What are AI coding agents like Devin and SWE-agent?

AI coding agents are autonomous systems that can plan, write, execute, and debug code across multiple steps without constant human guidance. Devin (by Cognition) and SWE-agent (Princeton) can take a GitHub issue, write code to fix it, run tests, and open a PR. These are more powerful than inline copilots but less reliable — they work best on well-scoped tasks with clear acceptance criteria and automated test suites.