diff --git a/src/AcDream.App/Streaming/StreamingRegion.cs b/src/AcDream.App/Streaming/StreamingRegion.cs
index b28b547..bcebe44 100644
--- a/src/AcDream.App/Streaming/StreamingRegion.cs
+++ b/src/AcDream.App/Streaming/StreamingRegion.cs
@@ -10,9 +10,11 @@ namespace AcDream.App.Streaming;
 /// </summary>
 public sealed class StreamingRegion
 {
-    public int CenterX { get; private set; }
-    public int CenterY { get; private set; }
-    public int Radius { get; }
+    public int CenterX    { get; private set; }
+    public int CenterY    { get; private set; }
+    public int Radius     { get; }
+    public int NearRadius { get; }
+    public int FarRadius  { get; }
 
     // Strictly the (2r+1)×(2r+1) window (clamped to world bounds).
     private readonly HashSet<uint> _visible = new();
@@ -43,12 +45,16 @@ public sealed class StreamingRegion
     /// </summary>
     public IReadOnlyCollection<uint> Resident => _resident;
 
-    public StreamingRegion(int cx, int cy, int radius)
+    public StreamingRegion(int centerX, int centerY, int nearRadius, int farRadius)
     {
-        Radius = radius;
-        Recenter(cx, cy);
+        NearRadius = nearRadius;
+        FarRadius  = farRadius;
+        Radius     = farRadius;  // outer ring drives Resident bookkeeping
+        Recenter(centerX, centerY);
     }
 
+    public StreamingRegion(int cx, int cy, int radius) : this(cx, cy, radius, radius) { }
+
     private void Recenter(int cx, int cy)
     {
         CenterX = cx;
diff --git a/tests/AcDream.Core.Tests/Streaming/StreamingRegionTwoTierTests.cs b/tests/AcDream.Core.Tests/Streaming/StreamingRegionTwoTierTests.cs
new file mode 100644
index 0000000..ccf8f13
--- /dev/null
+++ b/tests/AcDream.Core.Tests/Streaming/StreamingRegionTwoTierTests.cs
@@ -0,0 +1,18 @@
+using AcDream.App.Streaming;
+using Xunit;
+
+namespace AcDream.Core.Tests.Streaming;
+
+public class StreamingRegionTwoTierTests
+{
+    [Fact]
+    public void Constructor_TwoRadii_ExposesNearAndFarRadii()
+    {
+        var region = new StreamingRegion(centerX: 100, centerY: 100, nearRadius: 4, farRadius: 12);
+
+        Assert.Equal(4, region.NearRadius);
+        Assert.Equal(12, region.FarRadius);
+        Assert.Equal(100, region.CenterX);
+        Assert.Equal(100, region.CenterY);
+    }
+}