Constant MAX_COALESCE_APPROVALS 

pub const MAX_COALESCE_APPROVALS: u32 = 16; // 16u32

The maximum number of candidate approvals that can be coalesced into a single ValidDisputeStatementKind::ApprovalCheckingMultipleCandidates statement (and the corresponding approval vote). It is a hard, type-level ceiling enforced at decode time, and the maximum value the runtime accepts for max_approval_coalesce_count.