# Nestjs Notification

> Standards for Notification Types, Service Architecture, and FCM Integration. Use when building notification services or integrating FCM in NestJS. (triggers: notification.service.ts, notification.entity.ts, notification, push, fcm, alert, reminder)

- Skill: `comeonoliver/nestjs-notification` (Agent Skill)
- Install (CLI): `npx skillmds@latest add comeonoliver/nestjs-notification`
- Raw SKILL.md: https://api.skillmd.com/api/skills/comeonoliver/nestjs-notification/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: ComeOnOliver (https://skillmd.com/u/comeonoliver)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/comeonoliver/nestjs-notification

---


# NestJS Notification Architecture

## **Priority: P0 (Standard)**

Implement a "Dual-Write" notification system: persist to Database (In-App) and send via FCM (Push).

## Structure

```text
src/modules/notification/
├── notification.service.ts   # Logic: DB Save + FCM Send
├── entities/
│   └── notification.entity.ts # DB Schema + NotificationType Enum
└── types/
    └── notification.types.ts  # Interfaces for Payloads/Metadata
```

## Implementation Guidelines

- **Use Dual-Write**: Save to DB _first_, then attempt FCM. Catch FCM errors so they don't block the logic.
- **Define Granular Types**: Use `NotificationType` Enum (e.g., `APPOINTMENT_REMINDER`) for frontend icon/color logic.
- **Stringify Metadata**: Store routing data (IDs) as JSON string in DB, but Map to string-only Key-Values for FCM `data`.
- **Handle Tokens**: Check for `fcmToken` existence before sending. Fail gracefully if missing.
- **Serialize Dates**: Convert Dates to ISO strings before sending to FCM.

## Anti-Patterns

- **No Generic Types**: Avoid `type: string`. Always use the Enum.
- **No Blocking FCM**: Never `await` FCM without a `try/catch`. It shouldn't crash the request.
- **No Complex Data in Push**: Keep FCM `data` payload flat and minimal (IDs only). Fetch details on open.

## References

- [Service Pattern (Dual-Write)](references/service.md)
- [Type Definitions](references/types.md)