GHODA

The brief

Tâm Hợp is a metal-parts subcontractor: buy raw material, send it out for machining, deliver finished parts to large customers. The money and the metal move through half a dozen hands before anyone gets paid, and all of it was tracked in disconnected Excel files. A wrong number there is not a reporting problem — it is buying steel you didn't need.

The approach

A Next.js app on Postgres with a 30-model Prisma schema that follows the physical flow: forecast versions and customer orders at one end; material orders, supplier POs, goods receipts and lots in the middle; process steps for each stage of outsourced machining; deliveries at the far end. Money runs in parallel — advances, credit lines, funding sources — because in this business cash position decides what you're allowed to order.

Lot-level inventory was non-negotiable. Customers ask which batch a part came from, and an answer of "roughly March" is not an answer.

The harder parts

The business rules, not the code. Half the project was writing down formulas the client had only ever carried in their head, in docs/, and getting them confirmed before anything was implemented — because a costing formula that is subtly wrong produces plausible numbers for months before anyone notices.