Edit tool succeeds during Plan Mode when it should be blocked

Bug Description

While in Plan Mode, the Edit tool successfully modifies files despite the system explicitly stating:

"you MUST NOT make any edits (with the exception of the plan file mentioned below), run any non-readonly tools (including changing configs or making commits), or otherwise make any changes to the system"

Steps to Reproduce

1. Enter Plan Mode (e.g. via /plan or keyboard shortcut)
2. Use the Edit tool to modify a project file (not the plan file)
3. The edit succeeds and the file is modified

Expected Behavior

The Edit tool should be blocked/rejected for all files except the designated plan file during Plan Mode.

Actual Behavior

Edits to project files go through successfully, even though Plan Mode is active. In my case, I edited src/components/Hero.astro and src/components/GoogleReview.astro while Plan Mode was active.

Environment

• Claude Code CLI
• Model: Claude Opus 4.6 (1M context)
• macOS (Darwin 25.3.0)