> ## Documentation Index
> Fetch the complete documentation index at: https://docs.smlcrm.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Validation & observability

> Keep credentials healthy and track service health with Simulacrum's validation endpoint.

# Validation & observability

Use the validation endpoint to confirm API keys are active and to surface metadata for monitoring.

## Checking keys at startup

```python theme={null}
from simulacrum import Simulacrum
from simulacrum.exceptions import AuthError

client = Simulacrum(api_key="sim-key_id-secret")
try:
    validation = client.validate()
except AuthError as exc:
    raise SystemExit(f"API key rejected: {exc}")

if not validation.valid:
    raise SystemExit("API key is inactive or expired")
```

Store validation results with your service telemetry. The response exposes the owning client ID and expiration timestamp when available.

## Surfacing expiration alerts

```python theme={null}
from datetime import datetime, timedelta

expires_at = validation.expires_at
if expires_at and expires_at < datetime.utcnow() + timedelta(days=7):
    notify("Simulacrum API key expires soon", severity="warning")
```

Trigger alerts a week ahead so you can rotate keys without outages.

## Programmatic health checks

`validate()` executes a lightweight GET request. Schedule it in your orchestrator to confirm network reachability and authentication.

```python theme={null}
import asyncio

async def readiness_probe(client: Simulacrum) -> None:
    loop = asyncio.get_event_loop()
    await loop.run_in_executor(None, client.validate)
```

If the call raises `AuthError`, rotate the key. Any other `SimulacrumError` indicates upstream issues: retry with backoff and alert your on-call channel.