feat: wire configured harness execution

internal/router/router.go

@@ -31,6 +31,7 @@ type Router struct {
 	Now          func() time.Time
 	backoff      map[string]time.Time
 	attempts     map[string]int
+	OnLease      func(domain.Event) error
 }
 
 func (r *Router) init() {
@@ -99,6 +100,11 @@ func (r *Router) AssignPending() ([]domain.Event, error) {
 			}
 			r.attempts[t.ID]++
 			out = append(out, e)
+			if r.OnLease != nil {
+				if err := r.OnLease(e); err != nil {
+					return out, err
+				}
+			}
 			break
 		}
 	}