This text is about a new feature in R, staged installation of packages. It may be of interest to package authors and maintainers, and particularly to those who maintain packages that are affected. The problem I often have to run checks for all CRAN and BIOC packages to test the impact of my changes to R. This is to find about my own bugs, but often I also wake up existing bugs in packages or R or find out that some packages rely on undocumented API or …