Incrementally collapses paged variable items into a parsed name-to-value map.
Memory stays bounded by the DTO shape rather than the total number of paged items: only the
first value seen per requested name is retained, alongside the set of scope keys observed for
that name (used for collision detection). Items for undeclared variables are dropped, so large
values for variables outside the DTO are never accumulated.
Incrementally collapses paged variable items into a parsed name-to-value map.
Memory stays bounded by the DTO shape rather than the total number of paged items: only the first value seen per requested name is retained, alongside the set of scope keys observed for that name (used for collision detection). Items for undeclared variables are dropped, so large values for variables outside the DTO are never accumulated.