D461 - std::random_device is deterministic

Status: assumed Date: 2026-09-01

The entropy primitive behind std::random_device answers a fixed-seed sequence, advanced once per call, rather than a physically random value.

Why: every measurement this project takes depends on two runs of one build behaving identically. A guest reads this call only to seed its own generator, so a well-distributed value serves it as well as an unpredictable one, and only the deterministic choice keeps a run reproducible.

Rejected:

• A non-deterministic source, as the standard intends: correct in isolation, but it puts non-determinism back into exactly the layer this project removes it from.