I noticed that the parinfer project is archived. https://github.com/shaunlebron/parinfer Has development on the project stopped? Or is it simply considered complete?

I would say that repo acts as the spec for Parinfer and I believe Shaun considers it complete (with the caveat that smart mode as specified is really hard for most text editors to do). There are still implementations of parinfer being actively maintained however. At the very least: https://github.com/eraserhd/parinfer-rust

I looked at Atom and VS Code, but those both had last commits on master 2 years ago ¯\(ツ)/¯

I use parinfer-rust, works great.

i wrote an implementation in cljc from scratch if anyone's interested https://github.com/oakes/parinferish not 100% conforming, as the name implies =D

I let it collect dust for too long.

Although, I must thank some contributors who made some PRs and issues and got me to put it on my list again.