Gemini 3.1 Pro vs Kimi K2.7 Code (Workers AI)
Reading a 26.2K-token pull request costs $0.0524 on Gemini 3.1 Pro, 2.1× the $0.0249 it costs on Kimi K2.7 Code (Workers AI). Both sit in the mid-range price tier, so the choice between them is about review quality more than budget. In the benchmark Gemini 3.1 Pro caught 30 percentage points more of the known defects than Kimi K2.7 Code (Workers AI) (95% interval +16 pts to +44 pts, a − b).
Side by side
| Figure | Gemini 3.1 Pro | Kimi K2.7 Code (Workers AI) |
|---|---|---|
| Price tier | Mid-range | Mid-range |
| Bugs caughtshare of known bugs | 67% (better) | 38% |
| False alarmsper clean PR | 0.8 (better) | 2.6 |
| Cost per reviewmeasured | $0.2499 | $0.0567 (better) |
| Cost per bug caught | $0.4134 | $0.0805 (better) |
| Exact linecatches on the expected lines | 89% (better) | 79% |
| Review timemean | 349s (better) | 610s |
| Typical review calllist price | $0.0814 | $0.0346 (better) |
| Input / 1M tokens | $2.00 | $0.95 (better) |
| Output / 1M tokens | $12.00 | $4.00 (better) |
| Context window | 1M | 262.1K |
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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gemini 3.1 Pro | 67% | 67% | 38% | 78% | 88% | 56% | 33% | 67% | 67% | 67% | 100% | 100% | 50% | 50% |
| Kimi K2.7 Code (Workers AI) | 38% | 75% | 26% | 31% | 46% | 19% | 8% | 14% | 42% | 62% | 33% | 46% | 6% | 40% |
Of the 42 known bugs both were scored on, both caught 27 and neither caught 4. Gemini 3.1 Pro caught 5 bugs that Kimi K2.7 Code (Workers AI) missed: 2 in Ruby, 1 in Java, 1 in JavaScript and 1 in Rust, most of them concurrency bugs. Kimi K2.7 Code (Workers AI) caught 6 bugs that Gemini 3.1 Pro missed: 2 in TypeScript, 1 in Go, 1 in JavaScript, 1 in Kotlin and 1 in PHP.
On pull requests with no known bug, Gemini 3.1 Pro raised 0.8 false alarms per review and Kimi K2.7 Code (Workers AI) 2.6. A measured review cost $0.2499 on Gemini 3.1 Pro, 4.4× the cost of $0.0567 on Kimi K2.7 Code (Workers AI).
| Pull request | Language · kind | Gemini 3.1 Pro | Kimi K2.7 Code (Workers AI) |
|---|---|---|---|
| denoland/denoperf(libs/core): poll only ready handles and yield between I/O batches | Rust · Concurrency | 2/2 | 0/5 |
| pinojs/thread-streamrefactor: replace setTimeout with Atomics.waitAsync | JavaScript · Concurrency | 1/1 | 0/8 |
| rails/railsReimplement Action Cable redis adapter with redis-client | Ruby · Logic | 1/1 | 0/5 |
| socketry/asyncBarrier wait in completion order + `Queue#close`. | Ruby · Concurrency | 2/2 | 0/5 |
| jhy/jsoupStore cached child els in Attributes, not field | Java · Concurrency | 1/2 | 0/16 |
| TanStack/queryfix(query-core): fix hydration bugs for already resolved promises | TypeScript · Logic | 0/1 | 2/3 |
| colinhacks/zodfeat(v4): parse input containing reference cycles | TypeScript · Resource handling | 0/1 | 1/3 |
| go-gitea/giteaperf(gitdiff): optimize inline diff highlighting using cache | Go · Error handling | 0/1 | 1/4 |
| kotest/kotestFix DataClassEq comparator | Kotlin · Logic | 0/1 | 1/7 |
| nodejs/undicifeat: add configurable maxPayloadSize for WebSocket | JavaScript · Security | 0/1 | 1/4 |
| symfony/symfony[Security] Allow multiple OIDC discovery endpoints | PHP · Security | 0/1 | 1/4 |
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: Gemini 3.1 Pro and Kimi K2.7 Code (Workers AI).