Function with_integrity 

pub fn with_integrity<T>(integrity: WireIntegrity, f: impl FnOnce() -> T) -> T

The latency↔safety dial: run f with the checksum on (Checked) or off (Raw), overriding the process default for the duration. Scoped — never leaks. Raw is the fastest path (the FNV checksum is the bulk of small-message encode cost); Checked detects corruption. Pairs with with_numerics/with_compression_codec.