diff --git a/.gitignore b/.gitignore
index 6e79db6..e31eb74 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,3 +18,6 @@ build/
 /*/package/*.zip
 /*/package/patchers/
 /*/package/plugins/
+
+# UpdateGameDlls build-time lock file (created by UpdateGameDlls.ps1)
+AssemblyFromGame/.update.lock
diff --git a/AGENTS.md b/AGENTS.md
index fc315c3..7646c9f 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -78,13 +78,16 @@ Individual `.csproj` files only declare what is unique to that project (GUID, ve
 
 ### Automatic Game DLL Update
 
-`AssemblyFromGame/` holds publicized copies of two game DLLs used as compile-time references. They are refreshed automatically **before every build** by the `UpdateGameDlls` MSBuild target, which calls `UpdateGameDlls.ps1`.
+`AssemblyFromGame/` holds publicized copies of two game DLLs used as compile-time references. They are refreshed automatically **once per solution build** by the `UpdateGameDlls` MSBuild target, which calls `UpdateGameDlls.ps1`.
+
+The target runs only when the `UXAssist` project is being built (the designated trigger project), or when either DLL is missing from `AssemblyFromGame/`. This prevents redundant executions and file-write conflicts when projects are built in parallel (`dotnet build -m`). The PowerShell script additionally acquires an exclusive file lock (`AssemblyFromGame/.update.lock`) so that the rare case where the `!Exists` fallback triggers multiple projects concurrently is also handled safely.
 
 The script:
 1. Reads the Steam installation path from the Windows registry (`HKCU\Software\Valve\Steam`).
 2. Parses `steamapps/libraryfolders.vdf` to find the library that contains DSP (AppID `1366540`).
 3. Locates `<game_root>/DSPGAME_Data/Managed/`.
-4. For each DLL (`Assembly-CSharp.dll`, `UnityEngine.UI.dll`): if the game copy is newer than the local copy, runs `assembly-publicizer … --strip --overwrite` to regenerate the local file and stamps it with the source timestamp.
+4. Acquires an exclusive file lock on `AssemblyFromGame/.update.lock` (waits up to 60 s).
+5. For each DLL (`Assembly-CSharp.dll`, `UnityEngine.UI.dll`): if the game copy is newer than the local copy, runs `assembly-publicizer … --strip --overwrite` to regenerate the local file and stamps it with the source timestamp.
 
 The target can also be run explicitly:
 ```
diff --git a/AssemblyFromGame/Assembly-CSharp.dll b/AssemblyFromGame/Assembly-CSharp.dll
index 3d58485..a8efb84 100644
Binary files a/AssemblyFromGame/Assembly-CSharp.dll and b/AssemblyFromGame/Assembly-CSharp.dll differ
diff --git a/Directory.Build.targets b/Directory.Build.targets
index 4e217a3..f95247f 100644
--- a/Directory.Build.targets
+++ b/Directory.Build.targets
@@ -12,7 +12,22 @@
     Requires assembly-publicizer on PATH or in %USERPROFILE%\.dotnet\tools\:
         dotnet tool install -g BepInEx.AssemblyPublicizer.Cli
   -->
-  <Target Name="UpdateGameDlls" BeforeTargets="BeforeBuild">
+  <!--
+    The target is conditioned to run only when building the 'UXAssist' project (the
+    designated first-built project in this solution), OR when either game DLL is
+    missing entirely (e.g. after a manual deletion).  This ensures the target fires
+    exactly once per solution build even when projects are built in parallel (-m),
+    while still recovering automatically if the DLLs are absent.
+
+    The PowerShell script additionally acquires an exclusive file lock on
+    AssemblyFromGame/.update.lock so that the rare case where the !Exists fallback
+    triggers multiple projects concurrently is also handled safely.
+  -->
+  <Target Name="UpdateGameDlls" BeforeTargets="BeforeBuild"
+          Condition="'$(MSBuildProjectName)' == 'UXAssist'
+                     Or !Exists('$(MSBuildThisFileDirectory)AssemblyFromGame\Assembly-CSharp.dll')
+                     Or !Exists('$(MSBuildThisFileDirectory)AssemblyFromGame\UnityEngine.UI.dll')"
+          >
     <Exec
       Command="powershell.exe -NoProfile -ExecutionPolicy Bypass -File &quot;$(MSBuildThisFileDirectory)UpdateGameDlls.ps1&quot; -ProjectRoot &quot;$(MSBuildThisFileDirectory.TrimEnd('\\/'))&quot;"
       ConsoleToMSBuild="true"
diff --git a/UXAssist/Patches/FactoryPatch.cs b/UXAssist/Patches/FactoryPatch.cs
index f5b04ba..e6155da 100644
--- a/UXAssist/Patches/FactoryPatch.cs
+++ b/UXAssist/Patches/FactoryPatch.cs
@@ -2007,11 +2007,10 @@ public class FactoryPatch : PatchImpl<FactoryPatch>
                     var consume = (byte)Math.Min(DarkFogItemsInVoid[itemIdx], 4);
                     if (consume < 4)
                     {
-                        var metaverse = propertySystem.GetItemAvaliableProperty(_clusterSeedKey, 6006);
-                        if (metaverse > 0)
+                        var metaverseLong = propertySystem.GetItemAvaliableProperty(_clusterSeedKey, 6006);
+                        if (metaverseLong > 0L)
                         {
-                            if (metaverse > 10)
-                                metaverse = 10;
+                            var metaverse = metaverseLong > 10 ? 10 : (int)metaverseLong;
                             propertySystem.AddItemConsumption(_clusterSeedKey, 6006, metaverse);
                             var mainPlayer = GameMain.mainPlayer;
                             GameMain.history.AddPropertyItemConsumption(6006, metaverse, true);
diff --git a/UpdateGameDlls.ps1 b/UpdateGameDlls.ps1
index 9fadf80..8d01c38 100644
--- a/UpdateGameDlls.ps1
+++ b/UpdateGameDlls.ps1
@@ -130,7 +130,34 @@ if (-not $publicizer) {
 }
 
 # ---------------------------------------------------------------------------
-# 5. For each DLL: compare timestamps, publicize if game copy is newer
+# 5. Acquire an exclusive file lock so that concurrent MSBuild nodes (triggered
+#    by the !Exists fallback condition) cannot write the DLLs simultaneously.
+#    The lock is released automatically in the finally block.
+# ---------------------------------------------------------------------------
+$lockPath   = Join-Path $OUTPUT_DIR '.update.lock'
+$lockStream = $null
+try {
+    # Retry loop: wait up to 60 s for the lock (another node may be updating)
+    $deadline = [DateTime]::UtcNow.AddSeconds(60)
+    while ($true) {
+        try {
+            $lockStream = [System.IO.File]::Open(
+                $lockPath,
+                [System.IO.FileMode]::OpenOrCreate,
+                [System.IO.FileAccess]::ReadWrite,
+                [System.IO.FileShare]::None)
+            break   # lock acquired
+        } catch [System.IO.IOException] {
+            if ([DateTime]::UtcNow -ge $deadline) {
+                Write-Warning 'UpdateGameDlls: Timed out waiting for lock; skipping DLL update.'
+                exit 0
+            }
+            Start-Sleep -Milliseconds 200
+        }
+    }
+
+# ---------------------------------------------------------------------------
+# 6. For each DLL: compare timestamps, publicize if game copy is newer
 # ---------------------------------------------------------------------------
 $updated = 0
 foreach ($dll in $DSP_DLLS) {
@@ -176,3 +203,8 @@ if ($updated -gt 0) {
 } else {
     Write-Host 'UpdateGameDlls: All DLLs are up-to-date.'
 }
+
+} finally {
+    # Release the exclusive lock regardless of success or failure
+    if ($lockStream) { $lockStream.Close() }
+}