## Summary
`/collab` was intentionally removed in
[#12012](https://github.com/openai/codex/pull/12012), but the
TUI/app-server migration accidentally brought that slash-command path
back. This restores the earlier product decision so the TUI no longer
advertises or dispatches `/collab`. This command was redundant because
it did the same thing as `/plan` but in a less-intuitive way.
## What Changed
- Remove `SlashCommand::Collab` from the TUI slash-command surface.
- Delete the picker and app-event plumbing that only existed to service
`/collab`.
- Remove obsolete TUI test coverage for the deleted picker flow.
Eric Traut
efdcbba053