Ask HN: What do you think are the fundamental skills for software engineers?

As the software engineering landscape evolves, what do you think are the non-negotiable, fundamental skills every software engineer should have?

I've compiled my thoughts on this in a recent post (https://ruslanspivak.com/bb02/), but I'm curious to see what others think.

NOTE: The post contains a link to a page with Amazon affiliate book links, which you can ignore if you prefer.