# Configuration

`grad300-client` uses an
[astropy-style `ConfigNamespace`](https://docs.astropy.org/en/stable/config/)
to manage defaults.  The singleton {py:obj}`~grad300_client.conf` can be
imported and modified at runtime.

## Available parameters

| Parameter | Default | Description |
|-----------|---------|-------------|
| `base_url` | `https://grad300.lam.fr` | Base URL of the GRAD300 server |
| `api_prefix` | `/api/v1` | API prefix appended to `base_url` |
| `timeout` | `30.0` | HTTP timeout in seconds |
| `default_page_size` | `100` | Default page size for list/query methods |

## Changing defaults at runtime

```python
from grad300_client import conf

conf.base_url = "https://my-local-instance.example.com"
conf.timeout = 60.0
conf.default_page_size = 200
```

Changes apply to any `Grad300Client` instances created **after** the
modification.  Existing instances are not affected because they resolve
configuration values at construction time.

## Temporary overrides with a context manager

```python
from grad300_client import conf, Grad300

with conf.set_temp("base_url", "https://staging.grad300.lam.fr"):
    client = Grad300(user="user@example.com", password="pass")
    table = client.query_source("Sun")
# conf.base_url is restored here
```

## Per-instance overrides

Constructor keyword arguments always take precedence over `conf` values:

```python
client = Grad300(
    user="user@example.com",
    password="pass",
    base_url="https://dev.grad300.lam.fr",  # overrides conf.base_url
    timeout=10.0,                            # overrides conf.timeout
)
```