I think this was the issue:

https://github.com/prettier/prettier-vscode/issues/278

So vscode seems to run the default formater on save if not explicitly told not to for a specific file type. So we need to add
(to .vscode/settings.json):

  "[yaml]": {
    "editor.defaultFormatter": "esbenp.prettier-vscode",
    "editor.formatOnSave": false
  },

EDIT and add yamllint instead

Well, so its more editor configuration issue perhaps but sill worth addressing so that its the same for everyone. I guess I'm not alone to use vscode

I think we should have prettier in the pre-commit hooks, right? At the same time we should remove it from the other GitHub Actions workflow, so that we do prettier formatting in one single place: in the pre-commit hooks. I can probably take care of that.

I do not use vscode, so I will likely not be the one to take care of that part.

Always good to keep a sanity check on the CI (EDIT: the CI doesn't actually do the formatting; it just checks if it's formatted), as pre-commit hooks are easily bypassed.

Personally, I prefer format-on-save in the editor instead of commit hooks, as commit hooks can slow down committing and negatively affect DX. But I admit they're convenient in a project like this where not everyone will have their editor configured to format-on-save.

Always good to keep a sanity check on the CI, as pre-commit hooks are easily bypassed.

Personally, I prefer format-on-save in the editor instead of commit hooks, as commit hooks can slow down committing and negatively affect DX.

Yes, sorry, I was being unclear, we already have a GitHub Actions workflow job somewhere that does pre-commit run --all-files:

So my plan is:

1. move this out of the workflow it is currently buried in and move it into a more prominent place in its own workflow (right at the beginning so that we do not waste time running any other GitHub checks if pre-commit hooks fail).
2. get prettier into a pre-commit hook
3. remove the other occurrences of prettier formatting so that it is done only once

Installing and running pre-commit hooks locally should not be mandatory, because we run them in a GitHub Actions workflow anyway.

Sounds perfect !

I now realize that while the pre-commit tool is a near de facto convention in Python world, it is far from being the case in JavaScript world and I can not seem to find an equivalent, my grand master plan is foiled! : D

I will keep investigating, there are a bunch of things I would like to improve in the GitHub Actions workflows anyway...

But if I understood correctly the issue was in the IDE settings, right? There isn't anything that needs immediate attention, is there?

Yeah, there is nothing urgent :) Thanks for having a look !