The Root Agent automatically switches/toggles to Fast mode without any user interaction

Support Bug Reports
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

The Root Agent automatically switches/toggles to Fast mode without any user interaction.

While using the agent, the mode can unexpectedly change to Fast even though I did not click the Fast toggle or otherwise request a mode change. This makes agent behavior unpredictable and can unintentionally change how requests are processed.

Steps to Reproduce

Open Cursor IDE.
Start a conversation/task using the Root Agent.
Ensure Fast mode is not enabled.
Continue interacting with the agent normally.
Observe that the Root Agent may switch to Fast mode automatically, without clicking or interacting with the Fast mode control.

Expected Behavior

The Root Agent’s Fast mode should only be enabled or disabled through explicit user interaction.

If Fast mode is currently disabled, it should remain disabled until I intentionally enable it. Cursor should not silently change this setting while an agent session is running.

Operating System

MacOS

Version Information

Version: 3.15.6
VS Code Extension API: 1.128.0
Commit: a1f686545fd0ce8917bbd2449f733551a9bce420
Date: 2026-08-06T01:41:03.876Z
Layout: IDE
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.291
OS: Darwin arm64 25.5.0

For AI issues: which model did you use?

Composer 2.5

Additional Information

The concerning part of this issue is that the Root Agent appears to modify the Fast mode state autonomously. There is no user interaction with the Fast toggle when the change occurs.

It may be worth checking whether the mode is being changed as a result of agent state restoration, session transitions, model selection, UI state synchronization, or an internal fallback/retry mechanism.

Does this stop you from using Cursor

No - Cursor works, but with this issue

6

Hey there! Fast is the default for Composer 2.5 and the Grok models, so it’s on the moment you pick one rather than flipping partway through a session. That’s usually why it looks like it switched on its own.

To turn it off: open the model picker, hover that model’s row, click Edit, then switch Fast off under Options. It’s stored per model. I checked on latest stable and after a full quit and relaunch the model came back non-Fast, while models I hadn’t touched kept the Fast default.

If you’ve explicitly switched it off and it still comes back on, that’s something different. Let me know which model, and whether it’s the editor agent panel or a new agent tab.