ecommerce-expert

E-Commerce Architecture & Modern Storefront Expert (2026 Edition)

English | Bahasa Indonesia

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English

Description

Production guide for high-converting e-commerce architectures, headless storefronts (Medusa.js v2, Shopify Storefront API, Saleor), inventory atomicity, and multi-rail payment integrations (DOKU Checkout, SNAP BI, Stripe). Covers atomic stock reservations to prevent race-condition overselling during flash sales, cart session state machines, structured schema markup (Product, Offer, BreadcrumbList), and localized checkout workflows.

Trigger Conditions

• Designing or developing an e-commerce platform, marketplace, or custom storefront.
• Integrating headless commerce engines (Medusa.js v2, Shopify Storefront API).
• Preventing inventory race conditions during high-concurrency checkout traffic.
• Integrating localized Indonesian payment methods (DOKU Virtual Account, QRIS, Direct Debit).
• Optimizing product page Core Web Vitals and SEO schema.

Atomic Inventory Reservation Pattern (PostgreSQL / Drizzle)

Prevents overselling during high-concurrency flash sales using row-level pessimistic locking (FOR UPDATE):

// src/services/inventory.service.ts
import { db } from '@/lib/db';
import { sql } from 'drizzle-orm';

export interface ReserveStockResult {
  success: boolean;
  orderId?: string;
  errorMessage?: string;
}

export async function reserveProductStockAtomic(
  productId: string,
  requestedQuantity: number,
  orderId: string
): Promise<ReserveStockResult> {
  return await db.transaction(async (tx) => {
    // 1. Lock the inventory row strictly for update
    const [product] = await tx.execute(sql`
      SELECT id, stock_quantity, price_cents, is_active
      FROM products
      WHERE id = ${productId}
      FOR UPDATE
    `);

    if (!product || !product.is_active) {
      return { success: false, errorMessage: 'Product is unavailable.' };
    }

    if (product.stock_quantity < requestedQuantity) {
      return { success: false, errorMessage: 'Insufficient stock remaining.' };
    }

    // 2. Decrement available inventory atomically
    await tx.execute(sql`
      UPDATE products
      SET stock_quantity = stock_quantity - ${requestedQuantity},
          updated_at = NOW()
      WHERE id = ${productId}
    `);

    // 3. Create provisional stock reservation record (15-minute TTL)
    await tx.execute(sql`
      INSERT INTO stock_reservations (order_id, product_id, quantity, expires_at)
      VALUES (${orderId}, ${productId}, ${requestedQuantity}, NOW() + INTERVAL '15 minutes')
    `);

    return { success: true, orderId };
  });
}