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New skills (14): - nestjs-best-practices: 40 priority-ranked rules (kadajett) - fastapi: Pydantic v2, async SQLAlchemy, JWT auth (jezweb) - architecture-patterns: Clean Architecture, Hexagonal, DDD (wshobson) - python-performance-optimization: Profiling and optimization (wshobson) - ai-sdk: Vercel AI SDK streaming and agent patterns (vercel) - create-agent: Modular agent architecture with OpenRouter (openrouterteam) - proactive-agent: WAL Protocol, compaction recovery, self-improvement (halthelobster) - brand-guidelines: Brand identity enforcement (anthropics) - ui-animation: Motion design with accessibility (mblode) - marketing-ideas: 139 ideas across 14 categories (coreyhaines31) - pricing-strategy: SaaS pricing and tier design (coreyhaines31) - programmatic-seo: SEO at scale with playbooks (coreyhaines31) - competitor-alternatives: Comparison page architecture (coreyhaines31) - referral-program: Referral and affiliate programs (coreyhaines31) README reorganized by domain: Code Quality, Frontend, Backend, Auth, AI/Agent Building, Marketing, Design, Meta. Mosaic Stack is not limited to coding — the Orchestrator serves coding, business, design, marketing, writing, logistics, and analysis. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2.8 KiB
2.8 KiB
title, impact, impactDescription, tags
| title | impact | impactDescription | tags |
|---|---|---|---|
| Use Async Lifecycle Hooks Correctly | HIGH | Improper async handling blocks application startup | performance, lifecycle, async, hooks |
Use Async Lifecycle Hooks Correctly
NestJS lifecycle hooks (onModuleInit, onApplicationBootstrap, etc.) support async operations. However, misusing them can block application startup or cause race conditions. Understand the lifecycle order and use hooks appropriately.
Incorrect (fire-and-forget async without await):
// Fire-and-forget async without await
@Injectable()
export class DatabaseService implements OnModuleInit {
onModuleInit() {
// This runs but doesn't block - app starts before DB is ready!
this.connect();
}
private async connect() {
await this.pool.connect();
console.log('Database connected');
}
}
// Heavy blocking operations in constructor
@Injectable()
export class ConfigService {
private config: Config;
constructor() {
// BLOCKS entire module instantiation synchronously
this.config = fs.readFileSync('config.json');
}
}
Correct (return promises from async hooks):
// Return promise from async hooks
@Injectable()
export class DatabaseService implements OnModuleInit {
private pool: Pool;
async onModuleInit(): Promise<void> {
// NestJS waits for this to complete before continuing
await this.pool.connect();
console.log('Database connected');
}
async onModuleDestroy(): Promise<void> {
// Clean up resources on shutdown
await this.pool.end();
console.log('Database disconnected');
}
}
// Use onApplicationBootstrap for cross-module dependencies
@Injectable()
export class CacheWarmerService implements OnApplicationBootstrap {
constructor(
private cache: CacheService,
private products: ProductsService,
) {}
async onApplicationBootstrap(): Promise<void> {
// All modules are initialized, safe to warm cache
const products = await this.products.findPopular();
await this.cache.warmup(products);
}
}
// Heavy init in async hooks, not constructor
@Injectable()
export class ConfigService implements OnModuleInit {
private config: Config;
constructor() {
// Keep constructor synchronous and fast
}
async onModuleInit(): Promise<void> {
// Async loading in lifecycle hook
this.config = await this.loadConfig();
}
private async loadConfig(): Promise<Config> {
const file = await fs.promises.readFile('config.json');
return JSON.parse(file.toString());
}
get<T>(key: string): T {
return this.config[key];
}
}
// Enable shutdown hooks in main.ts
async function bootstrap() {
const app = await NestFactory.create(AppModule);
app.enableShutdownHooks(); // Enable SIGTERM/SIGINT handling
await app.listen(3000);
}
Reference: NestJS Lifecycle Events