reduced speed (approximately 10x) tool calling concurrency issues when using multiple sub agents - state issues

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?

agent automatically assigns sub tasks to agents, when those tasks complete, the model doesnt know or after the task/todo update (most likely) doesnt know that its complete, so the primary agent keeps going. I suspect that the heap and buffers arent being disposed, leading to the slowdown and the api errors 400 concurrency issue.

What Should Happen?

once the subagent is done it should trigger the logical sequence of agentic events as before.

Error Messages/Logs

api error 400 tool concurrency (i forget)

Steps to Reproduce

hmm ask to do a complicated task - i was updating auth + security settings on multiple microservices.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.17

Claude Code Version

2.1.19

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Cursor

Additional Information

_No response_