---name: bill-checkdescription: Checks a bill, invoice or statement, what each line is, whether the totals add up, what is unusual against the contract; use for "check this bill".---# Bill checkUse when: the user pastes a bill, an invoice, a utility statement, a service charge breakdown, or a final settlement.## InputThe bill as text. If there is a note for the related contract in `contracts/`, read it: the bill is checked against the agreed prices and terms.## Steps1. Table of lines: What | Quantity | Unit price | Amount | Period. Keep the wording of the bill.2. Check the arithmetic: lines add up to the subtotal; tax computed on the right base; total equals subtotal plus tax minus credits. Show the sums. For meters: consumption equals new reading minus old.3. Compare with the contract note if there is one: prices that differ, items not agreed, periods billed twice, fees not in the contract.4. Mark each unusual item with what to ask ("line 4: the admin fee is not in clause 5 of the lease; ask what it is for").5. Save `contracts/<slug>-bill-YYYY-MM.md`, or a section in the note (note "Bill check: <title>").6. Answer with "adds up" or "does not add up, by <amount>", and the unusual items.## OutputThe lines table, the arithmetic check, "Unusual" with what to ask.## Edge cases- The bill does not add up: say the difference and where it can come from; do not assume who is wrong.- A currency or unit differs from the contract: flag it before comparing.- No contract note: check the arithmetic and the internal consistency only, and say that no comparison was possible.