обработчик(A routine that manages a common and relatively simple condition or operation, such as error recovery or data movement; In some object-oriented programming languages that support messages, a subroutine that processes a particular message for a particular class of objects)
помощник(However, in today's Washigton Post article "Lillian McEwen breaks her 19-year silence about Justice Clarence Thomas" there is a sentence: "When Anita Hill accused Clarence Thomas of sexual harassment during his explosive 1991 Supreme Court confirmation hearing, Thomas vehemently denied the allegations and his handlers cited his steady relationship ..."; the word "handlers" for Supreme Court Nominee calls for 'помощники'Tamara Swanger)
куратор("...dependent in virtually every way on their US handlers" – практически полностью зависят от воли американских кураторов | Another example by 4uzhoj: "еще хороший пример из свежего: The reporting team has also determined with high certainty that Oleg Ivannikov was ... was military adviser and de facto handler of the political leadership of the LNR in 2014."ART Vancouver); оперативный работник, курирующий работу агента(т.н. куратор Val_Ships)
