fix(ui): gate — no void frames around the login wormhole; vitals icons centered

The login tunnel now covers from the first world-facing frame (the
sky-void backdrop can never present pre-tunnel) and holds through an
atomic tunnel-to-world swap at reveal completion — the void is
structurally unreachable on both edges, pinned by frame-sequence tests
across WorldSceneRenderer/WorldRevealCoordinator/LocalPlayerTeleport-
Controller/RuntimeWorldTransitState. Vitals detail icons draw at their
authored centered offsets in both stacked and side-by-side layouts.
Implemented and live-probed by the fix agent; finalized by the lead
after the agent parked post-verification (gates re-run green:
App 5512/3, Runtime 1747/0).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/AcDream.Runtime.Tests/World/RuntimeWorldTransitStateTests.cs

@@ -192,6 +192,69 @@ public sealed class RuntimeWorldTransitStateTests
         Assert.Equal(0, state.Snapshot.InvariantFailureCount);
     }
 
+    [Fact]
+    public void LoginMaterialization_ReleasesSimulationBeforeViewportAndCompletion()
+    {
+        // The login mirror of the portal materialization edge: retail's
+        // SmartBox::UseTime @ 0x00455410 blocking_for_cells branch resumes
+        // CObjectMaint/CPhysics when destination cells stop blocking — while
+        // the tunnel is still in front — identically for the initial login.
+        // Without this edge the login world stayed unavailable until
+        // Complete, so the WorldFadeIn second presented an empty world frame
+        // (the 2026-08-17 gate's exit-edge void).
+        var state = new RuntimeWorldTransitState();
+        long generation = state.BeginLoginReveal(OutdoorCell);
+        Assert.True(state.AcknowledgeDestinationReadiness(
+            Ready(generation, OutdoorCell)));
+
+        Assert.True(state.AcknowledgeLoginMaterialized(generation));
+
+        Assert.True(state.IsWorldSimulationAvailable);
+        Assert.True(state.Snapshot.Materialized);
+        Assert.False(state.Snapshot.WorldViewportObserved);
+        Assert.False(state.Snapshot.Completed);
+        // The portal materialization counter counts Kind == Portal only.
+        Assert.Equal(0, state.Snapshot.PortalMaterializationCount);
+        Assert.False(state.AcknowledgeLoginMaterialized(generation));
+
+        Assert.True(state.AcknowledgeWorldViewportVisible(generation));
+        Assert.True(state.Complete(generation));
+        Assert.True(state.Snapshot.Completed);
+        Assert.Equal(0, state.Snapshot.InvariantFailureCount);
+    }
+
+    [Fact]
+    public void LoginMaterializationBeforeReadiness_IsRejectedWithoutOpeningWorld()
+    {
+        var state = new RuntimeWorldTransitState();
+        long generation = state.BeginLoginReveal(OutdoorCell);
+
+        Assert.False(state.AcknowledgeLoginMaterialized(generation));
+
+        Assert.False(state.IsWorldSimulationAvailable);
+        Assert.False(state.Snapshot.Materialized);
+        Assert.Equal(1, state.Snapshot.InvariantFailureCount);
+    }
+
+    [Fact]
+    public void LoginMaterialization_RejectsPortalRevealsAndStaleGenerations()
+    {
+        var state = new RuntimeWorldTransitState();
+        long generation = BeginPortal(state, OutdoorCell);
+        Assert.True(state.AcknowledgeDestinationReadiness(
+            Ready(generation, OutdoorCell)));
+
+        // Wrong kind: a portal reveal must ride the sequence-correlated
+        // portal acknowledgement, never the login edge.
+        Assert.False(state.AcknowledgeLoginMaterialized(generation));
+        Assert.False(state.IsWorldSimulationAvailable);
+
+        // Stale/zero generations are rejected without invariant failures.
+        Assert.False(state.AcknowledgeLoginMaterialized(0));
+        Assert.False(state.AcknowledgeLoginMaterialized(generation + 1));
+        Assert.Equal(0, state.Snapshot.InvariantFailureCount);
+    }
+
     [Fact]
     public void EarlyViewport_IsRejectedWithoutFabricatingVisibility()
     {