[BUG] Models frequently confused when switching between sessions in claude agents

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?

Regularly when working in several tabs, each tab running claude agents with --pwd in different project I notice Claude Code using a model set in one chat, in another, overriding previous choices. It 'confuses' the model you want for each chat.

For example:

• agents session A in ~/repos/projA - I've got 5 chats going using a mix of Opus and Sonnet
• agents session B in ~/repos/projB - I've got 10 chats going using a mix of Opus and Sonnet

In a new, 6th chat in session A I /model opus and then later I switch to a Sonnet session in session B. That session is now using Opus (and definitely shouldn't be!)

This is affecting me a lot, for a long time I thought it was in my head but I've seen it more and more, it's a definite pattern. Could it be something about resuming an agent from background that loads an 'active' model that isn't reflective of the last model in use from the session history?

I've also noticed that /advisor settings sometimes travel between sessions, so an Opus advisor setting from my Sonnet session suddenly travels into my Fable session and I see an error about how Opus can't be an advisor to Fable.

What Should Happen?

The model being used should be religiously stored with and restored with the session. Model choices in one session shouldn't affect other sessions, including sessions being restored from the background e.g. after a reboot from claude agents.

Error Messages/Logs

Steps to Reproduce

This has been really hard to lock down. I'd try running two parallel claude agents sessions making sure to lock it down with --pwd to different project directories to get closest to my use case. And then setting models in various sessions, rebooting, restarting, restoring and making sure the models always stay as they should.

Claude Model

Not sure / Multiple models

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.207

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

_No response_