List the addressable agent roster

Status: accepted

ListAgents returns every retained agent in the current root session tree, including /root, sorted by canonical path and optionally filtered by path prefix. Each entry contains only path, role, and exact current activity status (starting, running, waiting, permission-blocked, interaction-blocked, or idle). It excludes opaque IDs, parent fields already encoded by the path, transcript or final-response content, and last-turn outcomes already delivered through the mailbox. Listing reflects addressable identities rather than runtime residency.