How should metals start mill?

[Quafadas]

I happened across this PR:
https://github.com/scalameta/metals/pull/8034/changes

As I read it, to run mill commands, metals;

• prefers using a workspace script
• falls back to using a wrapper script it downloads / fetches

As far as I can tell, this strategy follows the recommendations set out in mills own documentation.
https://mill-build.org/mill/cli/installation-ide.html

But a brief discord conversation didn't seem to generate universal happiness with this solution.

while I think we should all have mill on the $PATH, I still like to have a ./mill in my projects, so that CI can use it. Do I want a tool like IDEA or Metals use my personal local script? Perhaps not.

Suggestions to get mill on the path included,
https://mill-build.org/mill/cli/installation-ide.html#_global_installation
https://github.com/com-lihaoyi/homebrew-mill

but it's not clear these are relevant for metals, which follows the strategy above and does not, I believe, use the PATH.

My question, is whether there is a universal consensus on how metals should launch mill?

My reading of the PR and mill's docs, is that metals assumes the user has followed mill's documentation and prefers that approach. Metals falls back to it's own fallback script otherwise. This seems reasonable - from what I can tell, the existing solution makes sense, but the discussion is recorded for posterity.

[lihaoyi]

The current recommended way is via a bootstrap script for users, and Metals should probably follow suit for consistency

[lihaoyi]

Separately I'd like to try and standardize a way to install Mill on the PATH, since now that we support single-file scripts having it available ad-hoc outside a project would be useful. But for actual projects, having a bootstrap script with a pinned version will likely remain the preferred installation method

[Quafadas]

This makes sense, so in summary: the status quo is the (current) best state: nothing to do.

One thing might be useful in docs - knowledge that metals will use mill.bat on windows and mill on not-windows. Perhaps I'll add that tiny snippet in a doc PR. Coming soon (tm).