refactor(streaming): centralize world reveal lifetime

Compose destination readiness and lifecycle telemetry behind one App-layer coordinator so login and portal begin, preparation, materialization, visibility, completion, and cancellation cannot drift apart in GameWindow wiring.

src/AcDream.App/Streaming/WorldRevealCoordinator.cs

@@ -0,0 +1,69 @@
+namespace AcDream.App.Streaming;
+
+/// <summary>
+/// Owns one login/portal reveal lifetime across readiness and lifecycle
+/// diagnostics. This keeps the destination barrier and its observations on a
+/// single seam so callers cannot begin, prepare, or evaluate one owner while
+/// forgetting the other.
+/// </summary>
+internal sealed class WorldRevealCoordinator
+{
+    private readonly WorldRevealReadinessBarrier _readiness;
+    private readonly WorldRevealLifecycleTelemetry _lifecycle;
+
+    public WorldRevealCoordinator(
+        Func<uint, int, bool> isRenderNeighborhoodReady,
+        Func<uint, bool> isSpawnCellReady,
+        Func<uint, int, bool> isTerrainNeighborhoodReady,
+        Func<bool> areCompositeTexturesReady,
+        Action<uint, int> prepareCompositeTextures,
+        Action invalidateCompositeTextures,
+        Func<uint, bool> isSpawnClaimUnhydratable,
+        Action<string>? log = null)
+    {
+        _readiness = new WorldRevealReadinessBarrier(
+            isRenderNeighborhoodReady,
+            isSpawnCellReady,
+            isTerrainNeighborhoodReady,
+            areCompositeTexturesReady,
+            prepareCompositeTextures,
+            invalidateCompositeTextures,
+            isSpawnClaimUnhydratable);
+        _lifecycle = new WorldRevealLifecycleTelemetry(log);
+    }
+
+    public WorldRevealLifecycleSnapshot Snapshot => _lifecycle.Snapshot;
+    public int PortalMaterializationCount => _lifecycle.PortalMaterializationCount;
+
+    public long Begin(WorldRevealKind kind)
+    {
+        _readiness.Begin();
+        return _lifecycle.Begin(kind);
+    }
+
+    /// <summary>
+    /// Advances render-thread preparation and publishes the resulting
+    /// canonical readiness snapshot to lifecycle diagnostics.
+    /// </summary>
+    public WorldRevealReadinessSnapshot PrepareAndEvaluate(uint destinationCell)
+    {
+        _readiness.Prepare(destinationCell);
+        return Evaluate(destinationCell);
+    }
+
+    public WorldRevealReadinessSnapshot Evaluate(uint destinationCell)
+    {
+        WorldRevealReadinessSnapshot snapshot = _readiness.Evaluate(destinationCell);
+        _lifecycle.ObserveReadiness(snapshot);
+        return snapshot;
+    }
+
+    public void ObserveMaterialized() => _lifecycle.ObserveMaterialized();
+
+    public void ObserveWorldViewportVisible() =>
+        _lifecycle.ObserveWorldViewportVisible();
+
+    public void Complete() => _lifecycle.Complete();
+
+    public void Cancel() => _lifecycle.Cancel();
+}