# Objective

Starting a new terminal thread from the agent sidebar creates **two**
terminals instead of one, in a project that has no terminals yet. With
terminals already open, only one is created.

## Solution

`Sidebar::create_new_terminal` calls `AgentPanel::new_terminal` and then
focuses the panel. The spawn is async, so when `focus_panel` activates
the panel, `base_view` is still `Uninitialized` — and
`ensure_thread_initialized` reads that as an empty panel and spawns its
own "initial" terminal on top of the one already in flight.

Once terminals exist they are restored at panel load, so `base_view` is
already `Terminal` and the second spawn never happens. That's why the
bug only appears on a project with no terminals.

`restore_terminal` already guarded against this by marking the spawn
pending before calling `spawn_terminal`. This moves that marker into
`spawn_terminal` itself, so every spawn path arms it, and drops the
now-redundant assignment in `restore_terminal`. The marker is cleared
exactly where it already was: when the terminal lands, when the spawn
fails, and when the terminal is closed.

## Testing

- Added `test_new_terminal_prevents_initial_terminal_creation`, which
reproduces the sidebar's spawn-then-focus sequence. It fails without the
fix (the panel ends up with two terminals) and passes with it.
- `cargo test -p agent_ui --lib` — 405 passed.
- `cargo test -p sidebar --lib` — 142 passed.
- `./script/clippy -p agent_ui` — clean.
- Tested on macOS only. The race is platform-independent, but I can't
exercise the Linux/Windows terminal spawn paths.

## Self-Review Checklist:

- [X ] I've reviewed my own diff for quality, security, and reliability
- [ X] Unsafe blocks (if any) have justifying comments
- [ X] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [ X] Tests cover the new/changed behavior
- [ X] Performance impact has been considered and is acceptable

---

Release Notes:

- Fixed the agent panel creating two terminals when starting a new
terminal thread in a project with no existing terminals

---------

Co-authored-by: Claude Opus 5 <claude-opus-5@claude-cli>