[BUG] EBADF error when calling TodoWrite tool multiple times in succession

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?

Environment:

• OS: macOS (Darwin 25.0.0)
• Claude Code Version: 2.0.27
• Node.js Version: latest

Description:
When the TodoWrite tool is called multiple times in quick succession (within a few seconds), a spawn EBADF error occurs. The error does not prevent the main task from
completing, but it clutters the terminal with error messages.

Steps to Reproduce:

1. Run a slash command that uses TodoWrite to track task progress
2. Update the todo list by calling TodoWrite to mark first task as in_progress
3. Immediately call TodoWrite again to mark first task as completed and second task as in_progress
4. Observe EBADF error in terminal

Error Output:
Error: spawn EBADF
at ChildProcess.spawn (node:internal/child_process:420:11)
at spawn (node:child_process:762:9)
at file:///Users/cph/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:195:2523
at f51 (file:///Users/cph/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:195:3018)
at file:///Users/cph/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:195:3251
at Array.forEach (<anonymous>)
at ChildProcess.J (file:///Users/cph/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:195:3186)
at ChildProcess.emit (node:events:524:28)
at ChildProcess.emit (node:domain:489:12)
at maybeClose (node:internal/child_process:1104:16) {
errno: -9,
code: 'EBADF',
syscall: 'spawn'
}

Expected Behavior:
TodoWrite should handle multiple rapid calls gracefully without spawning errors.

Actual Behavior:
Multiple EBADF errors are thrown, though the underlying task (file writing) still completes successfully.

Possible Root Cause:

• Race condition when spawning child processes for UI updates
• File descriptor cleanup issue between successive calls
• Child process management not properly handling rapid succession calls

Impact:

• Low: Does not break functionality
• Medium: Creates confusing error output for users
• Workaround: Batch todo updates instead of multiple successive calls

Suggested Fix:

• Add file descriptor validity check before spawning
• Implement better child process lifecycle management
• Add debouncing or queuing for rapid TodoWrite calls

What Should Happen?

TodoWrite should handle multiple rapid calls gracefully without spawning errors.

Error Messages/Logs

Error Output:
  Error: spawn EBADF
      at ChildProcess.spawn (node:internal/child_process:420:11)
      at spawn (node:child_process:762:9)
      at file:///Users/cph/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:195:2523
      at f51 (file:///Users/cph/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:195:3018)
      at file:///Users/cph/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:195:3251
      at Array.forEach (<anonymous>)
      at ChildProcess.J (file:///Users/cph/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:195:3186)
      at ChildProcess.emit (node:events:524:28)
      at ChildProcess.emit (node:domain:489:12)
      at maybeClose (node:internal/child_process:1104:16) {
    errno: -9,
    code: 'EBADF',
    syscall: 'spawn'
  }

Steps to Reproduce

Steps to Reproduce:

1. Run a slash command that uses TodoWrite to track task progress
2. Update the todo list by calling TodoWrite to mark first task as in_progress
3. Immediately call TodoWrite again to mark first task as completed and second task as in_progress
4. Observe EBADF error in terminal

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.27

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_