I suspect it depends a lot on the llm/harness being used. But when I use Opus/cc or sol/codex, at the end of the turn everything compiles, passes tests, and passes lint. I never even look at code that can't compile. Maybe the LLM is generating weird stuff in-between, but I don't see it.

What you're describing feels like my experience back in 2024/25. Back then I was using a llm auto complete or the chat interface, and I would get weird stuff all the time. (not just gleam but any language).