GPT-5.6 Sol vs GPT-6 Luna
Reading a 26.2K-token pull request costs $0.1048 on GPT-5.6 Sol, 40× the $0.0026 it costs on GPT-6 Luna. GPT-5.6 Sol is a frontier model and GPT-6 Luna a economy one. The benchmark cannot separate their recall: GPT-5.6 Sol minus GPT-6 Luna is +5 pts (95% interval −6 pts to +17 pts).
Side by side
| Figure | GPT-5.6 Sol | GPT-6 Luna |
|---|---|---|
| Price tier | Frontier | Economy |
| Bugs caughtshare of known bugs | 72% (better) | 67% |
| False alarmsper clean PR | 1.2 | 0.7 (better) |
| Cost per reviewmeasured | $0.1127 | $0.0028 (better) |
| Cost per bug caught | $0.1732 | $0.0046 (better) |
| Exact linecatches on the expected lines | 92% | 97% (better) |
| Review timemean | 50s | 29s (better) |
| Typical review calllist price | $0.1532 | $0.0038 (better) |
| Input / 1M tokens | $4.00 | $0.10 (better) |
| Output / 1M tokens | $20.00 | $0.50 (better) |
| Context window | 1.1M | 1.1M |
Head to head
The known bugs both were scored on, by who caught each in at least one run.
By language
| Model | All | TypeScript6 bugs | Go4 bugs | Java4 bugs | Rust4 bugs | C#3 bugs | JavaScript3 bugs | Kotlin3 bugs | PHP3 bugs | Python3 bugs | Ruby3 bugs | Swift3 bugs | C++2 bugs | C1 bug |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| GPT-5.6 Sol | 72% | 67% | 50% | 69% | 75% | 56% | 100% | 67% | 100% | 100% | 67% | 100% | 50% | 0% |
| GPT-6 Luna | 67% | 83% | 25% | 65% | 75% | 56% | 67% | 67% | 67% | 100% | 67% | 100% | 50% | 0% |
Of the 42 known bugs both were scored on, both caught 27 and neither caught 8. GPT-5.6 Sol caught 5 bugs that GPT-6 Luna missed: 1 in Go, 1 in Java, 1 in JavaScript, 1 in PHP and 1 in Ruby. GPT-6 Luna caught 2 bugs that GPT-5.6 Sol missed: 1 in Ruby and 1 in TypeScript.
On pull requests with no known bug, GPT-5.6 Sol raised 1.2 false alarms per review and GPT-6 Luna 0.7. A measured review cost $0.1127 on GPT-5.6 Sol, 40× the cost of $0.0028 on GPT-6 Luna.
| Pull request | Language · kind | GPT-5.6 Sol | GPT-6 Luna |
|---|---|---|---|
| golang/gocrypto/tls: add LocalCertificate to ConnectionState | Go · Logic | 1/1 | 0/1 |
| sindresorhus/p-throttleAdd `weight` option | JavaScript · Logic | 1/1 | 0/1 |
| socketry/asyncBarrier wait in completion order + `Queue#close`. | Ruby · Concurrency | 1/1 | 0/1 |
| symfony/symfony[Security] Allow multiple OIDC discovery endpoints | PHP · Security | 1/1 | 0/1 |
| jhy/jsoupStore cached child els in Attributes, not field | Java · Concurrency | 1/6 | 0/2 |
| rails/railsReimplement Action Cable redis adapter with redis-client | Ruby · Logic | 0/1 | 1/1 |
| trpc/trpcfix(server): pass maxDurationMs timeout signal to subscription handlers | TypeScript · Concurrency | 0/1 | 1/1 |
Defects caught over all runs: a PR reviewed three times with one known bug shows 3/3 when it was caught every time.
Every bug each was scored on: GPT-5.6 Sol and GPT-6 Luna.