implementing-new-features

Original：🇺🇸 English

Translated

Implementation guide for new Streamlit features. Use when adding new elements, widgets, or features that span backend, frontend, and protobufs.

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Added on2026-02-11

NPX Install

npx skill4agent add streamlit/streamlit implementing-new-features

Most features need implementation in three areas:

New features should include:

Protobuf changes in

proto/

then run

make protobuf

Backend in
```
lib/streamlit/
```
- New elements: add to
```
lib/streamlit/__init__.py
```

Python unit tests in

lib/tests

Run:

uv run pytest lib/tests/streamlit/the_test_name.py

Frontend in

frontend/

New elements: add to

frontend/lib/src/components/core/Block/ElementNodeRenderer.tsx

Vitest tests in

*.test.tsx

Run:

cd frontend && yarn vitest lib/src/components/elements/NewElement/NewElement.test.tsx

E2E Playwright tests in

e2e_playwright/

Run:

make run-e2e-test e2e_playwright/name_of_the_test.py