Whether the employee is a lead of the team or not

Populate direct, source_team_ids and parent_team_ids on each returned membership (nested teams). Only honoured when filtering by a single employee_ids value without team_ids — the read that attributes one employee's own memberships, and the only one that resolves direct. Reads filtered by a single team already return source_team_ids/parent_team_ids without this flag (direct stays null there); bulk reads ignore it entirely. Unsupported filter combinations return 200 with empty attribution rather than an error. Attribution is resolved per employee and is significantly more expensive than a plain read: intended for per-profile lookups, not bulk synchronization.