# SregERP: Light-Steel DDD Modular Monolith

> A 9-crate Rust + Svelte 5 ERP for light-steel manufacturing with meter-level stock segment lineage, cut optimization, and realized-waste accounting.

- Client: Wisma Karya / Lentera Baja
- Year: 2026
- Disciplines: Rust & Axum 0.8, DDD Modular Monolith, SQLx & PostgreSQL 16, Svelte 5 Runes, Cut Optimization
- Page: https://ponkster.me/case-studies/sregerp
- Studio: ponkster.me (https://ponkster.me)
- Contact: origin.ponkster@gmail.com

## Challenge

Generic inventory systems count discrete SKUs, which fails completely in light-steel (baja ringan) manufacturing and distribution where every cut of a spandek roofing sheet or 50m coil creates child segments, offcut remainders, and potential margin leakage.

## Approach

We engineered SregERP as a 9-crate Rust DDD modular monolith (kernel, inventory, sales, procurement, fulfillment, hr, organization, expenses, web_api) on Axum 0.8, SQLx 0.9, and PostgreSQL 16, paired with a SvelteKit 5 runes interface. Every physical sheet is tracked as a StockSegment aggregate in meters with parent-child cut lineage, stock-form cut policies (largest-remainder for spandek sheets, best-fit for rolls), multi-branch holding scopes, and Monday-Saturday Gaji Harian payroll.

## Outcome

Eliminated unrecorded offcut waste by tying physical cut execution, Lapor Rusak damage grading, Prime/Clearance/Dead stock valuation, and weekly payroll directly into live P&L, Balance Sheet, and Cash Flow statements.

## Results

- 9-crate Rust DDD modular monolith with persistence-ignorant domain aggregates
- Meter-exact StockSegment lineage with sheet and roll cut-optimization policies
- Realized waste and damage-loss accounting across multi-branch warehouse operations

## Optional

- [Studio overview and all case studies](https://ponkster.me/llms.txt)