Hey, thanks for the report. This is a known issue. Plan mode with Composer 2 can sometimes ignore constraints and start making changes instead of planning. The team is aware.
As a workaround, you can add a rule in .cursor/rules/:
---
description: Plan mode safety
alwaysApply: true
---
CRITICAL: In PLAN mode, NEVER edit files or run commands. Only describe the plan. Wait for explicit user approval before any implementation.
Not perfect, but it noticeably reduces how often it happens.
Similar thread with details: Composer writing code in plan mode
Let me know if you have any questions.