From 869edd93b05bcbbdf017a5debf9db6ff7bdd2fa3 Mon Sep 17 00:00:00 2001
From: Erik <erik.nihlen@gmail.com>
Date: Fri, 22 May 2026 08:23:56 +0200
Subject: [PATCH] =?UTF-8?q?test(phys):=20A6.P3=20slice=201=20=E2=80=94=20a?=
 =?UTF-8?q?dd=20CollisionInfo.ContactPlaneWriteCount?=
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Internal test-only counter incremented by SetContactPlane. Required
by IndoorContactPlaneRetentionTests to assert CP retention works
post-Finding-2 fix (A6.P2).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 src/AcDream.Core/Physics/TransitionTypes.cs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/AcDream.Core/Physics/TransitionTypes.cs b/src/AcDream.Core/Physics/TransitionTypes.cs
index 4131eea..3b8257c 100644
--- a/src/AcDream.Core/Physics/TransitionTypes.cs
+++ b/src/AcDream.Core/Physics/TransitionTypes.cs
@@ -248,8 +248,17 @@ public sealed class CollisionInfo
     public List<uint> CollideObjectGuids = new();
     public uint? LastCollidedObjectGuid;
 
+    /// <summary>
+    /// Test-only counter for ContactPlane writes. Incremented by every
+    /// call to <see cref="SetContactPlane"/>. Used by
+    /// IndoorContactPlaneRetentionTests to assert that CP retention is
+    /// working (A6.P3 slice 1, 2026-05-21).
+    /// </summary>
+    internal int ContactPlaneWriteCount { get; private set; }
+
     public void SetContactPlane(Plane plane, uint cellId, bool isWater = false)
     {
+        ContactPlaneWriteCount++;
         ContactPlaneValid = true;
         ContactPlane = plane;
         ContactPlaneCellId = cellId;