For me the most annoying would be a technically correct solution that completely ignores the “higher-level style” of the surrounding code, at the same time defending the chosen solution by referencing some “best practices” that are not really applicable there for some higher-level reasons, or by insignificant performance concerns. Incidentally, LLMs often produce similar problems, only one doesn’t need to politely argue with them.

Writing unit tests, manual validation work, manual testing. Automating Deployments of infrastructure, DNS work, tracking down annoying one off bugs, fixing and validating dependency issues.

Basically this type of maintenance work for any sufficiently complex codebase. (Over 20k LOC)

When I was an QA intern / Software Dev Intern. I did all of that junk.

I don't think I'd trust a senior that didn't do at least some of those things themselves.

I mean, they just want to write code without testing it? Or fixing the bugs that come out of it?

Writing automated tests is not the same thing as testing it. Senior engineers write a lot of code, write some tests, do some manual validation. But its usually far from complete.

Other roles in a software team can handle making a complete test suite for a project, and making sure that it covers all of the required end user functionality. In some shops they will push all of these together into a "fullstack" kind of role, in other software shops they will have dedicated team members who's job it is to handle some of this burden. Interns historically filled in the glue for this.

I think I know what you mean in that the most experienced person often writes proof of concept code that others take over. But I can’t imagine a situation where someone is expected to specialize in everything but the PoC.

Also in my part of the Ruby community most folks love tests and are that their code gets better when they write tests. I’d be sad the day I’m writing code and someone else writes the tests.