fix(G.3): collapse streaming to the single dungeon landblock indoors (#133 FPS)

Dungeon FPS sat at ~30 (frame ~33ms) because the 25x25 streaming window around
the dungeon landblock pulled in ~129 NEIGHBORING landblocks + their thousands of
torch/particle emitters, all drawn though never visible. In AC all dungeons are
packed adjacent in the unused "ocean" map grid, so those neighbors are unrelated
dungeons. The FPS timeline proved it: 247 fps at login (lb 0/0, ~10K entities) →
17 → 30 as landblocks streamed in (lb 0→129) — the cost tracked LANDBLOCK count,
not entities.

Retail-faithful: ACE LandblockManager.GetAdjacentIDs returns ZERO adjacents for a
dungeon (`if (landblock.IsDungeon) return adjacents;`, Landblock.cs:577-582) —
every dungeon is a self-contained landblock you never see out of.

Fix: when the player stands in a sealed indoor cell (CurrCell.IsEnv &&
!SeenOutside — the same predicate that kills the sun/sky), collapse streaming to
just the player's dungeon landblock and unload the neighbors. Building interiors
(cottage/inn) have SeenOutside cells, so they are NOT gated and keep their
surrounding terrain (the frozen building/cellar demo is unaffected). Unloading the
neighbors also tears down their lights (removeTerrain → UnregisterOwner), shrinking
LightManager._all from ~2227 toward retail's ≤40 — which directly helps the A7
lighting bake landing next.

Mechanics (StreamingController):
- Edge IN: ClearPendingLoads() cancels the in-flight 25x25 window (new streamer
  ClearLoads control job — worker drops queued Loads, keeps Unloads), unload every
  resident neighbor, pin a radius-0 StreamingRegion, (re)load the dungeon block if
  needed.
- Stay collapsed: sweep any straggler that finished loading after the edge (a Load
  the worker had already dequeued before ClearLoads).
- Edge OUT (portal/teleport to outdoors): rebuild the full two-tier window at the
  new center, unload anything stale.

AP-36 added to the divergence register (the gate uses the cheap SeenOutside cell
predicate as an approximation of ACE's full landblock IsDungeon classification).
GameWindow also carries a TEMP ACDREAM_LOG_FPS=1 headless FPS line (strip after
the A7 FPS+lighting verification).

Build green; 58 streaming tests green (6 new dungeon-gate tests).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/AcDream.App/Rendering/GameWindow.cs

@@ -1914,6 +1914,7 @@ public sealed class GameWindow : IDisposable
             state:            _worldState,
             nearRadius:       _nearRadius,
             farRadius:        _farRadius,
+            clearPendingLoads: _streamer.ClearPendingLoads,
             removeTerrain:    id =>
             {
                 // Phase G.2: release any LightSources attached to entities
@@ -6882,7 +6883,20 @@ public sealed class GameWindow : IDisposable
                 observerCy = _liveCenterY + (int)System.Math.Floor(camPos.Y / 192f);
             }
 
-            _streamingController.Tick(observerCx, observerCy);
+            // Dungeon gate (#133 FPS): when the player stands in a SEALED EnvCell
+            // (indoor cell that doesn't see outside — the same predicate that kills
+            // the sun/sky, playerInsideCell below), collapse streaming to the single
+            // dungeon landblock. AC dungeons have no adjacent landblocks; the 25×25
+            // window otherwise pulls in ~129 unrelated ocean-grid dungeons. Building
+            // interiors (cottage/inn) have SeenOutside cells, so they are NOT gated
+            // and keep their surrounding terrain.
+            // Mirrors the playerInsideCell computation below (CurrCell → registry
+            // LoadedCell.SeenOutside): true only for a sealed indoor cell.
+            bool insideDungeon =
+                _physicsEngine.DataCache?.CellGraph.CurrCell is AcDream.Core.World.Cells.EnvCell pcEnv
+                && _cellVisibility.TryGetCell(pcEnv.Id, out var pcReg)
+                && pcReg is { SeenOutside: false };
+            _streamingController.Tick(observerCx, observerCy, insideDungeon);
 
             // Re-inject persistent entities rescued from unloaded landblocks
             // into the current center landblock (the one the observer is in).
@@ -8418,6 +8432,11 @@ public sealed class GameWindow : IDisposable
             }
             _lastFps = fps;
             _lastFrameMs = avgFrameTime;
+            // TEMP (A7 FPS measurement, strip after): headless FPS/frame-time so the
+            // launch log can be correlated against the [WB-DIAG] draw stats.
+            if (Environment.GetEnvironmentVariable("ACDREAM_LOG_FPS") == "1")
+                Console.WriteLine(
+                    $"[FPS] {fps:F1} fps | {avgFrameTime:F2} ms | lb {visibleLandblocks}/{totalLandblocks} | ent {entityCount} anim {animatedCount}");
             _perfAccum = 0;
             _perfFrameCount = 0;
         }
@@ -10589,6 +10608,7 @@ public sealed class GameWindow : IDisposable
                 state:            _worldState,
                 nearRadius:       _nearRadius,
                 farRadius:        _farRadius,
+                clearPendingLoads: _streamer.ClearPendingLoads,
                 removeTerrain:    id =>
                 {
                     if (_lightingSink is not null &&

src/AcDream.App/Streaming/LandblockStreamJob.cs

@@ -14,6 +14,16 @@ public abstract record LandblockStreamJob(uint LandblockId)
 {
     public sealed record Load(uint LandblockId, LandblockStreamJobKind Kind) : LandblockStreamJob(LandblockId);
     public sealed record Unload(uint LandblockId) : LandblockStreamJob(LandblockId);
+
+    /// <summary>
+    /// Control job: drop every queued (not-yet-started) Load from the worker's
+    /// priority queues, keeping Unloads. Posted by
+    /// <see cref="LandblockStreamer.ClearPendingLoads"/> when the player enters a
+    /// dungeon and the in-flight outdoor/neighbor window load must be cancelled
+    /// (#133 FPS — dungeons have no adjacent landblocks). LandblockId is 0 by
+    /// convention; readers pattern-match on the type.
+    /// </summary>
+    public sealed record ClearLoads() : LandblockStreamJob(0);
 }
 
 /// <summary>

src/AcDream.App/Streaming/LandblockStreamer.cs

@@ -141,6 +141,22 @@ public sealed class LandblockStreamer : IDisposable
         _inbox.Writer.TryWrite(new LandblockStreamJob.Unload(landblockId));
     }
 
+    /// <summary>
+    /// Cancel every queued-but-not-started Load. Posts a
+    /// <see cref="LandblockStreamJob.ClearLoads"/> control job which the worker
+    /// honours at read time, dropping all pending Loads from both priority
+    /// queues (Unloads survive). Used on the dungeon-entry edge to abort the
+    /// in-flight 25×25 neighbor window so the ~129 ocean-grid dungeons never
+    /// finish loading (#133 FPS). Loads the worker has ALREADY dequeued still
+    /// complete; the StreamingController's collapsed-sweep unloads those few.
+    /// </summary>
+    public void ClearPendingLoads()
+    {
+        if (System.Threading.Volatile.Read(ref _disposed) != 0)
+            throw new ObjectDisposedException(nameof(LandblockStreamer));
+        _inbox.Writer.TryWrite(new LandblockStreamJob.ClearLoads());
+    }
+
     /// <summary>
     /// Drain up to <paramref name="maxBatchSize"/> completed results.
     /// Non-blocking. Call from the render thread once per OnUpdate.
@@ -180,7 +196,18 @@ public sealed class LandblockStreamer : IDisposable
                 }
 
                 while (_inbox.Reader.TryRead(out var job))
+                {
+                    if (job is LandblockStreamJob.ClearLoads)
+                    {
+                        // Dungeon-entry cancellation: drop every queued Load,
+                        // keep Unloads. Handled at read time so it supersedes
+                        // Loads sitting in the priority queues ahead of it.
+                        DropLoadJobs(highPriority);
+                        DropLoadJobs(lowPriority);
+                        continue;
+                    }
                     EnqueuePrioritized(job, highPriority, lowPriority);
+                }
 
                 if (highPriority.Count == 0 && lowPriority.Count == 0)
                     continue;
@@ -233,6 +260,22 @@ public sealed class LandblockStreamer : IDisposable
         lowPriority.Enqueue(job);
     }
 
+    /// <summary>
+    /// Drop every <see cref="LandblockStreamJob.Load"/> from a priority queue,
+    /// preserving Unloads (and any other control jobs). Rotates the queue once
+    /// in place. Used by the <see cref="LandblockStreamJob.ClearLoads"/> path.
+    /// </summary>
+    private static void DropLoadJobs(Queue<LandblockStreamJob> queue)
+    {
+        int count = queue.Count;
+        for (int i = 0; i < count; i++)
+        {
+            var job = queue.Dequeue();
+            if (job is not LandblockStreamJob.Load)
+                queue.Enqueue(job);
+        }
+    }
+
     private static void RemoveLowPriorityJobsForLandblock(
         Queue<LandblockStreamJob> queue,
         uint landblockId,

src/AcDream.App/Streaming/StreamingController.cs

@@ -22,9 +22,16 @@ public sealed class StreamingController
     private readonly Func<int, IReadOnlyList<LandblockStreamResult>> _drainCompletions;
     private readonly Action<LoadedLandblock, LandblockMeshData> _applyTerrain;
     private readonly Action<uint>? _removeTerrain;
+    private readonly Action? _clearPendingLoads;
     private readonly GpuWorldState _state;
     private StreamingRegion? _region;
 
+    // True while streaming is collapsed to the single dungeon landblock the
+    // player stands in (the dungeon gate, #133 FPS). AC dungeons have NO
+    // adjacent landblocks — neighbors are unrelated ocean-grid dungeons that
+    // are never visible, so we stop loading the 25×25 window entirely.
+    private bool _collapsed;
+
     /// <summary>
     /// Near-tier radius (LBs from observer that load full detail: terrain +
     /// scenery + entities). Set at construction; readable thereafter.
@@ -71,13 +78,15 @@ public sealed class StreamingController
         GpuWorldState state,
         int nearRadius,
         int farRadius,
-        Action<uint>? removeTerrain = null)
+        Action<uint>? removeTerrain = null,
+        Action? clearPendingLoads = null)
     {
         _enqueueLoad = enqueueLoad;
         _enqueueUnload = enqueueUnload;
         _drainCompletions = drainCompletions;
         _applyTerrain = applyTerrain;
         _removeTerrain = removeTerrain;
+        _clearPendingLoads = clearPendingLoads;
         _state = state;
         NearRadius = nearRadius;
         FarRadius  = farRadius;
@@ -97,7 +106,32 @@ public sealed class StreamingController
     ///   <item><see cref="TwoTierDiff.ToUnload"/> → enqueue full unload</item>
     /// </list>
     /// </summary>
-    public void Tick(int observerCx, int observerCy)
+    public void Tick(int observerCx, int observerCy, bool insideDungeon = false)
+    {
+        uint centerId = StreamingRegion.EncodeLandblockId(observerCx, observerCy);
+
+        if (insideDungeon)
+        {
+            if (!_collapsed)
+                EnterDungeonCollapse(observerCx, observerCy, centerId);
+            else
+                SweepCollapsed(centerId);
+        }
+        else
+        {
+            if (_collapsed)
+                ExitDungeonExpand(observerCx, observerCy);
+            else
+                NormalTick(observerCx, observerCy);
+        }
+
+        DrainAndApply();
+    }
+
+    /// <summary>
+    /// Outdoor / building-interior streaming — the original two-tier model.
+    /// </summary>
+    private void NormalTick(int observerCx, int observerCy)
     {
         if (_region is null)
         {
@@ -116,9 +150,77 @@ public sealed class StreamingController
             foreach (var id in diff.ToDemote)   _state.RemoveEntitiesFromLandblock(id);
             foreach (var id in diff.ToUnload)   _enqueueUnload(id);
         }
+    }
 
-        // Drain up to N completions per frame so a big diff doesn't spike
-        // GPU upload time. Remaining completions wait for the next frame.
+    /// <summary>
+    /// Dungeon-entry edge: cancel the in-flight window load, unload every
+    /// resident neighbor, and pin streaming to the player's single dungeon
+    /// landblock. Retail-faithful — AC dungeons have no adjacent landblocks
+    /// (ACE <c>LandblockManager.GetAdjacentIDs</c> returns empty for a dungeon);
+    /// the 25×25 window was pulling in ~129 unrelated ocean-grid dungeons and
+    /// their thousands of emitters (#133 FPS). Unloading them also tears down
+    /// their lights, shrinking the static-light set toward retail's ≤40.
+    /// </summary>
+    private void EnterDungeonCollapse(int cx, int cy, uint centerId)
+    {
+        _collapsed = true;
+        _clearPendingLoads?.Invoke();
+
+        foreach (var id in _state.LoadedLandblockIds)
+            if (id != centerId) _enqueueUnload(id);
+
+        // Pin a radius-0 region so RecenterTo never re-expands while inside,
+        // and so the post-exit rebuild starts from a clean, consistent state.
+        _region = new StreamingRegion(cx, cy, 0, 0);
+        _region.MarkResidentFromBootstrap();
+
+        // The dungeon landblock itself must be (or become) loaded. If a prior
+        // ClearPendingLoads cancelled its queued load, re-enqueue it.
+        if (!_state.IsLoaded(centerId))
+            _enqueueLoad(centerId, LandblockStreamJobKind.LoadNear);
+    }
+
+    /// <summary>
+    /// While collapsed, unload any landblock that finished loading after the
+    /// collapse edge — a Load the worker had already dequeued before the
+    /// <see cref="LandblockStreamer.ClearPendingLoads"/> control job took
+    /// effect. At steady state only the dungeon landblock is resident, so this
+    /// is a no-op.
+    /// </summary>
+    private void SweepCollapsed(uint centerId)
+    {
+        foreach (var id in _state.LoadedLandblockIds)
+            if (id != centerId) _enqueueUnload(id);
+    }
+
+    /// <summary>
+    /// Dungeon-exit edge (portal to outdoors / teleport): rebuild the full
+    /// two-tier window at the new center and unload anything resident from the
+    /// collapsed state that falls outside it.
+    /// </summary>
+    private void ExitDungeonExpand(int observerCx, int observerCy)
+    {
+        _collapsed = false;
+        var rebuilt = new StreamingRegion(observerCx, observerCy, NearRadius, FarRadius);
+
+        foreach (var id in _state.LoadedLandblockIds)
+            if (!rebuilt.Resident.Contains(id)) _enqueueUnload(id);
+
+        var boot = rebuilt.ComputeFirstTickDiff();
+        foreach (var id in boot.ToLoadNear)
+            if (!_state.IsLoaded(id)) _enqueueLoad(id, LandblockStreamJobKind.LoadNear);
+        foreach (var id in boot.ToLoadFar)
+            if (!_state.IsLoaded(id)) _enqueueLoad(id, LandblockStreamJobKind.LoadFar);
+        rebuilt.MarkResidentFromBootstrap();
+        _region = rebuilt;
+    }
+
+    /// <summary>
+    /// Drain up to N completions per frame so a big diff doesn't spike GPU
+    /// upload time. Remaining completions wait for the next frame.
+    /// </summary>
+    private void DrainAndApply()
+    {
         var drained = _drainCompletions(MaxCompletionsPerFrame);
         foreach (var result in drained)
         {