diff --git a/Packages/src/Editor/FirstPartyTools/FirstPartyToolsEditorStartup.cs b/Packages/src/Editor/FirstPartyTools/FirstPartyToolsEditorStartup.cs
index 0420ae88c..549fa3457 100644
--- a/Packages/src/Editor/FirstPartyTools/FirstPartyToolsEditorStartup.cs
+++ b/Packages/src/Editor/FirstPartyTools/FirstPartyToolsEditorStartup.cs
@@ -11,6 +11,7 @@ public static void Initialize()
             DomainReloadDisableScopeRecovery.RestoreForEditorStartup();
             ExternalSceneChangeTracker.Initialize();
             ControlPlayModeEditorStartup.Initialize();
+            PausePointEditorStartup.Initialize();
             ExecuteDynamicCodeEditorStartup.Initialize();
             GetLogsEditorStartup.Initialize();
             ScreenshotEditorStartup.Initialize();
diff --git a/Packages/src/Editor/FirstPartyTools/PausePoint/AssemblyInfo.cs b/Packages/src/Editor/FirstPartyTools/PausePoint/AssemblyInfo.cs
index 99cb7a0a0..eaac1fe9a 100644
--- a/Packages/src/Editor/FirstPartyTools/PausePoint/AssemblyInfo.cs
+++ b/Packages/src/Editor/FirstPartyTools/PausePoint/AssemblyInfo.cs
@@ -1,5 +1,6 @@
 using System.Runtime.CompilerServices;
 
+[assembly: InternalsVisibleTo("UnityCLILoop.FirstPartyTools.Editor")]
 [assembly: InternalsVisibleTo("UnityCLILoop.Tests.Editor.SourcePausePointResolver")]
 [assembly: InternalsVisibleTo("UnityCLILoop.Tests.Editor.SourcePausePointCapture")]
 [assembly: InternalsVisibleTo("UnityCLILoop.Tests.Editor.SourcePausePointPatcher")]
diff --git a/Packages/src/Editor/FirstPartyTools/PausePoint/PausePointDomainReloadTracker.cs b/Packages/src/Editor/FirstPartyTools/PausePoint/PausePointDomainReloadTracker.cs
index 264d99fce..0112611e3 100644
--- a/Packages/src/Editor/FirstPartyTools/PausePoint/PausePointDomainReloadTracker.cs
+++ b/Packages/src/Editor/FirstPartyTools/PausePoint/PausePointDomainReloadTracker.cs
@@ -1,21 +1,30 @@
 using System;
 
-using UnityEditor;
+using UnityEngine;
 
 namespace io.github.hatayama.UnityCliLoop.FirstPartyTools
 {
-    // [InitializeOnLoad] runs this type's static field initializers once per AppDomain load, so
-    // LoadedAtUtc marks this domain's birth. Used by physics-callback dispatch diagnostics to
-    // report how long the current domain has been alive without a reload -- a suspected factor in
-    // the existing-instance physics-dispatch miss (see docs/regression-harness.md).
-    [InitializeOnLoad]
+    // MarkDomainLoaded is invoked once per AppDomain load by the composition-root bootstrap
+    // (through FirstPartyToolsEditorStartup), so the recorded timestamp marks this domain's
+    // birth. Used by physics-callback dispatch diagnostics to report how long the current
+    // domain has been alive without a reload -- a suspected factor in the existing-instance
+    // physics-dispatch miss (see docs/regression-harness.md).
     internal static class PausePointDomainReloadTracker
     {
-        public static readonly DateTime LoadedAtUtc = DateTime.UtcNow;
+        private static DateTime? _loadedAtUtc;
+
+        public static void MarkDomainLoaded()
+        {
+            Debug.Assert(!_loadedAtUtc.HasValue, "MarkDomainLoaded must run once per domain load");
+
+            _loadedAtUtc = DateTime.UtcNow;
+        }
 
         public static double SecondsSinceLoad()
         {
-            return (DateTime.UtcNow - LoadedAtUtc).TotalSeconds;
+            Debug.Assert(_loadedAtUtc.HasValue, "MarkDomainLoaded must run before SecondsSinceLoad");
+
+            return (DateTime.UtcNow - _loadedAtUtc.Value).TotalSeconds;
         }
     }
 }
diff --git a/Packages/src/Editor/FirstPartyTools/PausePoint/PausePointEditorStartup.cs b/Packages/src/Editor/FirstPartyTools/PausePoint/PausePointEditorStartup.cs
new file mode 100644
index 000000000..ef376e6cd
--- /dev/null
+++ b/Packages/src/Editor/FirstPartyTools/PausePoint/PausePointEditorStartup.cs
@@ -0,0 +1,12 @@
+namespace io.github.hatayama.UnityCliLoop.FirstPartyTools
+{
+    // Keeps pause-point startup wiring inside the pause-point assembly so the composition
+    // root only depends on the bundled-tool facade.
+    internal static class PausePointEditorStartup
+    {
+        public static void Initialize()
+        {
+            PausePointDomainReloadTracker.MarkDomainLoaded();
+        }
+    }
+}
diff --git a/Packages/src/Editor/FirstPartyTools/PausePoint/PausePointEditorStartup.cs.meta b/Packages/src/Editor/FirstPartyTools/PausePoint/PausePointEditorStartup.cs.meta
new file mode 100644
index 000000000..2dc8ffb74
--- /dev/null
+++ b/Packages/src/Editor/FirstPartyTools/PausePoint/PausePointEditorStartup.cs.meta
@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 1caf71ad9cb024a0d8ff2a5d31e82d1c
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 
diff --git a/Packages/src/Editor/FirstPartyTools/SetGameViewSize/SetGameViewSizeSchema.cs b/Packages/src/Editor/FirstPartyTools/SetGameViewSize/SetGameViewSizeSchema.cs
index 836289565..c1a658f60 100644
--- a/Packages/src/Editor/FirstPartyTools/SetGameViewSize/SetGameViewSizeSchema.cs
+++ b/Packages/src/Editor/FirstPartyTools/SetGameViewSize/SetGameViewSizeSchema.cs
@@ -1,5 +1,3 @@
-using System.ComponentModel;
-
 using io.github.hatayama.UnityCliLoop.ToolContracts;
 
 namespace io.github.hatayama.UnityCliLoop.FirstPartyTools
@@ -9,10 +7,8 @@ namespace io.github.hatayama.UnityCliLoop.FirstPartyTools
     /// </summary>
     public sealed class SetGameViewSizeSchema : UnityCliLoopToolSchema
     {
-        [Description("Target Game View rendering width in pixels. Provide with Height to change the resolution.")]
         public int? Width { get; set; }
 
-        [Description("Target Game View rendering height in pixels. Provide with Width to change the resolution.")]
         public int? Height { get; set; }
     }
 }