Function enabled 

pub fn enabled() -> bool

Escape hatch: IFC_LITE_RECT_FAST=0 is the GLOBAL rect-fast kill switch. It forces every opening back through the exact kernel (parity debugging / bisection) by disabling BOTH the legacy world-axis-aligned path gated here AND the parametric placement-frame path (param_enabled honours it), so setting this single flag is sufficient to route all rectangular openings through CSG. Default ON: the path is a pure optimization that defers on any precondition miss. To disable only the parametric path, set IFC_LITE_RECT_PARAM=0 instead.