Skill: Signal — Smart Notification Engine

Set up AI-powered notifications that decide IF, WHAT, WHEN, and HOW to notify each person. Signal uses Personize memory and governance to send the right message, to the right person, at the right time — or stay quiet when silence is better.

What This Skill Solves

Most notification systems are dumb rules: "if event X, send template Y." They don't know who the person is, what they care about, what was already sent, or whether this notification will help or annoy.

Signal replaces rules with intelligence:

IF — Should this person be notified at all? (AI scores 0-100 based on full entity context)
WHAT — What should the message say? (Uniquely personalized using everything known about the person)
WHEN — Now, or later in a digest? (AI decides priority: immediate / standard / digest)
HOW — Which channel? (Email, Slack, in-app, SMS — chosen based on context)

The intelligence comes from Personize SDK — memory, governance, and AI. Signal packages the orchestration into a reusable engine.

When This Skill is Activated

If the developer mentions notifications, alerts, or messaging, start with ASSESS.

If the developer has a specific question (e.g., "how do I add a Slack channel to Signal"), jump to the relevant action.

If the developer wants to understand the architecture, walk them through the engine flow.

When NOT to Use This Skill

Need raw memory operations → use entity-memory
Need shared workspaces without notifications → use collaboration
Need governance rules without notifications → use governance
Need CRM data sync → use entity-memory (CRM sync section)

Actions

Action	When to Use
ASSESS	Understand their stack, events, channels, and recipients
CONFIGURE	Generate Signal initialization code
CONNECT	Scaffold event hooks for their framework
GOVERN	Set up governance rules for notification guidelines
TEST	Run a dry-run evaluation and verify the decision

Action: ASSESS

Understand what the developer needs before writing code.

Questions to Ask

What events matter? — What happens in your product that should potentially trigger a notification?
- User lifecycle: signup, login, trial expiry, churn risk
- Usage: milestones, drops, feature adoption
- CRM: deal changes, meeting outcomes, support tickets
- System: sync complete, errors, billing events
Who are the recipients? — Who gets notified?
- End users (in-app, email)
- Internal team (Slack, email)
- Both (different channels)
What channels? — How should messages be delivered?
- Email (SES, SendGrid)
- Slack (webhook)
- In-app (bridge to existing UI)
- SMS (Twilio — community channel)
What governance rules exist? — What constraints apply?
- Max notifications per day per user
- Quiet hours / time zones
- Content policies (tone, compliance)
- Opt-out preferences
What framework? — Where do events originate?
- Express.js / Fastify / Next.js / NestJS
- Trigger.dev / n8n / cron jobs
- Webhook-based (external system pushes events)

Output

After assessment, summarize:

Events to handle (with types like user.signup, usage.drop)
Channels needed
Governance constraints
Framework/integration approach

Action: CONFIGURE

Generate the Signal initialization code based on the assessment.

Minimal Setup

import { Personize } from '@personize/sdk';
import { Signal, ConsoleChannel, ManualSource } from '@personize/signal';

const client = new Personize({ secretKey: process.env.PERSONIZE_SECRET_KEY! });
const manual = new ManualSource();

const signal = new Signal({
    client,
    channels: [new ConsoleChannel()],
    sources: [manual],
});

await signal.start();

Production Setup

import { Personize } from '@personize/sdk';
import {
    Signal,
    ManualSource,
    SesChannel,       // or SendGridChannel
    SlackChannel,
    InAppChannel,
} from '@personize/signal';

const client = new Personize({ secretKey: process.env.PERSONIZE_SECRET_KEY! });
const manual = new ManualSource();

const signal = new Signal({
    client,
    channels: [
        new SesChannel({ sourceEmail: 'notifications@yourapp.com' }),
        new SlackChannel({ webhookUrl: process.env.SLACK_WEBHOOK! }),
        new InAppChannel(async (recipient, payload) => {
            // Bridge to your existing notification UI
            await yourNotificationService.create({
                userId: recipient.userId,
                title: payload.subject,
                body: payload.body,
            });
            return { success: true, channel: 'in-app', timestamp: new Date().toISOString() };
        }),
    ],
    sources: [manual],
    engine: {
        dailyCap: 5,                              // max per user per day
        deduplicationWindowMs: 6 * 60 * 60 * 1000, // 6 hours
        memorize: true,                            // feedback loop
        workspaceUpdates: true,                    // track in workspace
    },
});

await signal.start();

// Schedule daily digests (weekdays 9 AM)
signal.schedule('daily-digest', '0 9 * * 1-5', async () => {
    const users = await getActiveUsers();
    await signal.digest.runBatch(users);
});

Configuration Reference

Option	Default	Description
`engine.dailyCap`	5	Max notifications per email per day
`engine.deduplicationWindowMs`	6h	Skip same event type within window
`engine.memorize`	true	Record sent notifications in memory
`engine.workspaceUpdates`	false	Create workspace entries on SEND/DEFER
`engine.concurrency`	5	Max parallel evaluations
`engine.maxEvaluationsPerMinute`	20	Rate limit for batch processing

Action: CONNECT

Scaffold event hooks that push product events into Signal.

Express.js Pattern

// event-hooks.ts — fire-and-forget, never throws, never blocks
import { ManualSource } from '@personize/signal';

const manual = new ManualSource(); // same instance used in Signal config

export const EventHooks = {
    async onUserSignup(email: string, data?: Record<string, unknown>) {
        manual.emit({
            id: `evt_${Date.now()}_${Math.random().toString(36).substring(2, 6)}`,
            type: 'user.signup',
            email,
            data: data || {},
            timestamp: new Date().toISOString(),
            metadata: { team: 'product' },
        });
    },

    async onUsageDrop(email: string, data: { metric: string; dropPercent: number }) {
        manual.emit({
            id: `evt_${Date.now()}_${Math.random().toString(36).substring(2, 6)}`,
            type: 'usage.drop',
            email,
            data,
            timestamp: new Date().toISOString(),
            metadata: { team: 'product' },
        });
    },
};

Using in Controllers

// In your signup controller
router.post('/signup', async (req, res) => {
    const user = await createUser(req.body);
    EventHooks.onUserSignup(user.email, { plan: user.plan }).catch(() => {});
    res.json(user);
});

Webhook Source (external events)

import { WebhookSource } from '@personize/signal';

const webhookSource = new WebhookSource({
    path: '/webhooks/signal',
    secret: process.env.WEBHOOK_SECRET,
    parser: (body) => ({
        id: body.id || `wh_${Date.now()}`,
        type: body.event || 'webhook.received',
        email: body.email || body.user_email,
        data: body.data || body,
        timestamp: body.timestamp || new Date().toISOString(),
    }),
});

// Mount on Express
app.use(webhookSource.middleware());

Action: GOVERN

Set up governance rules that guide Signal's AI decisions.

Governance Variables to Create

Use the Personize web app or SDK to create these governance variables:

1. Notification Guidelines (tag: notifications)

Notification Policy:
- Never notify about events the user has already seen in the product
- Prioritize actionable insights over informational updates
- Match tone to the urgency: critical = direct, informational = friendly
- Always include a specific next step, not generic "check it out"
- Maximum 3 notifications per user per day (engine enforces 5 as hard cap)

2. Channel Routing (tag: notifications)

Channel Selection:
- Slack: For internal team alerts (sales, support, ops)
- Email: For user-facing notifications that need persistence
- In-app: For real-time product notifications when user is active
- Digest: For low-priority updates that can wait for weekly summary

3. Frequency Policy (tag: communications)

Communication Frequency:
- New users (< 30 days): Max 1 notification per day. Focus on onboarding milestones.
- Active users: Max 3 per week. Only high-signal events.
- At-risk users: Increase frequency for re-engagement. Max 1 per day.
- Churned users: Do not notify. Only send win-back campaigns via marketing.

How Governance Flows into Signal

Signal's engine calls smartGuidelines() and smartDigest() in step 3 (context assembly). The AI sees these governance rules alongside the entity's full context and makes decisions accordingly. No code changes needed — update governance variables and Signal adapts.

Action: TEST

Verify Signal is working with a dry-run evaluation.

Quick Test

const result = await signal.trigger({
    id: 'test_001',
    type: 'user.signup',
    email: 'test@example.com',
    data: { plan: 'trial', source: 'website' },
    timestamp: new Date().toISOString(),
});

console.log('Action:', result.action);    // SEND | DEFER | SKIP
console.log('Score:', result.score);      // 0-100
console.log('Reasoning:', result.reasoning);
console.log('SDK calls:', result.sdkCallsUsed);
console.log('Duration:', result.durationMs, 'ms');

What to Verify

Pre-check works — Trigger the same event twice within 6 hours. Second should SKIP instantly (0 SDK calls).
Daily cap works — Trigger 6 events for the same email. The 6th should SKIP.
AI decision varies — Trigger different event types. Scores should vary based on context relevance.
Feedback loop — After a SEND, check that the notification was memorized: client.memory.recall({ query: 'signal:sent', email: '...' }).
Dedup via memory — After step 4, trigger a similar event. The AI should reference the recently sent notification in its reasoning.

Console Channel for Testing

Use ConsoleChannel during development — it logs decisions without delivering:

const signal = new Signal({
    client,
    channels: [new ConsoleChannel()],  // logs to stdout
    sources: [manual],
});

Available Resources

Resource	Contents
`../../signal/README.md`	Full Signal documentation — architecture, channels, sources, workspace, digest, cost controls
`../../signal/CLAUDE.md`	AI tool instructions for Signal package
`../../signal/examples/quickstart/`	Minimal setup example
`../../signal/examples/saas-onboarding/`	Signup → nurture → convert sequence
`../../signal/examples/sales-alerts/`	Usage drop alerts to sales team
`../../signal/examples/weekly-digest/`	Deferred items → compiled digest
`../../signal/examples/multi-team/`	Product + Sales + Marketing on same records
`../../signal/templates/CHANNEL_TEMPLATE.md`	How to build a new channel
`../../signal/templates/SOURCE_TEMPLATE.md`	How to build a new source
`recipes/quickstart.ts`	Minimal Signal setup recipe
`recipes/multi-team.ts`	Multi-team configuration recipe