Feature request: durable agent addresses + store-and-forward for cross-session messaging

Running a multi-session agent team (15+ Claude Code sessions coordinating via one repo).

Problem: Agents can't reliably message each other. No stable addresses (session
names rotate on restart), no mailbox for idle sessions (messages to sleeping
sessions are lost or unsendable), and sends can fail silently (green receipt,
nothing delivered).

Workaround today: identity via a hand-maintained hello log, delivery via
appending blocks to markdown files, confirmation via "recipient echo only",
human as router of last resort.

Ask: durable agent addresses + store-and-forward messaging with real delivery
receipts (delivered/read, errors instead of silent loss). Wake-on-message for
idle sessions would remove the human from the loop entirely.