GoKawiilGPT-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.
The short answer
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.
How we ran it
We reused the setup from the Astra vs Sol post so the numbers line up.
The pull requests are the 50 public benchmark PRs in the AI-Code-Review-Evals organization, ten each from Cal.com, Sentry, Discourse, Keycloak and Grafana. Each one introduces defects against a clean base branch.
Luna and Astra got the same prompt on the same diffs. The prompt asks for correctness, security, concurrency, resource and error-handling bugs, and excludes style, naming, docs and test suggestions. Each model returned structured findings.
Verification works the same way as before. For every pull request, the findings from Astra, Sol, Luna and the public Entelligence reviewer comments go into one anonymized list. GPT-6 Astra and GPT-5.6 Sol each judge that list separately against the diff, grouping duplicates and deciding whether each issue is a real bug. An issue only counts as verified when both judges call it real. They agreed on 91% of findings, and 143 distinct bugs passed both.
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