[BUG] One claude CLI session backgrounds and/or gets confused with another session

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?

I have several long running claude code sessions, e.g.:

• coder
• reviewer
• tester

Each has a specific SKILL.md file and is used as that persona only.

One day I asked "coder" to run full context, i..e do the code, then create sub-agents with the tester and reviewer skills, to tackle a bug.

Later on, I attempt to start the standalone "reviewer" session, and it could not be found; i.e. claude -r reviewer $\rightarrow$ "No sessions match reviewer"

Upon investigating with the /resume command, I see two sessions named "coder". Attempting to start the one with the longer idle time gives me a "this is a background session" message, and to use claude attach or claude stop to use it.

I issue the claude stop, then resume the session, and lo and behold it is the "reviewer" session.

What Should Happen?

Sessions should not be arbitrarily renamed and backgrounded.

Error Messages/Logs

None

Steps to Reproduce

May be intermittent:

• Try creating several standalone sessions with a particular skill
• Then in a separate session have session tackle a large task with the same skills

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.282, possibly before as well

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

iTerm2

Additional Information

See also #97232 , unclear which issue comes first or whether they are related.