FA-60671 / Loyalty points ledgers / Open access

Cancelled reward reinstatement: grace anchor · case 01

Reinstated points that had lapsed expire immediately or within days of reinstatement.

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

ROOT CAUSE

The grace period is added to the original lot expiry instead of the cancel day.

THE FAILURE

The grace period is added to the original lot expiry instead of the cancel day.

Unsuccessful approach: Anchoring grace on the redemption day shortens it by however long the cancellation took.

Case contract

Input {redemption:{day, sources:[[lot_expiry, pts]]}, cancel_day, grace, max_age}. Cancelling more than max_age days after the redemption returns {"error":"too late"}. Each source lot is reinstated with its original expiry if that expiry is on or after the cancel day, otherwise with expiry cancel_day + grace. Lots with the same resulting expiry are merged. Return {lots:[[expiry,pts]] by expiry, 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):
    r = x['redemption']
    if x['cancel_day'] - r['day'] > x['max_age']:
        return {'error': 'too late'}
    lots = {}
    for exp, p in r['sources']:
        e = exp if exp >= x['cancel_day'] else exp + x['grace']
        lots[e] = lots.get(e, 0) + p
    return {'lots': [[e, lots[e]] for e in sorted(lots)], 'total': sum(lots.values())}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['mixed sources', {'redemption': {'day': 100, 'sources': [[91, 300], [150, 200], [400, 100]]}, 'cancel_day': 110, 'grace': 30, 'max_age': 90}, {'lots': [[140, 300], [150, 200], [400, 100]], 'total': 600}], ['expires on cancel day', {'redemption': {'day': 100, 'sources': [[120, 51]]}, 'cancel_day': 120, 'grace': 30, 'max_age': 90}, {'lots': [[120, 51]], 'total': 51}], ['too late', {'redemption': {'day': 10, 'sources': [[500, 100]]}, 'cancel_day': 102, 'grace': 30, 'max_age': 90}, {'error': 'too late'}], ['age edge', {'redemption': {'day': 11, 'sources': [[500, 100], [20, 5]]}, 'cancel_day': 101, 'grace': 14, 'max_age': 90}, {'lots': [[115, 5], [500, 100]], 'total': 105}], ['merge grace lots', {'redemption': {'day': 50, 'sources': [[55, 10], [58, 21], [300, 7]]}, 'cancel_day': 60, 'grace': 45, 'max_age': 90}, {'lots': [[105, 31], [300, 7]], 'total': 38}], ['merge with original', {'redemption': {'day': 50, 'sources': [[200, 40], [150, 10], [90, 6]]}, 'cancel_day': 60, 'grace': 140, 'max_age': 90}, {'lots': [[90, 6], [150, 10], [200, 40]], 'total': 56}], ['late cancel grace base', {'redemption': {'day': 20, 'sources': [[25, 70]]}, 'cancel_day': 81, 'grace': 10, 'max_age': 90}, {'lots': [[91, 70]], 'total': 70}]], [['mixed sources', {'redemption': {'day': 100, 'sources': [[92, 300], [150, 200], [400, 100]]}, 'cancel_day': 110, 'grace': 30, 'max_age': 90}, {'lots': [[140, 300], [150, 200], [400, 100]], 'total': 600}], ['expires on cancel day', {'redemption': {'day': 100, 'sources': [[120, 52]]}, 'cancel_day': 120, 'grace': 30, 'max_age': 90}, {'lots': [[120, 52]], 'total': 52}], ['too late', {'redemption': {'day': 10, 'sources': [[500, 100]]}, 'cancel_day': 103, 'grace': 30, 'max_age': 90}, {'error': 'too late'}], ['age edge', {'redemption': {'day': 12, 'sources': [[500, 100], [20, 5]]}, 'cancel_day': 102, 'grace': 14, 'max_age': 90}, {'lots': [[116, 5], [500, 100]], 'total': 105}], ['merge grace lots', {'redemption': {'day': 50, 'sources': [[55, 10], [58, 22], [300, 7]]}, 'cancel_day': 60, 'grace': 45, 'max_age': 90}, {'lots': [[105, 32], [300, 7]], 'total': 39}], ['merge with original', {'redemption': {'day': 50, 'sources': [[200, 40], [150, 10], [90, 7]]}, 'cancel_day': 60, 'grace': 140, 'max_age': 90}, {'lots': [[90, 7], [150, 10], [200, 40]], 'total': 57}], ['late cancel grace base', {'redemption': {'day': 20, 'sources': [[25, 70]]}, 'cancel_day': 82, 'grace': 10, 'max_age': 90}, {'lots': [[92, 70]], 'total': 70}]], [['mixed sources', {'redemption': {'day': 100, 'sources': [[93, 300], [150, 200], [400, 100]]}, 'cancel_day': 110, 'grace': 30, 'max_age': 90}, {'lots': [[140, 300], [150, 200], [400, 100]], 'total': 600}], ['expires on cancel day', {'redemption': {'day': 100, 'sources': [[120, 53]]}, 'cancel_day': 120, 'grace': 30, 'max_age': 90}, {'lots': [[120, 53]], 'total': 53}], ['too late', {'redemption': {'day': 10, 'sources': [[500, 100]]}, 'cancel_day': 104, 'grace': 30, 'max_age': 90}, {'error': 'too late'}], ['age edge', {'redemption': {'day': 13, 'sources': [[500, 100], [20, 5]]}, 'cancel_day': 103, 'grace': 14, 'max_age': 90}, {'lots': [[117, 5], [500, 100]], 'total': 105}], ['merge grace lots', {'redemption': {'day': 50, 'sources': [[55, 10], [58, 23], [300, 7]]}, 'cancel_day': 60, 'grace': 45, 'max_age': 90}, {'lots': [[105, 33], [300, 7]], 'total': 40}], ['merge with original', {'redemption': {'day': 50, 'sources': [[200, 40], [150, 10], [90, 8]]}, 'cancel_day': 60, 'grace': 140, 'max_age': 90}, {'lots': [[90, 8], [150, 10], [200, 40]], 'total': 58}], ['late cancel grace base', {'redemption': {'day': 20, 'sources': [[25, 70]]}, 'cancel_day': 83, 'grace': 10, 'max_age': 90}, {'lots': [[93, 70]], 'total': 70}]], [['mixed sources', {'redemption': {'day': 100, 'sources': [[94, 300], [150, 200], [400, 100]]}, 'cancel_day': 110, 'grace': 30, 'max_age': 90}, {'lots': [[140, 300], [150, 200], [400, 100]], 'total': 600}], ['expires on cancel day', {'redemption': {'day': 100, 'sources': [[120, 54]]}, 'cancel_day': 120, 'grace': 30, 'max_age': 90}, {'lots': [[120, 54]], 'total': 54}], ['too late', {'redemption': {'day': 10, 'sources': [[500, 100]]}, 'cancel_day': 105, 'grace': 30, 'max_age': 90}, {'error': 'too late'}], ['age edge', {'redemption': {'day': 14, 'sources': [[500, 100], [20, 5]]}, 'cancel_day': 104, 'grace': 14, 'max_age': 90}, {'lots': [[118, 5], [500, 100]], 'total': 105}], ['merge grace lots', {'redemption': {'day': 50, 'sources': [[55, 10], [58, 24], [300, 7]]}, 'cancel_day': 60, 'grace': 45, 'max_age': 90}, {'lots': [[105, 34], [300, 7]], 'total': 41}], ['merge with original', {'redemption': {'day': 50, 'sources': [[200, 40], [150, 10], [90, 9]]}, 'cancel_day': 60, 'grace': 140, 'max_age': 90}, {'lots': [[90, 9], [150, 10], [200, 40]], 'total': 59}], ['late cancel grace base', {'redemption': {'day': 20, 'sources': [[25, 70]]}, 'cancel_day': 84, 'grace': 10, 'max_age': 90}, {'lots': [[94, 70]], 'total': 70}]], [['mixed sources', {'redemption': {'day': 100, 'sources': [[95, 300], [150, 200], [400, 100]]}, 'cancel_day': 110, 'grace': 30, 'max_age': 90}, {'lots': [[140, 300], [150, 200], [400, 100]], 'total': 600}], ['expires on cancel day', {'redemption': {'day': 100, 'sources': [[120, 55]]}, 'cancel_day': 120, 'grace': 30, 'max_age': 90}, {'lots': [[120, 55]], 'total': 55}], ['too late', {'redemption': {'day': 10, 'sources': [[500, 100]]}, 'cancel_day': 106, 'grace': 30, 'max_age': 90}, {'error': 'too late'}], ['age edge', {'redemption': {'day': 15, 'sources': [[500, 100], [20, 5]]}, 'cancel_day': 105, 'grace': 14, 'max_age': 90}, {'lots': [[119, 5], [500, 100]], 'total': 105}], ['merge grace lots', {'redemption': {'day': 50, 'sources': [[55, 10], [58, 25], [300, 7]]}, 'cancel_day': 60, 'grace': 45, 'max_age': 90}, {'lots': [[105, 35], [300, 7]], 'total': 42}], ['merge with original', {'redemption': {'day': 50, 'sources': [[200, 40], [150, 10], [90, 10]]}, 'cancel_day': 60, 'grace': 140, 'max_age': 90}, {'lots': [[90, 10], [150, 10], [200, 40]], 'total': 60}], ['late cancel grace base', {'redemption': {'day': 20, 'sources': [[25, 70]]}, 'cancel_day': 85, 'grace': 10, 'max_age': 90}, {'lots': [[95, 70]], 'total': 70}]]]
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
mixed sources	`{'lots': [[121, 300], [150, 200], [400, 100]], 'total': 600}`	`{'lots': [[140, 300], [150, 200], [400, 100]], 'total': 600}`	Failed
expires on cancel day	`{'lots': [[120, 51]], 'total': 51}`	`{'lots': [[120, 51]], 'total': 51}`	Passed
too late	`{'error': 'too late'}`	`{'error': 'too late'}`	Passed
age edge	`{'lots': [[34, 5], [500, 100]], 'total': 105}`	`{'lots': [[115, 5], [500, 100]], 'total': 105}`	Failed
merge grace lots	`{'lots': [[100, 10], [103, 21], [300, 7]], 'total': 38}`	`{'lots': [[105, 31], [300, 7]], 'total': 38}`	Failed
merge with original	`{'lots': [[90, 6], [150, 10], [200, 40]], 'total': 56}`	`{'lots': [[90, 6], [150, 10], [200, 40]], 'total': 56}`	Passed
late cancel grace base	`{'lots': [[35, 70]], 'total': 70}`	`{'lots': [[91, 70]], 'total': 70}`	Failed

SHA-256 / 568faecbbea11021c05e49f1b7dc034819ac2d3e4276d6e04fc93f99c4e7cd2c

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(x):
    r = x['redemption']
    if x['cancel_day'] - r['day'] > x['max_age']:
        return {'error': 'too late'}
    lots = {}
    for exp, p in r['sources']:
        e = exp if exp >= x['cancel_day'] else r['day'] + x['grace']
        lots[e] = lots.get(e, 0) + p
    return {'lots': [[e, lots[e]] for e in sorted(lots)], 'total': sum(lots.values())}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['mixed sources', {'redemption': {'day': 100, 'sources': [[91, 300], [150, 200], [400, 100]]}, 'cancel_day': 110, 'grace': 30, 'max_age': 90}, {'lots': [[140, 300], [150, 200], [400, 100]], 'total': 600}], ['expires on cancel day', {'redemption': {'day': 100, 'sources': [[120, 51]]}, 'cancel_day': 120, 'grace': 30, 'max_age': 90}, {'lots': [[120, 51]], 'total': 51}], ['too late', {'redemption': {'day': 10, 'sources': [[500, 100]]}, 'cancel_day': 102, 'grace': 30, 'max_age': 90}, {'error': 'too late'}], ['age edge', {'redemption': {'day': 11, 'sources': [[500, 100], [20, 5]]}, 'cancel_day': 101, 'grace': 14, 'max_age': 90}, {'lots': [[115, 5], [500, 100]], 'total': 105}], ['merge grace lots', {'redemption': {'day': 50, 'sources': [[55, 10], [58, 21], [300, 7]]}, 'cancel_day': 60, 'grace': 45, 'max_age': 90}, {'lots': [[105, 31], [300, 7]], 'total': 38}], ['merge with original', {'redemption': {'day': 50, 'sources': [[200, 40], [150, 10], [90, 6]]}, 'cancel_day': 60, 'grace': 140, 'max_age': 90}, {'lots': [[90, 6], [150, 10], [200, 40]], 'total': 56}], ['late cancel grace base', {'redemption': {'day': 20, 'sources': [[25, 70]]}, 'cancel_day': 81, 'grace': 10, 'max_age': 90}, {'lots': [[91, 70]], 'total': 70}]], [['mixed sources', {'redemption': {'day': 100, 'sources': [[92, 300], [150, 200], [400, 100]]}, 'cancel_day': 110, 'grace': 30, 'max_age': 90}, {'lots': [[140, 300], [150, 200], [400, 100]], 'total': 600}], ['expires on cancel day', {'redemption': {'day': 100, 'sources': [[120, 52]]}, 'cancel_day': 120, 'grace': 30, 'max_age': 90}, {'lots': [[120, 52]], 'total': 52}], ['too late', {'redemption': {'day': 10, 'sources': [[500, 100]]}, 'cancel_day': 103, 'grace': 30, 'max_age': 90}, {'error': 'too late'}], ['age edge', {'redemption': {'day': 12, 'sources': [[500, 100], [20, 5]]}, 'cancel_day': 102, 'grace': 14, 'max_age': 90}, {'lots': [[116, 5], [500, 100]], 'total': 105}], ['merge grace lots', {'redemption': {'day': 50, 'sources': [[55, 10], [58, 22], [300, 7]]}, 'cancel_day': 60, 'grace': 45, 'max_age': 90}, {'lots': [[105, 32], [300, 7]], 'total': 39}], ['merge with original', {'redemption': {'day': 50, 'sources': [[200, 40], [150, 10], [90, 7]]}, 'cancel_day': 60, 'grace': 140, 'max_age': 90}, {'lots': [[90, 7], [150, 10], [200, 40]], 'total': 57}], ['late cancel grace base', {'redemption': {'day': 20, 'sources': [[25, 70]]}, 'cancel_day': 82, 'grace': 10, 'max_age': 90}, {'lots': [[92, 70]], 'total': 70}]], [['mixed sources', {'redemption': {'day': 100, 'sources': [[93, 300], [150, 200], [400, 100]]}, 'cancel_day': 110, 'grace': 30, 'max_age': 90}, {'lots': [[140, 300], [150, 200], [400, 100]], 'total': 600}], ['expires on cancel day', {'redemption': {'day': 100, 'sources': [[120, 53]]}, 'cancel_day': 120, 'grace': 30, 'max_age': 90}, {'lots': [[120, 53]], 'total': 53}], ['too late', {'redemption': {'day': 10, 'sources': [[500, 100]]}, 'cancel_day': 104, 'grace': 30, 'max_age': 90}, {'error': 'too late'}], ['age edge', {'redemption': {'day': 13, 'sources': [[500, 100], [20, 5]]}, 'cancel_day': 103, 'grace': 14, 'max_age': 90}, {'lots': [[117, 5], [500, 100]], 'total': 105}], ['merge grace lots', {'redemption': {'day': 50, 'sources': [[55, 10], [58, 23], [300, 7]]}, 'cancel_day': 60, 'grace': 45, 'max_age': 90}, {'lots': [[105, 33], [300, 7]], 'total': 40}], ['merge with original', {'redemption': {'day': 50, 'sources': [[200, 40], [150, 10], [90, 8]]}, 'cancel_day': 60, 'grace': 140, 'max_age': 90}, {'lots': [[90, 8], [150, 10], [200, 40]], 'total': 58}], ['late cancel grace base', {'redemption': {'day': 20, 'sources': [[25, 70]]}, 'cancel_day': 83, 'grace': 10, 'max_age': 90}, {'lots': [[93, 70]], 'total': 70}]], [['mixed sources', {'redemption': {'day': 100, 'sources': [[94, 300], [150, 200], [400, 100]]}, 'cancel_day': 110, 'grace': 30, 'max_age': 90}, {'lots': [[140, 300], [150, 200], [400, 100]], 'total': 600}], ['expires on cancel day', {'redemption': {'day': 100, 'sources': [[120, 54]]}, 'cancel_day': 120, 'grace': 30, 'max_age': 90}, {'lots': [[120, 54]], 'total': 54}], ['too late', {'redemption': {'day': 10, 'sources': [[500, 100]]}, 'cancel_day': 105, 'grace': 30, 'max_age': 90}, {'error': 'too late'}], ['age edge', {'redemption': {'day': 14, 'sources': [[500, 100], [20, 5]]}, 'cancel_day': 104, 'grace': 14, 'max_age': 90}, {'lots': [[118, 5], [500, 100]], 'total': 105}], ['merge grace lots', {'redemption': {'day': 50, 'sources': [[55, 10], [58, 24], [300, 7]]}, 'cancel_day': 60, 'grace': 45, 'max_age': 90}, {'lots': [[105, 34], [300, 7]], 'total': 41}], ['merge with original', {'redemption': {'day': 50, 'sources': [[200, 40], [150, 10], [90, 9]]}, 'cancel_day': 60, 'grace': 140, 'max_age': 90}, {'lots': [[90, 9], [150, 10], [200, 40]], 'total': 59}], ['late cancel grace base', {'redemption': {'day': 20, 'sources': [[25, 70]]}, 'cancel_day': 84, 'grace': 10, 'max_age': 90}, {'lots': [[94, 70]], 'total': 70}]], [['mixed sources', {'redemption': {'day': 100, 'sources': [[95, 300], [150, 200], [400, 100]]}, 'cancel_day': 110, 'grace': 30, 'max_age': 90}, {'lots': [[140, 300], [150, 200], [400, 100]], 'total': 600}], ['expires on cancel day', {'redemption': {'day': 100, 'sources': [[120, 55]]}, 'cancel_day': 120, 'grace': 30, 'max_age': 90}, {'lots': [[120, 55]], 'total': 55}], ['too late', {'redemption': {'day': 10, 'sources': [[500, 100]]}, 'cancel_day': 106, 'grace': 30, 'max_age': 90}, {'error': 'too late'}], ['age edge', {'redemption': {'day': 15, 'sources': [[500, 100], [20, 5]]}, 'cancel_day': 105, 'grace': 14, 'max_age': 90}, {'lots': [[119, 5], [500, 100]], 'total': 105}], ['merge grace lots', {'redemption': {'day': 50, 'sources': [[55, 10], [58, 25], [300, 7]]}, 'cancel_day': 60, 'grace': 45, 'max_age': 90}, {'lots': [[105, 35], [300, 7]], 'total': 42}], ['merge with original', {'redemption': {'day': 50, 'sources': [[200, 40], [150, 10], [90, 10]]}, 'cancel_day': 60, 'grace': 140, 'max_age': 90}, {'lots': [[90, 10], [150, 10], [200, 40]], 'total': 60}], ['late cancel grace base', {'redemption': {'day': 20, 'sources': [[25, 70]]}, 'cancel_day': 85, 'grace': 10, 'max_age': 90}, {'lots': [[95, 70]], 'total': 70}]]]
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
mixed sources	`{'lots': [[130, 300], [150, 200], [400, 100]], 'total': 600}`	`{'lots': [[140, 300], [150, 200], [400, 100]], 'total': 600}`	Failed
expires on cancel day	`{'lots': [[120, 51]], 'total': 51}`	`{'lots': [[120, 51]], 'total': 51}`	Passed
too late	`{'error': 'too late'}`	`{'error': 'too late'}`	Passed
age edge	`{'lots': [[25, 5], [500, 100]], 'total': 105}`	`{'lots': [[115, 5], [500, 100]], 'total': 105}`	Failed
merge grace lots	`{'lots': [[95, 31], [300, 7]], 'total': 38}`	`{'lots': [[105, 31], [300, 7]], 'total': 38}`	Failed
merge with original	`{'lots': [[90, 6], [150, 10], [200, 40]], 'total': 56}`	`{'lots': [[90, 6], [150, 10], [200, 40]], 'total': 56}`	Passed
late cancel grace base	`{'lots': [[30, 70]], 'total': 70}`	`{'lots': [[91, 70]], 'total': 70}`	Failed

SHA-256 / 576e7e34795baffe013f1d00879a8ec2e494f447f12fe9e148897214fb234863

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 7 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

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 2026-09-29T14:46:47.966978+00:00.

Case digest / 01323e77226780fa6eae5885f2105ef7bf3b8ec7f7c69900ff77ef17b114a392