The Kozuchi Agent is a language-agnostic, open-weight software repair agent designed to turn bug reports into correct patches with auditable and repeatable runs. It utilizes explicit phases, persistent state, deterministic tools, and a model-independent action interface to handle long horizons and context persistence.
- Using locally hosted Qwen3.5-27B without fine-tuning, the agent resolves 374 out of 500 SWE-bench Verified instances on the official evaluator.
- On Multi-SWE-bench Java, it resolves 41/128 instances (32.03%), ranking first among strict open-weight submissions and fourth overall.
- On Python, it ranks 12th of 135 and first among open-weight systems, with per-phase behavior remaining within +/-5 percentage points across languages.
- Operationally, the CI-operated evaluation pipeline reduces operator touch-points from five to one across heterogeneous internal clusters.
The results indicate that the remaining gap in performance is primarily due to semantic correctness and selection errors rather than edit formatting or proprietary-model access.