A draft that opens with `!` is a shell command, as in Claude Code: the
composer turns amber with a Bash chip, Enter (or the Run button) runs it
in the session's worktree through POST /api/chat/sessions/{id}/shell,
and the exchange lands on the transcript as a user-side card. Commands
run since the last real message are folded into the next turn's prompt
as untrusted context. Output is capped, the process group is killed on
timeout, and a backgrounded child cannot hold the request open.
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
