nx_meal_cost_gate.nx source

1// nx_meal_cost_gate.nx -- proves the pantry x price bridge on per-run /tmp fixtures (never its own history). 2// Two cells are BITE-PROVEN: each first demonstrates that the failure mode is REAL against this very data, 3// then that the guard blocks it. A guard proven only against data that could not have tripped it is a comment. 4// license_tier: ORIGINAL No hw writes (Rule 26). 5import "nx_syscalls.nx" 6import "nx_meal_cost.nx" 7import "nx_gate_verdict.nx" 8 9const CG_PFX: i64 = 160 10const CG_FLD: i64 = 256 11const CG_MIN_SALE: i64 = 50 12 13func main(argc: i64, argv: *i64) -> i64 { 14 let ctr: *i64 = gv_ctr() 15 gv_head("nx_meal_cost -- what this meal costs given what you already have, and what is genuinely cheap" as *u8) 16 17 let ep: i64 = sys_now_realtime_sec() 18 let inv: *u8 = sys_mmap(CG_PFX) 19 var io: i64 = as_append(inv, 0, "/tmp/mcinv_" as *u8) 20 io = fd_apnum(inv, io, ep) 21 io = as_append(inv, io, "-" as *u8) 22 inv[io] = 0 as u8 23 let pr: *u8 = sys_mmap(CG_PFX) 24 var ro: i64 = as_append(pr, 0, "/tmp/mcpr_" as *u8) 25 ro = fd_apnum(pr, ro, ep) 26 ro = as_append(pr, ro, "-" as *u8) 27 pr[ro] = 0 as u8 28 29 let dom: *u8 = "family" as *u8 30 let area: *u8 = "testarea" as *u8 31 32 // pantry: the unit already holds garlic (3 bulbs, 90c of stock value) 33 iv_add(inv, dom, "garlic" as *u8, "Garlic" as *u8, "produce" as *u8, 3, "bulb" as *u8, "pantry" as *u8, 90, 0, "" as *u8) 34 35 // three stores in the area. `onlybeef` stocks ONE ingredient at an absurd price -- the coverage trap. 36 pr_add_store(pr, "bigmart" as *u8, "BigMart" as *u8, "BigMart" as *u8, area, "WA" as *u8, "weekly circular" as *u8) 37 pr_add_store(pr, "corner" as *u8, "Corner Store" as *u8, "indie" as *u8, area, "WA" as *u8, "shelf tag" as *u8) 38 pr_add_store(pr, "onlybeef" as *u8, "Only Beef" as *u8, "indie" as *u8, area, "WA" as *u8, "shelf tag" as *u8) 39 40 pr_set_price(pr, "bigmart" as *u8, "beef" as *u8, 899, "2026-08-01" as *u8, "lb" as *u8, "weekly circular" as *u8) 41 pr_set_price(pr, "bigmart" as *u8, "broccoli" as *u8, 249, "2026-08-01" as *u8, "lb" as *u8, "weekly circular" as *u8) 42 pr_set_price(pr, "corner" as *u8, "beef" as *u8, 1099, "2026-08-01" as *u8, "lb" as *u8, "shelf tag" as *u8) 43 pr_set_price(pr, "corner" as *u8, "broccoli" as *u8, 199, "2026-08-01" as *u8, "lb" as *u8, "shelf tag" as *u8) 44 pr_set_price(pr, "onlybeef" as *u8, "beef" as *u8, 100, "2026-08-02" as *u8, "lb" as *u8, "clearance tag" as *u8) 45 46 // the recipe: beef + broccoli + garlic + truffle. Truffle is deliberately UNPRICED. 47 let items: *i64 = sys_mmap(8 * 16) as *i64 48 items[0] = "beef" as *u8 as i64 49 items[1] = "broccoli" as *u8 as i64 50 items[2] = "garlic" as *u8 as i64 51 items[3] = "truffle" as *u8 as i64 52 // the same recipe minus the unpriced ingredient 53 let items3: *i64 = sys_mmap(8 * 16) as *i64 54 items3[0] = "beef" as *u8 as i64 55 items3[1] = "broccoli" as *u8 as i64 56 items3[2] = "garlic" as *u8 as i64 57 // just the two we must buy (for the store-coverage question) 58 let buy2: *i64 = sys_mmap(8 * 16) as *i64 59 buy2[0] = "beef" as *u8 as i64 60 buy2[1] = "broccoli" as *u8 as i64 61 62 // ---- T1 classification ---- 63 var t1: i64 = 1 64 if mc_status(inv, dom, pr, area, "garlic" as *u8) != MC_HAVE { t1 = 0 } 65 if mc_status(inv, dom, pr, area, "beef" as *u8) != MC_BUY { t1 = 0 } 66 if mc_status(inv, dom, pr, area, "truffle" as *u8) != MC_UNPRICED { t1 = 0 } 67 gv_check("T1 each ingredient classifies HAVE / BUY / UNPRICED against the real pantry" as *u8, t1, ctr) 68 69 // ---- T2 the meal summary ---- 70 let s4: *i64 = sys_mmap(8 * MC_SLOTS) as *i64 71 let todo: i64 = mc_meal(inv, dom, pr, area, items, 4, CG_MIN_SALE, s4) 72 var t2: i64 = 1 73 if s4[MC_N_HAVE] != 1 { t2 = 0 } 74 if s4[MC_N_BUY] != 2 { t2 = 0 } 75 if s4[MC_N_UNPRICED] != 1 { t2 = 0 } 76 if s4[MC_BUY_CENTS] != 299 { t2 = 0 } 77 if s4[MC_PANTRY_CENTS] != 90 { t2 = 0 } 78 if todo != 3 { t2 = 0 } 79 gv_check("T2 meal totals: 1 on hand, 2 to buy at 299c, 1 unpriced, 90c drawn from stock" as *u8, t2, ctr) 80 81 // ---- T3 BITE the unpriced guard. BOTH meals total 299c -- the NUMBER cannot tell them apart, which is 82 // exactly why completeness has to be reported separately from the total. 83 let s3: *i64 = sys_mmap(8 * MC_SLOTS) as *i64 84 mc_meal(inv, dom, pr, area, items3, 3, CG_MIN_SALE, s3) 85 var unp_bad: i64 = 0 86 if mc_total_is_complete(s4) == 0 { unp_bad = 1 } 87 var unp_good: i64 = 0 88 if mc_total_is_complete(s3) == 0 { unp_good = 1 } 89 var same_total: i64 = 0 90 if s3[MC_BUY_CENTS] == s4[MC_BUY_CENTS] { same_total = 1 } 91 gv_check("T3a the priced and part-priced meals post the IDENTICAL 299c total (the number cannot warn you)" as *u8, same_total, ctr) 92 gv_bite("T3b completeness flag fires on the meal hiding an unpriced ingredient, silent on the fully priced one" as *u8, unp_bad, unp_good, ctr) 93 94 // ---- T4 sale detection is MEASURED and fails closed ---- 95 var t4: i64 = 1 96 if mc_sale_delta(pr, area, "beef" as *u8) != 799 { t4 = 0 } // median 899 - cheapest 100 97 if mc_sale_delta(pr, area, "broccoli" as *u8) != 50 { t4 = 0 } // median 249 - cheapest 199 98 if mc_is_on_sale(pr, area, "beef" as *u8, CG_MIN_SALE) != 1 { t4 = 0 } 99 if mc_is_on_sale(pr, area, "beef" as *u8, 100000) != 0 { t4 = 0 } // threshold above the delta 100 if mc_is_on_sale(pr, area, "beef" as *u8, 0) != 0 { t4 = 0 } // FAIL-CLOSED on an unset threshold 101 if mc_is_on_sale(pr, area, "truffle" as *u8, CG_MIN_SALE) != 0 { t4 = 0 } // unknown is not a bargain 102 if s4[MC_SALE_CENTS] != 849 { t4 = 0 } 103 gv_check("T4 on-sale is measured vs the area median, unset threshold marks NOTHING, unknown is not cheap" as *u8, t4, ctr) 104 105 // ---- T5 BITE the store-coverage guard ---- 106 let sid: *u8 = sys_mmap(CG_FLD) 107 let best: i64 = mc_best_store(pr, area, buy2, 2, sid) 108 let naive: i64 = pr_basket(pr, "onlybeef" as *u8, buy2, 2) 109 var cov_bad: i64 = 0 110 if naive < best { cov_bad = 1 } // the trap is REAL against this very data 111 var cov_good: i64 = 0 112 if fd_streq(sid, "onlybeef" as *u8) == 1 { cov_good = 1 } // the guard must not have picked it 113 var t5: i64 = 1 114 if best != 1148 { t5 = 0 } // BigMart 899 + 249 115 if fd_streq(sid, "bigmart" as *u8) == 0 { t5 = 0 } 116 if mc_store_covers(pr, "onlybeef" as *u8, buy2, 2) != 1 { t5 = 0 } 117 gv_bite("T5a the naive basket ranks the 1-of-2 store cheapest, coverage guard refuses to pick it" as *u8, cov_bad, cov_good, ctr) 118 gv_check("T5b cheapest FULLY-STOCKING store is BigMart at 1148c, not the 100c one-item shop" as *u8, t5, ctr) 119 120 // ---- T6 shopping list carries unknown as -1, never as free ---- 121 let bi: *i64 = sys_mmap(8 * 16) as *i64 122 let bc: *i64 = sys_mmap(8 * 16) as *i64 123 let nb: i64 = mc_buy_list(inv, dom, pr, area, items, 4, bi, bc) 124 var t6: i64 = 1 125 if nb != 3 { t6 = 0 } 126 if bc[0] != 100 { t6 = 0 } 127 if bc[1] != 199 { t6 = 0 } 128 if bc[2] != (0 - 1) { t6 = 0 } 129 if fd_streq(bi[2] as *u8, "truffle" as *u8) == 0 { t6 = 0 } 130 let hi: *i64 = sys_mmap(8 * 16) as *i64 131 if mc_have_list(inv, dom, items, 4, hi) != 1 { t6 = 0 } 132 if fd_streq(hi[0] as *u8, "garlic" as *u8) == 0 { t6 = 0 } 133 gv_check("T6 shopping list marks the unpriced item -1 (never 0) and the on-hand list holds only garlic" as *u8, t6, ctr) 134 135 // ---- T7 a price carries its provenance ---- 136 let f: *u8 = sys_mmap(CG_FLD) 137 var t7: i64 = 1 138 if mc_price_asof(pr, area, "beef" as *u8, f) == 0 { t7 = 0 } 139 if fd_streq(f, "2026-08-02" as *u8) == 0 { t7 = 0 } 140 mc_price_source(pr, area, "beef" as *u8, f) 141 if fd_streq(f, "clearance tag" as *u8) == 0 { t7 = 0 } 142 if mc_price_asof(pr, area, "truffle" as *u8, f) != 0 { t7 = 0 } 143 gv_check("T7 the winning price carries its observation date + source (no implied live pricing)" as *u8, t7, ctr) 144 145 let rc: i64 = gv_verdict("MEAL-COST" as *u8, ctr, "unpriced is never free; a store must stock the basket to win it; sale is measured vs median" as *u8) 146 sys_exit(rc) 147 return 0 148}