Traceable Commodity

Private Commodity Traceability lets you follow certified commodity lots across every custody hop in a multi-party supply chain (farm, truck, silo, railway, origin port, vessel, and receiving port) while enforcing Canton's privacy model so non-involved parties see nothing.

Each account holds commodity lots carrying certifications (NON-GMO, Deforestation-free), quality ratings, and quantities in tons. Custody transfers update ownership with evidence references attached.

A full attestation can be generated for any quantity, tracing provenance, certifications, and the complete custody path. Everything is backed by Daml quantity conservation that makes double-spend mathematically impossible. The UI's Party View switcher lets judges flip between seven operational roles to see exactly what each participant can and cannot observe.

The custody layer is built in Daml on Canton 3.5.1. Contracts enforce quantity conservation across every split, combine, transfer, and storage operation ( the same certified source lot cannot substantiate multiple downstream commodities. Party visibility is modeled with narrow observer/signatory sets so non-involved companies cannot read private lot positions, transfer histories, or balances.

The frontend is Next.js 16 (App Router) with TypeScript, Tailwind CSS v4, and shadcn/ui components. Zustand manages UI state and party-view selections. A Next.js API gateway dispatches between an offline demo adapter and the Canton JSON API v2 — the same UI works in both modes. Daml TypeScript bindings are generated via dpm codegen-js. Anti-double-spend is verified with a dedicated script (attempt-double-spend.ts) that confirms Canton's ledger rejects the transaction with a conflict error.