MQTT 5.0 infrastructure for the Aether event fabric.

This crate provides the shared MQTT layer used by all Styrene ecosystem services (Omegon, Scry, Viz, Aether, etc.) to communicate over the Aether event bus.

Topic Schema

All events are published to topics following the hierarchy:

styrene/{operator_id}/{service}/{instance_id}/events/{event_type}

Use [TopicBuilder] to construct publish topics and subscription filters.

Broker Ownership

The MQTT broker is owned by the operator control plane (Auspex), not by individual services. Services connect as TCP clients. Auspex uses the embedded-broker feature to start an in-process rumqttd instance and holds an in-process link for its own aggregation pipeline.

Feature Gates

• embedded-broker — includes rumqttd for hosting the broker (Auspex only)
• tls — TLS support for remote broker connections (future)
• styrene-identity — Ed25519 enhanced auth (future)