FA-60751 / Loyalty points ledgers / Open access

Tier multiplier in force at transaction time: history ordering · case 01

An out-of-order tier history makes later transactions use an older tier.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The history is scanned in stored order without sorting by effective day.

VERIFIED REPAIR

Sort the history by effective day before scanning.

Unsuccessful approach: Sorting by tier name orders tiers alphabetically, not by date.

Case contract

Input {tier_history:[[effective_day,tier]] (any order), txns:[[day,base]], mult:{tier:pct}}. Each transaction earns floor(base*pct/100) using the tier with the latest effective_day <= transaction day ("member" before any entry). Unknown tier names earn at 100%. Return {points, total}.

Why this case matters

Member point balances, statements and the program liability depend on this ledger rule.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    hist = x['tier_history']
    out = []
    for day, base in x['txns']:
        tier = 'member'
        for eff, t in hist:
            if eff <= day:
                tier = t
            else:
                break
        pct = x['mult'].get(tier, 100)
        out.append(base * pct // 100)
    return {'points': out, 'total': sum(out)}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1001], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1251, 1500], 'total': 3751}], ['effective day', {'tier_history': [[100, 'silver'], [201, 'gold']], 'txns': [[100, 400], [201, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 101], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [151, 200], 'total': 351}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 334]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [334], 'total': 334}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 11]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 11], 'total': 88}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 201]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 251], 'total': 551}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 91]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [113], 'total': 113}]], [['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1002], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1252, 1500], 'total': 3752}], ['effective day', {'tier_history': [[100, 'silver'], [202, 'gold']], 'txns': [[100, 400], [202, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 102], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [153, 200], 'total': 353}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 335]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [335], 'total': 335}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 12]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 12], 'total': 89}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 202]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 252], 'total': 552}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 92]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [115], 'total': 115}]], [['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1003], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1253, 1500], 'total': 3753}], ['effective day', {'tier_history': [[100, 'silver'], [203, 'gold']], 'txns': [[100, 400], [203, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 103], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [154, 200], 'total': 354}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 336]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [336], 'total': 336}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 13]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 13], 'total': 90}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 203]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 253], 'total': 553}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 93]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [116], 'total': 116}]], [['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1004], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1255, 1500], 'total': 3755}], ['effective day', {'tier_history': [[100, 'silver'], [204, 'gold']], 'txns': [[100, 400], [204, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 104], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [156, 200], 'total': 356}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 337]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [337], 'total': 337}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 14]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 14], 'total': 91}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 204]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 255], 'total': 555}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 94]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [117], 'total': 117}]], [['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1005], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1256, 1500], 'total': 3756}], ['effective day', {'tier_history': [[100, 'silver'], [205, 'gold']], 'txns': [[100, 400], [205, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 105], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [157, 200], 'total': 357}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 338]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [338], 'total': 338}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 15]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 15], 'total': 92}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 205]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 256], 'total': 556}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 95]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [118], 'total': 118}]]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
tier changes midyear	`{'points': [1000, 1251, 1500], 'total': 3751}`	`{'points': [1000, 1251, 1500], 'total': 3751}`	Passed
effective day	`{'points': [500, 600], 'total': 1100}`	`{'points': [500, 600], 'total': 1100}`	Passed
unsorted history	`{'points': [101, 150], 'total': 251}`	`{'points': [151, 200], 'total': 351}`	Failed
legacy tier	`{'points': [334], 'total': 334}`	`{'points': [334], 'total': 334}`	Passed
before any tier	`{'points': [77, 11], 'total': 88}`	`{'points': [77, 11], 'total': 88}`	Passed
downgrade	`{'points': [300, 251], 'total': 551}`	`{'points': [300, 251], 'total': 551}`	Passed
late earns	`{'points': [113], 'total': 113}`	`{'points': [113], 'total': 113}`	Passed

SHA-256 / 668ed0755ff46c726b43a62aef916e5904c3e1bf4dc2ada753705992a55e5cd7

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    hist = sorted(x['tier_history'], key=lambda h: h[1])
    out = []
    for day, base in x['txns']:
        tier = 'member'
        for eff, t in hist:
            if eff <= day:
                tier = t
            else:
                break
        pct = x['mult'].get(tier, 100)
        out.append(base * pct // 100)
    return {'points': out, 'total': sum(out)}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1001], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1251, 1500], 'total': 3751}], ['effective day', {'tier_history': [[100, 'silver'], [201, 'gold']], 'txns': [[100, 400], [201, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 101], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [151, 200], 'total': 351}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 334]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [334], 'total': 334}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 11]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 11], 'total': 88}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 201]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 251], 'total': 551}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 91]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [113], 'total': 113}]], [['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1002], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1252, 1500], 'total': 3752}], ['effective day', {'tier_history': [[100, 'silver'], [202, 'gold']], 'txns': [[100, 400], [202, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 102], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [153, 200], 'total': 353}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 335]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [335], 'total': 335}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 12]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 12], 'total': 89}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 202]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 252], 'total': 552}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 92]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [115], 'total': 115}]], [['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1003], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1253, 1500], 'total': 3753}], ['effective day', {'tier_history': [[100, 'silver'], [203, 'gold']], 'txns': [[100, 400], [203, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 103], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [154, 200], 'total': 354}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 336]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [336], 'total': 336}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 13]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 13], 'total': 90}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 203]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 253], 'total': 553}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 93]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [116], 'total': 116}]], [['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1004], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1255, 1500], 'total': 3755}], ['effective day', {'tier_history': [[100, 'silver'], [204, 'gold']], 'txns': [[100, 400], [204, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 104], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [156, 200], 'total': 356}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 337]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [337], 'total': 337}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 14]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 14], 'total': 91}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 204]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 255], 'total': 555}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 94]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [117], 'total': 117}]], [['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1005], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1256, 1500], 'total': 3756}], ['effective day', {'tier_history': [[100, 'silver'], [205, 'gold']], 'txns': [[100, 400], [205, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 105], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [157, 200], 'total': 357}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 338]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [338], 'total': 338}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 15]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 15], 'total': 92}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 205]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 256], 'total': 556}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 95]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [118], 'total': 118}]]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
tier changes midyear	`{'points': [1000, 1001, 1250], 'total': 3251}`	`{'points': [1000, 1251, 1500], 'total': 3751}`	Failed
effective day	`{'points': [400, 500], 'total': 900}`	`{'points': [500, 600], 'total': 1100}`	Failed
unsorted history	`{'points': [151, 200], 'total': 351}`	`{'points': [151, 200], 'total': 351}`	Passed
legacy tier	`{'points': [334], 'total': 334}`	`{'points': [334], 'total': 334}`	Passed
before any tier	`{'points': [77, 11], 'total': 88}`	`{'points': [77, 11], 'total': 88}`	Passed
downgrade	`{'points': [300, 251], 'total': 551}`	`{'points': [300, 251], 'total': 551}`	Passed
late earns	`{'points': [91], 'total': 91}`	`{'points': [113], 'total': 113}`	Failed

SHA-256 / 8fe79db15df30c051a7bd9856d85c26318f9d56cd8ac8adcf9c3bee970d9e259

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    hist = sorted(x['tier_history'])
    out = []
    for day, base in x['txns']:
        tier = 'member'
        for eff, t in hist:
            if eff <= day:
                tier = t
            else:
                break
        pct = x['mult'].get(tier, 100)
        out.append(base * pct // 100)
    return {'points': out, 'total': sum(out)}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1001], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1251, 1500], 'total': 3751}], ['effective day', {'tier_history': [[100, 'silver'], [201, 'gold']], 'txns': [[100, 400], [201, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 101], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [151, 200], 'total': 351}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 334]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [334], 'total': 334}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 11]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 11], 'total': 88}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 201]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 251], 'total': 551}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 91]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [113], 'total': 113}]], [['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1002], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1252, 1500], 'total': 3752}], ['effective day', {'tier_history': [[100, 'silver'], [202, 'gold']], 'txns': [[100, 400], [202, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 102], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [153, 200], 'total': 353}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 335]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [335], 'total': 335}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 12]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 12], 'total': 89}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 202]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 252], 'total': 552}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 92]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [115], 'total': 115}]], [['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1003], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1253, 1500], 'total': 3753}], ['effective day', {'tier_history': [[100, 'silver'], [203, 'gold']], 'txns': [[100, 400], [203, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 103], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [154, 200], 'total': 354}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 336]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [336], 'total': 336}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 13]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 13], 'total': 90}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 203]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 253], 'total': 553}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 93]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [116], 'total': 116}]], [['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1004], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1255, 1500], 'total': 3755}], ['effective day', {'tier_history': [[100, 'silver'], [204, 'gold']], 'txns': [[100, 400], [204, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 104], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [156, 200], 'total': 356}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 337]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [337], 'total': 337}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 14]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 14], 'total': 91}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 204]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 255], 'total': 555}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 94]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [117], 'total': 117}]], [['tier changes midyear', {'tier_history': [[100, 'silver'], [200, 'gold']], 'txns': [[50, 1000], [150, 1005], [250, 1000]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [1000, 1256, 1500], 'total': 3756}], ['effective day', {'tier_history': [[100, 'silver'], [205, 'gold']], 'txns': [[100, 400], [205, 400]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [500, 600], 'total': 1100}], ['unsorted history', {'tier_history': [[300, 'platinum'], [100, 'gold']], 'txns': [[150, 105], [350, 100]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [157, 200], 'total': 357}], ['legacy tier', {'tier_history': [[10, 'diamond']], 'txns': [[20, 338]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [338], 'total': 338}], ['before any tier', {'tier_history': [[500, 'gold']], 'txns': [[1, 77], [499, 15]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [77, 15], 'total': 92}], ['downgrade', {'tier_history': [[10, 'gold'], [60, 'silver']], 'txns': [[59, 200], [61, 205]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [300, 256], 'total': 556}], ['late earns', {'tier_history': [[0, 'silver'], [30, 'platinum']], 'txns': [[15, 95]], 'mult': {'member': 100, 'silver': 125, 'gold': 150, 'platinum': 200}}, {'points': [118], 'total': 118}]]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
tier changes midyear	`{'points': [1000, 1251, 1500], 'total': 3751}`	`{'points': [1000, 1251, 1500], 'total': 3751}`	Passed
effective day	`{'points': [500, 600], 'total': 1100}`	`{'points': [500, 600], 'total': 1100}`	Passed
unsorted history	`{'points': [151, 200], 'total': 351}`	`{'points': [151, 200], 'total': 351}`	Passed
legacy tier	`{'points': [334], 'total': 334}`	`{'points': [334], 'total': 334}`	Passed
before any tier	`{'points': [77, 11], 'total': 88}`	`{'points': [77, 11], 'total': 88}`	Passed
downgrade	`{'points': [300, 251], 'total': 551}`	`{'points': [300, 251], 'total': 551}`	Passed
late earns	`{'points': [113], 'total': 113}`	`{'points': [113], 'total': 113}`	Passed

SHA-256 / a6aa004133bf274de7fb5e95d2650e5d09e58efe89ca92bbd37e211aad14dda3

Verification & scope

Stipulated bounded loyalty-program model with explicit toy rules; not any real program terms. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:46:48.595393+00:00.

Case digest / 28b02f14c81e131e80c4dea01ec620934740f973121630021b5cf88b47abba86