fix(streaming): stop replaying committed recenter retirements

Root cause: pending-only live projection buckets were misclassified as landblock presentation owners during origin recentering. That manufactured a second full cleanup receipt for a generation whose first receipt was still advancing; the duplicate guard threw and the broad retry path replayed the already-committed detach 243 times.

Keep pending live projections through the spatial identity map without issuing another receipt, and fail fast when a receipt-ledger invariant occurs after detachment. Evidence: docs/research/2026-08-02-collision-throughput-handoff/p1-retirement-receipt-loop.md. Release suite, lifecycle gate, and nine-stop soak pass.

src/AcDream.App/Streaming/GpuWorldState.cs

@@ -1349,8 +1349,14 @@ public sealed class GpuWorldState : ILiveEntitySpatialQuery
             if (id != 0u)
                 AddId(id);
         }
-        foreach (uint id in _pendingByLandblock.Keys)
-            AddId(id);
+        // A pending-only bucket owns live spatial projections, not a loaded
+        // landblock presentation generation. Those projections are retained
+        // below through _projectionLocations, but there is no terrain,
+        // collision, static-script, or renderer owner to retire. In
+        // particular, DetachLandblock deliberately parks surviving live
+        // projections here while its existing exact retirement receipt is
+        // still advancing. Emitting another full receipt during a recenter
+        // would give the same retired generation two cleanup owners.
         foreach (uint id in _pendingRenderIdsByLandblock.Keys)
             AddId(id);
         foreach (uint id in _pendingNearTierLandblocks)

src/AcDream.App/Streaming/LandblockPresentationPipeline.cs

@@ -322,8 +322,25 @@ public sealed class LandblockPresentationPipeline
     {
         GpuWorldRecenterRetirement detached =
             _state.DetachAllForOriginRecenter();
-        Exception? adoptionFailure =
-            _retirements.AdoptDetachedFull(detached.Landblocks);
+        Exception? adoptionFailure;
+        try
+        {
+            adoptionFailure =
+                _retirements.AdoptDetachedFull(detached.Landblocks);
+        }
+        catch (Exception error)
+        {
+            // Spatial detachment is already committed. A receipt-ledger
+            // invariant failure cannot be retried by detaching the same
+            // generation again; doing so was the 243-frame origin-recenter
+            // exception loop. Surface the committed edge so the controller
+            // fails fast instead of pretending the operation is resumable.
+            throw new StreamingMutationException(
+                "Origin-recenter retirement receipt adoption failed after " +
+                "the spatial generation detached.",
+                mutationCommitted: true,
+                error);
+        }
         Exception? failure = (detached.ObserverFailure, adoptionFailure) switch
         {
             (null, null) => null,

src/AcDream.App/Streaming/StreamingController.cs

@@ -1433,6 +1433,14 @@ public sealed class StreamingController
             transaction.PreparationCommitted = true;
             return true;
         }
+        catch (StreamingMutationException error) when (error.MutationCommitted)
+        {
+            // The old spatial generation is already gone. Re-entering this
+            // transaction would replay the detach against a new state, so a
+            // committed receipt/adoption invariant is terminal and must be
+            // surfaced to the caller.
+            throw;
+        }
         catch (Exception error)
         {
             Console.WriteLine(