Regulatory Report Period-over-Period Variance Explainer

Computes period-over-period variance across a regulatory report instance pair -- absolute and relative movement per line item against a policy-supplied materiality threshold (default plus per-line overrides), ranked by contribution (largest absolute movement first) -- and flags which movements require a written explanation, i.e. exceed materiality with no matching explanation on file. Does not judge whether a supplied explanation is adequate; that is a human review-and-approval step downstream (RGEC-K-2's gate: an unexplained material variance routes to review_required). Pairs with art-484-regrpt-editcheck-runner's rule-based edit checks -- this node handles analytical-review variance, not rule pass/fail.

Tool URL: https://ainumbers.co/chaingraph/art-485-regrpt-variance-explainer.html