Platform Liberation + AI Employee
One inventory engine. Three storefronts. 135,000 SKUs in real-time sync.
A 135K+ SKU laptop parts operation was running across 3 eBay accounts and 2 Shopify storefronts with no shared inventory layer. Parts sold on eBay stayed live on Shopify. Multi-quantity listings had no safe decrement logic. We rebuilt it as one system.
The Problem
“Parts sold on eBay were still showing available on Shopify. Every oversell was a customer complaint.”
Inventory oversell was the core failure. When a part sold on eBay, it could still show as available on Shopify. When it sold on Shopify, eBay listings stayed live. Multi-quantity listings had no safe decrement logic — cancellations, fraud flags, and restores all touched inventory differently and got it wrong. A third-party repair shop also needed to browse and reserve parts, with no system to support it.
What Was Built
Real-Time Inventory Sync
GitHub Actions + Shopify Webhooks- —135K+ SKU catalog synced from 3 eBay accounts via GitHub Actions — runs on every eBay event
- —Shopify sale → eBay listing ended or qty decremented within seconds via webhook chain
- —Multi-quantity safety: remaining qty calculated before any EndItem call — listings with stock never ended prematurely
- —Cancel reason logic: inventory cancels decrement qty (unit lost), all other reasons restore and relist on eBay automatically
Reseller API + Repair Shop Storefront
Next.js + Supabase- —/api/reseller/products — live inventory feed for third-party repair shops, per-client markup in Supabase
- —Reserve flow: shop reserves → qty decremented in Supabase → Shopify adjusted → eBay ended if qty hits 0
- —Cancel flow: cancelled order → relist on eBay + restore qty — fully automated
- —Stock changes on any channel propagate across all storefronts immediately
OnlineUsedLaptops.com — Second Storefront
Next.js App Router- —Filtered view of the same Supabase inventory — complete device categories only, separate brand identity
- —Separate Shopify store with independent webhook registration and token management
- —Product schema injected in SSR'd initial HTML — resolved RSC Suspense streaming bug hiding schema from crawlers
- —7 location pages, blog, warranty page — full SEO and AEO coverage
Sara — AI Employee
Claude Haiku + Prompt Caching- —Handles customer queries across the full 135K SKU catalog — live 24/7
- —Prompt-cached system prompt for cost efficiency — sub-cent per conversation
- —Chargeback defense metadata flags, AS-IS sale gate, shipping enforcement — code-level, not prompt-only
- —Compatibility mismatch intercepts and order lookup by phone/email — zero human handoff needed
Ready?