[BUG] File Corruption When Running Multiple Claude Code Terminals

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?

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ENVIRONMENT
================================================================================

• OS: Windows 11 Home Single Language 10.0.26200
• Shell: PowerShell / bash (Git Bash)
• Claude Code Model: Claude Opus 4.6 (1M context)
• Node.js: v22.19.0
• npm: 10.8.0
• PHP: 8.4.7
• Laravel: 12.54.1
• Vite: 7.3.1
• Local Dev Server: Laragon Full 6.0 (Apache 2.4.63, MySQL 8.0.30)
• Project Path: D:\Developer\Laravel_Applications\financial_reviews
• Git Branch: dev (up to date with origin/dev)

================================================================================
SUMMARY
================================================================================

Running two Claude Code terminal sessions concurrently on the same project
resulted in silent file corruption across 24+ source files. Corrupted files
were overwritten with identical binary/encrypted-looking data, making the
project unbootable (Apache 500 errors, Vite/Tailwind Oxide Rust panics,
and MySQL startup failures from a separate but concurrent issue).

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WHAT HAPPENED
================================================================================

1. Two Claude Code terminal sessions were opened simultaneously, each working

on different features within the same project directory:
D:\Developer\Laravel_Applications\financial_reviews

1. Both sessions were left running for an extended

period.

1. Upon returning, the following symptoms were observed:

• Apache returned "Internal Server Error" (HTTP 500)
• Vite dev server (npm run dev) crashed with a Rust panic in Tailwind

CSS Oxide engine

• MySQL also failed to start (separate tablespace ID collision issue

in an unrelated database)

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CORRUPTION DETAILS
================================================================================

All corrupted files shared the IDENTICAL binary signature, starting with:

Hex: 24 1a 9c 92 6d 85 ce 6d 6f 93 4c d2 44 fc dc 3b
98 25 67 cf 3f 77 ea c1 c5 b7 19 f8 16 ee f9 6f
76 48 30 f5 c9 61 87 35 a3 da 2a ee a0 d8 92 c3
cc 6c cd 9b 9b 53 a0 69 79 01 e4 94 72 d5 4f 37
aa 93 9e 81 25 4c 5d dd d7 25 b1 ba 1c c7 68 6b

The file command identified these files as "data" instead of text/source.
The corruption was NOT random — every corrupted file started with the exact
same byte sequence, suggesting a systematic write issue rather than random
disk corruption.

What Should Happen?

No file corruption.

Error Messages/Logs

1. Apache error log:
   E:/...../.htaccess:
   Invalid command '$\x1a\x9c\x92m\x85\xcemo\x93L\xd2D\xfc\xdc;\x98%g
   \xcf?w\xea\xc1\xc5\xb7\x19\xf8\x16\xee\xf9ovH0\xf5\xc9a\x875\xa3
   \xda*\xee\xa0\xd8\x92\xc3\xccl\xcd\x9b\x9bS\xa0iy\x01\xe4\x94r\xd5
   O7\xaa\x93\x9e\x81%L]\xdd\xd7%\xb1\xba\x1c\xc7hk', perhaps misspelled
   or defined by a module not included in the server configuration

2. Vite/Tailwind Oxide panic:
   thread '<unnamed>' panicked at crates\oxide\src\extractor\pre_processors\vue.rs:18:59:
   called `Result::unwrap()` on an `Err` value: Utf8Error { valid_up_to: 2, error_len: Some(1) }

Steps to Reproduce

1. Open two Claude Code terminal sessions in the same project directory
2. Ask each terminal to work on different features that involve editing

multiple files

1. Let both sessions run concurrently for an extended period
2. Check files for binary corruption using: find . -type f -name "*.php"

-exec file {} \; | grep -v "text\|ASCII\|UTF-8"

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.78

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_