Cowork Sandbox completely unusable — missing srt binary

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?

Description

Cowork is completely non-functional. Every action fails immediately with:

CLI output was not valid JSON. This may indicate an error during startup.
Output: sandbox-helper: failed to start command: fork/exec /usr/local/lib/node_modules_global/bin/srt: no such file or directory

The srt binary is missing from the sandbox environment. This is an infrastructure-side issue — nothing a user can fix.

Impact

• Cowork is 100% unusable — no actions can be performed
• I have two custom skills (with sub-skills and source documentation) trapped inside session loving-gracious-pascal
• These skills took multiple days to build and cannot be rebuilt without the source context inside the session
• Skills saved in Cowork are only persisted to the session filesystem, not at the account level — so there is no other way to access them

Steps to Reproduce

1. Open Cowork
2. Attempt any action
3. Error appears immediately

Support Timeline

• 25+ emails to support@anthropic.com over 48+ hours
• Zero human responses
• In-app feedback submitted — no response
• This is a last resort to get visibility on the issue

Requests

1. Fix the missing srt binary in the Cowork sandbox image
2. Recover/extract my skill files from session loving-gracious-pascal
3. Consider persisting skills at the account level rather than tying them to ephemeral sandbox sessions

Environment

• Platform: Cowork (web)
• Plan: Max ($200/month)
• Browser: Chrome (Mac)

What Should Happen?

Cowork should start without errors and I should be able to access my skills and use all features. Specifically: the srt binary should be present in the sandbox image at the expected path, skills saved in Cowork should persist reliably across sessions, and Max plan customers should receive timely human support when a product is completely non-functional.

Error Messages/Logs

CLI output was not valid JSON. This may indicate an error during startup. Output: sandbox-helper: failed to start command: fork/exec /usr/local/lib/node_modules_global/bin/srt: no such file or directory

Steps to Reproduce

1. Log in to Claude.ai on a Max plan account
2. Open Cowork
3. Attempt any action (run a skill, create a file, execute any task)
4. Sandbox immediately fails with the srt binary not found error
5. No workaround exists — the binary is missing from the sandbox image itself

No specific code or files needed to trigger this. The error occurs on every action, every time, before any user code runs.​​​​​​​​​​​​​​​​

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unknown — Cowork was functioning normally prior to this issue. The regression appeared without any action on my end, suggesting a sandbox image update removed or failed to include the srt binary.

Claude Code Version

Unknown — the srt binary is missing from the sandbox, so no version can be retrieved. Cowork manages its own sandbox environment and does not expose the CLI version to the user.

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_