Develop R packages following best practices with devtools, roxygen2, and testthat. Supports both tidyverse and base R coding styles. Use when creating new R packages, adding functions to packages, writing documentation, creating tests, managing dependencies, building vignettes, creating package websites with pkgdown, or preparing for CRAN submission. Triggers on R package development tasks, DESCRIPTION file editing, roxygen2 documentation, testthat testing, pkgdown website setup, or R CMD check issues.