Harden lease lifecycle durability

internal/ui/ui.go

@@ -422,6 +422,11 @@ func (s Server) action(w http.ResponseWriter, r *http.Request, id, action string
 		http.Error(w, "unknown action", 404)
 		return
 	}
+	if action == "block" {
+		// A browser-created block is an explicit operator decision. Preserve
+		// that fact even if its prose happens to contain a system keyword.
+		body["block_reason"] = string(domain.BlockReasonOperator)
+	}
 	b, _ := json.Marshal(body)
 	e := domain.Event{ID: domain.NewID(), Type: typ, TaskID: id, Version: t.Version + 1, Payload: b, Surface: string(authz.Web)}
 	if err := s.Store.Append(e); err != nil {