Constant F_SILENCE_BASE64 

pub const F_SILENCE_BASE64: &str = "/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////w==";

F-silence’s base64, quoted from spec §4.2.

A literal, never a value an assertion computes — the discipline webhook-binding.md WB-8 states and §4.2 adopts: an expected value derived by the code under test is an expectation that cannot disagree.