feat(cli): migrate away the dead config keys

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/cli/src/update.ts

@@ -554,6 +554,33 @@ function migrateImportedLayout(
  * migrations must preserve semantics and are protected by update backups.
  */
 
+/** Remove a `key: <scalar>` line from a config source, e.g. `compatibilityDate: "..."`. */
+function removeScalarConfigKey(source: string, key: string): string {
+  return source.replace(new RegExp(`^[ \\t]*${key}:.*\\n`, "m"), "");
+}
+
+/**
+ * Remove a `key: { ... }` object property from a config source, using balanced-brace
+ * scanning so a nested `{ ... }` inside the value can't truncate the removal early.
+ */
+function removeObjectConfigKey(source: string, key: string): string {
+  const match = new RegExp(`^[ \\t]*${key}\\s*:\\s*\\{`, "m").exec(source);
+  if (!match) return source;
+  const lineStart = match.index;
+  const openBrace = match.index + match[0].length - 1;
+  const closeBrace = findMatching(source, openBrace);
+  if (closeBrace < 0) return source;
+
+  let end = closeBrace + 1;
+  while (source[end] === " " || source[end] === "\t") end++;
+  if (source[end] === ",") end++;
+  while (source[end] === " " || source[end] === "\t") end++;
+  if (source[end] === "\r") end++;
+  if (source[end] === "\n") end++;
+
+  return source.slice(0, lineStart) + source.slice(end);
+}
+
 const MIGRATIONS: Migration[] = [
   {
     version: "0.8.0",
@@ -820,6 +847,27 @@ const MIGRATIONS: Migration[] = [
       // no application source rewrite is required.
     },
   },
+  {
+    version: "0.9.0",
+    id: "remove-dead-config-keys",
+    description: "Delete compatibilityDate, frameworkBehaviour, functions, and compatibility",
+    apply(ctx) {
+      const file = join(ctx.appRoot, "wrnexus.config.ts");
+      if (!existsSync(file)) return;
+
+      const before = readFileSync(file, "utf8");
+      let after = before;
+      after = removeScalarConfigKey(after, "compatibilityDate");
+      after = removeScalarConfigKey(after, "frameworkBehaviour");
+      after = removeObjectConfigKey(after, "functions");
+      after = removeObjectConfigKey(after, "compatibility");
+
+      if (after === before) return;
+
+      ctx.report.changedAutomatically.push(`${file}: removed dead compatibility keys`);
+      if (!ctx.dryRun) writeFileSync(file, after, "utf8");
+    },
+  },
 ];
 
 /** Release tooling uses this to require an explicit migration entry per version. */