Development record

The site check's overlapping-bubbles gate measures the COIL arrangement only: the counter lives inside the coil packer and never sees the by-links layout, so a links arrangement can ship with overlapping bubbles while the gate reports zero. Widening it is not a one-line change — the published positions are normalised to the unit disk while the radii are quoted in reference pixels, so a correct check has to compare both in one space (an attempt that compared them across spaces reported 159,600 overlaps on a 400-node fixture). Found while diagnosing why the by-links arrangement never settles (iss-2608231243286557). The renderer-side half of that defect IS fixed: the collision resolver no longer adds padding the layout never promised.