Cursor froze & leaked memory during plan mode with Opus 4.5

[jpark]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Cursor froze and started consuming about 1GB of memory per second. Had to force quit Cursor when it reached about 125GB of memory. It also used up my credit.

Steps to Reproduce

1. Told Cursor “I’ve updated some npm dependencies and now npm run test is failing. Fix it, verify, and then give a concise explanation.” in plan mode.
2. After generating some output for about 30 seconds, the entire IDE froze and started leaking memory.

Expected Behavior

Plan mode to complete successfully without freezing IDE.

Operating System

MacOS

Version Information

Version: 2.4.21
VSCode Version: 1.105.1
Commit: dc8361355d709f306d5159635a677a571b277bc0
Date: 2026-01-22T16:57:59.675Z
Build Type: Stable
Release Track: Default
Electron: 39.2.7
Chromium: 142.0.7444.235
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Darwin arm64 24.6.0

For AI issues: which model did you use?

Opus 4.5 (Thinking)

For AI issues: add Request ID with privacy disabled

Request ID: 4c31fba4-0d4e-42dc-9237-b7e3600882f2
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Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor

[Colin]

Thanks for reporting this @jpark!

We’ve had a few reports like this on Plan Mode, and a fix is coming.

Window crashed when model generate plan with plan mode

Thanks for the detailed logs. I’ve shared the infinite loop bug in metrics collection with the team. It’s a regression in 2.4.x. Right now there’s only one workaround: use Ask or Agent mode instead of Plan mode. The issue doesn’t trigger there. As soon as there’s a fix, we’ll update the thread. Sorry for the inconvenience. Plan mode is indeed broken in your case.