I configured the sub-agent option in Cursor settings — I selected Composer 2.5, used edit mode, and turned off fast mode. However, when I use Opus 4.8 to do planning, the sub-agent still chooses Composer 2.5 - fast, which causes my usage to burn like crazy.
@Gopher thanks for starting a separate thread, it’s easier to track the IDE case separately from the CLI report.
Confirmed, this is the same known bug, but on the IDE side. The subagent gets resolved to composer-2.5-fast, even though settings have regular Composer 2.5 selected and fast mode is turned off.
There isn’t a reliable workaround on the IDE side right now, because the bug is that the subagent model selection in settings isn’t respected. If you’re using custom subagent definitions with YAML frontmatter, you can try explicitly setting model: inherit so the subagent inherits the parent model, but for built-in subagents when planning on Opus 4.8 this won’t guarantee the result.
One request, if you can, please send the Request ID from the session where the subagent switched to fast Chat menu in the top right > Copy Request ID. This will help with debugging.
For the usage that got billed as fast due to this bug, email [email protected] and they can check it on your account.
I’ll post an update in this thread once there’s a fix.
