Opus 5.5 ported HAProxy to Rust in 9.5 hours
Boris Cherny had Opus 5.5 and Fable 5.1 each port HAProxy from C to Rust. Both passed nearly all of HAProxy's tests, but Opus finished faster and for 51% less money.
Receipts
Boris Cherny had two models port HAProxy from C to Rust
Cherny ran Opus 5.5 and Fable 5.1 head to head on porting HAProxy from C to Rust, and says both passed nearly all of HAProxy's tests. Opus 5.5 finished in 9.5 hours against Fable 5.1's 12, for 51% less cost.
Opus 5.5 is a really good model. It's been my daily driver the last few weeks.
Next.js evals: three models tied at 97%, Grok 4.7 cheaper at 94%
Guillermo Rauch posted fresh Next.js eval results: Opus 5.5, GPT-6 Sol and Fable 5.1 all at 97%, Grok 4.7 at 94%. Rauch notes Grok is 2x to 7x cheaper. Among the three tied models, Next.js says Opus ranks first on average cost.
Kenton Varda says early access testers mistook Opus 5.5 for a new Fable
Varda, who says he still reads the code AI writes, rates Opus 5.5 similar in quality to Fable but with clearer comments and far less invented jargon. He has not been happy with code quality from any GPT model, including Astra, though he finds them better at spotting and diagnosing bugs.
In early access a bunch of us were convinced it was a new Fable, totally shocked when they told us it was Opus.