Full review of the ECHO v1.5.1 architecture plus the phased plan to
convert the plugin to multi-member (group) memory: identity model,
schema-5 member namespacing, concurrency posture, rename map, and the
five settled design decisions (shared rollups, group-visible prefs,
shared-key first, /chorus-* commands, per-member + group inboxes).
Deployment endpoint: chorusapi.mpm.to.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>