Clean the export I supply according to its brief. Work on a new copy; preserve the original and all source rows. If cleaning rules are absent, propose safe rules and ask before applying changes that alter meaning.

Keep identifiers as text, including leading zeros. Retain original date and amount fields and add normalized fields. Apply only unambiguous transformations supported by the brief. Leave unclear values unchanged in the original fields and log the issue; never turn an unknown amount into zero or assume a currency. Flag exact duplicates and conflicting records separately. Do not silently remove or merge either kind.

Save cleaned.csv, exceptions.csv and reconciliation.md. The exception log must identify the source row/ID, issue, treatment and decision needed. Reconcile input/output row counts. State which rows are included in any numeric totals and why others are excluded. Sum only known, eligible numeric values by currency; do not combine currencies without an authorized conversion rule. Treat these as scoped totals, not a final accounting total.

Return the saved files and unresolved decisions. Do not write to a live system, overwrite inputs or send data elsewhere.