Tobi Lutke created an auto/ folder in the Shopify Liquid repository with files: autoresearch.md (his version of program.md) and autoresearch.sh (his bench script).
His program.md defined combined_us as the primary metric, set the modification scope to lib/liquid/*.rb and lib/liquid/tags/*.rb, and required all unit tests to pass. The agent ran roughly experiments and produced a PR with commits.
Results: % faster parse and render time, % fewer memory allocations. On a -year-old Ruby codebase that human engineers had already optimized. The agent found micro-optimizations that humans missed for two decades.