Writes product and tech specs for new Streamlit features. Use when designing new API commands, widgets, or significant changes that need team review before implementation.

Review internal documentation (*.md files) against the current codebase state and propose updates for outdated or incorrect information.

Explains Streamlit's internal architecture including backend runtime, frontend rendering, and WebSocket communication. Use when debugging cross-layer issues, understanding how features work end-to-end, planning architectural changes, or onboarding to the codebase. Covers ForwardMsg/BackMsg protocol, script rerun model, element tree, widget state management, and more.

Uploads agent-generated artifacts (specs, plans, learnings) to the streamlit.wiki for sharing via PR comments. Use when you have agent artifacts to share with reviewers.

Runs Python unit tests with coverage, analyzes coverage reports, and implements meaningful tests to increase coverage by ~0.2%. Use when you want to systematically improve Python test coverage with high-value test cases.

Runs frontend unit tests with coverage, analyzes coverage reports, and implements meaningful tests to increase coverage by ~0.2%. Use when you want to systematically improve frontend test coverage with high-value test cases.

Implement a feature from a product/tech spec, URL, or GitHub issue. Reads the spec, implements the feature following Streamlit patterns, and creates a merge-ready PR. Use when given a spec folder path, document URL, or issue link to implement.

Generates polished website release notes between two git tags for docs.streamlit.io. Use when preparing a new Streamlit release or reviewing changes between versions.

Analyze and fix failed GitHub Actions CI jobs for the current branch/PR. Use when CI checks fail, PR checks show failures, or you need to diagnose lint/type/test errors and verify fixes locally.

Diagnose and fix flaky Playwright e2e tests. Use when tests fail intermittently, show timeout errors, have snapshot mismatches, or exhibit browser-specific failures.

Finalizes branch changes for merging by simplifying code, running checks, reviewing changes, and creating a PR if needed. Use when ready to merge changes into the target branch.

Lists available make commands for Streamlit development. Use for build, test, lint, or format tasks.

Debug Streamlit frontend and backend changes using make debug with hot-reload. Use when testing code changes, investigating bugs, checking UI behavior, or needing screenshots of the running app.

Creates a draft pull request on GitHub with proper labels, branch naming, and description formatting. Use when changes are ready to be submitted as a PR to the streamlit/streamlit repository.

Validates all code changes before committing by running format, lint, type, and unit test checks. Use after making backend (Python) or frontend (TypeScript) changes, before committing or finishing a work session.

Assesses whether branch or PR changes are high-risk for externally hosted or embedded Streamlit usage and recommends whether external e2e coverage with `@pytest.mark.external_test` is needed. Use during code review, PR triage, or test planning when changes touch routing, auth, websocket/session behavior, embedding, assets, cross-origin behavior, SiS/Snowflake runtime, storage, or security headers.

Address all valid review comments on a PR for the current branch in the streamlit/streamlit repo. Covers both inline review comments and general PR (issue) comments. Use when a PR has reviewer feedback to address, including code changes, style fixes, and documentation updates.

Run e2e tests for the API service. Use when the user wants to run API E2E tests.

Use this skill when making changes to the enterprise submodule (`.source/`) or enterprise packages (`enterprise/packages/*`), or when the enterprise submodule needs to be initialized/updated.

Skill for integrating Better Auth - the comprehensive TypeScript authentication framework.

Use when creating HTML email templates with React components - welcome emails, password resets, notifications, order confirmations, newsletters, or transactional emails.

Use when building email features, emails going to spam, high bounce rates, setting up SPF/DKIM/DMARC authentication, implementing email capture, ensuring compliance (CAN-SPAM, GDPR, CASL), handling webhooks, retry logic, or deciding transactional vs marketing.

## Trigger Conditions

Update all dependencies across frontend and backend projects. Reads changelogs for breaking changes, checks affected code, runs tests, and provides a summary. Use when updating npm dependencies across the monorepo.