diff --git a/frontend/excalidraw-diag.html b/frontend/excalidraw-diag.html
index 18d080a..799dbb2 100644
--- a/frontend/excalidraw-diag.html
+++ b/frontend/excalidraw-diag.html
@@ -19,7 +19,7 @@ function add(msg, cls='') {
 
 add('--- Step 1: Testing esm.sh connectivity ---');
 try {
-  const res = await fetch('https://esm.sh/react@18', { method: 'HEAD' });
+  const res = await fetch('https://esm.sh/react@18.3.1', { method: 'HEAD' });
   add(`✓ esm.sh reachable (HTTP ${res.status})`, 'pass');
 } catch(e) {
   add(`✗ esm.sh unreachable: ${e.message}`, 'fail');
@@ -27,7 +27,7 @@ try {
 
 add('\n--- Step 2: Importing React ---');
 try {
-  const React = await import('https://esm.sh/react@18');
+  const React = await import('https://esm.sh/react@18.3.1');
   add(`✓ React imported (keys: ${Object.keys(React.default||React).slice(0,5).join(',')})`, 'pass');
   window.React = React;
 } catch(e) {
@@ -36,7 +36,7 @@ try {
 
 add('\n--- Step 3: Importing ReactDOM ---');
 try {
-  const ReactDOM = await import('https://esm.sh/react-dom@18');
+  const ReactDOM = await import('https://esm.sh/react-dom@18.3.1');
   add(`✓ ReactDOM imported`, 'pass');
   window.ReactDOM = ReactDOM;
 } catch(e) {
diff --git a/frontend/excalidraw-diag2.html b/frontend/excalidraw-diag2.html
index 4a7c869..968fce4 100644
--- a/frontend/excalidraw-diag2.html
+++ b/frontend/excalidraw-diag2.html
@@ -14,8 +14,8 @@
 <div id="app"></div>
 
 <script type="module">
-import React from "https://esm.sh/react@18";
-import ReactDOM from "https://esm.sh/react-dom@18/client";
+import React from "https://esm.sh/react@18.3.1";
+import ReactDOM from "https://esm.sh/react-dom@18.3.1/client";
 const log = document.getElementById('log');
 function add(msg, cls='') { log.innerHTML += `<span class="${cls}">${msg}</span>\n`; }
 
diff --git a/frontend/excalidraw-diag3.html b/frontend/excalidraw-diag3.html
index 76f4333..4f504b9 100644
--- a/frontend/excalidraw-diag3.html
+++ b/frontend/excalidraw-diag3.html
@@ -1,6 +1,9 @@
 <!DOCTYPE html>
 <html>
-<head><meta charset="UTF-8"><title>Excalidraw Error Capture</title>
+<head><meta charset="UTF-8">
+  <meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate">
+  <meta http-equiv="Pragma" content="no-cache">
+  <meta http-equiv="Expires" content="0"><title>Excalidraw Error Capture</title>
 <style>
   body { font-family:monospace; background:#1e1e1e; color:#ddd; padding:20px; }
   .pass { color:#4caf50; } .fail { color:#f44336; }
@@ -14,8 +17,8 @@
 <div id="app"></div>
 
 <script type="module">
-import React from "https://esm.sh/react@18";
-import ReactDOM from "https://esm.sh/react-dom@18/client";
+import React from "https://esm.sh/react@18.3.1";
+import ReactDOM from "https://esm.sh/react-dom@18.3.1/client";
 const log = document.getElementById('log');
 function add(msg, cls='') { log.innerHTML += `<span class="${cls}">${msg}</span>\n`; }
 
diff --git a/frontend/excalidraw-diag4.html b/frontend/excalidraw-diag4.html
new file mode 100644
index 0000000..ff6c474
--- /dev/null
+++ b/frontend/excalidraw-diag4.html
@@ -0,0 +1,74 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="UTF-8">
+<meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate">
+<meta http-equiv="Pragma" content="no-cache">
+<meta http-equiv="Expires" content="0">
+<title>Excalidraw Final Test</title>
+<style>
+  body { font-family:monospace; background:#1e1e1e; color:#ddd; padding:20px; }
+  .pass { color:#4caf50; } .fail { color:#f44336; }
+  pre { background:#2d2d2d; padding:10px; border-radius:4px; }
+  #app { margin-top:20px; border:1px dashed #555; min-height:100px; padding:10px; }
+</style>
+</head>
+<body>
+<h2>Excalidraw Final Test (Import Map)</h2>
+<pre id="log"></pre>
+<div id="app"></div>
+
+<script type="importmap">
+{
+  "imports": {
+    "react": "https://esm.sh/react@18.3.1",
+    "react-dom": "https://esm.sh/react-dom@18.3.1",
+    "react-dom/": "https://esm.sh/react-dom@18.3.1/"
+  }
+}
+</script>
+
+<script type="module">
+import React from "react";
+import ReactDOM from "react-dom/client";
+const log = document.getElementById('log');
+function add(msg, cls='') { log.innerHTML += `<span class="${cls}">${msg}</span>\n`; }
+
+add('React version: ' + React.version, 'info');
+
+class ErrorBoundary extends React.Component {
+  constructor(props) { super(props); this.state = { error: null }; }
+  static getDerivedStateFromError(error) { return { error }; }
+  componentDidCatch(error, info) {
+    add(`✗ ERROR: ${error.message}`, 'fail');
+    add(`  ${(error.stack||'').split('\n').slice(0,3).join('\n')}`, 'info');
+  }
+  render() {
+    if (this.state.error) return React.createElement('div', {style:{color:'red',padding:'20px'}}, 'Error: '+this.state.error.message);
+    return this.props.children;
+  }
+}
+
+try {
+  window.EXCALIDRAW_ASSET_PATH = 'https://esm.sh/@excalidraw/excalidraw@0.18.0/dist/prod/';
+  const ExcalidrawLib = await import('@excalidraw/excalidraw@0.18.0');
+  const { Excalidraw } = ExcalidrawLib;
+  add('Excalidraw loaded', 'pass');
+
+  const root = ReactDOM.createRoot(document.getElementById('app'));
+  root.render(
+    React.createElement(ErrorBoundary, null,
+      React.createElement(Excalidraw, {
+        theme: 'dark',
+        excalidrawRef: (api) => add('✓ EXCALIDRAW MOUNTED!', 'pass'),
+        onChange: () => {},
+      })
+    )
+  );
+  add('render() called - waiting for mount...', 'info');
+} catch(e) {
+  add(`✗ ${e.message}`, 'fail');
+}
+</script>
+</body>
+</html>
diff --git a/frontend/excalidraw-editor.html b/frontend/excalidraw-editor.html
index ba3f267..df57b8a 100644
--- a/frontend/excalidraw-editor.html
+++ b/frontend/excalidraw-editor.html
@@ -2,6 +2,9 @@
 <html lang="en">
 <head>
   <meta charset="UTF-8">
+  <meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate">
+  <meta http-equiv="Pragma" content="no-cache">
+  <meta http-equiv="Expires" content="0">
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <title>Excalidraw Editor</title>
   <style>
@@ -89,11 +92,22 @@
     <button id="btn-export-svg" title="Export SVG">📐 SVG</button>
   </div>
 
-  <!-- Import React, ReactDOM, and Excalidraw in a single module (order matters!) -->
+  <!-- Import map: force ALL modules (Excalidraw + sub-deps) to use React 18.3.1 -->
+  <script type="importmap">
+  {
+    "imports": {
+      "react": "https://esm.sh/react@18.3.1",
+      "react-dom": "https://esm.sh/react-dom@18.3.1",
+      "react-dom/": "https://esm.sh/react-dom@18.3.1/"
+    }
+  }
+  </script>
+
+  <!-- Single module script -->
   <script type="module">
-    import React from "https://esm.sh/react@18.3.1";
-    import ReactDOM from "https://esm.sh/react-dom@18.3.1";
-    import * as ExcalidrawLib from "https://esm.sh/@excalidraw/excalidraw@0.18.0";
+    import React from "react";
+    import ReactDOM from "react-dom";
+    import * as ExcalidrawLib from "@excalidraw/excalidraw@0.18.0";
 
     window.React = React;
     window.ReactDOM = ReactDOM;
diff --git a/frontend/js/excalidraw-viewer.js b/frontend/js/excalidraw-viewer.js
index 4600662..161b2e0 100644
--- a/frontend/js/excalidraw-viewer.js
+++ b/frontend/js/excalidraw-viewer.js
@@ -32,7 +32,7 @@ export function renderExcalidraw(container, data, vaultName, filePath, opts = {}
   // Build the iframe
   const iframe = document.createElement('iframe');
   iframe.id = editorId;
-  iframe.src = '/static/excalidraw-editor.html';
+  iframe.src = '/static/excalidraw-editor.html?v=' + Date.now();
   iframe.sandbox.add('allow-scripts');
   iframe.sandbox.add('allow-same-origin');
   iframe.style.cssText = 'width:100%;height:100%;border:none;';