The interactive reader (ssh mail@ / hub Mail) was read-only; the send path
existed only for agents (bot mode). Add compose (c), reply (r), reply-all (a)
to the TUI with a To/Cc/Subject/Body form (tab/arrows to move fields, ctrl+d
send, esc cancel). Reply prefills + quotes the original and threads via
In-Reply-To. Tests drive the model key-by-key through send.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>