Cursor is not using Composer 2.5 as the Explore subagent model

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I’m using Cursor Pro and I have also added my own API keys for OpenAI and Anthropic in the settings.

In the settings, I selected Composer 2.5 as the Explore subagent model. However, as shown in the screenshot, when Cursor creates Explore subagents, it still uses Opus 4.8 Extra High instead of Composer 2.5.

I’m also experiencing a separate issue when trying to use Composer 2.5, which I have already mentioned in another topic.

Could anyone please let me know if I’m missing a setting, or if this is expected behavior? Is there any way to force Cursor to use Composer 2.5 for Explore subagents when using my own API keys?

I would really appreciate any guidance or suggestions.

Thank you.

Steps to Reproduce

BYOK

Screenshots / Screen Recordings

Screenshot 2026-06-18 at 00.17.52.png
Screenshot 2026-06-18 at 00.17.52.png1974×1202 244 KB

Operating System

MacOS

Version Information

Version: 3.7.42
VS Code Extension API: 1.105.1
Commit: 5702c9cfca656d8710fad58402fe37f14345e3a0
Date: 2026-06-15T19:39:42.738Z
Layout: editor
Build Type: Stable
Release Track: Default
Electron: 39.8.1
Chromium: 142.0.7444.265
Node.js: 22.22.1
V8: 14.2.231.22-electron.0
xterm.js: 6.1.0-beta.256
OS: Darwin arm64 25.5.0

Does this stop you from using Cursor

No - Cursor works, but with this issue

3

Screenshot 2026-06-18 at 00.18.13
Screenshot 2026-06-18 at 00.18.13924×1674 70.2 KB

6

Hey, thanks for the report. This isn’t a bug, it’s expected behavior. I’ll explain.

When you have your own API keys enabled OpenAI or Anthropic, Cursor pins all subagents, including Explore, to the parent agent’s model. Your parent is Opus 4.8 Extra High, so the Explore subagents inherit that, and the Explore subagent model picker won’t apply in this mode.

Also, Composer 2.5 is a Cursor proprietary model, so it can’t be served through your own OpenAI or Anthropic keys at all. So even if you picked it, it still wouldn’t work with BYOK enabled.

What you can do is if you want Explore subagents to use Composer 2.5, turn off the API Keys toggles in settings. Then requests will go through your Cursor subscription, and Composer 2.5 will be available. This is the same root cause as in your other thread about This model does not support custom API keys.

Let me know if you’ve got questions.

7

Please note that this issue only occurs when the OpenAI API key is enabled.

If I disable the OpenAI key, the issue disappears. I can use Anthropic without any problems, and the sub-agent correctly uses Composer as expected.