Wrong subagent or build from plan agent being used

Support Bug Reports
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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Sometimes, when I have Auto selected and I press “Build” from a plan, it uses the model that was used to create the plan instead (ex. GPT-5.5 Medium).

Sometimes even if “Explore subagent model” is set to “Composer Fast 2.5”, it uses random models like “Sonnet 4.6 Medium”.

Because of these issues a lot of my API usage included in the plan has been depleated.

Steps to Reproduce

It seems random, sometimes it uses the expected model, sometimes it uses whatever model it wants.

Expected Behavior

The correct model is used in both cases.

Screenshots / Screen Recordings

Screenshot 2026-06-22 at 16.36.56.png
Screenshot 2026-06-22 at 16.36.56.png1826×380 67 KB

Operating System

MacOS

Version Information

Version: 3.8.11
VS Code Extension API: 1.105.1
Commit: e56ad3440df06d22ca7501e65fd518e905486ef0
Date: 2026-06-18T01:40:18.333Z
Layout: editor
Build Type: Stable
Release Track: Default
Electron: 40.10.3
Chromium: 144.0.7559.236
Node.js: 24.15.0
V8: 14.4.258.32-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

5

Hey, thanks for the report. There are actually two different known bugs here, I’ll reply to each one.

  1. Build uses the plan model instead of Auto

The Build control has its own model picker, and by default it’s set to Inherit Agent model. That means it inherits the last Composer model, usually the one the plan was created with, like GPT-5.5, not the Auto you see. As a workaround, click the model picker on the Build or plan-execution row and explicitly pick Auto or Composer instead of Inherit. This is a known bug, no ETA for a fix yet.

  1. Explore subagent model is ignored and Sonnet runs

The Explore subagent model setting only affects the Explore subagent. Other built-in subagents have a hardcoded model, and task subagents inherit the parent agent model. That’s why you see Sonnet 4.6 Medium even if you set Composer Fast 2.5. This is also a known bug.

For custom subagents defined in .cursor/agents or .claude/agents, you can pin the model using bracket syntax in the frontmatter, for example:

model: composer-2.5[fast=false]

There isn’t a clean workaround for the built-in picker in Settings yet.

On usage, I get it. That part is something the team handles case by case via [email protected], so reach out to them if you want to dig into it for your account.

I’ll post an update in the thread when we hear more on either bug.

6

Hi,

I am facing same issue in cursor GUI and unable to usage agent chat for free tier, is there any solution to this

Tried rules and disabling Models but nothing worked

composer 2.5 by default getting converted to composer 2.5-fast in agent window within seconds

7

Hey @nikhilbohra21, your case is a bit different from what the thread author is reporting. In their case it’s about Build from the plan and the Explore subagent. In your case it looks like the agent window Composer 2.5 is mostly switching by itself to Composer 2.5-fast, and you’re also on the free tier, which is a separate situation.

To avoid mixing different cases in one thread, please start a separate thread for your issue. Also add these details:

  • Your Cursor version (Help > About) and your OS
  • A screenshot showing the selected model and what it switches to
  • The Request ID for a request where the model switched to fast (chat menu in the top right > Copy Request ID)
  • Please confirm if this happens in a normal chat or when running a subagent

With that info, we can figure out what’s happening in your case. Drop the link to the new thread here if you want.