[BUG]

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?

Title: [Windows] Cowork workspace fails to start — .verified SDK hash never matches the installed claude binary (2.1.260)

Environment

Windows, Claude Desktop (Cowork / local agent workspace)
SDK bundle: claude-code-vm\2.1.260
Path: %LOCALAPPDATA%\Claude-3p\claude-code-vm\2.1.260\

Symptom
Failed to start Claude's workspace, with:
RPC error -1: SDK version 2.1.260 not verified at ...\claude-code-vm\2.1.260\.verified

Finding

claude binary size: 214,687,216 bytes
Actual SHA256: 7a2fdc74b6836ea3d183f665b869f0ee3baebc9713cbebffe5838da4ea7bd82e
.verified contents: ad1c0b3f2de334f4bcb4a783c275b1af7a5945c0c955a9c7352cf4fa0666a7ec
These never match. File timestamps show claude written at 23:43:01 and .verified written at 23:43:02 — the app writes both in one pass, yet records a hash that does not correspond to the binary it just wrote.

Tried, all ineffective

What Should Happen?

Full VM bundle reset (removed vm_bundles + claude-code-vm), reboot
Confirmed the Cowork VM service is running
Re-download with VPN on and off (download only succeeds with VPN on)
Manually writing the correct hash into .verified — works for exactly one launch, then reverts
attrib +r on .verified — reverted
icacls /deny write/delete on .verified — reverted (file appears to be recreated)

Error Messages/Logs

Steps to Reproduce

Ask
Fix the SDK integrity check so the .verified marker matches the shipped binary (Windows counterpart of #78373).

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Claude 1.49585.0 (41ad1d) 2026-09-08T05:21:03.000Z

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_