> ## Documentation Index
> Fetch the complete documentation index at: https://mf2.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Observability

> Error tracking and logging with Sentry and BetterStack.

`@repo/observability` tracks errors with [Sentry](https://docs.sentry.io) and aggregates logs with [BetterStack](https://betterstack.com/docs). Separate configs for client and server.

## Usage

Initialize on the client:

```ts title="apps/app/instrumentation-client.ts" theme={null}
import { initClientObservability } from "@repo/observability/client";

initClientObservability();
```

Initialize on the server:

```ts title="apps/app/instrumentation.ts" theme={null}
import { initServerObservability } from "@repo/observability/server";

initServerObservability();
```

## Structured Logging

Send structured logs to BetterStack:

```ts title="apps/api/routes/payments.ts" theme={null}
import { log } from "@repo/observability/server";

log.info("Checkout session created", {
  userId: session.userId,
  priceId: session.priceId,
});
```

Sentry captures unhandled errors automatically. Use `captureError()` from `@repo/observability/error` only for caught exceptions you want to track.

## Environment Variables

See [Environment Variables: Error tracking](/setup/env#error-tracking-sentry) and [Observability](/setup/env#observability-betterstack).

## Learn More

* [Sentry documentation](https://docs.sentry.io)
* [BetterStack documentation](https://betterstack.com/docs)