fix: trigger and permissions

.github/workflows/codegen.yml

@@ -1,14 +1,17 @@
 name: Echo Registry Codegen
 
 on:
-  push:
+  pull_request:
     paths:
       - "src/agents/**"
 
 jobs:
   codegen:
     runs-on: ubuntu-latest
 
+    permissions:
+      contents: write # Allows the action to create a pull request
+
     steps:
       - uses: actions/checkout@v4
         with: