GPT-5.6 Luna Max Underperforms as a Codex Subagent, Dev Finds

daniel_mac8 · x · 2026-08-03

A developer testing various model combinations for an open-source Codex plugin named sol-advisor reported that GPT-5.6 Luna Max performs poorly as a subagent. He speculates this is likely because the model hasn't been post-trained specifically for subagent architectures.

Instead, a combination of GPT-5.6 Sol High (orchestrator) + Sol/Terra (implementers) yielded much better results. The author noted that while Luna Max offers great efficiency and base capabilities, its incompatibility with subagent workflows forced its removal from this specific project.

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