How each numbered document type counts, one row each for invoice, quote, credit_note, debit_note and receipt: prefix, last_number (the highest number already used or skipped), next_number, and next_preview, the number the next one prints (this year's form, such as INV-2026-042). Copy next_preview, never build it. Change a next number, or a credit note, debit note or receipt prefix, with sales_settings_numbering_set; invoice and quote prefixes with sales_settings_upsert (prefix_set_with names the tool). A row with available false is not set up in this environment yet; unavailable_reason says why and what still works. Takes no arguments: any argument is refused with VALIDATION_ERROR.