diff --git a/src/AcDream.App/Rendering/GameWindow.cs b/src/AcDream.App/Rendering/GameWindow.cs
index d425bcb..3adb7bd 100644
--- a/src/AcDream.App/Rendering/GameWindow.cs
+++ b/src/AcDream.App/Rendering/GameWindow.cs
@@ -1896,8 +1896,7 @@ public sealed class GameWindow : IDisposable
                 float localY = result.Position.Y - (lbY - _liveCenterY) * 192f;
                 uint wireCellId = ((uint)lbX << 24) | ((uint)lbY << 16) | (result.CellId & 0xFFFFu);
                 var wirePos = new System.Numerics.Vector3(localX, localY, result.Position.Z);
-                var wireRot = System.Numerics.Quaternion.CreateFromAxisAngle(
-                    System.Numerics.Vector3.UnitZ, _playerController.Yaw);
+                var wireRot = YawToAcQuaternion(_playerController.Yaw);
 
                 if (result.MotionStateChanged)
                 {
@@ -1956,6 +1955,34 @@ public sealed class GameWindow : IDisposable
         }
     }
 
+    /// <summary>
+    /// Convert our internal yaw (math convention: 0=+X East, PI/2=+Y North)
+    /// to AC's quaternion heading convention.
+    /// AC heading: 0=West, 90=North, 180=East, 270=South.
+    /// Formula from holtburger Quaternion::from_heading.
+    /// </summary>
+    private static System.Numerics.Quaternion YawToAcQuaternion(float yaw)
+    {
+        // Our yaw → AC heading in degrees:
+        // yaw=0 → East → AC 180°, yaw=PI/2 → North → AC 90°
+        // heading_deg = 180 - yaw_degrees
+        float yawDeg = yaw * (180f / MathF.PI);
+        float headingDeg = 180f - yawDeg;
+        if (headingDeg < 0f) headingDeg += 360f;
+        if (headingDeg >= 360f) headingDeg -= 360f;
+
+        // holtburger from_heading: theta = (450 - heading_deg) in radians
+        float theta = (450f - headingDeg) * (MathF.PI / 180f);
+        float halfTheta = theta * 0.5f;
+        float w = MathF.Cos(halfTheta);
+        float z = MathF.Sin(halfTheta);
+
+        // Canonicalize: w must be non-negative
+        if (w < 0f) { w = -w; z = -z; }
+
+        return new System.Numerics.Quaternion(0f, 0f, z, w);
+    }
+
     private void OnCameraModeChanged(bool isFlyMode)
     {
         if (_input is null) return;