Function verify_data_update 

pub fn verify_data_update(
    payload: &DataUpdate,
    node_count: u32,
    redundancy_buffer: u8,
    ordered_signers: &[SignerXy],
) -> Result<(), DataUpdateError>

Verify a full DataUpdate payload against caller-supplied signer pubkeys.

Caller contract

• node_count is the registry node count for payload.registry_version.
• signatures_required is the threshold to verify against (passed explicitly because callers may use a value distinct from payload.signatures_required, e.g. the job’s configured value).
• ordered_signers holds one (x, y) per set bit of payload.signers_bitmap, in ascending bit-index order — the same order EVM Validator.verify combines pubkeys. The caller is responsible for resolving the authentic pubkeys; this function trusts the supplied set.

Re-derives the selection bitmap internally and enforces signers ⊆ selection. Checks run in the same order as the on-chain monolith: scalar validity → signer threshold → selection subset → signer-count match → coalition reconstruction → message hash → Schnorr recovery.