225,000 Lines of Tests, Written and Merged by Agents - Kush Agrawal, Duolingo

Kush Agrawal of Duolingo described a scheduled pipeline on the company's iOS codebase in which coding agents write unit tests for untested code and open pull requests. A lifecycle manager shepherds each PR through CI fixes, AI review and merge, and engineers act as the final reviewers. Since March the system has merged more than 700 pull requests containing about 225,000 lines of tests, and coverage rose from 11% to 24%. The value of the talk is that it reports measured results for the whole loop, not a demo of one agent writing one test. The same structure applies to other large migrations where the work is repetitive and each change can be checked by CI before a human signs off.