Task still rejects composer-2.5 in the IDE, allowlist is only composer-2.5-fast

[Olivier_Berthet1 (Olivier Berthet)]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Closed Help thread 166082 already has this error from July. I hit it again today in the Cursor IDE Task tool, 17 Sep 2026, not CLI.

How do I spawn a non-fast composer-2.5 Task subagent? Only composer-2.5-fast is accepted

I’m trying to use regular Composer 2.5 (not fast) for small Task subagents, and I can’t find a way to do it. This isn’t the Cursor Desktop “Agents” UI or an Agents folder workflow. I’m in the Cursor agent/CLI flow, where the parent agent dispatches work via the Task tool (subagent_type: generalPurpose, etc.), with an explicit model parameter. I have tried passing this to Task for the model value: composer-2.5 → rejected composer-2.5[fast=false] → rejected composer-2.5-fast → works Rejection…

I set the Task model to composer-2.5. Rejected. I retried the same call unchanged. Rejected again. The allowed list returned one slug: composer-2.5-fast.

A grok 4.6 model (cursor-grok-4.6-high) was accepted in the same session after I named it in chat.

Please treat composer-2.5 as a valid inline Task slug, not only the fast variant.

OS: Windows 10.0.26200
Cursor: 3.20.21 (f09fca384ceca23f7bf21f9c23655b162641d740)
Request ID: 2227871c-3eba-43c1-ae41-7330e131ace7

Invalid model selection “composer-2.5”. Model could not be resolved to a valid subagent model.
Allowed model slugs:

• composer-2.5-fast

Related open bug (CLI/SDK whitelist, same one-slug shape):

Cursor CLI: can't choose model for subagents

Where does the bug appear (feature/product)? Cursor CLI Describe the Bug Can’t choose subagent model. Task tool only whitelists “composer-2.5-fast”. Steps to Reproduce Ask “what models I can use in Task tool?” or create a subagent with specified model and ask what model it is using in the prompt. Expected Behavior Should support all models Screenshots / Screen Recordings [Screenshot 2026-05-26 172300.png] Operating System Windows 10/11 Version Information CLI Version 2026.05.24-dd…

Steps to Reproduce

I set the Task model to composer-2.5. Rejected. I retried the same call unchanged. Rejected again. The allowed list returned one slug: composer-2.5-fast.

Expected Behavior

Please treat composer-2.5 as a valid inline Task slug, not only the fast variant.

Operating System

Windows 10/11

Version Information

3.20.21 (f09fca384ceca23f7bf21f9c23655b162641d740)

For AI issues: which model did you use?

composer-2.5 (also cursor-grok-4.6-high accepted after named in chat)

For AI issues: add Request ID with privacy disabled

2227871c-3eba-43c1-ae41-7330e131ace7

Additional Information

Related CLI/SDK whitelist thread is 161628. Closed Help thread is 166082. OS: Windows 10.0.26200

Does this stop you from using Cursor

No - Cursor works, but with this issue

[Colin]

Hey @Olivier_Berthet1, thanks for the detailed report and for linking the earlier thread.

You’re reading the behavior right: the inline model list for Task mirrors your model picker with one variant per model family, and Composer 2.5 defaults to Fast, so only composer-2.5-fast shows up. This is a known limitation the team is tracking, and I’ve added your report to it.

Two ways to get standard Composer 2.5 subagents today:

1. In the model picker, select Composer 2.5 and turn Fast off, then start a fresh chat. composer-2.5 will then appear in the allowed list alongside composer-2.5-fast.
2. Define a custom subagent (for example .cursor/agents/composer-standard.md) with model: composer-2.5[fast=false] in the frontmatter and dispatch it by name. The bracket syntax is honored there, just not in the inline Task parameter.