feat: ChunkStreamer unload path and SpawnReady property

VoxelEngine.Tests/Streaming/ChunkStreamerTests.cs

@@ -170,4 +170,74 @@ public class ChunkStreamerTests
 
         Assert.Equal(registry.Stone.Id, world.GetBlock(5, 6, 7).Id);
     }
+
+    [Fact]
+    public void Tick_PlayerMovesAway_UnloadsOldChunksAndDisposesRenderer()
+    {
+        var cfg = new Configuration
+        {
+            RenderDistanceHorizontal = 0,
+            RenderDistanceVertical = 0,
+            MaxGenerateJobsInFlight = 100,
+            MaxMeshUploadsPerFrame = 100,
+        };
+        var (streamer, world, created) = CreateStreamer(cfg);
+
+        streamer.Tick(new Vector3i(0, 0, 0));   // loads (0,0,0)
+        Assert.Single(created);
+        Assert.NotNull(world.GetChunk(new Vector3i(0, 0, 0)));
+
+        streamer.Tick(new Vector3i(5, 0, 0));   // (0,0,0) now out of range; (5,0,0) loaded
+
+        Assert.True(created[0].Disposed);
+        Assert.Null(world.GetChunk(new Vector3i(0, 0, 0)));
+        Assert.False(streamer.IsReady(new Vector3i(0, 0, 0)));
+    }
+
+    [Fact]
+    public void Tick_UnloadKeepsModificationStoreDiff()
+    {
+        var cfg = new Configuration
+        {
+            RenderDistanceHorizontal = 0,
+            RenderDistanceVertical = 0,
+            MaxGenerateJobsInFlight = 100,
+            MaxMeshUploadsPerFrame = 100,
+        };
+        var registry = new BlockRegistry();
+        var store = new InMemoryChunkModificationStore();
+        var world = new World.World(registry, store);
+        var mesher = new FakeMesher();
+        var executor = new SynchronousJobExecutor();
+        Func<float[], IChunkRenderer> factory = m => new FakeRenderer(m);
+        Func<Vector3i, VoxelChunk> generate = _ => new VoxelChunk();
+        var streamer = new ChunkStreamer(cfg, world, generate, mesher, registry, executor, factory);
+
+        var pos = new Vector3i(0, 0, 0);
+        streamer.Tick(pos);
+        store.RecordEdit(pos, 0, registry.Stone.Id);
+
+        streamer.Tick(new Vector3i(99, 0, 0));  // unloads (0,0,0)
+        Assert.True(store.HasDiff(pos));        // diff survives unload
+    }
+
+    [Fact]
+    public void SpawnReady_FlipsTrueOnceSpawnAreaLoaded()
+    {
+        var cfg = new Configuration
+        {
+            RenderDistanceHorizontal = 1,
+            RenderDistanceVertical = 0,
+            SpawnReadyRadiusHorizontal = 1,
+            MaxGenerateJobsInFlight = 100,
+            MaxMeshUploadsPerFrame = 1,         // throttle to expose progression
+        };
+        var (streamer, _, _) = CreateStreamer(cfg);
+
+        Assert.False(streamer.SpawnReady);
+        // Tick once per chunk needed (3×3×1 = 9 chunks at this Y). Spawn area
+        // restricted by Y bounds (only Y=0 valid here) → 9 ticks.
+        for (int i = 0; i < 9; i++) streamer.Tick(new Vector3i(0, 0, 0));
+        Assert.True(streamer.SpawnReady);
+    }
 }

World/Streaming/ChunkStreamer.cs

@@ -26,12 +26,17 @@ public sealed class ChunkStreamer : IDisposable
     private readonly HashSet<Vector3i> _ready = new();
     private readonly PriorityQueue<Vector3i, int> _pendingLoad = new();
     private readonly ConcurrentQueue<ChunkJobResult> _completed = new();
+    private readonly Queue<Vector3i> _pendingUnload = new();
 
     private Vector3i _lastPlayerChunk = new(int.MinValue, int.MinValue, int.MinValue);
     private int _inFlight;
+    private bool _spawnReady;
+    private bool _spawnAnchorSet;
+    private Vector3i _spawnAnchor;
 
     public int RendererCount => this._renderers.Count;
     public bool IsReady(Vector3i pos) => this._ready.Contains(pos);
+    public bool SpawnReady => this._spawnReady;
 
     public ChunkStreamer(
         Configuration cfg,
@@ -59,14 +64,16 @@ public sealed class ChunkStreamer : IDisposable
             this._lastPlayerChunk = playerChunkPos;
         }
 
-        // Dispatch BEFORE drain: with a synchronous executor (tests) work
-        // completes before Submit() returns, so we want to pick up those
-        // results in this same tick. With the production threadpool executor,
-        // jobs don't finish synchronously — Drain harvests whatever previous
-        // ticks' workers completed in the meantime. Either way, this order is
-        // correct.
+        // Unloads first to free in-flight slots, then dispatch BEFORE drain:
+        // with a synchronous executor (tests), Submit() runs work to completion
+        // before returning, so a single tick must drain its own dispatches.
+        // With the production threadpool executor, jobs don't finish in this
+        // tick — Drain harvests results submitted on previous ticks. Either way
+        // this ordering is correct.
+        this.ProcessUnloads();
         this.DispatchJobs();
         this.DrainCompleted();
+        this.UpdateSpawnReady();
     }
 
     public void DrawAll(Action<Vector3i, IChunkRenderer> drawCallback)
@@ -82,25 +89,49 @@ public sealed class ChunkStreamer : IDisposable
 
     private void RecomputeTargetSet(Vector3i p)
     {
+        if (!this._spawnAnchorSet)
+        {
+            this._spawnAnchor = p;
+            this._spawnAnchorSet = true;
+        }
+
         int h = this._cfg.RenderDistanceHorizontal;
         int v = this._cfg.RenderDistanceVertical;
 
+        var target = new HashSet<Vector3i>();
         for (int dx = -h; dx <= h; dx++)
         for (int dy = -v; dy <= v; dy++)
         for (int dz = -h; dz <= h; dz++)
         {
             int cy = p.Y + dy;
             if (cy < 0 || cy >= WorldConstants.WorldHeightChunks) continue;
+            target.Add(new Vector3i(p.X + dx, cy, p.Z + dz));
+        }
 
-            var pos = new Vector3i(p.X + dx, cy, p.Z + dz);
-            if (this._tracked.Contains(pos)) continue;
-
-            this._tracked.Add(pos);
-            int priority = dx * dx + dy * dy + dz * dz;
+        foreach (var pos in target)
+        {
+            if (this._tracked.Add(pos))
+            {
+                int priority = (pos.X - p.X) * (pos.X - p.X)
+                             + (pos.Y - p.Y) * (pos.Y - p.Y)
+                             + (pos.Z - p.Z) * (pos.Z - p.Z);
                 this._pendingLoad.Enqueue(pos, priority);
             }
         }
 
+        // Anything currently tracked but no longer in target → unload.
+        var toRemove = new List<Vector3i>();
+        foreach (var tracked in this._tracked)
+        {
+            if (!target.Contains(tracked)) toRemove.Add(tracked);
+        }
+        foreach (var pos in toRemove)
+        {
+            this._tracked.Remove(pos);
+            this._pendingUnload.Enqueue(pos);
+        }
+    }
+
     private void DrainCompleted()
     {
         int budget = this._cfg.MaxMeshUploadsPerFrame;
@@ -112,6 +143,41 @@ public sealed class ChunkStreamer : IDisposable
         }
     }
 
+    private void ProcessUnloads()
+    {
+        while (this._pendingUnload.TryDequeue(out Vector3i pos))
+        {
+            if (this._renderers.TryGetValue(pos, out IChunkRenderer? renderer))
+            {
+                renderer.Dispose();
+                this._renderers.Remove(pos);
+            }
+            this._world.RemoveChunk(pos);
+            this._ready.Remove(pos);
+            Log.Debug("Unloaded {Pos}", pos);
+        }
+    }
+
+    private void UpdateSpawnReady()
+    {
+        if (this._spawnReady || !this._spawnAnchorSet) return;
+
+        int hs = this._cfg.SpawnReadyRadiusHorizontal;
+        int v = this._cfg.RenderDistanceVertical;
+        Vector3i a = this._spawnAnchor;
+
+        for (int dx = -hs; dx <= hs; dx++)
+        for (int dy = -v; dy <= v; dy++)
+        for (int dz = -hs; dz <= hs; dz++)
+        {
+            int cy = a.Y + dy;
+            if (cy < 0 || cy >= WorldConstants.WorldHeightChunks) continue;
+            if (!this._ready.Contains(new Vector3i(a.X + dx, cy, a.Z + dz))) return;
+        }
+        this._spawnReady = true;
+        Log.Information("Spawn area ready at anchor {Anchor}", a);
+    }
+
     private void InstallResult(ChunkJobResult result)
     {
         if (result.Error != null || result.Mesh == null || result.Chunk == null)