New Feature Implementation Guide

Most features need implementation in three areas:

• Backend: lib/streamlit/
• Frontend: frontend/
• Protobufs: proto/

New features should include:

• Python unit tests in lib/tests
• Vitest unit tests
• E2E Playwright tests in e2e_playwright/

Order of Implementation

1. Protobuf changes in proto/ then run make protobuf

   • New elements: add to proto/streamlit/proto/Element.proto

2. Backend in lib/streamlit/

   • New elements: add to lib/streamlit/__init__.py