# Developer guide

Start with the public behavior you want to exercise. A useful contribution has a concrete input, an observable result and enough connection details for another developer to reproduce it without access to your application.

## Establish a baseline

Follow [installation](https://coordinatordb.com/docs/get-started/setup/install), start a local server and run a query through the supplied client:

```sh
./coordinator client --database data --query "SELECT 1 AS connected FORMAT csv"
```

The result is one row containing `1`. Record the executable you tested, the operating system, the interface and any configuration changes. Keep credentials and private connection addresses out of shared examples.

## Make one behavior reviewable

Use a small table and deterministic data. For a reported problem, show the expected result beside the observed result. For a new integration example, explain connection ownership, error handling and how the example cleans up its own data.

Check the [public connection model](https://coordinatordb.com/docs/resources/develop-contribute/introduction/architecture) before choosing native TCP, HTTP or an embedded connection. Then add a [regression case](https://coordinatordb.com/docs/resources/develop-contribute/contribute/tests) that demonstrates the change. A documentation correction should include a runnable example when the correction affects SQL or connection behavior.