There we go. be more like the blueprint

Author: NullVoxPopuli

addon/rollup.config.mjs

@@ -38,7 +38,10 @@ export default {
     // `dependencies` and `peerDependencies` as well as standard Ember-provided
     // package names.
     addon.dependencies(),
-    addon.declarations(),
+    addon.declarations(
+      'declarations',
+      'pnpm ember-tsc --declaration --declarationDir declarations',
+    ),
 
     // Remove leftover build artifacts when starting a new build.
     addon.clean(),

addon/tsconfig.json

@@ -5,8 +5,6 @@
     "unpublished-development-types/**/*"
   ],
   "compilerOptions": {
-    "declarationDir": "declarations",
-    "allowJs": true,
     "rootDir": "./src",
     "types": ["ember-source/types", "@glint/ember-tsc/types"]
   }