GPT-5.6 Luna vs. GPT-6 Astra: Is a $1.20 Model Good Enough for Code Review?

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GPT-5.6 Luna costs $0.20 per million input tokens and $1.20 per million output tokens. GPT-6 Astra costs $10 and $50. On the same pull requests, one Luna review cost $0.0041 and one Astra review cost $0.113, a 28x difference.

Our last post compared Astra with GPT-5.6 Sol. This time we wanted to know what you give up if every pull request goes through the cheapest model.

Luna found 69 verified bugs across 50 pull requests. Astra found 92. Luna cost $0.20 for the whole run and Astra cost $5.66. Luna was wrong more often, with 24 of its 93 findings failing verification against Astra’s 4 of 96, and it found 9 of the 24 security bugs where Astra found 19.

Our read: Luna is good enough for everyday correctness bugs at that price, and we wouldn’t let it review authentication or permission code on its own.

(Excerpted from the original; full article via the source link below.)

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