@fluojs/notifications

Channel-agnostic notification orchestration for fluo. It freezes the shared contract for notification channels, provides explicit module registration with familiar dynamic-module ergonomics, and exposes optional queue-backed delivery and lifecycle event publication seams.

Table of Contents

• Installation
• When to Use
• Quick Start
• Common Patterns
  • Queue-backed bulk delivery
  • Lifecycle publication through an event publisher
  • Intentional limitations
• Public API Overview
• Related Packages
• Example Sources

Installation

npm install @fluojs/notifications

When to Use

• When you want one shared dispatch contract for multiple notification channels without coupling sibling packages to each other.
• When application code should depend on NotificationsService instead of provider-specific SDKs or transport details.
• When bulk delivery may need to be offloaded to a queue, but direct in-process dispatch should still remain available.
• When notification lifecycle events (requested, queued, delivered, failed) should be observable through an event publication seam.

Quick Start

1. Register the foundation module

Register notifications with NotificationsModule.forRoot(...) or NotificationsModule.forRootAsync(...) by passing explicit NotificationChannel values in channels.

import { Module } from '@fluojs/core';
import {
  NotificationsModule,
  type NotificationChannel,
} from '@fluojs/notifications';

const emailChannel: NotificationChannel = {
  channel: 'email',
  async send(notification) {
    console.log('sending email', notification.subject, notification.payload);

    return {
      externalId: 'email-123',
      metadata: { provider: 'demo-email' },
    };
  },
};

@Module({
  imports: [
    NotificationsModule.forRoot({
      channels: [emailChannel],
    }),
  ],
})
export class AppModule {}

2. Inject NotificationsService

import { Inject } from '@fluojs/core';
import { NotificationsService } from '@fluojs/notifications';

@Inject(NotificationsService)
export class WelcomeService {
  constructor(private readonly notifications: NotificationsService) {}

  async sendWelcomeEmail(userId: string, email: string) {
    await this.notifications.dispatch({
      channel: 'email',
      recipients: [email],
      subject: 'Welcome to fluo',
      payload: {
        template: 'welcome-email',
        userId,
      },
    });
  }
}

NotificationsModule.forRoot(...) and NotificationsModule.forRootAsync(...) export NotificationsService, NOTIFICATIONS, and NOTIFICATION_CHANNELS as global providers by default. Set global: false when these providers should stay visible only to the module that imports the notifications module. Application services should declare dependencies with fluo's class-level @Inject(...) decorator so the standard-decorator DI container can resolve the service without parameter decorators.

Migration boundary: channel registration is value-based, not metadata-based. Do not rely on NestJS provider discovery, @Injectable() metadata, or emitDecoratorMetadata to register channels. Build NotificationChannel objects in application code or return them from NotificationsModule.forRootAsync({ inject, useFactory, global? }), then pass them through the channels option.

Common Patterns

Queue-backed bulk delivery

Use the optional queue seam when many notifications should be deferred to background workers. The queue adapter is an application-owned integration; @fluojs/notifications only calls the abstract adapter contract.

NotificationsModule.forRoot({
  channels: [emailChannel],
  queue: {
    adapter: {
      async enqueue(job) {
        return queue.enqueue(job);
      },
      async enqueueMany(jobs) {
        return Promise.all(jobs.map((job) => queue.enqueue(job)));
      },
    },
    bulkThreshold: 50,
  },
});

Behavioral contract notes:

• Bulk queue delegation starts when the notification count reaches bulkThreshold.
• dispatch() stays direct by default even when a queue adapter is configured. Use dispatch(..., { queue: true }) to opt one single notification into queue-backed delivery.
• Use dispatch(..., { queue: false }) to force direct delivery even when a queue adapter exists.
• Queue-backed delivery is opt-in for single dispatch and threshold-driven for dispatchMany(...).
• Queue jobs include a deterministic id idempotency key derived from notification.id when present, otherwise from the notification envelope. Queue adapters should pass this value to backing queues that support deduplication.
• dispatchMany(..., { continueOnError: true }) collects failures instead of throwing on the first failed direct delivery or sequential queue fallback enqueue.
• When queue enqueue fails, the service emits deterministic notification.dispatch.failed lifecycle events before rethrowing the enqueue error to the caller. Queued bulk dispatch also publishes a terminal queued or failed event for every notification that already emitted requested, including queue-missing, channel-resolution, and provider/adapter failure paths.
• If enqueueMany(...) is unavailable, bulk queue delivery falls back to enqueueing each job individually in input order. With continueOnError: true, successful enqueues remain visible in results while failed enqueues are returned in failures; without it, the first enqueue failure is rethrown after the remaining requested fallback jobs receive failed lifecycle events.
• The foundation package does not assume or import a concrete queue implementation, create queue clients/workers, or close/drain application-owned queue resources.

Lifecycle publication through an event publisher

Publish caller-visible lifecycle events without coupling the foundation package to @fluojs/event-bus directly. The event publisher is also application-owned; the foundation package does not create, import, close, or drain a concrete event bus.

NotificationsModule.forRoot({
  channels: [emailChannel],
  events: {
    publishLifecycleEvents: true,
    publisher: {
      async publish(event) {
        await eventBus.publish(event);
      },
    },
  },
});

Published event names:

• notification.dispatch.requested
• notification.dispatch.queued
• notification.dispatch.delivered
• notification.dispatch.failed

If events.publisher is configured, lifecycle event publication defaults to on unless publishLifecycleEvents: false is set. Channel deliveries that omit externalId receive a deterministic fallback delivery id derived from the notification envelope so dispatch results remain stable for callers without relying on time or random data. Channel resolution failures publish requested and then failed events before throwing NotificationChannelNotFoundError; treat those failures as permanent configuration errors. Queue enqueue and provider delivery failures also publish failed events, but callers should classify their retry behavior from the underlying adapter/provider error. Publication failures for success-path lifecycle events remain best-effort so a delivered notification is not converted into an application failure. Publication failures for notification.dispatch.failed are caller-visible as AggregateError values that include both the original dispatch error and the publisher error so failed-event guarantees are not silently weakened.

Intentional limitations

The foundation package intentionally does not:

• ship built-in email, Slack, or Discord implementations
• inspect process.env directly
• depend on @fluojs/queue or @fluojs/event-bus concrete runtime types
• create, import, close, or drain concrete queue or event-bus resources; queue adapters and event publishers are application-owned integrations
• encode provider-specific payload semantics into the shared contract

These limitations are part of the package contract so leaf packages can evolve independently while sharing one stable orchestration layer.

Public API Overview

Core

• NotificationsModule.forRoot(options) / NotificationsModule.forRootAsync(options)
• NotificationsService
• NotificationsService.createPlatformStatusSnapshot()
• Notifications
• NOTIFICATIONS
• NOTIFICATION_CHANNELS

Contracts

• NotificationDispatchRequest
• NotificationDispatchOptions
• NotificationDispatchManyOptions
• NotificationDispatchResult
• NotificationDispatchBatchResult
• NotificationDispatchFailure
• NotificationDispatchStatus
• NotificationChannel
• NotificationChannelContext
• NotificationChannelDelivery
• NotificationPayload
• NotificationsQueueAdapter
• NotificationsQueueJob
• NotificationsQueueOptions
• NotificationsModuleOptions
• NotificationsAsyncModuleOptions
• NotificationsEventsOptions
• NotificationsEventPublisher
• NotificationLifecycleEvent
• NotificationLifecycleEventName

Status and errors

• createNotificationsPlatformStatusSnapshot(...)
• NotificationsPlatformStatusSnapshot
• NotificationsStatusAdapterInput
• NotificationsConfigurationError
• NotificationChannelNotFoundError
• NotificationQueueNotConfiguredError

Status snapshots include operationMode, dependency diagnostics, ownership, readiness, and health fields for platform diagnostics. When a queue adapter is configured, details.dependencies includes notifications.queue-adapter; when lifecycle events are published through an event publisher, it includes notifications.event-publisher. Those optional integrations mark ownership.externallyManaged: true while the foundation package still reports ownsResources: false because it does not create, close, or drain concrete queue or event-bus resources.

Related Packages

• @fluojs/queue: Recommended when bulk notification delivery should run in the background.
• @fluojs/event-bus: Recommended when notification lifecycle events should be published to the wider app.
• @fluojs/config: Recommended for passing provider configuration into forRootAsync() without direct environment access.

Example Sources

• packages/notifications/src/module.test.ts: Module registration, async wiring, queue seam, and tolerant bulk dispatch examples.
• packages/notifications/src/public-surface.test.ts: Public contract verification for root exports and TypeScript-only types.
• packages/notifications/src/status.test.ts: Health/readiness contract examples.