Full-stack Example

The repository includes a full-stack banking example in examples/example-alvyn-full-stack-app. It demonstrates how Alvyn fits into a web application rather than requiring a particular server or UI framework.

Included Stack

• Vite and Nitro for the development and server runtime
• React with Apollo Client for the browser UI
• Elysia and GraphQL Yoga for the GraphQL endpoint
• GraphQL-over-SSE for live subscriptions
• PostgreSQL with Alvyn event streams and an event-backed balance snapshot
• Testcontainers for a reusable local PostgreSQL development database

Live Banking Flow

The example defines separate bank-account and transaction aggregates. Deposits and withdrawals are appended to the transaction stream, while BankAccountBalance maintains a derived balance snapshot. GraphQL subscription resolvers consume the aggregate subscription API to publish live transaction and balance updates to the selected account.

The withdrawal mutation also demonstrates typed GraphQL errors: insufficient funds are returned with an INSUFFICIENT_FUNDS code and a payload containing the current balance and requested amount.

Run It Locally

From the example directory:

pnpm install
pnpm dev

When DATABASE_URL is not set, the Vite configuration starts or reuses the alvyn-example-postgres-dev PostgreSQL container through Docker. To use an existing database, provide DATABASE_URL before starting the app.

The example is intended for learning and local development. It does not provide authentication or authorization and should not be used as a production banking service.

See the example source on GitHub for the complete application.