AGENTS.md

This project ships a Rust CLI that provisions R on Ubuntu and automates reverse dependency checks for R packages.

Architectural outline

src/lib.rs exposes run(), which wires together argument parsing, workspace creation, R toolchain resolution and installation, repository preparation, and the final xfun::rev_check() invocation.
src/cli.rs uses clap for argument parsing. Keep the CLI surface lean; new flags require corresponding documentation updates.
src/r_version.rs talks to https://api.r-hub.io/rversions/resolve. Changes here must continue to support setup-r style shorthand (e.g. release, oldrel-1). Prefer blocking reqwest to avoid pulling tokio into the call
src/r_install.rs downloads the .deb, installs prerequisites, and creates /usr/local/bin symlinks with xshell. Assume Ubuntu-only environments.
src/revdep.rs clones repositories, writes an install bootstrap R script, and invokes xfun::rev_check() after preinstalling binaries from Posit Package Manager. Keep both scripts deterministic and avoid editing user repositories outside revdep/. Only the interactive xfun::rev_check() phase should reach stdout.
src/workspace.rs manages workspace directories. Remote clones default to <repo> alongside the current working directory, while temporary files live under revdeprun-work/. Respect user-provided workspaces without deleting their content.
src/util.rs holds shared helpers; keep it small and well-tested.

Tests (cargo test) and doc tests should run on macOS and Linux without needing R. Avoid adding integration tests that require R installation.
Reuse xshell for shell calls instead of std::process::Command directly.
Keep new dependencies minimal and compatible with the MSRV declared in Cargo.toml.
If the revdep recipe changes, reflect it in build_revdep_script and add a regression test that checks for critical fragments.
README changes must mirror CLI options and behavioral adjustments.
Update CHANGELOG.md using Keep a Changelog conventions.