Function verify_chain 

pub async fn verify_chain(
    pool: &AnyPool,
    state: &AuditState,
) -> Result<ChainVerifyReport, KipukaError>

Re-walk the entire audit trail and verify the tamper-evident hash chain.

Reads every row in id order and checks, for each, that (1) its prev_hash equals the previous row’s stored record_hash (linkage — detects deletion and reordering) and (2) its record_hash recomputes from its own fields via the configured AuditState::chain_hash (integrity — detects in-place edits). The first violation short-circuits and is reported in ChainVerifyReport::broken_at/detail.

This is the review-time counterpart to the write-time chaining in write_event; the same AuditState (key + algorithm) that wrote the rows must be supplied, or unkeyed rows would be checked with an HMAC (or vice versa) and every hash would mismatch.