feat: do better file detection to check that the universal file is added to the diff too

packages/cli/src/lib/diff/handlers.ts

@@ -61,13 +61,34 @@ class PackageJsonHandler {
       await this.syncField('main:src');
     }
     await this.syncField('types');
-
+    await this.syncFiles();
     await this.syncScripts();
     await this.syncPublishConfig();
     await this.syncDependencies('dependencies');
     await this.syncDependencies('devDependencies');
   }
 
+  private async syncFiles() {
+    const hasUniversalFile = this.targetPkg.files.includes('universal.js');
+    const hasConfigTypeScriptFile =
+      typeof this.targetPkg.configSchema === 'string';
+
+    if (hasUniversalFile || hasConfigTypeScriptFile) {
+      const files = [...this.pkg.files];
+      if (hasUniversalFile) {
+        files.push('universal.js');
+      }
+
+      if (hasConfigTypeScriptFile) {
+        files.push(this.targetPkg.configSchema);
+      }
+
+      await this.syncField('files', { files });
+    } else {
+      await this.syncField('files');
+    }
+  }
+
   // Make sure a field inside package.json is in sync. This mutates the targetObj and writes package.json on change.
   private async syncField(
     fieldName: string,

plugins/github-actions/package.json

@@ -64,6 +64,6 @@
   },
   "files": [
     "dist",
-    "universal"
+    "universal.js"
   ]
 }