Claude Prompt

/devlyn:resolve "Add a bench-cli cart command that reads a cart JSON file, prices it from data/catalog.json, combines duplicate SKU quantities, applies line promotions before an order coupon, and prints one exact JSON total with cents-based discounts, tax, shipping, and item rows.\n\nThe command should be `bench-cli cart --input <path>`. The input JSON is `{ \"state\": string, \"coupon\": string | null, \"items\": [{ \"sku\": string, \"qty\": number }] }`. Use integer cents for every public amount. Read all products, stock, tax codes, promotions, coupons, tax rates, shipping, and the free-shipping threshold from `data/catalog.json`; changing those catalog values must change the result without a code change.\n\nDuplicate SKUs must be combined before stock validation and promotion math. On success, stdout must be exactly one JSON object whose only keys are `subtotal_cents`, `line_discount_cents`, `coupon_discount_cents`, `tax_cents`, `shipping_cents`, `total_cents`, and `items`, with no stderr. The `items` array has one row per SKU in first-seen order, and every row has exactly `sku`, `qty`, `line_subtotal_cents`, `line_discount_cents`, and `line_total_cents`. Each line subtotal is the combined quantity times its catalog unit price, each line total is its line subtotal minus its line discount, and the top-level line discount is the sum of the item line discounts.\n\nFor a catalog `buy_x_get_y_free` promotion, the line discount is `Math.floor(qty / (buy_qty + free_qty)) * free_qty * unit_cents`. A `per_unit_discount_cents` promotion applies only when the combined quantity is at least its configured `min_qty`, and its line discount is `per_unit_discount_cents * qty`. Apply these line promotions before the order coupon. When a coupon is present and the post-line-discount subtotal meets `coupon.min_subtotal_cents`, its discount is `Math.round((subtotal_cents - line_discount_cents) * coupon.percent / 100)`; otherwise `coupon_discount_cents` is `0`.\n\nCompute tax after line promotions and before the coupon: a product is taxable exactly when its `tax_code` maps to `true` in `catalog.taxable_codes`, the rate is `catalog.tax_rates[state]`, and `tax_cents` is `Math.round(taxable_post_line_discount_cents * rate)`. Shipping is free when `subtotal_cents - line_discount_cents - coupon_discount_cents` is at least `catalog.free_shipping_min_cents`; otherwise it is `catalog.shipping_cents`. The final formula is `total_cents = subtotal_cents - line_discount_cents - coupon_discount_cents + tax_cents + shipping_cents`.\n\nInvalid JSON, missing `items`, an unknown SKU, a non-positive or non-integer quantity, an unknown coupon, an unknown state, or a combined quantity over stock must exit `2`, print exactly one JSON error object to stderr, and print nothing to stdout. A combined stock failure has the exact shape `{ \"error\": \"invalid_stock\", \"sku\": string, \"available\": number, \"requested\": number }`, where `requested` is the combined quantity.\n\nUpdate `tests/cli.test.js` so existing tests still pass and at least two new tests cover the cart command, including one successful cart and one validation failure. Parsing and file-read failures must surface as JSON errors rather than silent catches. Do not add dependencies. Only touch `bin/cli.js` and `tests/cli.test.js`; do not touch server or web files." --pair-verify