# ADR 0008 — Stale or missing required telemetry is Unknown

**Status:** Accepted baseline

## Decision

When required telemetry is unavailable beyond its freshness policy, Pulse reports Unknown rather than retaining or inferring Healthy.

## Rationale

False green status is more dangerous than explicit uncertainty.

## Consequences

- Responses carry freshness metadata.
- Alert rules define unknown behavior.
- UI shows last known value only with age.
- Tests inject stale/missing sources throughout the product.