Fun fact: Design work on Kimi Delta Attention started in Jan 2025. It took a year and a half of relentless iteration and fighting through scaling problems to bring it to the frontier. Kudos to the amazing team!

Have seen some questions about the updated classifiers and wanted to clarify. As with the original classifiers, a small fraction of routine coding and debugging tasks will be flagged and fall back to Opus. We're excited for guys to get access back tomorrow.

Update: Lobehub has integrated the current most powerful Claude Sonnet model, Sonnet 5. This new model features a 1M context window, a default output length of 64K, supports up to 128K outputs, and fully supports adaptive thinking. On BrowseComp and OSWorld-Verified, Sonnet 5 shows major improvements over Sonnet 4.6. Although Opus 4.8 remains the preferred model for pursuing higher accuracy on these tasks, Sonnet 5 offers developers a cheaper option with quality far superior to previous versions. At the same time, we are also announcing a $2 free credit for users to try this model! Go try it now! 🚀

For context, Tianhang left Qwen before Qwen 2.5 over office-attendance disagreements, despite being the only Qwen team member based in Seattle at the time. I only got to know most of the Qwen researchers after Qwen 2.5. They are the people who made the team what it is today. I’ve also seen contributions from @ChujieZheng. It’s funny how people who joined later but contributed heavily are sometimes treated as too junior to comment on those who came before them. We’re living in a fast-moving era. What matters is contribution, not tenure, titles, or who happened to arrive first. Also, the first person to do something is an explorer, but not automatically a leader. I don’t care who is called the leader. I care about who is actually doing great work.

@ChujieZheng i was responsible for delivery of the RL ckpt. so i think head of rl is accurate description for people to quickly understand what i do yes i left after first qwen release. my linkedin has exact details of what i did for years. welcome if interested