bun-runtime-expert

Bun 1.2+ Runtime Expert (2026 High-Performance Standard)

English | Bahasa Indonesia

---

English

Orchestration & Integration

Connects and orchestrates with domain skills:

• Backend & APIs: js-backend-expert (Hono on Bun, Fastify/Express migration), api-design-expert (REST & WebSocket contracts), and sse-websocket-streaming-expert (native Bun.serve WebSockets).
• Database & Storage: database-orm-expert (Drizzle ORM with native bun:sql, PostgreSQL/SQLite) and file-upload-media-expert (zero-dependency Bun.s3 client).
• Quality & Testing: autonomous-tdd-debugger, e2e-testing-expert, and anti-slop for executing high-speed bun test suites with snapshot matching.
• Orchestration: brainstorming and zero-to-prod-orchestrator (Phase 4: Backend & APIs).

Description

Expert-level guidance for engineering ultra-low-latency backend microservices with Bun 1.2+. Covers the native PostgreSQL driver (import { SQL } from 'bun'), native S3 object storage (Bun.s3), git-friendly text lockfiles (bun.lock), multi-core HTTP clustering via reusePort, built-in SQLite, and high-speed Jest-compatible unit testing via bun:test.

Trigger Conditions

• Scaffolding new high-performance microservices, REST APIs, or WebSocket hubs using Bun.
• Querying PostgreSQL or SQLite without external drivers using native Bun.sql.
• Interacting with Amazon S3, Cloudflare R2, or MinIO using zero-dependency Bun.s3.
• Running multi-core HTTP services with automatic load distribution across CPU cores.
• Executing unit and integration tests using bun test.
• Migrating legacy Node.js/npm codebases to Bun's native execution layer.

---

Bun 1.2+ Core Architectural Features

1. Native PostgreSQL Client (import { SQL } from 'bun')

Bun 1.2 includes a built-in, high-speed PostgreSQL driver that communicates directly via binary wire protocol without pg or postgres.js:

// src/lib/db.ts
import { SQL } from 'bun';

// Instantiate pooled database client
export const sql = new SQL({
  url: process.env.DATABASE_URL || 'postgres://user:password@localhost:5432/production_db',
  max: 20, // Connection pool size
  idleTimeout: 30, // Max idle time in seconds
});

export interface UserAccount {
  id: string;
  email: string;
  balance: number;
}

// 1. Tagged template query with automatic parameterized SQL injection defense
export async function getActiveUser(email: string): Promise<UserAccount | null> {
  const users = await sql<UserAccount[]>`
    SELECT id, email, balance 
    FROM users 
    WHERE email = ${email} AND active = true 
    LIMIT 1
  `;
  return users[0] ?? null;
}

// 2. Atomic Database Transaction
export async function transferFunds(fromUserId: string, toUserId: string, amount: number) {
  return await sql.begin(async (tx) => {
    const debit = await tx`
      UPDATE users 
      SET balance = balance - ${amount} 
      WHERE id = ${fromUserId} AND balance >= ${amount} 
      RETURNING id, balance
    `;

    if (debit.length === 0) {
      throw new Error('Insufficient funds or sender not found');
    }

    await tx`
      UPDATE users 
      SET balance = balance + ${amount} 
      WHERE id = ${toUserId}
    `;

    return { success: true };
  });
}