diff --git a/Update.json b/Update.json
index 3cc9edb0..7f8f039a 100644
--- a/Update.json
+++ b/Update.json
@@ -3649,6 +3649,17 @@
                 }
             ],
             "Notes": "修复了 MonochromeUI / NewBootstrap 新界面在深色模式下加载时出现的白色闪烁（FOUC/CLS）问题。"
+        },
+        "3.5.4": {
+            "UpdateDate": 1785114353055,
+            "Prerelease": true,
+            "UpdateContents": [
+                {
+                    "PR": 997,
+                    "Description": "fix: pin Monaco to 0.52.2 to stop intermittent editor load failures"
+                }
+            ],
+            "Notes": "修复了提交代码页面上 Monaco 编辑器有时无法加载、退化为纯文本框的问题（Monaco 0.53.0 的上游 bug）。"
         }
     }
 }
\ No newline at end of file
diff --git a/XMOJ.user.js b/XMOJ.user.js
index 9ab9ad5c..fc6781e5 100644
--- a/XMOJ.user.js
+++ b/XMOJ.user.js
@@ -1,6 +1,6 @@
 // ==UserScript==
 // @name         XMOJ
-// @version      3.5.3
+// @version      3.5.4
 // @description  XMOJ增强脚本
 // @author       @XMOJ-Script-dev, @langningchen and the community
 // @namespace    https://github/langningchen
@@ -551,7 +551,11 @@ let _earlyObs = null;
 })();
 
 const CaptchaSiteKey = "0x4AAAAAAALBT58IhyDViNmv";
-const MonacoCDN = "https://cdnjs.cloudflare.com/ajax/libs/monaco-editor/0.53.0/min/vs";
+// 0.53.0 leaks its minified helper variables (m, r, o, ...) into the global scope from every
+// chunk file, so whichever chunk happens to be evaluated last clobbers the others and the
+// editor randomly fails to load (microsoft/monaco-editor#5015). 0.52.2 ships a single bundle
+// and is not affected. cdnjs has no fixed release newer than 0.53.0 yet.
+const MonacoCDN = "https://cdnjs.cloudflare.com/ajax/libs/monaco-editor/0.52.2/min/vs";
 const AdminUserList = ["zhuchenrui2", "shanwenxiao", "chenlangning", "admin"];
 
 // Pre-declared so that closures defined before the async init block can reference them
@@ -751,8 +755,19 @@ let GetUserBadge = async (Username) => {
         }
     }
 };
+let MonacoLoadPromise = null;
 async function ensureMonaco() {
     if (typeof monaco !== 'undefined') return;
+    // Callers can overlap (submit page editor, merge view, freopen snippets). Without this guard
+    // each of them appends its own loader.js, and the second loader resets the AMD registry while
+    // the first one is still resolving modules.
+    if (MonacoLoadPromise === null) {
+        MonacoLoadPromise = loadMonaco();
+        MonacoLoadPromise.catch(() => { MonacoLoadPromise = null; });
+    }
+    return MonacoLoadPromise;
+}
+async function loadMonaco() {
     const loaderUrl = MonacoCDN + '/loader.js';
     if (typeof require === 'undefined' || typeof require.config === 'undefined') {
         await new Promise((resolve, reject) => {
diff --git a/package.json b/package.json
index d94bfece..c0a7cbf0 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "xmoj-script",
-  "version": "3.5.3",
+  "version": "3.5.4",
   "description": "an improvement script for xmoj.tech",
   "main": "AddonScript.js",
   "scripts": {