Project specific snapshot dependencies for R

.init.R

local({
    # https://packagemanager.posit.co/client/#/repos/cran/setup
    url = "https://packagemanager.posit.co/cran/2023-09-01"
    r_version = gsub("\\.\\d+$", "", as.character(getRversion()))
    cran_version = rev(unlist(strsplit(url, "/+")))[1]
    dir = sprintf("~/.R/library/%s-%s", r_version, cran_version)
    message(sprintf("Using %s", url))
    message(sprintf("Using %s", dir))
    options(repos=url)
    if (!dir.exists(dir))
        dir.create(dir, recursive=TRUE)
    .libPaths(dir)
})

.Rprofile

local({
    # Source any possible project-specific .init.R first
    # as it might set .libPaths for custom dependencies.
    # https://gist.github.com/otsaloma/f3b8f61a39bf81df0bcc0e5fd80e9ad1
    components = unlist(strsplit(getwd(), "/"))
    for (i in length(components):1) {
        args = as.list(c(components[1:i], ".init.R"))
        path = do.call(file.path, args)
        if (file.exists(path)) {
            source(path)
            break
        }
    }
})

# Make sure your later .Rprofile doesn't overwrite the above,
# e.g. if you want to set default repos, use the following form.
# options(repos=getOption("repos", "https://cran.rstudio.com/"))

Updated to use RStudio's snapshots as Microsoft's MRAN has been unreliable for a while now.