Agent can't write in file

Bug Reports
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Both Gemini 3 and Opus 4.5 can’t write code in file with path G:\GitHub\RUSTDemo\assets\shaders\enemy_sdf.wgsl - Chat shows that the model has written the code for the file, but there is no dif of the deleted and added code.

I opened a new Chat and asked to check Grok Code Fast - it had no problems with writing.

Steps to Reproduce

Don’t know

Screenshots / Screen Recordings

2025-11-25_13-29-21.png
2025-11-25_13-29-21.png704×616 19.5 KB

Operating System

Windows 10/11

Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.1.32 (user setup)
VSCode Version: 1.105.1
Commit: ef979b1b43d85eee2a274c25fd62d5502006e420
Date: 2025-11-25T05:00:12.749Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Windows_NT x64 10.0.22631

For AI issues: which model did you use?

Gemini 3 Pro preview, Opus 4.5 Thinking

For AI issues: add Request ID with privacy disabled

e16b7dba-30f2-47b6-85bb-0506178af5db after 1a086543-b46f-4d27-bcae-ac00ff0f2d9e
GCF try: 20c73ae4-ab39-41db-afd9-4906a4608434

Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor

2

Hey, thanks for the report. It seems like there’s a model-specific issue where Gemini 3 Pro and Opus 4.5 Thinking claim to write code, but the changes don’t actually apply.

To help investigate, could you please share:

  • Console errors: Help > Toggle Developer Tools > Console tab - any errors when the models try to write?
  • Agent thoughts: When the models claim to write the file, what do their thought processes show?
  • File state: Is the file enemy_sdf.wgsl open in the editor when this happens?
  • Does it reproduce: Does this happen with other file types, or just .wgsl shader files?

For now, continue using Grok Code Fast for this file as a temporary solution.

3

So far, I’ve only noticed this with one file in one chat. In a nearby new chat, GCF successfully wrote information inside, but in the old chat the code did not writes many times.