Consider fish_add_path for PATH manipulation in shell env fish commands #482
Description
Currently you're setting PATH directly with rv's active ruby paths prepended, there's a lot of space for wonkiness here though (mise struggles with this at present) for fish users who use the blessed path (no pun intended) via fish_add_path. This prepends new paths to a fish_user_paths variable (default a harmless noop if the path is already in the list, though there are options for different behavior such as scooting it to the front on re-add), then prepends that list to your base PATH. It's very flexible, there are options for appending instead of prepending, etc — and it makes it very easy to reason about, robust, and fish-y (and simple code-wise) to ensure certain paths are always at the front, even if the underlying PATH changes during the session. Basically tailor-made for language runtime+package manager tools.
Perhaps this was already considered and rejected for some reason, but it's a feature a lot of non-fish users are often not aware of, so thought I'd throw it out there. I would definitely feel better about that in the env snippet over the direct PATH manipulation. Loving the tool so far though, fantastic work!