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Case study 13 / 26

Sita Shree Gold System

Billing, inventory and VAT registers for a gold and jewellery business — the first production deployment of the jewellery platform, prepared against Nepal's Electronic Billing Procedure 2082.

Status
Deployed
Domain
web
Source of claims
Private repository README (reviewed). Source and deployment are not public.

A full-stack jewellery billing and inventory system running in production on Vercel with Neon Postgres. Alongside sales, purchasing, workshop and stock audit, it carries the controls an e-billing submission needs: a data-correction register, statutory VAT registers and a permanent audit trail.

01/The problem

A jewellery business needs billing it can defend to the tax authority: invoices that are never renumbered, corrections that leave a trail, and registers in the regulator's format — on top of weight-and-purity pricing for every piece in the shop.

02/The system

A full-stack jewellery billing and inventory system running in production on Vercel with Neon Postgres. Alongside sales, purchasing, workshop and stock audit, it carries the controls an e-billing submission needs: a data-correction register, statutory VAT registers and a permanent audit trail.

03/Scope

  1. 01Gold and silver rates fetched on a schedule from the national federation's published rates, with history, stale detection and manual override.
  2. 02Items with barcode, QR and RFID, full weight breakdown, making charge, wastage and valuation; physical tag printing at label-printer sizes.
  3. 03Sales, purchases and returns, credit and debit notes, customer and supplier ledgers, and old-gold exchange.
  4. 04Data correction as a register: request → authorise by a different person → apply; finalised documents change only by credit/debit note, cancellation or return, behind a trigger-protected trail.
  5. 05Nepal VAT configuration, fiscal-year reporting, Schedule 8/9/10 registers and an e-billing submission package with sample documents.
  6. 06RBAC with 10 roles enforced per permission on the server, rate limiting, helmet and brute-force login protection.
  7. 07A companion Next.js storefront and back office for the shop: append-only metal rates and audit logs, real Code 128 and QR tags rendered server-side, double-submit CSRF and a nine-role write matrix.

04/Engineering

Four-eyes corrections

A correction to a relied-upon record must be authorised by someone other than its requester, and the trail is protected at the database level — not just in application code.

Rates are frozen into history

Historical transactions keep the metal rate used at the time, so a later rate change can never silently revalue a past invoice.

One product, many deployments

Hostname-resolved schema-per-tenant isolation lets the same build serve many shops — or run offline on a single PC at the counter.

05/Interface

Interface screenshots of this commercial product are not public. The visual above is an abstract representation of its modules — not the product itself.

06/Tech stack

  • React 19
  • TypeScript
  • Vite
  • Tailwind CSS 4
  • Express
  • Prisma
  • PostgreSQL (Neon)
  • Zod
  • Vercel

07/Result

Verified outcomes

  • Running in production on Vercel with Neon Postgres.
  • Server suites cover lifecycle, security, money, calendar and rates; separate suites cover compliance operations and tenant isolation.

Known limitations

  • No IRD certification or verified CBMS transmission is claimed.

08/Links

Private commercial codebase — no public links.

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