Weird behavior with Composer 2

Support Bug Reports
,
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Composer 2 has proven to be an excellent model,however , I’ve noticed two behaviors that don’t exactly follow a pattern but occur with some frequency, which don’t happen with other models:

  • Even though users and specifications are written in Brazilian Portuguese (PT-BR), at various times it starts generating inputs and interacting with users in the chat using European Portuguese (PT-PT).

  • Several times when we select the “Plan” mode to make a request, it simply ignores the selection and starts execution without writing any plan.

Steps to Reproduce

  • Even though users and specifications are written in Brazilian Portuguese (PT-BR), at various times it starts generating inputs and interacting with users in the chat using European Portuguese (PT-PT).

  • Several times when we select the “Plan” mode to make a request, it simply ignores the selection and starts execution without writing any plan.

Expected Behavior

If im interacting with Brazilian Portuguese, dont switch to European Portuguese, and if im selecting plan, dont execute automatically as other models do.

Operating System

Windows 10/11

Version Information

Version: 2.6.22 (user setup)
VSCode Version: 1.105.1
Commit: c6285feaba0ad62603f7c22e72f0a170dc8415a0
Date: 2026-03-27T15:59:31.561Z
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
OS: Windows_NT x64 10.0.22631

For AI issues: which model did you use?

Composer 2

Does this stop you from using Cursor

No - Cursor works, but with this issue

6

Hi @felippe.serralvo, thanks for reporting. The Plan mode issue is a known bug, and we are working on resolving it. In the meantime, there are a few tips that can help until it is fully resolved:

  • Start a new chat wherever possible.
  • Start the chat in plan mode and immediately begin the plan (switching between modes or switching modes mid-conversation is more likely to produce this behavior).
  • You can also remind the agent in the prompt that is in plan mode (less important, but still helpful).

Regarding the language switching, this is a known quirk of LLMs - they can sometimes drift between languages, especially because Brazilian Portuguese and European Portuguese are so close. The best thing you can is add a Cursor rule and always apply it and this will help steer the model towards Brazilian Portuguese, but it is not a guarantee.

You can ask cursor to create a user rule for you like so:

description: Always respond in Brazilian Portuguese

globs:

alwaysApply: true

---

Always respond in Brazilian Portuguese (PT-BR). Never use European Portuguese (PT-PT). This includes vocabulary, spelling, and expressions — e.g. use "você" instead of "tu", "celular" instead of "telemóvel", "tela" instead of "ecrã".
9

Even about with other models this dont happen ?

10

The plan mode issue is specific to Composer 2, but the language issue is something that can impact all models.

11

Thank you for your answer!