DeepSeek V4 Flash (Workers AI) vs Gemini 3.1 Pro
Reading a 26.2K-token pull request costs $0.0524 on Gemini 3.1 Pro, 4.5× the $0.0115 it costs on DeepSeek V4 Flash (Workers AI). DeepSeek V4 Flash (Workers AI) is a economy model and Gemini 3.1 Pro a mid-range one. The benchmark cannot separate their recall: DeepSeek V4 Flash (Workers AI) minus Gemini 3.1 Pro is −19 pts (95% interval −30 pts to −8 pts).
Side by side
| Figure | DeepSeek V4 Flash (Workers AI) | Gemini 3.1 Pro |
|---|---|---|
| Price tier | Economy | Mid-range |
| Bugs caughtshare of known bugs | 49% | 67% (better) |
| False alarmsper clean PR | 1.3 | 0.8 (better) |
| Cost per reviewmeasured | $0.0178 (better) | $0.2499 |
| Cost per bug caught | $0.0309 (better) | $0.4134 |
| Exact linecatches on the expected lines | 88% | 89% (better) |
| Review timemean | 137s (better) | 349s |
| Typical review calllist price | $0.0147 (better) | $0.0814 |
| Input / 1M tokens | $0.44 (better) | $2.00 |
| Output / 1M tokens | $1.32 (better) | $12.00 |
| Context window | 1M | 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| DeepSeek V4 Flash (Workers AI) | 49% | 46% | 25% | 55% | 46% | 22% | 56% | 61% | 78% | 61% | 44% | 67% | 50% | 0% |
| Gemini 3.1 Pro | 67% | 67% | 38% | 78% | 88% | 56% | 33% | 67% | 67% | 67% | 100% | 100% | 50% | 50% |
Of the 42 known bugs both were scored on, both caught 27 and neither caught 7. DeepSeek V4 Flash (Workers AI) caught 3 bugs that Gemini 3.1 Pro missed: 1 in JavaScript, 1 in Kotlin and 1 in PHP, most of them security bugs. Gemini 3.1 Pro caught 5 bugs that DeepSeek V4 Flash (Workers AI) missed: 1 in C, 1 in C#, 1 in Ruby, 1 in Rust and 1 in TypeScript.
On pull requests with no known bug, DeepSeek V4 Flash (Workers AI) raised 1.3 false alarms per review and Gemini 3.1 Pro 0.8. A measured review cost $0.0178 on DeepSeek V4 Flash (Workers AI), 93% less than $0.2499 on Gemini 3.1 Pro.
| Pull request | Language · kind | DeepSeek V4 Flash (Workers AI) | Gemini 3.1 Pro |
|---|---|---|---|
| nodejs/undicifeat: add configurable maxPayloadSize for WebSocket | JavaScript · Security | 2/3 | 0/1 |
| kotest/kotestFix DataClassEq comparator | Kotlin · Logic | 1/3 | 0/1 |
| symfony/symfony[Security] Allow multiple OIDC discovery endpoints | PHP · Security | 1/3 | 0/1 |
| OrchardCMS/OrchardCoreSimplify using `StringValues` in Liquid templates | C# · Security | 0/3 | 2/2 |
| c-ares/c-aresEvent Thread could stall when not notified of new queries on existing connections that are in a bad state | C · Resource handling | 0/3 | 1/2 |
| nushell/nushellreorganize nushell configuration | Rust · Error handling | 0/4 | 1/2 |
| rails/railsReimplement Action Cable redis adapter with redis-client | Ruby · Logic | 0/3 | 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: DeepSeek V4 Flash (Workers AI) and Gemini 3.1 Pro.