Constant MAX_INCLUSION_PROOF_ITEMS 

pub const MAX_INCLUSION_PROOF_ITEMS: u32 = _; // 128u32

Upper bound on an MmrInclusionProof’s items. A single-leaf proof needs at most the subtree height plus the other peaks, each at most 63; this constant is a ceiling no valid proof reaches. Enforced at decode, which bounds calculate_root’s work on untrusted input.