fix(excalidraw): pin React 18.3.1 exact version (esm.sh was resolving to React 19)

frontend/excalidraw-diag.html

@@ -0,0 +1,69 @@
+<!DOCTYPE html>
+<html>
+<head><meta charset="UTF-8"><title>Excalidraw Diagnostic</title>
+<style>
+  body { font-family: monospace; background:#1e1e1e; color:#ddd; padding:20px; }
+  .pass { color:#4caf50; } .fail { color:#f44336; } .info { color:#ff9800; }
+  pre { background:#2d2d2d; padding:10px; border-radius:4px; overflow-x:auto; }
+</style>
+</head>
+<body>
+<h2>Excalidraw Diagnostic</h2>
+<pre id="log"></pre>
+
+<script type="module">
+const log = document.getElementById('log');
+function add(msg, cls='') {
+  log.innerHTML += `<span class="${cls}">${msg}</span>\n`;
+}
+
+add('--- Step 1: Testing esm.sh connectivity ---');
+try {
+  const res = await fetch('https://esm.sh/react@18', { method: 'HEAD' });
+  add(`✓ esm.sh reachable (HTTP ${res.status})`, 'pass');
+} catch(e) {
+  add(`✗ esm.sh unreachable: ${e.message}`, 'fail');
+}
+
+add('\n--- Step 2: Importing React ---');
+try {
+  const React = await import('https://esm.sh/react@18');
+  add(`✓ React imported (keys: ${Object.keys(React.default||React).slice(0,5).join(',')})`, 'pass');
+  window.React = React;
+} catch(e) {
+  add(`✗ React import failed: ${e.message}`, 'fail');
+}
+
+add('\n--- Step 3: Importing ReactDOM ---');
+try {
+  const ReactDOM = await import('https://esm.sh/react-dom@18');
+  add(`✓ ReactDOM imported`, 'pass');
+  window.ReactDOM = ReactDOM;
+} catch(e) {
+  add(`✗ ReactDOM import failed: ${e.message}`, 'fail');
+}
+
+add('\n--- Step 4: Importing Excalidraw ---');
+try {
+  window.EXCALIDRAW_ASSET_PATH = 'https://esm.sh/@excalidraw/[email protected]/dist/prod/';
+  const ExcalidrawLib = await import('https://esm.sh/@excalidraw/[email protected]');
+  add(`✓ Excalidraw imported (keys: ${Object.keys(ExcalidrawLib).slice(0,8).join(',')})`, 'pass');
+  window.ExcalidrawLib = ExcalidrawLib;
+} catch(e) {
+  add(`✗ Excalidraw import failed: ${e.message}`, 'fail');
+}
+
+add('\n--- Step 5: CSP Check ---');
+add('Check browser console (F12) for CSP violation messages', 'info');
+add('Look for: "Refused to load the script..." or "violates the following CSP directive..."', 'info');
+
+add('\n--- Step 6: Browser Info ---');
+add(`User-Agent: ${navigator.userAgent}`, 'info');
+add(`ES Modules: ${typeof import.meta !== 'undefined' ? 'supported' : 'NOT supported'}`, 'info');
+
+add('\n=== Diagnostic complete ===');
+add('If all ✓ above: Excalidraw should work. Check F12 console for errors.', 'info');
+add('If any ✗: That\'s the problem. Share the error message.', 'info');
+</script>
+</body>
+</html>