Agent-Skills.md

Agent Skills: NestJS Notification Architecture

Build dual-write notification services with database persistence and FCM push delivery in NestJS. Use when creating notification entities, sending push via FCM, or implementing in-app notification feeds. (triggers: notification.service.ts, notification.entity.ts, notification, push, fcm, alert, reminder)

UncategorizedID: hoangnguyen0403/agent-skills-standard/nestjs-notification

Repository

hoangnguyen0403/agent-skills-standard
HoangNguyen0403License: Apache-2.0
362103

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pnpm dlx add-skill https://github.com/HoangNguyen0403/agent-skills-standard/tree/HEAD/skills/nestjs/nestjs-notification

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skills/nestjs/nestjs-notification/SKILL.md

Skill Metadata

Name
nestjs-notification
Description
"Build dual-write notification services with database persistence and FCM push delivery in NestJS. Use when creating notification entities, sending push via FCM, or implementing in-app notification feeds. (triggers: notification.service.ts, notification.entity.ts, notification, push, fcm, alert, reminder)"

NestJS Notification Architecture

Priority: P0 (Standard)

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

Workflow: Send a Notification

  1. Save to database — Persist the notification entity with type enum and metadata.
  2. Check FCM token — Verify the recipient has a valid fcmToken; skip push if missing.
  3. Send push — Call FCM inside try/catch; never let FCM failure block the request.
  4. Serialize data — Convert Dates to ISO strings; keep FCM data payload flat (IDs only).

Dual-Write Service Example

See implementation examples

Structure

See implementation examples

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