Function reconstruct_legs 

fn reconstruct_legs(
    stored: &[Waypoint],
    geometry: &mut RouteGeometry,
    ends: Endpoints,
    rules: LegRules<'_>,
    router: Option<&mut ClosedRouter>,
) -> Reconstruction

Rebuild the edge geometry of a wire whose authored corners are stored, keeping every straight (axis-aligned, unblocked) leg as a single edge and routing ONLY the legs that are non-colinear or blocked. start/end are the resolved grid endpoints. Straight legs never touch the router, so an unaffected route (all legs straight) is reconstructed byte-identically with zero pathfinding.

When a leg needs routing, router must be Some (already built and occupied by the other routes); the leg’s new bends are spliced into the corner list so the “every corner is a waypoint” invariant is restored. Interior waypoints that fall inside an obstacle are dropped (only on the routing path, where router is Some). Nothing here writes the document.