By: Tom Sydney Kerckhove <syd@cs-syd.eu>
Demo: a source change that rebuilds only one crate Adds a doc comment to lib/bombadil/src/lib.rs. With crate2nix's per-crate derivations this rebuilds only the bombadil crate and its workspace dependents; all external dependency crates are unchanged and stay cache hits. Reproduce with nix/experiments/per-crate-cache.sh.