Copilot CLI output has thread problems

[zachbryant]

Describe the bug

When copilot returns a response in Agency, output is mangled until the response is complete. This happens for its own thinking as well. Here is a prime example of the output being mangled:

It reminds me of the old joke

Some people, when confronted with a problem, think “I know, I'll use multithreading.” have Now problems. two they.

Would love to see it fixed so I can read the response sooner.

Affected version

GitHub Copilot CLI 1.0.61.
agency 2026.6.10.7

Steps to reproduce the behavior

1. Ask a question in agency copilot CLI
2. See response mangled (may need to get past the first response or two)

Expected behavior

Responses are read out cleanly as they arrive.

Additional context

Linux codespaces-8bfbdd 6.8.0-1052-azure #58~22.04.1-Ubuntu SMP x86_64 GNU/Linux

Bash

[TobiasW-T]

Seems to be a duplicate of #3749 .