refactor: better codemirror loading.

Author: knightedcodemonkey

.oxlintrc.json

@@ -12,6 +12,13 @@
     "no-console": "error",
     "no-unused-vars": "error",
     "no-shadow": "error",
+    "no-restricted-syntax": [
+      "error",
+      {
+        "selector": "CallExpression[callee.type='MemberExpression'][callee.property.name=/^(then|catch|finally)$/]",
+        "message": "Prefer async/await over promise chains (.then/.catch/.finally)."
+      }
+    ],
     "import/no-cycle": "error",
     "import/no-duplicates": "error",
     "import/no-self-import": "error",

AGENTS.md

@@ -44,6 +44,7 @@ Repository structure:
 - Preserve progressive loading behavior (lazy-load optional compilers/runtime pieces where possible).
 - Do not introduce bundler-only assumptions into src/ runtime code.
 - Prefer async/await over promise chains.
+- Do not use IIFE, find another pattern instead.
 
 ## CDN and runtime expectations
 

src/editor-codemirror.js

@@ -1,6 +1,7 @@
 import { cdnImports, importFromCdnWithFallback } from './cdn.js'
 
 let codeMirrorRuntime = null
+let codeMirrorRuntimePromise = null
 
 const resolveLanguageExtension = (runtime, language) => {
   if (language === 'javascript-jsx') {
@@ -18,9 +19,7 @@ const resolveLanguageExtension = (runtime, language) => {
   return runtime.css()
 }
 
-const ensureCodeMirrorRuntime = async () => {
-  if (codeMirrorRuntime) return codeMirrorRuntime
-
+const loadCodeMirrorRuntime = async () => {
   const [
     state,
     view,
@@ -92,10 +91,25 @@ const ensureCodeMirrorRuntime = async () => {
     throw new Error('CodeMirror runtime did not expose expected APIs.')
   }
 
-  codeMirrorRuntime = runtime
   return runtime
 }
 
+const ensureCodeMirrorRuntime = async () => {
+  if (codeMirrorRuntime) return codeMirrorRuntime
+  if (!codeMirrorRuntimePromise) {
+    codeMirrorRuntimePromise = loadCodeMirrorRuntime()
+  }
+
+  try {
+    const runtime = await codeMirrorRuntimePromise
+    codeMirrorRuntime = runtime
+    return runtime
+  } catch (error) {
+    codeMirrorRuntimePromise = null
+    throw error
+  }
+}
+
 export const createCodeMirrorEditor = async ({
   parent,
   value,