[BUG] Cowork SDK binary download truncated at ~13MB by app's HTTP client on macOS — checksum fails

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?

Failed to start Claude's workspace
Download failed. Check your internet connection and try again.
Restarting Claude or your computer sometimes resolves this. If it persists, you can reinstall the workspace.

The download_and_sdk_prepare step consistently fails because the app's internal downloader truncates the SDK binary at exactly 13,369,248 bytes (out of ~50MB). curl downloads the same URL without issue.

What Should Happen?

Claude Cowork to start with the "Failed to start Claude's workspace
Download failed. Check your internet connection and try again.
Restarting Claude or your computer sometimes resolves this. If it persists, you can reinstall the workspace." error on Mac 26.4

Error Messages/Logs

▎ From main.log:                                                                                                           
  ▎ Downloading from https://downloads.claude.ai/claude-code-releases/2.1.87/linux-arm64/claude.zst
  ▎ Downloaded file size: 48406528 bytes, transferred bytes: 13369248 bytes (expected: 50454874)                             
  ▎ Checksum mismatch: expected=6c04ee19..., actual=6ffe78a7...                                                              
  ▎ Download attempt 3/3 failed — All download attempts failed

Steps to Reproduce

Start Claude Desktop and try to run a query in CoWork

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.78

Claude Code Version

2.1.87

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Workaround: Download manually via curl and install to ~/Library/Application Support/claude/claude-code-vm/2.1.87/