#NotificationChannel

#Import

1import { NotificationChannel } from "alepha/api/notifications";

#Overview

One delivery channel, and the extension point of the whole module.

A channel is a service, not a primitive: it has dependencies (an http client, an options atom, a boot-time config check) and this codebase models transports as services. Discovery is alepha.services().

⚠️ A channel must be listed in its module's services[]. alepha.services() walks the registry and filters on instanceof, so it sees instantiated services only: a channel that is exported but never injected is invisible, and the symptom is the boot check refusing a template that declares your own channel.

#What a plugin has to declare

A channel is three things, not one: the class below, the option block a template writes, and, for a sink, the fact that it is one. The last two are declaration merges, and they belong in the package's single entry point, because an augmentation only applies where it is in scope.

1declare module "alepha/api/notifications" {2  interface NotificationChannels<V> {3    discord?: { to?: string; message: (v: V) => string | Promise<string> };4  }5  interface NotificationSinkChannels {6    discord: true;7  }8}

Declaring only the first compiles, and then push() keeps demanding a contact for a message going to a chatroom.

#Two members that look optional and are not

render() must return a recipient. It is not decoration: the sender writes it straight into notification_deliveries.contact, which is NOT NULL, and it is the only reason the sender never has to ask what kind of channel it is talking to. An addressable channel returns the contact it was given; a sink returns <channel>:<destination>.

providerName() should be overridden by any channel that is an adapter over a swappable transport, to name that transport. The default is the channel's own class name, which is right for a channel that IS its transport and wrong for one that wraps a provider: without the override, every receipt records NotificationEmailChannel where an operator is looking for BrevoEmailProvider. Nothing asserts on that field by default, so getting it wrong degrades the audit trail silently.