FAILURE MAP
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FA-59796 / Subscription proration billing / Open access

Renewal price with lock and increase cap: lock expiry day · case 01

Renewals on the lock expiry day lose the locked price.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The lock is treated as expired on its last valid day.

VERIFIED REPAIR

Restore the contract rule at the lock expiry day step: use `x['renewal_day'] <= x['lock_until']`.

Unsuccessful approach: The attempt honors the lock one day past its expiry.

Case contract

Input {last_paid, list_price, locked|None, lock_until, renewal_day, cap_pct}. While the lock is active (renewal_day <= lock_until) the target is min(list_price, locked); otherwise list_price. The renewal price is min(target, last_paid*(100+cap_pct)//100). Return cents.

Why this case matters

Grandfathered prices and increase caps protect renewing subscribers; their interplay sets the renewal amount.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    if x['locked'] is not None and x['renewal_day'] < x['lock_until']:
        target = min(x['list_price'], x['locked'])
    else:
        target = x['list_price']
    ceiling = x['last_paid'] * (100 + x['cap_pct']) // 100
    return min(target, ceiling)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression', {'last_paid': 6548, 'list_price': 6483, 'locked': 6448, 'lock_until': 196, 'renewal_day': 196, 'cap_pct': 5}, 6448), ('regression', {'last_paid': 2000, 'list_price': 3042, 'locked': 1900, 'lock_until': 55, 'renewal_day': 55, 'cap_pct': 5}, 1900), ('partial-repair probe', {'last_paid': 2000, 'list_price': 3442, 'locked': 2000, 'lock_until': 83, 'renewal_day': 84, 'cap_pct': 5}, 2100), ('partial-repair probe', {'last_paid': 2000, 'list_price': 4561, 'locked': 1900, 'lock_until': 96, 'renewal_day': 97, 'cap_pct': 20}, 2400), ('normal control', {'last_paid': 1000, 'list_price': 1000, 'locked': 1500, 'lock_until': 328, 'renewal_day': 201, 'cap_pct': 20}, 1000), ('normal control', {'last_paid': 2000, 'list_price': 3312, 'locked': 2500, 'lock_until': 173, 'renewal_day': 173, 'cap_pct': 20}, 2400), ('normal control', {'last_paid': 4900, 'list_price': 4900, 'locked': None, 'lock_until': 83, 'renewal_day': 100, 'cap_pct': 20}, 4900), ('normal control', {'last_paid': 222, 'list_price': 222, 'locked': 222, 'lock_until': 231, 'renewal_day': 231, 'cap_pct': 5}, 222)], [('regression', {'last_paid': 2000, 'list_price': 3042, 'locked': 1900, 'lock_until': 55, 'renewal_day': 55, 'cap_pct': 5}, 1900), ('regression', {'last_paid': 5437, 'list_price': 5507, 'locked': 5337, 'lock_until': 225, 'renewal_day': 225, 'cap_pct': 5}, 5337), ('partial-repair probe', {'last_paid': 4984, 'list_price': 7349, 'locked': 4984, 'lock_until': 94, 'renewal_day': 95, 'cap_pct': 20}, 5980), ('partial-repair probe', {'last_paid': 7649, 'list_price': 7649, 'locked': 7549, 'lock_until': 183, 'renewal_day': 184, 'cap_pct': 10}, 7649), ('normal control', {'last_paid': 4217, 'list_price': 4172, 'locked': 4217, 'lock_until': 1, 'renewal_day': 2, 'cap_pct': 0}, 4172), ('normal control', {'last_paid': 4900, 'list_price': 4441, 'locked': 4900, 'lock_until': 309, 'renewal_day': 310, 'cap_pct': 0}, 4441), ('normal control', {'last_paid': 2000, 'list_price': 2000, 'locked': 2000, 'lock_until': 91, 'renewal_day': 92, 'cap_pct': 5}, 2000), ('normal control', {'last_paid': 4900, 'list_price': 4900, 'locked': 4900, 'lock_until': 26, 'renewal_day': 27, 'cap_pct': 5}, 4900)], [('regression', {'last_paid': 5437, 'list_price': 5507, 'locked': 5337, 'lock_until': 225, 'renewal_day': 225, 'cap_pct': 5}, 5337), ('regression', {'last_paid': 2000, 'list_price': 3888, 'locked': 2000, 'lock_until': 333, 'renewal_day': 333, 'cap_pct': 10}, 2000), ('partial-repair probe', {'last_paid': 2000, 'list_price': 2000, 'locked': 1900, 'lock_until': 374, 'renewal_day': 375, 'cap_pct': 0}, 2000), ('partial-repair probe', {'last_paid': 4900, 'list_price': 5949, 'locked': 4900, 'lock_until': 379, 'renewal_day': 380, 'cap_pct': 10}, 5390), ('normal control', {'last_paid': 4900, 'list_price': 7407, 'locked': None, 'lock_until': 112, 'renewal_day': 113, 'cap_pct': 5}, 5145), ('normal control', {'last_paid': 485, 'list_price': 654, 'locked': None, 'lock_until': 58, 'renewal_day': 58, 'cap_pct': 20}, 582), ('normal control', {'last_paid': 1219, 'list_price': 1057, 'locked': 1119, 'lock_until': 293, 'renewal_day': 294, 'cap_pct': 10}, 1057), ('normal control', {'last_paid': 1000, 'list_price': 1000, 'locked': 1000, 'lock_until': 85, 'renewal_day': 85, 'cap_pct': 20}, 1000)], [('regression', {'last_paid': 2000, 'list_price': 3888, 'locked': 2000, 'lock_until': 333, 'renewal_day': 333, 'cap_pct': 10}, 2000), ('regression', {'last_paid': 1000, 'list_price': 1000, 'locked': 900, 'lock_until': 392, 'renewal_day': 392, 'cap_pct': 5}, 900), ('partial-repair probe', {'last_paid': 7896, 'list_price': 8057, 'locked': 7896, 'lock_until': 71, 'renewal_day': 72, 'cap_pct': 20}, 8057), ('partial-repair probe', {'last_paid': 4900, 'list_price': 5888, 'locked': 5400, 'lock_until': 13, 'renewal_day': 14, 'cap_pct': 20}, 5880), ('normal control', {'last_paid': 2000, 'list_price': 3222, 'locked': 2500, 'lock_until': 57, 'renewal_day': 260, 'cap_pct': 0}, 2000), ('normal control', {'last_paid': 1000, 'list_price': 1000, 'locked': 1500, 'lock_until': 110, 'renewal_day': 262, 'cap_pct': 10}, 1000), ('normal control', {'last_paid': 7522, 'list_price': 7059, 'locked': 8022, 'lock_until': 19, 'renewal_day': 388, 'cap_pct': 20}, 7059), ('normal control', {'last_paid': 2000, 'list_price': 2000, 'locked': None, 'lock_until': 285, 'renewal_day': 285, 'cap_pct': 20}, 2000)], [('regression', {'last_paid': 1000, 'list_price': 1000, 'locked': 900, 'lock_until': 392, 'renewal_day': 392, 'cap_pct': 5}, 900), ('regression', {'last_paid': 3101, 'list_price': 3101, 'locked': 3001, 'lock_until': 113, 'renewal_day': 113, 'cap_pct': 10}, 3001), ('partial-repair probe', {'last_paid': 1000, 'list_price': 1000, 'locked': 900, 'lock_until': 109, 'renewal_day': 110, 'cap_pct': 5}, 1000), ('partial-repair probe', {'last_paid': 8551, 'list_price': 8551, 'locked': 8451, 'lock_until': 130, 'renewal_day': 131, 'cap_pct': 0}, 8551), ('normal control', {'last_paid': 2000, 'list_price': 2000, 'locked': None, 'lock_until': 173, 'renewal_day': 263, 'cap_pct': 5}, 2000), ('normal control', {'last_paid': 4105, 'list_price': 4394, 'locked': 4005, 'lock_until': 133, 'renewal_day': 322, 'cap_pct': 20}, 4394), ('normal control', {'last_paid': 2000, 'list_price': 2000, 'locked': 2500, 'lock_until': 167, 'renewal_day': 167, 'cap_pct': 10}, 2000), ('normal control', {'last_paid': 4900, 'list_price': 5180, 'locked': 4900, 'lock_until': 0, 'renewal_day': 66, 'cap_pct': 20}, 5180)]]
for i, (label, args, expected) in enumerate(fixtures[N-1]):
    check("%s %d" % (label, i), 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 fixtureActualExpectedOutcome
regression 064836448Failed
regression 121001900Failed
partial-repair probe 221002100Passed
partial-repair probe 324002400Passed
normal control 410001000Passed
normal control 524002400Passed
normal control 649004900Passed
normal control 7222222Passed

SHA-256 / 3024e28af4edf0ce484f5793799c65ba7bbf1522c792273043f1bbbf4c3e5eb3

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    if x['locked'] is not None and x['renewal_day'] <= x['lock_until'] + 1:
        target = min(x['list_price'], x['locked'])
    else:
        target = x['list_price']
    ceiling = x['last_paid'] * (100 + x['cap_pct']) // 100
    return min(target, ceiling)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression', {'last_paid': 6548, 'list_price': 6483, 'locked': 6448, 'lock_until': 196, 'renewal_day': 196, 'cap_pct': 5}, 6448), ('regression', {'last_paid': 2000, 'list_price': 3042, 'locked': 1900, 'lock_until': 55, 'renewal_day': 55, 'cap_pct': 5}, 1900), ('partial-repair probe', {'last_paid': 2000, 'list_price': 3442, 'locked': 2000, 'lock_until': 83, 'renewal_day': 84, 'cap_pct': 5}, 2100), ('partial-repair probe', {'last_paid': 2000, 'list_price': 4561, 'locked': 1900, 'lock_until': 96, 'renewal_day': 97, 'cap_pct': 20}, 2400), ('normal control', {'last_paid': 1000, 'list_price': 1000, 'locked': 1500, 'lock_until': 328, 'renewal_day': 201, 'cap_pct': 20}, 1000), ('normal control', {'last_paid': 2000, 'list_price': 3312, 'locked': 2500, 'lock_until': 173, 'renewal_day': 173, 'cap_pct': 20}, 2400), ('normal control', {'last_paid': 4900, 'list_price': 4900, 'locked': None, 'lock_until': 83, 'renewal_day': 100, 'cap_pct': 20}, 4900), ('normal control', {'last_paid': 222, 'list_price': 222, 'locked': 222, 'lock_until': 231, 'renewal_day': 231, 'cap_pct': 5}, 222)], [('regression', {'last_paid': 2000, 'list_price': 3042, 'locked': 1900, 'lock_until': 55, 'renewal_day': 55, 'cap_pct': 5}, 1900), ('regression', {'last_paid': 5437, 'list_price': 5507, 'locked': 5337, 'lock_until': 225, 'renewal_day': 225, 'cap_pct': 5}, 5337), ('partial-repair probe', {'last_paid': 4984, 'list_price': 7349, 'locked': 4984, 'lock_until': 94, 'renewal_day': 95, 'cap_pct': 20}, 5980), ('partial-repair probe', {'last_paid': 7649, 'list_price': 7649, 'locked': 7549, 'lock_until': 183, 'renewal_day': 184, 'cap_pct': 10}, 7649), ('normal control', {'last_paid': 4217, 'list_price': 4172, 'locked': 4217, 'lock_until': 1, 'renewal_day': 2, 'cap_pct': 0}, 4172), ('normal control', {'last_paid': 4900, 'list_price': 4441, 'locked': 4900, 'lock_until': 309, 'renewal_day': 310, 'cap_pct': 0}, 4441), ('normal control', {'last_paid': 2000, 'list_price': 2000, 'locked': 2000, 'lock_until': 91, 'renewal_day': 92, 'cap_pct': 5}, 2000), ('normal control', {'last_paid': 4900, 'list_price': 4900, 'locked': 4900, 'lock_until': 26, 'renewal_day': 27, 'cap_pct': 5}, 4900)], [('regression', {'last_paid': 5437, 'list_price': 5507, 'locked': 5337, 'lock_until': 225, 'renewal_day': 225, 'cap_pct': 5}, 5337), ('regression', {'last_paid': 2000, 'list_price': 3888, 'locked': 2000, 'lock_until': 333, 'renewal_day': 333, 'cap_pct': 10}, 2000), ('partial-repair probe', {'last_paid': 2000, 'list_price': 2000, 'locked': 1900, 'lock_until': 374, 'renewal_day': 375, 'cap_pct': 0}, 2000), ('partial-repair probe', {'last_paid': 4900, 'list_price': 5949, 'locked': 4900, 'lock_until': 379, 'renewal_day': 380, 'cap_pct': 10}, 5390), ('normal control', {'last_paid': 4900, 'list_price': 7407, 'locked': None, 'lock_until': 112, 'renewal_day': 113, 'cap_pct': 5}, 5145), ('normal control', {'last_paid': 485, 'list_price': 654, 'locked': None, 'lock_until': 58, 'renewal_day': 58, 'cap_pct': 20}, 582), ('normal control', {'last_paid': 1219, 'list_price': 1057, 'locked': 1119, 'lock_until': 293, 'renewal_day': 294, 'cap_pct': 10}, 1057), ('normal control', {'last_paid': 1000, 'list_price': 1000, 'locked': 1000, 'lock_until': 85, 'renewal_day': 85, 'cap_pct': 20}, 1000)], [('regression', {'last_paid': 2000, 'list_price': 3888, 'locked': 2000, 'lock_until': 333, 'renewal_day': 333, 'cap_pct': 10}, 2000), ('regression', {'last_paid': 1000, 'list_price': 1000, 'locked': 900, 'lock_until': 392, 'renewal_day': 392, 'cap_pct': 5}, 900), ('partial-repair probe', {'last_paid': 7896, 'list_price': 8057, 'locked': 7896, 'lock_until': 71, 'renewal_day': 72, 'cap_pct': 20}, 8057), ('partial-repair probe', {'last_paid': 4900, 'list_price': 5888, 'locked': 5400, 'lock_until': 13, 'renewal_day': 14, 'cap_pct': 20}, 5880), ('normal control', {'last_paid': 2000, 'list_price': 3222, 'locked': 2500, 'lock_until': 57, 'renewal_day': 260, 'cap_pct': 0}, 2000), ('normal control', {'last_paid': 1000, 'list_price': 1000, 'locked': 1500, 'lock_until': 110, 'renewal_day': 262, 'cap_pct': 10}, 1000), ('normal control', {'last_paid': 7522, 'list_price': 7059, 'locked': 8022, 'lock_until': 19, 'renewal_day': 388, 'cap_pct': 20}, 7059), ('normal control', {'last_paid': 2000, 'list_price': 2000, 'locked': None, 'lock_until': 285, 'renewal_day': 285, 'cap_pct': 20}, 2000)], [('regression', {'last_paid': 1000, 'list_price': 1000, 'locked': 900, 'lock_until': 392, 'renewal_day': 392, 'cap_pct': 5}, 900), ('regression', {'last_paid': 3101, 'list_price': 3101, 'locked': 3001, 'lock_until': 113, 'renewal_day': 113, 'cap_pct': 10}, 3001), ('partial-repair probe', {'last_paid': 1000, 'list_price': 1000, 'locked': 900, 'lock_until': 109, 'renewal_day': 110, 'cap_pct': 5}, 1000), ('partial-repair probe', {'last_paid': 8551, 'list_price': 8551, 'locked': 8451, 'lock_until': 130, 'renewal_day': 131, 'cap_pct': 0}, 8551), ('normal control', {'last_paid': 2000, 'list_price': 2000, 'locked': None, 'lock_until': 173, 'renewal_day': 263, 'cap_pct': 5}, 2000), ('normal control', {'last_paid': 4105, 'list_price': 4394, 'locked': 4005, 'lock_until': 133, 'renewal_day': 322, 'cap_pct': 20}, 4394), ('normal control', {'last_paid': 2000, 'list_price': 2000, 'locked': 2500, 'lock_until': 167, 'renewal_day': 167, 'cap_pct': 10}, 2000), ('normal control', {'last_paid': 4900, 'list_price': 5180, 'locked': 4900, 'lock_until': 0, 'renewal_day': 66, 'cap_pct': 20}, 5180)]]
for i, (label, args, expected) in enumerate(fixtures[N-1]):
    check("%s %d" % (label, i), 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 fixtureActualExpectedOutcome
regression 064486448Passed
regression 119001900Passed
partial-repair probe 220002100Failed
partial-repair probe 319002400Failed
normal control 410001000Passed
normal control 524002400Passed
normal control 649004900Passed
normal control 7222222Passed

SHA-256 / c95dd8cde9780f60e915d3b5ab3a234039bd32108acc39f2d1e2e3791f4a92c2

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    if x['locked'] is not None and x['renewal_day'] <= x['lock_until']:
        target = min(x['list_price'], x['locked'])
    else:
        target = x['list_price']
    ceiling = x['last_paid'] * (100 + x['cap_pct']) // 100
    return min(target, ceiling)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression', {'last_paid': 6548, 'list_price': 6483, 'locked': 6448, 'lock_until': 196, 'renewal_day': 196, 'cap_pct': 5}, 6448), ('regression', {'last_paid': 2000, 'list_price': 3042, 'locked': 1900, 'lock_until': 55, 'renewal_day': 55, 'cap_pct': 5}, 1900), ('partial-repair probe', {'last_paid': 2000, 'list_price': 3442, 'locked': 2000, 'lock_until': 83, 'renewal_day': 84, 'cap_pct': 5}, 2100), ('partial-repair probe', {'last_paid': 2000, 'list_price': 4561, 'locked': 1900, 'lock_until': 96, 'renewal_day': 97, 'cap_pct': 20}, 2400), ('normal control', {'last_paid': 1000, 'list_price': 1000, 'locked': 1500, 'lock_until': 328, 'renewal_day': 201, 'cap_pct': 20}, 1000), ('normal control', {'last_paid': 2000, 'list_price': 3312, 'locked': 2500, 'lock_until': 173, 'renewal_day': 173, 'cap_pct': 20}, 2400), ('normal control', {'last_paid': 4900, 'list_price': 4900, 'locked': None, 'lock_until': 83, 'renewal_day': 100, 'cap_pct': 20}, 4900), ('normal control', {'last_paid': 222, 'list_price': 222, 'locked': 222, 'lock_until': 231, 'renewal_day': 231, 'cap_pct': 5}, 222)], [('regression', {'last_paid': 2000, 'list_price': 3042, 'locked': 1900, 'lock_until': 55, 'renewal_day': 55, 'cap_pct': 5}, 1900), ('regression', {'last_paid': 5437, 'list_price': 5507, 'locked': 5337, 'lock_until': 225, 'renewal_day': 225, 'cap_pct': 5}, 5337), ('partial-repair probe', {'last_paid': 4984, 'list_price': 7349, 'locked': 4984, 'lock_until': 94, 'renewal_day': 95, 'cap_pct': 20}, 5980), ('partial-repair probe', {'last_paid': 7649, 'list_price': 7649, 'locked': 7549, 'lock_until': 183, 'renewal_day': 184, 'cap_pct': 10}, 7649), ('normal control', {'last_paid': 4217, 'list_price': 4172, 'locked': 4217, 'lock_until': 1, 'renewal_day': 2, 'cap_pct': 0}, 4172), ('normal control', {'last_paid': 4900, 'list_price': 4441, 'locked': 4900, 'lock_until': 309, 'renewal_day': 310, 'cap_pct': 0}, 4441), ('normal control', {'last_paid': 2000, 'list_price': 2000, 'locked': 2000, 'lock_until': 91, 'renewal_day': 92, 'cap_pct': 5}, 2000), ('normal control', {'last_paid': 4900, 'list_price': 4900, 'locked': 4900, 'lock_until': 26, 'renewal_day': 27, 'cap_pct': 5}, 4900)], [('regression', {'last_paid': 5437, 'list_price': 5507, 'locked': 5337, 'lock_until': 225, 'renewal_day': 225, 'cap_pct': 5}, 5337), ('regression', {'last_paid': 2000, 'list_price': 3888, 'locked': 2000, 'lock_until': 333, 'renewal_day': 333, 'cap_pct': 10}, 2000), ('partial-repair probe', {'last_paid': 2000, 'list_price': 2000, 'locked': 1900, 'lock_until': 374, 'renewal_day': 375, 'cap_pct': 0}, 2000), ('partial-repair probe', {'last_paid': 4900, 'list_price': 5949, 'locked': 4900, 'lock_until': 379, 'renewal_day': 380, 'cap_pct': 10}, 5390), ('normal control', {'last_paid': 4900, 'list_price': 7407, 'locked': None, 'lock_until': 112, 'renewal_day': 113, 'cap_pct': 5}, 5145), ('normal control', {'last_paid': 485, 'list_price': 654, 'locked': None, 'lock_until': 58, 'renewal_day': 58, 'cap_pct': 20}, 582), ('normal control', {'last_paid': 1219, 'list_price': 1057, 'locked': 1119, 'lock_until': 293, 'renewal_day': 294, 'cap_pct': 10}, 1057), ('normal control', {'last_paid': 1000, 'list_price': 1000, 'locked': 1000, 'lock_until': 85, 'renewal_day': 85, 'cap_pct': 20}, 1000)], [('regression', {'last_paid': 2000, 'list_price': 3888, 'locked': 2000, 'lock_until': 333, 'renewal_day': 333, 'cap_pct': 10}, 2000), ('regression', {'last_paid': 1000, 'list_price': 1000, 'locked': 900, 'lock_until': 392, 'renewal_day': 392, 'cap_pct': 5}, 900), ('partial-repair probe', {'last_paid': 7896, 'list_price': 8057, 'locked': 7896, 'lock_until': 71, 'renewal_day': 72, 'cap_pct': 20}, 8057), ('partial-repair probe', {'last_paid': 4900, 'list_price': 5888, 'locked': 5400, 'lock_until': 13, 'renewal_day': 14, 'cap_pct': 20}, 5880), ('normal control', {'last_paid': 2000, 'list_price': 3222, 'locked': 2500, 'lock_until': 57, 'renewal_day': 260, 'cap_pct': 0}, 2000), ('normal control', {'last_paid': 1000, 'list_price': 1000, 'locked': 1500, 'lock_until': 110, 'renewal_day': 262, 'cap_pct': 10}, 1000), ('normal control', {'last_paid': 7522, 'list_price': 7059, 'locked': 8022, 'lock_until': 19, 'renewal_day': 388, 'cap_pct': 20}, 7059), ('normal control', {'last_paid': 2000, 'list_price': 2000, 'locked': None, 'lock_until': 285, 'renewal_day': 285, 'cap_pct': 20}, 2000)], [('regression', {'last_paid': 1000, 'list_price': 1000, 'locked': 900, 'lock_until': 392, 'renewal_day': 392, 'cap_pct': 5}, 900), ('regression', {'last_paid': 3101, 'list_price': 3101, 'locked': 3001, 'lock_until': 113, 'renewal_day': 113, 'cap_pct': 10}, 3001), ('partial-repair probe', {'last_paid': 1000, 'list_price': 1000, 'locked': 900, 'lock_until': 109, 'renewal_day': 110, 'cap_pct': 5}, 1000), ('partial-repair probe', {'last_paid': 8551, 'list_price': 8551, 'locked': 8451, 'lock_until': 130, 'renewal_day': 131, 'cap_pct': 0}, 8551), ('normal control', {'last_paid': 2000, 'list_price': 2000, 'locked': None, 'lock_until': 173, 'renewal_day': 263, 'cap_pct': 5}, 2000), ('normal control', {'last_paid': 4105, 'list_price': 4394, 'locked': 4005, 'lock_until': 133, 'renewal_day': 322, 'cap_pct': 20}, 4394), ('normal control', {'last_paid': 2000, 'list_price': 2000, 'locked': 2500, 'lock_until': 167, 'renewal_day': 167, 'cap_pct': 10}, 2000), ('normal control', {'last_paid': 4900, 'list_price': 5180, 'locked': 4900, 'lock_until': 0, 'renewal_day': 66, 'cap_pct': 20}, 5180)]]
for i, (label, args, expected) in enumerate(fixtures[N-1]):
    check("%s %d" % (label, i), 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 fixtureActualExpectedOutcome
regression 064486448Passed
regression 119001900Passed
partial-repair probe 221002100Passed
partial-repair probe 324002400Passed
normal control 410001000Passed
normal control 524002400Passed
normal control 649004900Passed
normal control 7222222Passed

SHA-256 / b51db86e6a04d4d81a1a9f1cfce0f9c68fd5f3c308f9b4884a32186a1f14b4d5

Verification & scope

A deterministic teaching model of a stipulated billing rule. It makes no claim to reproduce any billing provider's exact behaviour and is not billing software. 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 2026-09-29T14:46:39.628223+00:00.

Case digest / 5b11dde33fd966c33e24e745dfe3fefbc7b1f83b3f6d78950bc3198c5fa28877