Doing some tests with formatting the whole project and already caught a problem. There are some (+- 6) @ts-ignore comments that stop working because of prettier breaking the ignored line into multiple lines.

Example:

// @ts-ignore todo: should it be this.fragment.nodes[0].node.data instead?
b`${node}.textContent = ${string_literal(this.fragment.nodes[0].data)};`

to

// @ts-ignore todo: should it be this.fragment.nodes[0].node.data instead?
b`${node}.textContent = ${string_literal(
	this.fragment.nodes[0].data
)};`

They are pretty easy to fix. It's just a matter of moving the comment or adding a new one. Anyway, will dig a little deeper to know if these can be properly fixed instead of relying on the ignore comment.

Pre-commit hooks are something that have come up before in #4123, which I closed because I don't really care for them.

The ESLint and Prettier ignore files look like reasonable changes.

Trailing commas are something that I was trying to push for (and I included when writing the prettierrc), but have been mostly abandoned in new code because Rich doesn't liking them. (His argument is that you spend a lot more of your time looking at code than looking at diffs, which is true. But I suspect part of it also is that, when he's left to his own devices, the git history is fairly illegible anyway, but that's part of a different conversation. 😷)

We haven't been running Prettier on new code at all for some time now (partly because it makes a complete mess of our extensive use of template literals), and I'd probably be in favor of completely removing it, now that eslint/typescript integration is in a better place.

Yeah, It's really annoying having to deal with prettier formatting template literals awkwardly to prevent reaching the max line width. Removing prettier would definitely help in this case, but we could also use a bigger line max width which could maybe solve this particular issue. My biggest pain point with prettier in the project at the moment is having everything auto-formatted because, as you said, new code is not being run through prettier and the config is right there, waiting to be properly used 😆.

Anyway, I can modify the PR to focus only on the eslint part, but I still would like to standardize quote type and other small formatting issues (simple formatting/styling related rules only). Just for some cognitive sanity 🙏

About the git hook, yeah, I was thinking about all the dependencies and scripts that it adds, but thought that the advantages would outweigh them. No problem in removing it if the CI lint task is enough 👍