shiny-golem

Auto-invoked when creating or modifying Shiny layouts using bslib. Governs page types (page_sidebar, page_navbar, page_fillable), cards, value boxes, layout functions, navsets, theming with bs_theme(), and accordion components.

Auto-invoked when validating or QC-ing SDTM/ADaM datasets against CDISC standards — required variables, naming conventions, types, labels, controlled terminology, ISO 8601 dates, missing-value handling, and cross-domain consistency. Use when asked to validate CDISC data, check standards compliance, audit a clinical dataset, or produce a data-validation report before building a Shiny app on clinical data.

Auto-invoked when creating or modifying DT (DataTables) tables in Shiny. Governs DTOutput/renderDT patterns, server-side processing, row selection, proxy updates, formatting, and extensions.

Auto-invoked when creating or modifying a golem-based Shiny application. Governs project scaffolding, module creation, asset management, testing, and deployment within the golem framework.

Auto-invoked when creating or modifying gt tables in Shiny. Governs gt_output/render_gt patterns, the pipeline API, column formatting, conditional styling, spanners, and summary rows for publication-quality tables.

Auto-invoked when creating or modifying a leprechaun-based Shiny application. Governs project scaffolding, a la carte feature addition, module creation, build system, and deployment within the leprechaun framework.

Auto-invoked when creating or modifying interactive plotly charts in Shiny. Governs plotlyOutput/renderPlotly, scattergl for large data, plotlyProxy partial updates (restyle/relayout/addTraces/deleteTraces), event_data with source, ggplotly conversion and cleanup, and crosstalk linked views.

Auto-invoked for any R code request. Governs the write-source-test-validate WORKFLOW and artifact/test structure. Defers Shiny domain patterns (modules, reactives, tables, layout) to the dedicated skills, which take precedence on those topics.

R package development with devtools, testthat, and roxygen2. Use when the user is working on an R package, running tests, writing documentation, or building package infrastructure.

Auto-invoked when working with R6 classes in Shiny applications. Governs R6 class anatomy, reactive bridging patterns, shared state across modules, testing, and when to prefer R6 over reactiveValues.

Auto-invoked when creating or modifying a Shiny application without a framework (golem, rhino, or leprechaun). Governs what is unique to framework-less apps — when to use raw Shiny vs. a framework, R/ auto-sourcing, www/ assets, config without a framework, a startup preflight, deployment, and when to graduate. Defers the three-file layout to the shiny-app-structure rule, modules to shiny-modules, reactivity to reactive-programming, and testing to shiny-testing.

Auto-invoked when creating or modifying reactable tables in Shiny. Governs reactableOutput/renderReactable patterns, colDef customization, row selection, grouping, cell rendering, and programmatic updates.

Auto-invoked when working with reactive primitives in Shiny applications. Governs reactive(), reactiveVal(), reactiveValues(), observe(), observeEvent(), isolate(), req(), debounce(), throttle(), and bindEvent() — with the reactive graph mental model and common invalidation bugs.

Auto-invoked when creating or modifying rhandsontable tables in Shiny. Governs rHandsontableOutput/renderRHandsontable patterns, reading edits back to R, column types and validation, read-only controls, and hot_to_r() usage.

Auto-invoked when creating or modifying a rhino-based Shiny application. Governs project scaffolding, box module imports, view/logic separation, Sass/JS pipelines, and Cypress testing within the rhino framework.

Auto-invoked when moving long-running, uncacheable work off the Shiny main thread so one slow computation does not block other users. Governs ExtendedTask (Shiny 1.8+, the preferred pattern) with bind_task_button(), and future_promise() for older apps. For the mirai backend specifically (workers, mirai_map, HPC), defer to the mirai skill; for capturing async errors, see shiny-error-handling.

Auto-invoked when implementing bookmarkable state in Shiny — saving/restoring app state via URL or server. Governs enableBookmarking(), the function(request) UI signature, bookmarkButton(), setBookmarkExclude(), URL vs server stores, tab/multi-button bookmarking, updateQueryString(), the onBookmark/onRestore/onBookmarked/onRestored callbacks for non-input state, bookmarking with modules, and reproducibility with set.seed/repeatable.

Auto-invoked when caching expensive work in a Shiny app — storing results so they are not recomputed for inputs already seen. Governs bindCache() for reactives and render outputs (with cache-scope correctness), cachem backends (memory/disk/layered), and memoise() for pure functions and data loading. Use after shiny-profiling shows a reactive recomputing with unchanged inputs.

Auto-invoked when implementing file upload or download functionality in Shiny. Governs fileInput/downloadHandler patterns, CSV/Excel/PDF export, multi-file upload, progress indicators, and common pitfalls with temp file paths and MIME types.

Auto-invoked when adding logging or error handling to a Shiny app — log4r setup, the with_error_handling() wrapper, error code catalog + incident ids, req()/validate()/tryCatch() selection, sanitized production errors, the global shiny.error safety net, async (ExtendedTask/mirai) error capture, and the pharma no-PHI-in-logs rule. Use whenever code can fail at runtime (data loads, I/O, DB, parsing, computation, async) or when wiring logging into global.R/server.R/modules.

Auto-invoked when creating or modifying Shiny modules. Governs the NS/moduleServer pattern, namespace rules, reactivity contracts, and inter-module communication to prevent common errors.

Auto-invoked when reviewing or optimizing Shiny application performance. The entry point for a perf review — governs the measure-first workflow, ROI ordering, reactive-graph optimization, data-layer performance (pool/dbplyr/arrow), UI-rendering and memory, plus the cross-cutting anti-pattern quick reference and review checklist. Defers the tool-heavy specializations to dedicated skills: shiny-profiling (profvis/reactlog/tictoc/loadtest), shiny-caching (bindCache/memoise/cachem), shiny-async (ExtendedTask/future).

Auto-invoked when measuring or diagnosing Shiny performance — finding WHERE an app is slow before changing anything. Governs profvis (R flame graphs), reactlog (reactive over-invalidation), shiny.tictoc (JS-side render timing), and shinyloadtest (multi-user load testing). Pairs with the shiny-performance review workflow; reach for shiny-caching / shiny-async once profiling has located the bottleneck.

Auto-invoked when writing or modifying tests for Shiny applications. Governs the three-layer testing hierarchy (unit → testServer → integration), testthat patterns, testServer() for reactive logic, shinytest2::AppDriver for E2E tests, snapshot testing, and dependency injection for reproducible tests.

Auto-invoked when creating or maintaining Shiny apps built with shinydashboard or bs4Dash. Governs dashboardPage/dashboardHeader/dashboardSidebar/dashboardBody, box/tabBox/infoBox/valueBox, sidebarMenu/menuItem with tabItems/tabItem, dynamic sidebars and conditional menu items, programmatic tab switching, and bs4Dash (Bootstrap 4) equivalents.