Build your own harness, folks. Reading papers like this makes me realize how underexplored harness engineering really is. The authors find that on whole-repository migration, GPT-5.6 Sol goes from 6.5% to 31.0% when Codex is replaced with the HERMES harness, with the same model and effort setting. The gain comes from the harness. HERMES pairs each repository component with a resident LLM that knows its own code and dependencies. A dependency-aware step decides which components to activate,…