# Development

## Stack

The initial implementation uses Python 3.12 and the standard library. The
first slice intentionally avoids runtime dependencies so the repository can be
tested immediately in local and agent environments.

## Layout

```text
src/user_engine/
  domain/      transport- and persistence-neutral domain schemas
  ports.py     adapter protocols for identity, authorization, events, audit,
               membership export, application bindings, and secrets
  testing/     local fixtures for tests and examples
tests/         standard-library unittest suite
```

The domain layer should not import HTTP frameworks, database clients, or
platform-specific SDKs. Those integrations belong behind ports.

## Commands

```bash
make test
```

The command runs:

```bash
PYTHONPATH=src python3 -m unittest discover -s tests -p 'test_*.py'
```

## Implementation Rule

Add new behavior in this order:

1. domain schema or port;
2. local fixture or adapter;
3. test that proves the boundary;
4. infrastructure adapter or API surface.