Technology stack and add-ons

The technology stack and add-ons are modeled inputs because they change generated artifacts. They remain orthogonal to the product domain: choosing Redis should not alter what an appointment means.

Stack decisions

Supported infrastructure intent includes relational database selection, read-side cache, and asynchronous task execution. The generator uses those choices to emit adapters, dependencies, local topology, environment contracts, and health probes.

Choose based on requirements:

database compatibility and operational environment;
read workload and acceptable staleness;
whether reactions can run outside the request;
broker availability and delivery semantics;
team ownership and destination constraints.

Avoid selecting infrastructure only because it is fashionable. Every added runtime component creates configuration, observability, failure, and recovery responsibilities.

Add-ons

Add-ons provide prefab platform capabilities such as authentication, notifications, file uploads, and audit trail. Their configuration belongs in the model; secret values belong in the runtime control plane.

An add-on should define:

enabled state and version;
product-relevant policy;
provider or storage selection;
event or field bindings;
required environment-variable names;
generated health/configuration signals.

Domain integration

Use domain events and explicit bindings to connect product behavior to add-ons. For example, a notification trigger can subscribe to AppointmentConfirmed and resolve the recipient from the event payload.

Do not place email-provider SDK calls inside a domain action. The domain emits meaning; the add-on adapter handles delivery.

Changes after delivery

Rotate a key or change an endpoint in configuration—normally no regeneration.
Change notification templates or file policy captured in the model—regenerate.
Change the database engine or queue topology—regenerate and review migration/operations impact.
Fix a shared add-on emitter defect—update the generator, then rebuild affected releases.

See Add-ons reference, Infrastructure reference, and Configuration and secrets.