[mst]

I've been known to outright use 'nitpick:' - and if it's a nitpick that matters to me personally will tend to supply a diff for them to grab. Keeping the effort required to resolve it in line with how much it matters to the codebase and/or other developers working on it tends to make people a lot happier about the suggestion.

[sibit]

We use the following:

Nit: This is a minor thing. Technically you should do it, but it won’t hugely impact things.

Optional: I think this may be a good idea, but it’s not strictly required.

FYI: I don’t expect you to do this in this PR, but you may find this interesting to think about for the future.

None of these block a merge and anything beyond these type of comments will be a in-person discussion.

[mst]

I think for optional I'd just write "It may be worth ..." and I think I might prefer using 'Maybe:' as a tag because 'Optional:' implies to me "I'm sure this is a good idea but it's not strictly required" which is enough different to seem worth separating the two.

The FYI tag is a fantastic idea and I shall try and remember to use it in future.