A relation is emitted by two parallel walks that must stay symmetric : the LET sub-query (buildVariables) and the projected key (aqlFields). When a definition declares AQL::REQUIRES and the authorizer denies it, the LET is not emitted — so the matching marker must also disappear from the projected fields, otherwise the RETURN would reference an unbound variable. This helper performs that field-side purge : it is applied at every point where a prepared fields array meets its edges/joins registries, right before buildVariables() / aqlFields() run on them.

Resolution mirrors buildVariables() : the definition is looked up in the registry under the field key, a string value being a one-hop alias to another registry entry. A marker without a resolvable array definition is left untouched (buildVariables skips it anyway — nothing to desynchronize).

The check itself is delegated to isAuthorized() with the whole definition (its AQL::REQUIRES key equals Field::REQUIRES), so the semantics are exactly the field-level ones : no marker → allowed, no authorizer → allowed (fail open), a list of subjects → logical OR. The definition-level gate COMPOSES with the field-level Field::REQUIRES (evaluated downstream) : either level can drop the relation.

The function is pure and idempotent : applying it twice — e.g. once on the LET walk and once on the projection walk of a wrapped reference — yields the same fields, which is precisely what keeps both walks symmetric.