streamlit

**[REQUIRED]** Use for ALL Streamlit tasks: creating, editing, debugging, beautifying, styling, theming, or optimizing Streamlit applications. Also required for building custom components (inline or packaged), using st.components.v2, or any HTML/JS/CSS component work. Triggers: streamlit, st., dashboard, app.py, beautify, style, CSS, color, background, theme, button, widget styling, custom component, st.components, packaged component, pyproject.toml, asset_dir, CCv2, HTML/JS component.

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.

Review internal documentation (*.md files) against the current codebase state and propose updates for outdated or incorrect information.

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.

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

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.

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.

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.

Use for ALL Streamlit tasks: creating, editing, debugging, beautifying, styling, theming, optimizing, or deploying Streamlit apps. Also custom components, st.components.v2, HTML/JS/CSS work. Discovers and loads version-matched reference docs from the user's installed Streamlit (>=1.57). Triggers: streamlit, st., dashboard, app.py, beautify, style, CSS, color, background, theme, button, widget styling, custom component, st.components, CCv2, session state, performance, cache, fragment, slow rerun, deploy.

Build Streamlit apps with st_pivot_table — a BI-focused pivot table component supporting multi-dimensional pivoting, subtotals, conditional formatting, Excel/CSV/TSV export, drill-down, drag-and-drop, date hierarchies with period-over-period comparisons, synthetic measures (including formula measures), Top N / Bottom N and value-predicate analytical filters (0.5.0+), show-values-as analytical display modes (running total, rank, % of parent, index), values axis placement (values_axis rows/columns, 0.5.0+), multi-field chained sorting (0.5.0+), custom member grouping — combine multiple dimension values into a named group for cleaner rollups (member_groups, 0.6.0+), server-side pre-aggregation for large datasets, and aggregation result memoization for significant latency reduction on display-only reruns (number_format, style, show_values_as — groupby is skipped on repeat renders in threshold_hybrid mode). Use when: user wants a pivot table in Streamlit, mentions streamlit_pivot / st_pivot_table, needs interactiv