small Nix tool I wrote tonight: nix-binary-cache-gc
https://codeberg.org/cyclopentane/nix-binary-cache-gc
Essentially it's a garbage collector for static binary caches (i.e. directories that statically contain .narinfo and .nar files and that are served by a regular webserver). It's dependency-aware, and uses the #tvix / #snix crates.
(Previously I just deleted all files older than a certain amount of days with find and rm, but that tore up the dependency graphs on the cache and regularly caused errors)