diff --git a/packages/core/src/index.ts b/packages/core/src/index.tsx
similarity index 98%
rename from packages/core/src/index.ts
rename to packages/core/src/index.tsx
index ea9e536dc..6ec85e06d 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.tsx
@@ -228,6 +228,6 @@ export function apply(ctx: Context, config: Config) {
         }
       }
 
-      return output.length === 1 ? output[0] : `<message forward>${output.join('\n')}</message>`
+      return output.length === 1 ? output[0] : <message forward>{output.join('\n')}</message>
     })
 }