Composer 2 fails to instantiate for custom subagents

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

composer-2 does not successfully instantiate as a subagent when selected as the model within a .cursor/agents/ definition. Instead, the subagent resolves to inherit.

From tool call:

Invalid model selection “Composer2”… Allowed model slugs: (none)

Steps to Reproduce

Create a custom subagent and assign it the model of composer-2

Operating System

MacOS

Version Information

macOS Sequoia 15.7.1

Apple M3 Pro

Cursor Version: 3.3.30

For AI issues: which model did you use?

Composer 2

Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor

6

Hi Joseph!

You’re on Cursor 3.3.30, so this should already include the newer subagent model-selection behavior. Could you double-check that the custom subagent file uses the canonical model slug exactly like this?

---
name: your-agent
description: Your agent description
model: composer-2
---

The model field should use the exact model ID with the hyphen, composer-2, not Composer2. The current subagents docs show this format here: https://cursor.com/docs/subagents#model-configuration

If your file already has model: composer-2 and this still resolves to inherit or errors with Allowed model slugs: (none), please reply with the exact frontmatter block and the full error text. That would point to a current bug rather than an old-version issue.

7

Hia, frontmatter here:

name: code-writer

model: composer-2

description: Writes code, tests, implementation, fixes. Reads named files, applies engineering standards, reports.

-–

8

Thanks for sharing that. Your frontmatter looks correct.

Since model: composer-2 with the right format still fails on 3.3.30, this is a bug on our end. Could you share the full error output you see when the subagent fails? A screenshot or the complete error text would help our engineering team pinpoint the issue.

Also, if you can grab the Request ID from that failed attempt (three dots menu at the top right of the chat > Copy Request ID), that would speed things up.