The process-wide singleton generator.
It is one shared stream: safe for atomic synchronous draws, but not isolated. A flow that must not perturb (or be perturbed by) another should inject its own createRng instance instead of relying on this. Accessed lazily at call time (never at module load) so the logic layer stays Foundry-free and unit tests can install their own singleton.
The shared, ambient generator — the sohl.random singleton. This is the default-injected source for sohl.entity.roll.SimpleRoll, hit-location selection, and the
rand()expression helper when noRngis passed explicitly.