[BUG] Claude Code v2.1.88 deleted entire Windows 11 C: drive contents including user profile - autonomous deletion while session unattended

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?

Environment

• Claude Code version: 2.1.88
• OS: Windows 11
• Installation method: npm (auto-updated)
• Location: Sweden (CEST, UTC+2)

What happened

On March 31, 2026, around 16:00 CEST (14:00 UTC), Claude Code
auto-updated to v2.1.88.

I ran a session around 16:00 CEST — everything normal.
I ran another session starting around 20:00 CEST — everything normal.
I left the session running unattended (did not close it).

Approximately 40 minutes later I returned to find:

• Mass file deletion across C: drive
• Installed applications deleted
• User profile files deleted/corrupted
• Windows still boots but machine is not operable
• Significant free disk space gained — consistent with mass deletion

Claude Code was the only active process with filesystem write access
during this window.

Impact

• Machine not operable
• Work files lost including active project directories
• Personal and professional data lost

Related issues

• #29023 — identical pattern on v2.1.58 (Windows user profile deleted)
• #30988 — autonomous file deletion without user instruction

Possible connection

The leaked source code for v2.1.88 reveals a feature called KAIROS —
an autonomous background daemon mode that operates while the user is
idle. Whether this feature was accidentally enabled in this build is
unknown, but the behavior (autonomous operation during 40-minute idle
period) matches the described KAIROS behavior exactly.

Request

• Confirmation whether KAIROS or any background agent was active

in v2.1.88 production builds

• Guidance on file recovery options
• Response on liability for data loss caused by this defect
• potential attack?

What Should Happen?

I do not know what has happend, files are deleted after installation it seems.

Error Messages/Logs

Did not see errors

Steps to Reproduce

Steps to Reproduce - what i was doing

1. Auto- Install Claude Code v2.1.88 via npm (auto-update from previous version)
2. Start a Claude Code session on Windows 11 auto mode
3. Work normally for an extended period (I worked ~16:00-17:00 CEST)
4. Start a second session later (~20:00 CEST)
5. Allow Claude Code to complete its current task
6. Leave the session running but unattended — do NOT close the terminal
7. Return after approximately 40 minutes
8. Observe mass file deletion across C: drive

Expected behavior

Claude Code should stop all operations when the current task is
complete and await new user input. No filesystem operations should
occur while session is idle and unattended.

Actual behavior

Claude Code continued operating autonomously during the 40-minute
idle period, resulting in mass deletion of files across C: drive
including installed applications, user profile files, and work
directories.

Notes on reproducibility

• I cannot reproduce this myself as my machine is not operable
• I cannot confirm exact trigger conditions
• The autonomous idle behavior may be non-deterministic or

version/session specific

• Prior confirmed case #29023 (v2.1.58) suggests this is a

recurring class of bug, not a one-time event

• Reproduction may require leaving a long-running session

unattended on Windows 11 with v2.1.88

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

Before 2.1.88

Claude Code Version

Cannot 2.1.88 last update

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

My laptop is not in function anymore and cannot provide more details.