Notification pipeline

The canonical scenario: a new chat message arrives and three side effects happen in different components, gated by user state owned by yet another component. None of them know about each other. Reading the trigger file tells a product manager exactly what happens, and reading the components tells nobody anything but their own job.

This is the scenario the rest of the docs use to compare against useEffect/saga/listener alternatives.

Open the full example in StackBlitz Open the full example in GitHub

Scenario

A new WebSocket message arrives. We want to:

1. Show a toast — unless the user is already viewing this conversation.
2. Play a beep sound — unless the user disabled sound, or DND is on. Burst-protect with debounce.
3. Increment a badge counter — unless the message is from the user themselves.

User state owned by separate components:

• <SettingsPanel> owns { sound, notifications, dnd }.
• <ActiveConversation> knows the activeChannelId.
• <SessionProvider> owns the currentUserId.

File layout

• Directorysrc/

  • Directorytriggers/

    • message.trigger.ts the whole scenario
  • Directoryfeatures/

    • Directorychat/

      • Chat.tsx producer (useEvent) + provider (useCondition for activeChannelId)
    • Directorysession/

      • SessionProvider.tsx provider (useCondition for currentUserId)
    • Directorysettings/

      • SettingsPanel.tsx provider (useCondition for settings)
    • Directorynotifications/

      • NotificationLayer.tsx reactor (3 useAction)
  • App.tsx mounts them all
  • main.tsx wraps the tree in <TriggerRuntimeProvider>

1. The trigger

src/triggers/message.trigger.ts

import { createTrigger } from '@triggery/core';

type Settings = { sound: boolean; notifications: boolean; dnd: boolean };
type Message  = { id: string; author: string; authorId: string; text: string; channelId: string };

export const messageTrigger = createTrigger<{
  events: {
    'new-message': Message;
  };
  conditions: {
    settings:        Settings;
    activeChannelId: string | null;
    currentUserId:   string;
  };
  actions: {
    showToast:      { title: string; body: string };
    playSound:      'beep' | 'mention';
    incrementBadge: string;             // channelId
  };
}>({
  id: 'message-received',
  events: ['new-message'],
  required: ['settings', 'currentUserId'],
  handler({ event, conditions, actions, check }) {
    const msg = event.payload;

    // Already in this conversation — silent.
    if (msg.channelId === conditions.activeChannelId) return;

    // From the user themselves — never alert them about their own message.
    if (msg.authorId === conditions.currentUserId) return;

    // Always increment the badge for unread.
    actions.incrementBadge?.(msg.channelId);

    // Toast only if notifications are enabled.
    if (check.is('settings', s => s.notifications)) {
      actions.showToast?.({
        title: msg.author,
        body:  msg.text,
      });
    }

    // Sound only if enabled and not DND. Debounce in case of bursts.
    if (check.is('settings', s => s.sound && !s.dnd)) {
      actions.debounce(800).playSound?.('beep');
    }
  },
});

The whole rule is twenty lines, reads as a spec, and is easy to test (no React render needed).

2. The providers

Three components register conditions. Each one is responsible for the state it already owns — none of them imports another.

src/features/settings/SettingsPanel.tsx

import { useCondition } from '@triggery/react';
import { useState } from 'react';
import { messageTrigger } from '../../triggers/message.trigger';

export function SettingsPanel() {
  const [settings, setSettings] = useState({
    sound:         true,
    notifications: true,
    dnd:           false,
  });

  useCondition(messageTrigger, 'settings', () => settings, [settings]);

  return (
    <fieldset>
      <legend>Notifications</legend>
      <label>
        <input
          type="checkbox"
          checked={settings.notifications}
          onChange={e => setSettings(s => ({ ...s, notifications: e.target.checked }))}
        />
        Show toasts
      </label>
      <label>
        <input
          type="checkbox"
          checked={settings.sound}
          onChange={e => setSettings(s => ({ ...s, sound: e.target.checked }))}
        />
        Play sound
      </label>
      <label>
        <input
          type="checkbox"
          checked={settings.dnd}
          onChange={e => setSettings(s => ({ ...s, dnd: e.target.checked }))}
        />
        Do Not Disturb
      </label>
    </fieldset>
  );
}

src/features/session/SessionProvider.tsx

import { useCondition } from '@triggery/react';
import { messageTrigger } from '../../triggers/message.trigger';

export function SessionProvider({ userId, children }: { userId: string; children: React.ReactNode }) {
  useCondition(messageTrigger, 'currentUserId', () => userId, [userId]);
  return <>{children}</>;
}

src/features/chat/Chat.tsx (producer + provider for activeChannelId)

import { useEvent, useCondition } from '@triggery/react';
import { useState } from 'react';
import { messageTrigger } from '../../triggers/message.trigger';

export function Chat({ channelId }: { channelId: string | null }) {
  useCondition(messageTrigger, 'activeChannelId', () => channelId, [channelId]);

  const fireMessage = useEvent(messageTrigger, 'new-message');

  return (
    <button
      type="button"
      onClick={() =>
        fireMessage({
          id:        crypto.randomUUID(),
          author:    'Alice',
          authorId:  'u-alice',
          text:      'are you free for lunch?',
          channelId: 'c-lunch',
        })
      }
    >
      simulate inbound message
    </button>
  );
}

3. The reactor

One component registers all three action handlers. It owns the actual side effects.

src/features/notifications/NotificationLayer.tsx

import { useAction } from '@triggery/react';
import { useEffect, useRef } from 'react';
import { toast } from 'sonner';
import { messageTrigger } from '../../triggers/message.trigger';
import { useBadgeStore } from '../../stores/badge';

export function NotificationLayer() {
  const audio = useRef<HTMLAudioElement | null>(null);
  const increment = useBadgeStore(s => s.increment);

  useEffect(() => {
    audio.current = new Audio('/beep.mp3');
  }, []);

  useAction(messageTrigger, 'showToast', ({ title, body }) => {
    toast.success(title, { description: body });
  });

  useAction(messageTrigger, 'playSound', kind => {
    if (kind === 'mention') audio.current!.volume = 1;
    else                    audio.current!.volume = 0.6;
    audio.current!.play().catch(() => {});
  });

  useAction(messageTrigger, 'incrementBadge', channelId => {
    increment(channelId);
  });

  return null;
}

4. Wire the app

src/main.tsx

import { createRuntime } from '@triggery/core';
import { TriggerRuntimeProvider } from '@triggery/react';
import { StrictMode } from 'react';
import { createRoot } from 'react-dom/client';
import { App } from './App';

const runtime = createRuntime();

createRoot(document.getElementById('root')!).render(
  <StrictMode>
    <TriggerRuntimeProvider runtime={runtime}>
      <App />
    </TriggerRuntimeProvider>
  </StrictMode>,
);

src/App.tsx

import { useState } from 'react';
import { Chat } from './features/chat/Chat';
import { NotificationLayer } from './features/notifications/NotificationLayer';
import { SessionProvider } from './features/session/SessionProvider';
import { SettingsPanel } from './features/settings/SettingsPanel';

export function App() {
  const [activeChannel, setActiveChannel] = useState<string | null>(null);

  return (
    <SessionProvider userId="u-bob">
      <SettingsPanel />
      <Chat channelId={activeChannel} />
      <NotificationLayer />
      <button onClick={() => setActiveChannel(activeChannel === 'c-lunch' ? null : 'c-lunch')}>
        toggle active channel
      </button>
    </SessionProvider>
  );
}

What this buys you

	Before (useEffect)	With Triggery
Files touched to change rule	Chat.tsx (and any other useEffect-ridden component)	message.trigger.ts only
Tested without rendering	No	Yes
Toggling dnd requires	Re-render of Chat	One getter call at fire time
<Chat> re-renders on settings change	Yes	No
Adding a fourth side effect (e.g. log to analytics)	Modify Chat	New useAction in <AnalyticsLayer> — no other file changes

Test it

A complete vitest, no React:

src/triggers/message.trigger.test.ts

import { createTestRuntime, mockAction, mockCondition } from '@triggery/testing';
import { describe, expect, it, vi } from 'vitest';
import { messageTrigger } from './message.trigger';

describe('message-received', () => {
  it('skips when channelId matches activeChannelId', async () => {
    const rt = createTestRuntime({ triggers: [messageTrigger] });
    const showToast = vi.fn();
    mockCondition(rt, messageTrigger, 'settings', { sound: true, notifications: true, dnd: false });
    mockCondition(rt, messageTrigger, 'currentUserId', 'u-bob');
    mockCondition(rt, messageTrigger, 'activeChannelId', 'c-lunch');
    mockAction(rt, messageTrigger, 'showToast', showToast);

    await rt.fire('new-message', {
      id: '1', author: 'Alice', authorId: 'u-alice', text: 'hi', channelId: 'c-lunch',
    });

    expect(showToast).not.toHaveBeenCalled();
  });

  it('shows toast when channel is different and notifications are on', async () => {
    const rt = createTestRuntime({ triggers: [messageTrigger] });
    const showToast = vi.fn();
    mockCondition(rt, messageTrigger, 'settings', { sound: false, notifications: true, dnd: false });
    mockCondition(rt, messageTrigger, 'currentUserId', 'u-bob');
    mockCondition(rt, messageTrigger, 'activeChannelId', 'c-other');
    mockAction(rt, messageTrigger, 'showToast', showToast);

    await rt.fire('new-message', {
      id: '1', author: 'Alice', authorId: 'u-alice', text: 'hi', channelId: 'c-lunch',
    });

    expect(showToast).toHaveBeenCalledWith({ title: 'Alice', body: 'hi' });
  });
});

Variations

Same recipe — Solid Hooks API is identical; Solid signal makes the settings provider trivial.

Same recipe — Vue Composition API version with provide/inject runtime plugin.

WebSocket sync Replace the simulate button with a real `socket.on('new-message', fireMessage)`.

Anti-spaghetti When would this scenario become two triggers instead of one?