_density_order.py b/experiments/summarize_density_order.py
index 5caab77..7ead56a 100644
--- a/experiments/summarize_density_order.py
+++ b/experiments/summarize_density_order.py
@@ -83,6 +83,20 @@ def density_metrics(case, key):
         "interval_negative_enthalpy_witnesses": witness_h.get("negative_enthalpy_samples")}
 
 
+def check_non_density_layouts(records):
+    reference = {}
+    for (campaign, name), (_, (_, mesh, case)) in records.items():
+        model = case["n"], case["J"]
+        layout = {key: value for key, value in case["block_sizes"].items()
+                  if key not in ("value/density", "residual/barotropic_closure")}
+        current = mesh, layout
+        if model in reference:
+            require(current == reference[model],
+                    f"Non-density layout or mesh changed for (n,J)={model}: {campaign}/{name}")
+        else:
+            reference[model] = current
+
+
 def build_rows(audits):
     """Deduplicate overlapping audited case records, never average repeat runs."""
     records = {}
@@ -97,6 +111,9 @@ def build_rows(audits):
                     require(records[key][1] == payload, "Overlapping audit records disagree: " + str(key))
                 else:
                     records[key] = audit_path, payload
+    # Separate passing audits may never have seen the other density orders.
+    # Enforce their shared non-density discretization before deriving ratios.
+    check_non_density_layouts(records)
     frozen, coupled = [], []
     for (campaign, name), (audit_path, (commit, mesh, case)) in sorted(records.items()):
         common = {"audit_json": audit_path, "campaign": campaign, "case": name, "producer_commit": commit,
@@ -298,6 +315,21 @@ def plot_figure(frozen, coupled, output):
 
 
 class Tests(unittest.TestCase):
+    def test_cross_audit_non_density_layout(self):
+        def case(density_size, gravity_size=23):
+            return {"n": 1.5, "J": 0., "block_sizes": {"value/density": density_size,
+                "residual/barotropic_closure": density_size, "value/gravity_potential": gravity_size,
+                "residual/poisson_balance": gravity_size}}
+        records = {("q2", "sample"): ("audit_q2.json", ("commit2", "mesh", case(27))),
+                   ("q3", "sample"): ("audit_q3.json", ("commit3", "mesh", case(64)))}
+        check_non_density_layouts(records)
+        records[("q3", "sample")] = ("audit_q3.json", ("commit3", "mesh", case(64, 24)))
+        with self.assertRaisesRegex(ValueError, "Non-density layout"):
+            check_non_density_layouts(records)
+        records[("q3", "sample")] = ("audit_q3.json", ("commit3", "changed_mesh", case(64)))
+        with self.assertRaisesRegex(ValueError, "mesh changed"):
+            check_non_density_layouts(records)
+
     def test_uncertain_plot_observation_breaks_trend(self):
         row = {"negative_mass": 1e-30, "negative_classification": "uncertain_witnesses_only"}
         plotted, note = plot_observation(row, "negative_mass", negative=True)
@@ -413,6 +445,7 @@ def main():
     summary = {"schema": "density_order_summary_v1", "generator_sha256": digest(Path(__file__)),
                "input_audit_sha256": {str(path.resolve()): digest(path) for path in args.audits},
                "scope": "Presentation of audited observations only; no campaign files reopened and no independent FEM work.",
+               "cross_order_layout_check": "Mesh identity and all non-density block names/sizes match for every repeated (n,J), including records loaded from separate audits.",
                "notes": ["Frozen controls are fixed-q26 L2 projections; EOS error norms use separate unsliced q30.",
                          "Negative-mass denominator is the absolute measured density mass, not a substituted exact target mass.",
                          "Uncertainty scales are reconstruction indicators, not rigorous bounds; zero observed negativity is not a global positivity certificate.",