[BUG] @ searching has inconsistent case sensitivity

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When I try to use the @ file search inside Claude Code it seems to show inconsistent results depending on the casing I started with, examples below.

What Should Happen?

It should ignore case so the last two examples should show one and two results.

Error Messages/Logs

Steps to Reproduce

I have these files in my project:

Startup.ts
StartupManager.ts

✅ I type: @Startup and it will show both files in the suggestion as expected.

✅ I type: @startup and it will show both files in the suggestion as expected.

✅ I type: @startupman and it will show one file as expected.

✅ I type: @StartupMan (uppercase M) and it will show one file as expected.

❌ I type: @Startupman (lowercase M) and it will show no files. I would expect StartupManager to appear.

❌ I type: @StartUp (uppercase U) and it will show no files. I would expect both files to appear.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unknown but it worked recently, maybe one week ago or max two

Claude Code Version

2.0.72

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Warp

Additional Information

Quick example in practice. First shows 1 result, second shows no results.

<img width="346" height="109" alt="Image" src="https://github.com/user-attachments/assets/c3a82533-e358-4941-9b7b-670f333f965d" />

<img width="306" height="105" alt="Image" src="https://github.com/user-attachments/assets/4b5e4147-c49b-40b0-b7dd-0d83832e3846" />