Hey, there are likely two things going on here:
- The model picker resets to Composer 2 Fast
This is a known issue. When you open a new chat, the selected model can reset to Composer 2 Fast even if you picked another one or disabled it in settings. The team is aware. For now, the workaround is to manually check the selected model every time you start a new chat.
- Sub-agents use Composer 2 Fast in the background
Even when the main agent is running on Opus 4.6, the built-in sub-agents (Explore, Bash, Browser) use the fast model by default. This is expected. Sub-agents handle helper tasks and pass results back to the main agent. If you want sub-agents to use the selected model too:
- Turn on Max Mode in the chat settings
- Or create custom sub-agents with
model: inheritin.cursor/agents/. Details here: https://cursor.com/docs/subagents
More details on how this works are in this solved thread: Issues with Agent Mode switching to "Fast Mode" models
Also, can you share your Cursor version and a screenshot of the model picker? I want to confirm your settings are applying correctly.