[BUG] macOS Desktop App "Coworkd" VM Infinite Loop silently drains Pro Quota via orphaned subagents

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?

Bug Description

There is a severe bug in the Claude macOS Desktop App involving the "Local Agent Mode" (Cowork feature). A background daemon (coworkd) running inside a hidden Linux VM goes into an infinite loop, spawning orphaned headless instances of claude that completely drain the user's Pro usage quota in seconds (jumping from 6% to 100%), even when the app, IDEs, and Terminals are completely closed.

Environment

• OS: macOS 26.4
• Application: Claude Desktop App (macOS) / coworkd / claude-code
• Date of incident: April 22, 2026
• Impact: Total loss of paid Pro quota limits without user interaction.

Evidence from Local Logs

Upon inspecting the local macOS logs (~/Library/Application Support/Claude/logs), I discovered the exact mechanism of the quota drain:

1. VM Initialization: The macOS app silently spins up a Linux VM in the background via vzgvisor (seen in vzgvisor.log and cowork_vm_swift.log).
2. Orphaned Agents: Inside the VM, a coworkd daemon is running. It spawned headless subagents with generated user names (e.g., lucid-exciting-dirac, epic-intelligent-keller). This is visible in coworkd.log.
3. The Infinite Loop: My main.log is flooded with thousands of consecutive errors:

[warn] [LOCAL_SESSION] Subagent parent not found for user message - possible out of order processing

1. The Drain: These background instances are being executed with the following parameters, consuming massive context instantly:

--model claude-sonnet-4-6 --max-thinking-tokens 31999

main.log
coworkd.log

What Should Happen?

• Background syncs or "Local Agent" daemons should never consume user subscription quotas without explicit foreground execution.
• If a subagent loses its parent process (Subagent parent not found), it should gracefully exit, not enter an infinite loop of max-token API calls.

Error Messages/Logs

Steps to Reproduce

1. The user does not need to do anything. The terminal, VS Code, and active Claude Desktop windows were entirely CLOSED for days.
2. The background claudevm.bundle process executes the subagents on its own.
3. The Pro quota immediately spikes to 100%.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.3883.0 (93ff6c) 2026-04-21T17:24:01.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_