GPT-5.5 and Opus 4.7 are comparable when using the same harness mini-swe-agent. GPT-5.5 demonstrates a significant performance delta only when integrated with the Codex module. We hypothesize that the superior performance of Opus 4.7 on mini-swe-agent relative to the more complex Claude Code harness stems from the tight feedback loop (edit-run-check), well suited for the CAD generation task.