Cost-per-decade 0.1.0

When lifespans differ, the sticker price settles nothing. A $280 item that lasts 20 years runs $140 per decade; a $40 item replaced every 2 years runs $200. The cheap one wins the checkout line and loses by $60 per decade. Cost-per-decade is a terminal calculator for that arithmetic: cost per decade, cost per use, horizon totals, and the break-even year where the durable option beats the replacement ladder. The tool prints the verdict with the numbers behind it. A $900 purchase lasting 6 years against a $45 one lasting 4 ends a 5-year horizon with the cheap option ahead by $810. It exits 1 when the cheap option wins at your horizon, so a script can gate the purchase. The 30-year example above breaks even in year 12 and saves $40 over the window. Lifespans are your estimate, not a measurement, and the math is only as honest as the number you feed it. Repairs that stretch a life past its first death get modeled by bumping the lifespan input, resale value is ignored, and inflation is left out, which holds for a 30-year window at 2026 prices and gets increasingly wrong past that. The verdict compares cost only; fit, feel and fail modes are your job. --json emits machine output. Python 3.8+, one file, standard library only, no network calls, MIT licensed.

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