Harness engineering is search-based software engineering. What did we learn the first time?

• Local optima: stop retrying the same approach; change the search strategy.
• Fitness functions: passing tests is not enough; maintainability and future cost of change matter.
• Premature convergence and overfitting: more agents do not guarantee diversity, and passing known evals does not guarantee generalisation.
• Representation matters: some structural improvements require temporarily broken intermediate states.
• The open work is measuring architectural quality, detecting stagnation and testing which SBSE techniques actually transfer to LLM coding agents.
• https://codykenb.github.io/harness-sbse/
• https://claude.dev/blog/automating-eval-design-and-hillclimbing/

• #coding-agents
• #harness-engineering
• #sbse
• #software-engineering