diff --git a/Aetheria.State.Daemon.Smoke/Program.cs b/Aetheria.State.Daemon.Smoke/Program.cs
index a1ebb51c7..8e1fb84f2 100644
--- a/Aetheria.State.Daemon.Smoke/Program.cs
+++ b/Aetheria.State.Daemon.Smoke/Program.cs
@@ -2954,15 +2954,39 @@ internal sealed class AetheriaDaemonYmirSmokeChecks
         RequireEqual(1, zone.DroppedPickups.Count, "nearby pickup without a Ymir contact fact must remain in the world");
         RequireEqual(0, CargoQuantity(ship, salvage.ItemKey), "proximity must not mutate cargo");
 
+        var forgedContact = new AetheriaRuntimeWorldBeginContact
+        {
+            FactId = "ymir-fact-forged-identity",
+            EntityAIndex = 0,
+            EntityAId = "another-entity",
+            PickupIndex = 7,
+            NormalX = 1
+        };
+        var rejectedForgedIdentity = false;
+        try
+        {
+            AetheriaRuntimeDaemonTickRunner.Tick(Path.Combine(Path.GetTempPath(), "aetheria-pickup-forged-identity.cc"), run,
+                new AetheriaRuntimeDaemonTickOptions { WorldPhysics = new ScriptedWorldPhysics(forgedContact), FrameId = 2, FixedDeltaSeconds = 0.1, SimulationTimeSeconds = 0.2, Catalog = catalog, BuildPublications = false });
+        }
+        catch (InvalidOperationException)
+        {
+            rejectedForgedIdentity = true;
+        }
+        Require(rejectedForgedIdentity, "a Ymir contact whose stable identity disagrees with the live entity must fail closed");
+        RequireEqual(1, zone.DroppedPickups.Count, "forged contact identity must not remove the pickup");
+        RequireEqual(0, CargoQuantity(ship, salvage.ItemKey), "forged contact identity must not mutate cargo");
+        RequireEqual(0, run.PickupContactReceipts.Count, "forged contact identity must not mint a consumption receipt");
+
         var contact = new AetheriaRuntimeWorldBeginContact
         {
             FactId = "ymir-fact-pickup-7",
             EntityAIndex = 0,
+            EntityAId = ship.EntityId,
             PickupIndex = 7,
             NormalX = 1
         };
         AetheriaRuntimeDaemonTickRunner.Tick(Path.Combine(Path.GetTempPath(), "aetheria-pickup-contact-dedup.cc"), run,
-            new AetheriaRuntimeDaemonTickOptions { WorldPhysics = new ScriptedWorldPhysics(contact, contact), FrameId = 2, FixedDeltaSeconds = 0.1, SimulationTimeSeconds = 0.2, Catalog = catalog, BuildPublications = false });
+            new AetheriaRuntimeDaemonTickOptions { WorldPhysics = new ScriptedWorldPhysics(contact, contact), FrameId = 3, FixedDeltaSeconds = 0.1, SimulationTimeSeconds = 0.3, Catalog = catalog, BuildPublications = false });
         RequireEqual(0, zone.DroppedPickups.Count, "one Ymir contact must consume the pickup");
         RequireEqual(1, CargoQuantity(ship, salvage.ItemKey), "duplicate contact facts must commit cargo exactly once");
         RequireEqual(1, run.GameEvents.Count(value => value.Kind == "pickup.collected" && value.PickupIndex == 7),
@@ -2972,7 +2996,7 @@ internal sealed class AetheriaDaemonYmirSmokeChecks
 
         zone.DroppedPickups = [new AetheriaRuntimeDroppedPickupCommit { PickupIndex = 8, PositionX = 10, Item = new AetheriaRuntimeLoadoutItemCommit { ItemKey = salvage.ItemKey, Quantity = 1 }, LifetimeSeconds = 30 }];
         AetheriaRuntimeDaemonTickRunner.Tick(Path.Combine(Path.GetTempPath(), "aetheria-pickup-expiry-smoke.cc"), run,
-            new AetheriaRuntimeDaemonTickOptions { WorldPhysics = new ScriptedWorldPhysics(), FrameId = 3, FixedDeltaSeconds = 30, SimulationTimeSeconds = 30, BuildPublications = false });
+            new AetheriaRuntimeDaemonTickOptions { WorldPhysics = new ScriptedWorldPhysics(), FrameId = 4, FixedDeltaSeconds = 30, SimulationTimeSeconds = 30, BuildPublications = false });
         RequireEqual(0, zone.DroppedPickups.Count, "pickup must expire after the fossil thirty-second lifetime");
         Require(run.GameEvents.Any(value => value.Kind == "pickup.expired" && value.PickupIndex == 8),
             "daemon lifetime owner must emit authoritative pickup expiry event");
diff --git a/Aetheria.State.Daemon/AetheriaYmirWorldPhysics.cs b/Aetheria.State.Daemon/AetheriaYmirWorldPhysics.cs
index 0dc62840a..4b2798143 100644
--- a/Aetheria.State.Daemon/AetheriaYmirWorldPhysics.cs
+++ b/Aetheria.State.Daemon/AetheriaYmirWorldPhysics.cs
@@ -92,8 +92,9 @@ public sealed class AetheriaYmirWorldPhysics : IAetheriaRuntimeWorldPhysics, IDi
 
         var key = new WorldKey(runId, zone.ZoneIndex);
         if (_sessions.TryGetValue(key, out var existing) &&
-            existing.LastFrameId == frameId && existing.LastSimulationStepIndex == simulationStepIndex)
-            return existing.LastResult!;
+            existing.LastFrameId == frameId && existing.LastSimulationStepIndex == simulationStepIndex &&
+            existing.LastResult != null)
+            return existing.LastResult;
         if (existing != null &&
             (frameId < existing.LastFrameId ||
              (frameId == existing.LastFrameId && simulationStepIndex < existing.LastSimulationStepIndex)))
@@ -137,8 +138,9 @@ public sealed class AetheriaYmirWorldPhysics : IAetheriaRuntimeWorldPhysics, IDi
             throw new InvalidOperationException(
                 $"Payload phase requires the retained world phase for run '{runId}' zone {zone.ZoneIndex} " +
                 $"at frame/step {frameId}/{simulationStepIndex}.");
-        if (state.LastPayloadFrameId == frameId && state.LastPayloadSimulationStepIndex == simulationStepIndex)
-            return state.LastPayloadResult!;
+        if (state.LastPayloadFrameId == frameId && state.LastPayloadSimulationStepIndex == simulationStepIndex &&
+            state.LastPayloadResult != null)
+            return state.LastPayloadResult;
         if (deltaSeconds <= 0)
             throw new ArgumentOutOfRangeException(nameof(deltaSeconds));
 
diff --git a/Packages/org.gamecult.aetheria.state/Runtime/AetheriaRuntimeDaemonSimulation.cs b/Packages/org.gamecult.aetheria.state/Runtime/AetheriaRuntimeDaemonSimulation.cs
index c91169c9a..284483883 100644
--- a/Packages/org.gamecult.aetheria.state/Runtime/AetheriaRuntimeDaemonSimulation.cs
+++ b/Packages/org.gamecult.aetheria.state/Runtime/AetheriaRuntimeDaemonSimulation.cs
@@ -181,9 +181,13 @@ namespace GameCult.Aetheria.State.Verse
                     !string.IsNullOrWhiteSpace(value.FactId)))
             {
                 var entityIndex = contact.EntityAIndex >= 0 ? contact.EntityAIndex : contact.EntityBIndex;
+                var contactEntityId = contact.EntityAIndex >= 0 ? contact.EntityAId : contact.EntityBId;
                 entitiesByIndex.TryGetValue(entityIndex, out var entity);
-                var entityId = entity?.EntityId ??
-                    (contact.EntityAIndex >= 0 ? contact.EntityAId : contact.EntityBId);
+                if (entity != null && !string.Equals(contactEntityId, entity.EntityId, StringComparison.Ordinal))
+                    throw new InvalidOperationException(
+                        $"Ymir fact '{contact.FactId}' entity identity '{contactEntityId}' does not match " +
+                        $"live entity {entityIndex} identity '{entity.EntityId}'.");
+                var entityId = entity?.EntityId ?? contactEntityId;
                 var priorReceipt = AetheriaRuntimePickupContactReceipts.Find(run, contact.FactId);
                 if (priorReceipt != null)
                 {