handback

The mailbox reply flow with the recipient fixed to your parent — the from of your message-zero, the bootstrap handoff you drained on launch.

1. Find your message-zero — the message whose subject begins spawn:, in your archive/ (or inbox/ if still unread):

   zero="$(grep -rlE '^subject: spawn:' "$(mb_dir "$(mb_resolve_self)")"/{archive,inbox} 2>/dev/null | head -1)"
   

2. Run the mailbox reply flow against $zero — compose the return body per the mailbox compose rules and stream it in. Confirm to the operator what was sent and to whom (mb_whois for the parent's friendly name).

If there is no spawn: message-zero you were not created with a return channel, so there is no parent — use dispatch to send to a named peer instead.