question about `runs.post` caching, and readme note

[peterbecich]

Does the Magic Nix Cache cache what has been successfully built if the job fails or is canceled? I am guessing yes based on: subscribe_uds_post_build_hook https://github.com/DeterminateSystems/magic-nix-cache/blob/296e9dc1af825f2c961c1caa61832609b1bf8a49/magic-nix-cache/src/pbh.rs#L21 Is that implemented with a runs.post hook? https://docs.github.com/en/actions/sharing-automations/creating-actions/metadata-syntax-for-github-actions#runspost

If true, can we add this detail to the readme? Thank you