Stabilize mapped SoA layout across row changes

Aetheria.State.Daemon.Smoke/Program.cs

@@ -4380,13 +4380,19 @@ internal sealed class AetheriaDaemonYmirSmokeChecks
 
         using var soaCache = new CultCache();
         using var soaPublisher = new AetheriaRuntimeDaemonSoaFramePublisher(soaCache, producerEpoch: 1);
-        var soaFrame = soaPublisher.BuildCurrentZoneEntities(
+        using var soaFrame = soaPublisher.BuildCurrentZoneEntities(
             new AetheriaRuntimeDaemonFrameDocument { FrameId = 2, Run = run });
         var mineIdentity = soaFrame.View.Identities.Single(identity =>
             identity.EntityId == $"{run.RunId}:zone:0:physical-payload:{mine.PayloadId}");
         Require(mineIdentity.Kind == "physical-payload" && mineIdentity.AssetRef == "prefab.entity.mine" &&
                 !mineIdentity.Selectable && mineIdentity.EntityIndex < -1,
             "the playable SoA must carry the retained Ymir mine through its provider-owned asset identity");
+        var activeBodyExtent = soaFrame.View.Buffers[0].ByteLength;
+        var activeColumns = soaFrame.View.Columns.ToDictionary(
+            column => column.ColumnId,
+            column => (column.ByteOffset, column.ElementStride),
+            StringComparer.Ordinal);
+        soaFrame.Dispose();
 
         var objects = AetheriaRuntimeGameDocuments.ObjectsViewport(
             new AetheriaRuntimeDaemonFrameDocument { FrameId = 2, Run = run },
@@ -4411,6 +4417,18 @@ internal sealed class AetheriaDaemonYmirSmokeChecks
             "Aetheria must apply authored blast damage after the delay");
         Require(run.GameEvents.Count(value => value.Kind == "deployable.detonated") == 1,
             "daemon must publish one authoritative detonation event");
+
+        using var settledSoaFrame = soaPublisher.BuildCurrentZoneEntities(
+            new AetheriaRuntimeDaemonFrameDocument { FrameId = 3, Run = run });
+        Require(activeBodyExtent == settledSoaFrame.View.Buffers[0].ByteLength,
+            "one SoA layout version must retain a fixed body extent when active entity count changes");
+        foreach (var column in settledSoaFrame.View.Columns)
+        {
+            var activeColumn = activeColumns[column.ColumnId];
+            Require(activeColumn.ByteOffset == column.ByteOffset &&
+                    activeColumn.ElementStride == column.ElementStride,
+                $"SoA column '{column.ColumnId}' must retain its byte interpretation across active row changes");
+        }
     }
 
     private static void DeployableRangeExpiryDetonatesAfterYmirMovement()

Packages/org.gamecult.aetheria.state/Runtime/AetheriaRuntimeDaemonSoaFramePublisher.cs

@@ -179,7 +179,10 @@ namespace GameCult.Aetheria.State.Verse
             if (count > Capacity)
                 throw new InvalidOperationException($"Aetheria entity SoA capacity {Capacity} was exceeded by {count} rows.");
             var generation = Math.Max(frame.FrameId, 0);
-            var layout = EntityHotSlabLayout.Create(count);
+            // LayoutVersion owns byte interpretation. Keep offsets and body extent fixed for the
+            // publisher capacity so a mapped frame may advance before reactive row metadata
+            // without causing the same layout version to reinterpret its bytes.
+            var layout = EntityHotSlabLayout.Create(Capacity);
             if (!_localPublisher.TryAcquireWrite(out var write))
                 throw new InvalidOperationException("CultMesh has no unleased frame slot for the Aetheria SoA generation.");
             try

docs/aetheria-current-codebase-model.md

@@ -174,6 +174,15 @@ radius/mass/inverse mass, render scale, visibility, LOD, and render group. This
 is the right direction for a thin Unity client: daemon state appears as a native
 view instead of a serialized object graph.
 
+The publisher's `LayoutVersion` owns byte interpretation. Column offsets,
+strides, and the mapped body extent are therefore derived from the fixed SoA
+capacity, not the current active row count. Active element counts, identities,
+and render groups remain reactive metadata. A mapped generation may advance
+before that metadata notification without changing what any existing offset
+means: removed rows are cleared, and newly added rows remain outside the old
+element count until the matching metadata arrives. Neither EveUnity nor the
+transport may repair or reinterpret a mismatched generation.
+
 Current limitation: physics body radius, mass, inverse mass, render scale, LOD,
 and render group are still generic defaults in the publisher. Entity identity
 and position are real; body semantics are not yet rich enough to replace all