Growing Harness Turns Task Feedback into Reusable Agent Code
Moving recurring control out of context and into code means smaller models can run competent agents at a fraction of the inference cost, and the grown harness accumulates capability as reusable specialist code rather than prompts. Teams building agents on cost-sensitive or small-model deployments can apply this failure-guided repair loop directly, especially where Tool-Calling baselines collapse at the 4B scale. The ablations on trace-local edits, joint repair and gate rollback give a concrete recipe for anyone attempting similar harness-growing systems.