I've think they're also much better at creating useful end to end UI tests than unit or integration tests, but unfortunately those are hard to create self contained environments for without bringing a lot of baggage and docker containers, which not all agent VMs might support yet. Getting headless QT running was a pain too, but now ChatGPT Codex can see screenshots and show them in chat (Claude Code can't show them in the chat for some reason) and it's been generating much better end to end tests than I've seen for unit/integration.