Shared single-host engine roles consumed via lookup('engine', ...), mirroring the central postgres/mariadb pattern: meta/services flags, overlay topology in meta/server, compose templates, per-consumer provisioning in 02_init. Lets apps drop their embedded sidecars and become unpinned/NFS-shareable in swarm.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>