checkpoint: preserve user-gated FW closeout fixes

tests/AcDream.App.Tests/Rendering/Walk/WalkProductionFrameContextTests.cs

@@ -128,4 +128,49 @@ public sealed class WalkProductionFrameContextTests
             new CellVisibility(), new WalkBuildingRegistry(), Vector3.Zero, Vector3.UnitY,
             default, 1024f, 768f));
     }
+
+    [Fact]
+    public void Reset_RebindsCameraValuesAndRetainsTheRayCaster()
+    {
+        Matrix4x4 firstProjection = SimpleViewProjection();
+        var ctx = new WalkProductionFrameContext(
+            new CellVisibility(), new WalkBuildingRegistry(), Vector3.Zero, Vector3.UnitY,
+            firstProjection, 1024f, 768f);
+        IWalkRayCaster retainedRays = ctx.Rays;
+
+        var eye = new Vector3(4f, 5f, 6f);
+        Vector3 forward = Vector3.UnitX;
+        Matrix4x4 secondProjection =
+            Matrix4x4.CreateLookAt(eye, eye + forward, Vector3.UnitZ)
+            * Matrix4x4.CreatePerspectiveFieldOfView(MathF.PI / 4f, 16f / 9f, 0.1f, 500f);
+
+        ctx.Reset(eye, forward, secondProjection, 1760f, 990f);
+
+        Assert.Same(retainedRays, ctx.Rays);
+        Assert.Equal(eye, ctx.WorldViewpoint);
+        Assert.Equal(1760f, ctx.ViewportWidth);
+        Assert.Equal(990f, ctx.ViewportHeight);
+        Assert.Equal(forward, ctx.CyPlane.Normal);
+        Assert.Equal(-Vector3.Dot(eye, forward) - WalkProductionFrameContext.ZNear, ctx.CyPlane.D);
+    }
+
+    [Fact]
+    public void Reset_WithBadProjectionLeavesThePreviousBindingUsable()
+    {
+        Matrix4x4 projection = SimpleViewProjection();
+        var eye = new Vector3(1f, 2f, 3f);
+        var ctx = new WalkProductionFrameContext(
+            new CellVisibility(), new WalkBuildingRegistry(), eye, Vector3.UnitY,
+            projection, 1024f, 768f);
+        Vector3 rayBeforeFailure = ctx.Rays.RayThrough(200f, 300f);
+
+        Assert.Throws<ArgumentException>(() =>
+            ctx.Reset(new Vector3(9f), Vector3.UnitX, default, 1f, 1f));
+
+        Assert.Equal(eye, ctx.WorldViewpoint);
+        Assert.Equal(1024f, ctx.ViewportWidth);
+        Assert.Equal(768f, ctx.ViewportHeight);
+        Assert.Equal(Vector3.UnitY, ctx.CyPlane.Normal);
+        Assert.Equal(rayBeforeFailure, ctx.Rays.RayThrough(200f, 300f));
+    }
 }