# Alerts that show their work

Every rule can be replayed against your history before it exists, and every evaluation is recorded after. When a page arrives you can see exactly why — and when one doesn't, you can see that too.

## Previewed before it can page you

The preview runs the same code the scheduler runs, over the range you pick — per-window verdicts, would-fire spans and all. What the chart shows is what would have happened.

- **signals**: error_rate · p95 · p99 · apdex · throughput
- **sources**: traces · logs · metrics · SQL
- **evaluates**: every 60s
- **fires.after**: N consecutive breaches
- **group.by**: service.name · attr.*
- **routes.to**: slack · pagerduty · discord · email · webhook

## From threshold to resolution

### builder_query — Alert on anything

Seven built-in trace signals — error rate, P95/P99 latency, Apdex, throughput — plus any query-builder draft over traces, logs or metrics. Raw SQL when the builder can't say it.

### preview — Evaluator-faithful preview

The preview replays the rule over history with the exact code the scheduler runs every minute. If it says the rule would have fired twice last Tuesday, that is what would have happened.

### group by — One rule, per-group incidents

Group by service.name or any attribute and each group gets its own breach count, its own incident and its own history. A spike in one service never hides behind the average of twelve.

### alert_checks — Every check on the record

Each evaluation writes its observed value, sample count and verdict — including failed queries, so a gap is visible instead of silent. When a rule stays quiet, a diagnosis panel walks the pipeline stage by stage.

### renotify 30m — Delivery that survives

Queued dispatch with five attempts and backoff, every provider response stored, custom templates per destination, and a renotify interval while the incident stays open. Slack, PagerDuty, Discord, email, webhooks, Hazel.

## Related

- [Error Tracking](https://maple.dev/features/error-tracking.md)
- [Metrics & Dashboards](https://maple.dev/features/metrics-dashboards.md)
- [Distributed Tracing](https://maple.dev/features/distributed-tracing.md)
- [API Performance](https://maple.dev/use-cases/api-performance.md)