Build a 13-week cash flow forecast for {{business_name}} in this workbook, starting from an opening cash balance of {{opening_cash_balance}}. Use the data in {{source_sheets_or_tables}}, such as open invoices, bills, payroll, and recurring costs. Create one column per week with rows for opening cash, receipts by type, payments by type (payroll, rent, suppliers, taxes, loan repayments, other), net cash flow, and closing cash, where closing cash equals opening cash plus receipts minus payments. Use formulas, not typed values, so I can roll it forward each week. Put every timing assumption, such as how many days customers take to pay, in a separate assumptions table. Highlight any week where closing cash falls below {{minimum_cash_buffer}} and suggest options, such as chasing specific receivables or moving payment dates. Flag missing data instead of filling it in. Recommend reviewing borrowing or other financing decisions with a qualified accountant.