substrate
Adding a fourth image to the two-machine scenario makes the bootstrap
fail every time, with the store's readiness check producing no output at
all — which says the container was not running rather than that the
database was slow. Three images pass nine assertions; four never get past
the store.
More memory did not change it, so memory is not the cause; the change is
kept because the reasoning holds on its own. Disk is the most likely
explanation and nothing has measured it.
It blocks proving the mesh runs its own artifact store, since the
registry module needs a registry image to mirror. The module is written
and accepted; what is unproven is a machine assigned it serving another.
