Fairshare Bill Splitter

Use this when the user wants to split a restaurant bill, check, receipt, takeout order, or any single bill between people: evenly or item by item (who had what), with tax, tip, service charge, coupons, delivery fees, or rounding up. Tax, tip, and service charge are shared in proportion to each person's pre-tax subtotal; every share is exact to the cent and the shares add up exactly to the total (largest-remainder rounding). Optional paid_by lists who owes the payer. Does not read receipt photos (pass the items as text), handle several payers or many bills (use settle_group_expenses), or convert currencies.

Use this when a group (trip, vacation, roommates, couple, event) has several shared expenses paid by different people and wants to know who owes who and how to settle up. Each expense can be split equally, by exact amounts, by percentages, or by shares. Returns each person's balance (paid minus share, summing to exactly zero) and the fewest payments that settle every balance to the cent, plus a CSV of payments, balances, and expenses. One currency per call: mixed currencies are rejected and nothing is converted. Does not send payment requests, move money, or remember the group; for one restaurant bill use split_bill.

Use this when roommates or housemates want to split rent fairly: by bedroom size (square feet or metres) with a shared-space portion split per occupant, by income, or equally, with optional per-room adjustments (private bathroom, no window), couples sharing a room, and utilities split per occupant. Every amount is exact to the cent and the parts add up exactly to the rent. Does not give legal or tenancy advice, collect rent, or handle one-off shared expenses (use settle_group_expenses for those).