A lot of linters already have options built in to output CI specific formats, e.g. ruff creates annotations. But these make the output very hard to read in normal use, so it doesn't make sense to have them as a default in the config.

It would be nice if prek would either detect (CI=true || GITHUB_ACTIONS=true) or add an option to turn 'CI mode' on, which would use args_ci instead of args. args_ci could then contain the relevant options.

Adding args_ci as a key will only cause a warning and thus will not break compatibility with pre-commit:
[WARNING] Unexpected key(s) present on https://github.com/scop/pre-commit-shfmt => shfmt: args_ci