CLI subagents changing model to composer 2.5 fast mode by itself

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Hey, I’ll give an honest answer because there’s a nuance here.

The mechanism itself, explicitly setting the option via fast=false, is correct. But right now we only have a confirmed working case at the SDK level using params: [{ id: "fast", value: "false" }], you can see it in this thread: Cursor CLI calling `composer2-fast` despite always calling with `composer2. I can’t confirm that the bracket syntax composer-2.5[fast=false] in the .cursor/agents/ frontmatter reliably forces non-fast on the CLI. We don’t have confirmation for that yet. So it’s a workaround worth trying, but it’s not a guaranteed fix.

A couple clarifications:

  • For inheriting the parent model, it’s more reliable to fully remove the model field from the frontmatter, instead of setting model: inherit, since inherit doesn’t always work on the CLI.
  • As of today, the only stable confirmed path for non-fast is the SDK with fast: false. On the CLI, routing into fast still happens sometimes, and we’re tracking it.

Try the bracket variant on your setup and verify in the dashboard which model actually ran. If it still routes to composer-2.5-fast, send the Request ID from the parent chat three dots > Copy Request ID. Once there’s an update on a fix, I’ll post it in the thread.