Make "Organize sidebar by project" group machines under one project and add per-thread target selection

What variant of Codex are you using?

App

What feature would you like to see?

Codex App already has Organize sidebar -> By project and Organize sidebar -> By connection.

I would like the existing By project mode to become truly project-first when the same logical project exists on multiple machines/connections.

Today, a user with several machines and several recurring projects still has to manage host/folder targets separately. With 3 machines and 5-10 projects, that can become 15-30 project targets, even when many refer to the same Git repository or logical project.

Desired behavior in Organize sidebar -> By project:

• Show one top-level group per logical project, for example .dotfiles, tanstack, or nextjs.
• Under that project, show available execution targets/machines, for example:
• Local
• Mac mini
• SSH devbox
• When creating a new thread from that project, let me choose which machine/connection the thread should run on.
• In an existing thread, show which machine the current turn will run on.
• Allow changing the target machine for a later turn in the same thread, when the same project is available there.
• If a thread has run on more than one machine, show that clearly in the thread metadata/history.

The key request is not just grouping by connection. It is project-first navigation plus explicit execution-target selection per thread/turn.

Additional information

This is related to #24295, but the model requested here is different.

#24295 asks for Connection -> Project -> Thread grouping. That helps users who navigate host-first.

This request is for improving the existing Organize sidebar -> By project mode:

Project -> Thread with Machine/Connection indicator

or visually:

Project
Threads, each with a run-location indicator (Local, Mac mini, SSH devbox)