  We propose that quantum entanglement is a special sort of selection artefact,
explicable as a combination of (i) collider bias and (ii) a boundary constraint
on the collider variable. We show that the proposal is valid for a special
class of (`W-shaped') Bell experiments involving delayed-choice entanglement
swapping, and argue that it can be extended to the ordinary (`V-shaped') case.
The proposal requires no direct causal influence outside lightcones, and may
hence offer a way to reconcile Bell nonlocality and relativity. The main
argument is a detailed version of an approach previously outlined in
arXiv:2404.13928 [quant-ph].
