feat: sample recent business events

internal/observability/catalog.go

@@ -9,6 +9,7 @@ var components = []string{"workflow", "schedule", "execution_recovery"}
 var taskStates = []string{"WAITING", "LEASED", "RUNNING", "NEEDS_REVIEW", "SUCCEEDED", "FAILED", "CANCELLED"}
 var deliveryStates = []string{"PENDING", "LEASED", "ACKED", "EXPIRED"}
 var workflowStates = []string{"RUNNING", "WAITING", "CANCELLING", "NEEDS_REVIEW", "SUCCEEDED", "FAILED", "CANCELLED"}
+var eventTypes = []string{"task.accepted", "task.started", "task.succeeded", "task.failed", "task.needs_review", "task.requeued", "workflow.started", "workflow.advanced", "workflow.recovered", "workflow.blocked", "workflow.stopped"}
 
 // Every exported family is declared here, including each allowed label value.
 // Adding a metric therefore requires a code review; no user identifier is valid.
@@ -42,6 +43,7 @@ func catalog() map[string]descriptor {
 	c["orbit_result_delivery_oldest_age_seconds"] = descriptor{gauge, "Age of the oldest sampled pending result delivery", nil}
 	c["orbit_weave_workflows_state"] = descriptor{gauge, "Bounded count of Weave instances by durable state", map[string][]string{"state": workflowStates}}
 	c["orbit_weave_workflow_oldest_age_seconds"] = descriptor{gauge, "Age of the oldest sampled unfinished Weave instance", nil}
+	c["orbit_business_events_recent"] = descriptor{gauge, "Bounded count of fixed event categories in the recent window", map[string][]string{"event": eventTypes}}
 	c["orbit_business_snapshot_total"] = descriptor{counter, "Completed bounded business-state snapshots by outcome", map[string][]string{"outcome": {"success", "error", "timeout"}}}
 	c["orbit_business_snapshot_duration_seconds"] = descriptor{histogram, "Bounded business-state snapshot duration in seconds", nil}
 	c["orbit_business_snapshot_last_success_timestamp_seconds"] = descriptor{gauge, "Unix time of the last successful bounded business-state snapshot", nil}