Module env 

Rail-env resolution helpers (first_set / first_nonempty / first_set_u32) — un-gated, pure std::env.

Functions

first_nonempty

First key whose var is present AND non-empty (weight-tier semantics).

first_set

First key whose var is present in the environment — even if empty.

first_set_u32

First key whose var is present AND parses as u32; otherwise default. (A set-but-unparseable var falls through — the behavior of every existing per-client env_u32, single- and multi-key alike.)