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Rulesets

Fiscal layer

Rulesets

Rules are immutable, versioned, and date-sensitive. Historical gaps are MANUAL_REVIEW, never a silent current-rate fallback.

Pinned snapshots

Production determinations use immutable, versioned ruleset snapshots with provenance (authority, source, retrievedAt, effectiveFrom / effectiveTo). Rates are rationals, not floating point. Live third-party tax APIs are not required to process or verify a receipt.

If a historical date is not in the snapshot, status is MANUAL_REVIEW with reason historical_rate_not_in_ruleset. Current rates are never applied silently to older transactions.