The wire contract ADR 0046 left open: two topic exchanges (mesh.events,
mesh.rpc, kept apart so # is a clean audit); the routing key as the event
type namespaced by origin (module.*, mesh.*, node.*); metadata in AMQP
headers (required x-event-id/x-source/x-node/x-time/content-type; optional
x-causation-id/x-schema; unknown x- headers ignored) with the body only the
payload; persistent messages; per-consumer durable dead-lettered queues
with prefetch; at-least-once with idempotent consumers (no false exactly-
once). The precedent is ADR 0043 for declarations.
Supersedes the sdk's first cut (metadata in body -> headers); that and the
queue config are code to align in mesh-sdk and mesh-tools.
Claude-Session: https://claude.ai/code/session_01LrgweAeERJYBg88c5cKDzF
