[client]

RESIST — streetwear store with race-safe checkout

Online store and back office for a Bacolod streetwear brand, where two shoppers can never buy the last shirt and every sales channel draws from one stock count.

RESIST storefront homepage with a full-width banner reading "Faster than my excuses" — Storefront homepage. The banner, gallery and testimonials are all managed from the admin.

Product page for the Endurance Division Tee with price, size picker and Add to bag button — Product page. Each size shows live availability: on hand minus units held in open checkouts.

Admin stock dashboard with units on hand, held, running low and sold out, and a per-size stock table — Stock dashboard. Held units return automatically when a checkout expires, so no cron job is needed.

Admin orders page with paid sales per channel and orders tagged In person, Pop-up and Instagram — Orders across channels. In-person, Instagram and pop-up sales come off the same shelf as website orders. (Demo data.)

Admin stock history table listing each sale with units, balance after, order, channel and admin — Stock history. Every change is logged with the balance after it and the admin who made it. (Demo data.)

Context

RESIST is a streetwear brand from Bacolod that sells through its website, Facebook and Instagram messages, and in person at pop-ups. Filipino shoppers expect to pay with GCash, Maya or QR Ph, not just cards.

Problem

Small drops sell out fast, so stock had to stay correct under pressure: no overselling when two people check out the last unit, no stock stuck in abandoned checkouts, and no orders lost to a late or repeated payment notification. And because many sales happen outside the website, the stock count had to stay true across every channel, not just online.

What I did

Built the storefront, checkout and admin in Next.js 16 with PostgreSQL and Drizzle ORM.
Integrated PayMongo Checkout for GCash, Maya, QR Ph, card and GrabPay, with signed, idempotent webhooks; the success page also confirms payment directly so orders don't wait on a delayed webhook.
Made stock holds derived, not stored: a checkout holds its units until it expires, and an abandoned checkout frees them the moment it does, with no cron job or queue.
Locked the affected rows during checkout and payment (SELECT … FOR UPDATE, in a fixed order) so concurrent shoppers can't both buy the last unit, and covered it with a concurrency test against a real database.
Handled the edge case honestly: a payment that lands after its hold expired, when the stock already sold elsewhere, is still recorded as paid and flagged Oversold for the admin instead of being dropped.
Built a "Record a sale" flow so in-person, Facebook, Instagram and pop-up sales come off the same shelf as website orders, in the same transaction, with the channel and the admin who entered it.
Wrote every stock change to an auditable ledger, and added order confirmation emails through Gmail or Resend, a flat shipping fee, and admin-managed banner, gallery and testimonials.

Impact

One stock count is the source of truth for every channel the brand sells through.
Overselling is prevented under concurrent checkouts, and abandoned checkouts never lock up stock.
The store is live at resist-store.vercel.app.