[BUG] RPC error: ensure user: useradd failed: exit status 12: useradd: cannot create directory /sessions/clever-adoring-planck

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:
Cowork fails to start — useradd exit status 12: cannot create directory in /sessions/

Body:

## Bug Description

Claude Cowork consistently fails to start new sessions with a server-side RPC error. Persisting for 36+ hours across multiple attempts and multiple container names.

## Error Message

RPC error: ensure user: useradd failed: exit status 12: useradd: cannot create directory /sessions/clever-adoring-planck

## Affected Containers (all same error)

- /sessions/tender-trusting-rubin
- /sessions/peaceful-vigilant-albattani
- /sessions/clever-adoring-planck

## Steps to Reproduce

1. Open Claude Desktop
2. Click to start a Cowork session
3. Error appears immediately — session never starts
4. Retry — different container name, same error every time

## Expected Behavior

Cowork spins up a sandbox session successfully.

## Actual Behavior

Server-side useradd fails with exit status 12 (cannot create home directory) on every attempt. The session never starts.

## Analysis

This is a server-side infrastructure issue, not a local client problem. Exit status 12 from useradd means the system cannot create the user's home directory — points to disk quota, permissions, or resource exhaustion on Anthropic's container provisioning infrastructure.

Local troubleshooting already ruled out:
- Claude Code reinstalled (now v2.1.109, native install via claude install)
- Local directory permissions verified writable
- claude doctor shows no local issues

## Environment

- OS: macOS (Apple Silicon)
- Claude Code version: 2.1.109
- Install method: Native (~/.local/bin/claude)
- Plan: Claude Max
- Duration: 36+ hours, still ongoing

### What Should Happen?

It should load and work!

### Error Messages/Logs

```shell

Steps to Reproduce

Open Cowork and say Hi!

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude Latest

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

RPC error: ensure user: useradd failed: exit status 12: useradd: cannot create directory /sessions/clever-adoring-planck