diff --git a/src/AcDream.Core/Physics/PhysicsDiagnostics.cs b/src/AcDream.Core/Physics/PhysicsDiagnostics.cs
index 06a3180c..51ee9977 100644
--- a/src/AcDream.Core/Physics/PhysicsDiagnostics.cs
+++ b/src/AcDream.Core/Physics/PhysicsDiagnostics.cs
@@ -31,6 +31,19 @@ public static class PhysicsDiagnostics
     public static bool ProbeResolveEnabled { get; set; } =
         Environment.GetEnvironmentVariable("ACDREAM_PROBE_RESOLVE") == "1";
 
+    /// <summary>
+    /// Retail teleport readiness gate (§3.4, 2026-06-21). When true, every transition of
+    /// the <c>TeleportArrivalReadiness</c> verdict (NotReady → Ready / Impossible) emits one
+    /// <c>[arrival-gate]</c> line: the destination cell id, landblock id, verdict,
+    /// <c>PhysicsEngine.LandblockCount</c> at the moment it flips, and whether the
+    /// flip was forced (Impossible) or natural (Ready).
+    ///
+    /// <para>Initial state from <c>ACDREAM_PROBE_RESOLVE=1</c> — shares the existing probe
+    /// flag because this is a readiness-path extension; no new env var needed.</para>
+    /// </summary>
+    public static bool ProbeArrivalGateEnabled { get; set; } =
+        Environment.GetEnvironmentVariable("ACDREAM_PROBE_RESOLVE") == "1";
+
     /// <summary>
     /// When true, every change to <c>PlayerMovementController.CellId</c>
     /// emits one <c>[cell-transit]</c> line: old → new cell, current
@@ -534,6 +547,7 @@ public static class PhysicsDiagnostics
     public static void ResetForTest()
     {
         ProbeResolveEnabled           = false;
+        ProbeArrivalGateEnabled       = false;
         ProbeCellEnabled              = false;
         ProbeBuildingEnabled          = false;
         ProbeCellSetEnabled           = false;