Observer health
Observers — projections, reducers, and reactors — consume event sequences to build read models and trigger side effects. These tools let an agent check their health, find failures, and surface maintenance the store recommends.
| Tool | Description |
|---|---|
list_observers | List observers in a namespace, with health and replay status. Optionally filter by type (reactor, reducer, projection, or all). |
get_observer | Show detailed information about a specific observer — its type, running state, owner, handled sequence numbers, and observed event types. |
list_failed_partitions | List observer partitions that have failed and are paused. |
list_recommendations | List active maintenance recommendations the store has raised. |
A troubleshooting flow
Section titled “A troubleshooting flow”When an observer is stuck or a read model looks stale:
list_observers— check the observer’s running state and how far its sequence numbers have progressed.get_observer— inspect the observer in detail, including which event types it observes.list_failed_partitions— see whether a partition has failed and paused the observer.list_recommendations— see whether the store already recommends a fix.
A quarantined observer does not auto-resume; an operator has to clear the quarantine. Use the Cratis CLI or the management API to replay, retry, or clear quarantine once you have diagnosed the cause here.
Finding the consumers of an event type
Section titled “Finding the consumers of an event type”get_observer shows the event types a single observer consumes. For the reverse — every consumer of a given event type across the store, plus its fields — use the design-time event catalog.