diff --git a/Aetheria.State.Daemon/AetheriaYmirWorldPhysics.cs b/Aetheria.State.Daemon/AetheriaYmirWorldPhysics.cs
index 42d8c73f3..6d5731fef 100644
--- a/Aetheria.State.Daemon/AetheriaYmirWorldPhysics.cs
+++ b/Aetheria.State.Daemon/AetheriaYmirWorldPhysics.cs
@@ -5,6 +5,7 @@ namespace Aetheria.State.Daemon;
 
 public sealed class AetheriaYmirWorldPhysics : IAetheriaRuntimeWorldPhysics, IDisposable
 {
+    private const long PersistenceRolloverJournalEntries = 64;
     private const string EntityPrefix = "aetheria.daemon.entity.";
     private const string PickupPrefix = "aetheria.daemon.pickup.";
     private const string PhysicalPayloadPrefix = "aetheria.physical-payload.";
@@ -76,6 +77,10 @@ public sealed class AetheriaYmirWorldPhysics : IAetheriaRuntimeWorldPhysics, IDi
             throw new InvalidOperationException(
                 $"Cannot persist Ymir payload world for run '{runId}' zone {zoneIndex} at frame {frameId}.");
 
+        TryRollPersistenceGeneration(state, payload: false);
+        if (state.PayloadSession != null)
+            TryRollPersistenceGeneration(state, payload: true);
+
         return new AetheriaYmirZonePersistenceCapture(
             runId,
             zoneIndex,
@@ -586,6 +591,20 @@ public sealed class AetheriaYmirWorldPhysics : IAetheriaRuntimeWorldPhysics, IDi
             ? value
             : -1;
 
+    private static void TryRollPersistenceGeneration(SessionState state, bool payload)
+    {
+        var current = payload ? state.PayloadSession : state.WorldSession;
+        if (current == null || current.PersistenceJournalEntryCount < PersistenceRolloverJournalEntries ||
+            !current.TryCreateCompactedPersistenceBaseline(out var replacement))
+            return;
+
+        if (payload)
+            state.PayloadSession = replacement!;
+        else
+            state.WorldSession = replacement!;
+        current.Dispose();
+    }
+
     private static (double X, double Y) Normalize(
         double x,
         double y,
@@ -598,7 +617,7 @@ public sealed class AetheriaYmirWorldPhysics : IAetheriaRuntimeWorldPhysics, IDi
 
     private sealed class SessionState(YmirSession worldSession)
     {
-        public YmirSession WorldSession { get; } = worldSession;
+        public YmirSession WorldSession { get; set; } = worldSession;
         public YmirSession? PayloadSession { get; set; }
         public long LastFrameId { get; set; } = -1;
         public int LastSimulationStepIndex { get; set; } = -1;
diff --git a/docs/aetheria-current-codebase-model.md b/docs/aetheria-current-codebase-model.md
index 212a87271..2c2f55b04 100644
--- a/docs/aetheria-current-codebase-model.md
+++ b/docs/aetheria-current-codebase-model.md
@@ -99,13 +99,21 @@ under Unity `Assets/Scripts/ServerShared/Behaviors`.
   an exclusive lock while selectively hydrating another record. Startup phase
   traces report state open, catalog, Ymir restore, and client publication costs.
 
-The remaining restart bottleneck is inside Ymir reconstruction, not CultCache
-I/O: the current resume format validates state by replaying its entire
-generation journal. Indexed hydration reduced journal page loading to tens of
-milliseconds, but replay remains proportional to session lifetime. Ymir needs
-a bounded baseline checkpoint plus journal tail before daemon restart cost is
-independent of uptime; increasing timeouts or hiding the phase is not an
-acceptable substitute.
+Ymir reconstruction remains full replay within a session generation, but it is
+now bounded by an explicit quiescent generation rollover. When a private world
+or payload journal reaches 64 commands, `AetheriaYmirWorldPhysics` asks Ymir to
+create a replacement baseline before private capture. Ymir refuses while a
+contact episode is active or a mutation has not reached Step; Aetheria keeps
+the old replay path in that case and never infers contact safety itself. A
+successful replacement is captured before the matching public frame commits,
+and the prior session is disposed only after the in-memory owner swaps.
+
+The migration witness paid 733 ms once to restore the historical generation;
+the following restart restored the compact generation in 74 ms, including
+private-cache open, selected journal hydration, and native world creation.
+Historical journal pages remain durable and cold. Retention/garbage collection
+of obsolete generations is separate from restart authority and must not be
+smuggled into filtered hydration.
 
 ## Materialized Import And Publication Ownership