Architecture Overview

Veylent is a monorepo containing four main components, managed by Nx.

veylent/
├── apps/
│   ├── desktop/        Tauri 2 (Rust + React) desktop app
│   ├── api/            NestJS backend server
│   ├── web/            Verification web app (React + Vite)
│   ├── verify/         Mobile verification app (Expo)
│   └── docs/           This documentation (Docusaurus)
├── libs/
│   └── shared/
│       ├── types/      Shared TypeScript types (signing record, API results)
│       └── crypto/     Record decryption and scan check (verifyAnchor)
└── contracts/          Solidity smart contracts (Hardhat)

Data Flow

Communication Protocols

Path	Protocol	Data
Desktop -> API	HTTPS POST	Anchor ID, composite hash, previous anchor ID, encrypted payload
API -> Blockchain	JSON-RPC	anchorDocument transaction; anchorBlock and event lookups
API -> Database	Prisma/SQL	Anchor record (anchor ID, tx hash, encrypted payload)
Phone -> Web App	HTTPS GET	Verification URL from QR
Web App / Mobile / Desktop -> API	HTTPS GET	Verification query by anchor ID

The verification query only needs the server's database for the encrypted payload. The on-chain part (block, composite hash, previous anchor ID, timestamp) can be read directly from the contract by anyone.

Technology Stack

Component	Technology	Why
Desktop frontend	React 19, TypeScript	Component model, ecosystem
Desktop backend	Rust (Tauri 2)	PDF manipulation, cryptography, security
API server	NestJS, TypeScript	Structured backend, validation, modules
Database	PostgreSQL (Prisma)	Relational data, migrations
Blockchain	Ethereum-compatible (Hardhat for dev)	Smart contracts, public verifiability
Verification web	React, Vite	Lightweight, fast loading for mobile
Monorepo	Nx 22	Task orchestration, caching, dependencies