Module env_overrides 

Shared helpers for reading config parameters from environment variables.

Used by category_weights.rs and the Group-C operational-parameter overrides documented in docs/parameter-strategy.md. The pattern is: Lazy::new reads the env var once at first access; tests verify the pure parser (parse_*_or_default) directly so they do not need to mutate process-global env state.

Functions

parse_f64_or_default

parse_fraction_or_default

parse_open_fraction_or_default

Parse a fraction strictly inside the open interval (0, 1). Used for parameters where 0.0 or 1.0 produce algorithmic degeneracy (e.g. PPR_ALPHA=1.0 makes restart probability zero, yielding all-zero rankings).

parse_u32_or_default

parse_usize_or_default

read_env_f64

read_env_fraction

read_env_open_fraction

read_env_u32

read_env_usize