nx_taxlot_lib.nx

nx_taxlot_lib.nx -- CAPITAL-GAINS TAX-LOT ACCOUNTING with the IRS wash-sale rule. Integer-exact. Realizing a capital gain/loss is not subtraction -- it is lot selection, holding-period classification, and the wash-sale disallowance (IRC section 1091). This organ does all three in exact integer minor units. *THE WASH-SALE FAIL-CLOSED PROPERTY (the flagship): if you sell at a LOSS and buy a substantially identical security within +/-30 days, the loss is DISALLOWED for the current year. Consumer tax tools routinely mis-handle this and let a taxpayer claim a loss the IRS will reject. Here the disallowed loss is not silently dropped and not silently claimed -- it is computed proportionally to the replacement shares and DEFERRED into the replacement lot's cost basis (tl_adjusted_replacement_basis), so it is preserved, not destroyed (history is additive). A GAIN is never washed; a loss with no replacement in the window is fully allowed. allowed + disallowed == the original loss, always (conservation). FIFO lot consumption is fail-closed against overdraw: it returns the shares actually sold, which is less than requested when the book is short -- it cannot sell shares the book does not hold. NO FLOATS. Days are integer day-numbers; money is minor units. Thresholds are declared constants (Rule 11). license_tier: ORIGINAL No hw writes (Rule 26). LIB.