cas

Check-digit mathematics toolbox for DeepSeek Harness (dsh): generate, validate and detect check digits for 13 schemes (Luhn, Verhoeff, Damm, ISBN, EAN, UPC, ISIN, CUSIP, IBAN, CAS, ABA) plus ISBN-10/13 conversion — zero runtime dependencies

Scientific computing plugin for DeepSeek Harness: numeric + symbolic math (mathjs + Algebrite)