Collaboration and delivery

These Domain concepts authorize work, publish facts, react to them, represent communications, and own outbound capability ports.

Concepts

Concept	Role
Policy	Model-aware authorization.
Event	Immutable domain fact.
Listener	Synchronous or queued reaction.
Notification	Notification representation.
Mailable	Mail representation.
Contract	Domain-owned capability port.

Listener modes

Mode	Restriction
Synchronous	May not call a UseCase, open a transaction, or imply durability.
Queued	Is at-least-once, must be idempotent, and may call one UseCase.

Event delivery

Use the event delivery tiers to choose synchronous, after-commit, queued, or outbox delivery without overstating guarantees.