FA-59606 / Subscription proration billing / Open access

Sequential plan changes within one cycle: same-time collapse · case 01

Two changes submitted in the same second produce two sets of proration lines.

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

ROOT CAUSE

Simultaneous changes are all applied instead of only the last.

VERIFIED REPAIR

Restore the contract rule at the same-time collapse step: use `dedup[-1] = [t, p]`.

Unsuccessful approach: The attempt keeps the first simultaneous change instead of the last.

Case contract

Input {start, end, initial price, changes: [[t, price]]}. Changes are ordered by time; at equal times only the last applies. A change outside [start, end) or to the current price is ignored. Each effective change emits a credit line -(current*(end-t)/span) and a debit line new*(end-t)/span, magnitudes half-up, and the new price becomes current. Return the list of line amounts.

Why this case matters

Customers who change plans several times in a cycle must be credited for the plan they actually had at each change.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(x):
    span = x['end'] - x['start']
    ch = sorted(x['changes'], key=lambda c: c[0])
    dedup = []
    for t, p in ch:
        if dedup and dedup[-1][0] == t:
            dedup.append([t, p])
        else:
            dedup.append([t, p])
    cur = x['initial']
    lines = []
    for t, p in dedup:
        if t < x['start'] or t >= x['end'] or p == cur:
            continue
        left = x['end'] - t
        lines.append(-((cur * left * 2 + span) // (2 * span)))
        lines.append((p * left * 2 + span) // (2 * span))
        cur = p
    return lines
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression', {'start': 983, 'end': 1348, 'initial': 2000, 'changes': [[1164, 5000], [1164, 7000]]}, [-1008, 3529]), ('regression', {'start': 791, 'end': 822, 'initial': 5000, 'changes': [[791, 1000], [806, 3745], [806, 2000]]}, [-5000, 1000, -516, 1032]), ('partial-repair probe', {'start': 3, 'end': 34, 'initial': 5000, 'changes': [[34, 2000], [14, 5000], [14, 2000], [16, 5000]]}, [-3226, 1290, -1161, 2903]), ('partial-repair probe', {'start': 818, 'end': 848, 'initial': 2000, 'changes': [[822, 4662], [848, 5000], [815, 5000], [832, 2000], [832, 7000]]}, [-1733, 4040, -2486, 3733]), ('normal control', {'start': 925, 'end': 955, 'initial': 1000, 'changes': [[940, 1000], [922, 5000]]}, []), ('normal control', {'start': 984, 'end': 1015, 'initial': 2000, 'changes': [[1001, 5000], [1014, 3956], [981, 1000]]}, [-903, 2258, -161, 128]), ('normal control', {'start': 605, 'end': 636, 'initial': 1000, 'changes': [[610, 1000], [625, 5000], [602, 1000], [602, 2000]]}, [-355, 1774]), ('normal control', {'start': 446, 'end': 811, 'initial': 2000, 'changes': [[443, 5000]]}, [])], [('regression', {'start': 791, 'end': 822, 'initial': 5000, 'changes': [[791, 1000], [806, 3745], [806, 2000]]}, [-5000, 1000, -516, 1032]), ('regression', {'start': 818, 'end': 848, 'initial': 2000, 'changes': [[822, 4662], [848, 5000], [815, 5000], [832, 2000], [832, 7000]]}, [-1733, 4040, -2486, 3733]), ('partial-repair probe', {'start': 314, 'end': 345, 'initial': 5000, 'changes': [[345, 5000], [311, 2000], [337, 1000], [340, 768], [340, 7000]]}, [-1290, 258, -161, 1129]), ('partial-repair probe', {'start': 707, 'end': 737, 'initial': 1000, 'changes': [[704, 1000], [716, 3529], [710, 2000], [735, 1000], [735, 2000]]}, [-900, 1800, -1400, 2470, -235, 133]), ('normal control', {'start': 526, 'end': 557, 'initial': 5000, 'changes': []}, []), ('normal control', {'start': 534, 'end': 565, 'initial': 5000, 'changes': [[565, 1007], [565, 1000], [539, 1000], [537, 2000]]}, [-4516, 1806, -1677, 839]), ('normal control', {'start': 670, 'end': 700, 'initial': 2000, 'changes': [[678, 520], [700, 1000], [691, 5000]]}, [-1467, 381, -156, 1500]), ('normal control', {'start': 968, 'end': 1333, 'initial': 1000, 'changes': [[1333, 1000], [965, 5000], [1171, 2000]]}, [-444, 888])], [('regression', {'start': 818, 'end': 848, 'initial': 2000, 'changes': [[822, 4662], [848, 5000], [815, 5000], [832, 2000], [832, 7000]]}, [-1733, 4040, -2486, 3733]), ('regression', {'start': 314, 'end': 345, 'initial': 5000, 'changes': [[345, 5000], [311, 2000], [337, 1000], [340, 768], [340, 7000]]}, [-1290, 258, -161, 1129]), ('partial-repair probe', {'start': 707, 'end': 737, 'initial': 1000, 'changes': [[704, 1000], [716, 3529], [710, 2000], [735, 1000], [735, 2000]]}, [-900, 1800, -1400, 2470, -235, 133]), ('partial-repair probe', {'start': 263, 'end': 293, 'initial': 2000, 'changes': [[283, 3865], [283, 1000]]}, [-667, 333]), ('normal control', {'start': 796, 'end': 827, 'initial': 2000, 'changes': [[819, 2000], [827, 2383], [799, 1000], [827, 1000]]}, [-1806, 903, -258, 516]), ('normal control', {'start': 918, 'end': 948, 'initial': 1000, 'changes': [[920, 4137], [928, 1000], [948, 1000], [948, 7000]]}, [-933, 3861, -2758, 667]), ('normal control', {'start': 198, 'end': 563, 'initial': 1000, 'changes': [[263, 5000], [461, 2011], [195, 5000], [493, 1242]]}, [-822, 4110, -1397, 562, -386, 238]), ('normal control', {'start': 597, 'end': 627, 'initial': 2000, 'changes': [[594, 4502], [594, 7000]]}, [])], [('regression', {'start': 314, 'end': 345, 'initial': 5000, 'changes': [[345, 5000], [311, 2000], [337, 1000], [340, 768], [340, 7000]]}, [-1290, 258, -161, 1129]), ('regression', {'start': 707, 'end': 737, 'initial': 1000, 'changes': [[704, 1000], [716, 3529], [710, 2000], [735, 1000], [735, 2000]]}, [-900, 1800, -1400, 2470, -235, 133]), ('partial-repair probe', {'start': 263, 'end': 293, 'initial': 2000, 'changes': [[283, 3865], [283, 1000]]}, [-667, 333]), ('partial-repair probe', {'start': 268, 'end': 299, 'initial': 2000, 'changes': [[265, 1000], [277, 7070], [277, 1000]]}, [-1419, 710]), ('normal control', {'start': 903, 'end': 1268, 'initial': 1000, 'changes': [[900, 3996]]}, []), ('normal control', {'start': 925, 'end': 956, 'initial': 2000, 'changes': [[935, 95], [925, 5000], [956, 1000], [956, 1000]]}, [-2000, 5000, -3387, 64]), ('normal control', {'start': 382, 'end': 747, 'initial': 2000, 'changes': [[508, 5000]]}, [-1310, 3274]), ('normal control', {'start': 414, 'end': 445, 'initial': 2000, 'changes': [[445, 1000], [434, 1000], [431, 8555]]}, [-903, 3864, -3036, 355])], [('regression', {'start': 707, 'end': 737, 'initial': 1000, 'changes': [[704, 1000], [716, 3529], [710, 2000], [735, 1000], [735, 2000]]}, [-900, 1800, -1400, 2470, -235, 133]), ('regression', {'start': 263, 'end': 293, 'initial': 2000, 'changes': [[283, 3865], [283, 1000]]}, [-667, 333]), ('partial-repair probe', {'start': 140, 'end': 170, 'initial': 2000, 'changes': [[137, 5000], [158, 1000], [157, 2000], [157, 1000]]}, [-867, 433]), ('partial-repair probe', {'start': 479, 'end': 509, 'initial': 2000, 'changes': [[476, 5319], [484, 5000], [505, 5000], [507, 5000], [507, 1000]]}, [-1667, 4167, -333, 67]), ('normal control', {'start': 398, 'end': 429, 'initial': 5000, 'changes': [[429, 4572], [429, 1000]]}, []), ('normal control', {'start': 677, 'end': 1042, 'initial': 5000, 'changes': [[1042, 5000], [1042, 5000]]}, []), ('normal control', {'start': 849, 'end': 879, 'initial': 5000, 'changes': [[879, 7238], [846, 4596], [846, 5000], [863, 2000]]}, [-2667, 1067]), ('normal control', {'start': 358, 'end': 388, 'initial': 5000, 'changes': [[355, 4064], [386, 5000], [373, 2000]]}, [-2500, 1000, -133, 333])]]
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 fixture	Actual	Expected	Outcome
regression 0	`[-1008, 2521, -2521, 3529]`	`[-1008, 3529]`	Failed
regression 1	`[-5000, 1000, -516, 1933, -1933, 1032]`	`[-5000, 1000, -516, 1032]`	Failed
partial-repair probe 2	`[-3226, 1290, -1161, 2903]`	`[-3226, 1290, -1161, 2903]`	Passed
partial-repair probe 3	`[-1733, 4040, -2486, 1067, -1067, 3733]`	`[-1733, 4040, -2486, 3733]`	Failed
normal control 4	`[]`	`[]`	Passed
normal control 5	`[-903, 2258, -161, 128]`	`[-903, 2258, -161, 128]`	Passed
normal control 6	`[-355, 1774]`	`[-355, 1774]`	Passed
normal control 7	`[]`	`[]`	Passed

SHA-256 / f9e2ad8d58e055ef08cfa9d619d4212155e46a39de48eca11bd2ca1cbe96d0ff

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(x):
    span = x['end'] - x['start']
    ch = sorted(x['changes'], key=lambda c: c[0])
    dedup = []
    for t, p in ch:
        if dedup and dedup[-1][0] == t:
            pass
        else:
            dedup.append([t, p])
    cur = x['initial']
    lines = []
    for t, p in dedup:
        if t < x['start'] or t >= x['end'] or p == cur:
            continue
        left = x['end'] - t
        lines.append(-((cur * left * 2 + span) // (2 * span)))
        lines.append((p * left * 2 + span) // (2 * span))
        cur = p
    return lines
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression', {'start': 983, 'end': 1348, 'initial': 2000, 'changes': [[1164, 5000], [1164, 7000]]}, [-1008, 3529]), ('regression', {'start': 791, 'end': 822, 'initial': 5000, 'changes': [[791, 1000], [806, 3745], [806, 2000]]}, [-5000, 1000, -516, 1032]), ('partial-repair probe', {'start': 3, 'end': 34, 'initial': 5000, 'changes': [[34, 2000], [14, 5000], [14, 2000], [16, 5000]]}, [-3226, 1290, -1161, 2903]), ('partial-repair probe', {'start': 818, 'end': 848, 'initial': 2000, 'changes': [[822, 4662], [848, 5000], [815, 5000], [832, 2000], [832, 7000]]}, [-1733, 4040, -2486, 3733]), ('normal control', {'start': 925, 'end': 955, 'initial': 1000, 'changes': [[940, 1000], [922, 5000]]}, []), ('normal control', {'start': 984, 'end': 1015, 'initial': 2000, 'changes': [[1001, 5000], [1014, 3956], [981, 1000]]}, [-903, 2258, -161, 128]), ('normal control', {'start': 605, 'end': 636, 'initial': 1000, 'changes': [[610, 1000], [625, 5000], [602, 1000], [602, 2000]]}, [-355, 1774]), ('normal control', {'start': 446, 'end': 811, 'initial': 2000, 'changes': [[443, 5000]]}, [])], [('regression', {'start': 791, 'end': 822, 'initial': 5000, 'changes': [[791, 1000], [806, 3745], [806, 2000]]}, [-5000, 1000, -516, 1032]), ('regression', {'start': 818, 'end': 848, 'initial': 2000, 'changes': [[822, 4662], [848, 5000], [815, 5000], [832, 2000], [832, 7000]]}, [-1733, 4040, -2486, 3733]), ('partial-repair probe', {'start': 314, 'end': 345, 'initial': 5000, 'changes': [[345, 5000], [311, 2000], [337, 1000], [340, 768], [340, 7000]]}, [-1290, 258, -161, 1129]), ('partial-repair probe', {'start': 707, 'end': 737, 'initial': 1000, 'changes': [[704, 1000], [716, 3529], [710, 2000], [735, 1000], [735, 2000]]}, [-900, 1800, -1400, 2470, -235, 133]), ('normal control', {'start': 526, 'end': 557, 'initial': 5000, 'changes': []}, []), ('normal control', {'start': 534, 'end': 565, 'initial': 5000, 'changes': [[565, 1007], [565, 1000], [539, 1000], [537, 2000]]}, [-4516, 1806, -1677, 839]), ('normal control', {'start': 670, 'end': 700, 'initial': 2000, 'changes': [[678, 520], [700, 1000], [691, 5000]]}, [-1467, 381, -156, 1500]), ('normal control', {'start': 968, 'end': 1333, 'initial': 1000, 'changes': [[1333, 1000], [965, 5000], [1171, 2000]]}, [-444, 888])], [('regression', {'start': 818, 'end': 848, 'initial': 2000, 'changes': [[822, 4662], [848, 5000], [815, 5000], [832, 2000], [832, 7000]]}, [-1733, 4040, -2486, 3733]), ('regression', {'start': 314, 'end': 345, 'initial': 5000, 'changes': [[345, 5000], [311, 2000], [337, 1000], [340, 768], [340, 7000]]}, [-1290, 258, -161, 1129]), ('partial-repair probe', {'start': 707, 'end': 737, 'initial': 1000, 'changes': [[704, 1000], [716, 3529], [710, 2000], [735, 1000], [735, 2000]]}, [-900, 1800, -1400, 2470, -235, 133]), ('partial-repair probe', {'start': 263, 'end': 293, 'initial': 2000, 'changes': [[283, 3865], [283, 1000]]}, [-667, 333]), ('normal control', {'start': 796, 'end': 827, 'initial': 2000, 'changes': [[819, 2000], [827, 2383], [799, 1000], [827, 1000]]}, [-1806, 903, -258, 516]), ('normal control', {'start': 918, 'end': 948, 'initial': 1000, 'changes': [[920, 4137], [928, 1000], [948, 1000], [948, 7000]]}, [-933, 3861, -2758, 667]), ('normal control', {'start': 198, 'end': 563, 'initial': 1000, 'changes': [[263, 5000], [461, 2011], [195, 5000], [493, 1242]]}, [-822, 4110, -1397, 562, -386, 238]), ('normal control', {'start': 597, 'end': 627, 'initial': 2000, 'changes': [[594, 4502], [594, 7000]]}, [])], [('regression', {'start': 314, 'end': 345, 'initial': 5000, 'changes': [[345, 5000], [311, 2000], [337, 1000], [340, 768], [340, 7000]]}, [-1290, 258, -161, 1129]), ('regression', {'start': 707, 'end': 737, 'initial': 1000, 'changes': [[704, 1000], [716, 3529], [710, 2000], [735, 1000], [735, 2000]]}, [-900, 1800, -1400, 2470, -235, 133]), ('partial-repair probe', {'start': 263, 'end': 293, 'initial': 2000, 'changes': [[283, 3865], [283, 1000]]}, [-667, 333]), ('partial-repair probe', {'start': 268, 'end': 299, 'initial': 2000, 'changes': [[265, 1000], [277, 7070], [277, 1000]]}, [-1419, 710]), ('normal control', {'start': 903, 'end': 1268, 'initial': 1000, 'changes': [[900, 3996]]}, []), ('normal control', {'start': 925, 'end': 956, 'initial': 2000, 'changes': [[935, 95], [925, 5000], [956, 1000], [956, 1000]]}, [-2000, 5000, -3387, 64]), ('normal control', {'start': 382, 'end': 747, 'initial': 2000, 'changes': [[508, 5000]]}, [-1310, 3274]), ('normal control', {'start': 414, 'end': 445, 'initial': 2000, 'changes': [[445, 1000], [434, 1000], [431, 8555]]}, [-903, 3864, -3036, 355])], [('regression', {'start': 707, 'end': 737, 'initial': 1000, 'changes': [[704, 1000], [716, 3529], [710, 2000], [735, 1000], [735, 2000]]}, [-900, 1800, -1400, 2470, -235, 133]), ('regression', {'start': 263, 'end': 293, 'initial': 2000, 'changes': [[283, 3865], [283, 1000]]}, [-667, 333]), ('partial-repair probe', {'start': 140, 'end': 170, 'initial': 2000, 'changes': [[137, 5000], [158, 1000], [157, 2000], [157, 1000]]}, [-867, 433]), ('partial-repair probe', {'start': 479, 'end': 509, 'initial': 2000, 'changes': [[476, 5319], [484, 5000], [505, 5000], [507, 5000], [507, 1000]]}, [-1667, 4167, -333, 67]), ('normal control', {'start': 398, 'end': 429, 'initial': 5000, 'changes': [[429, 4572], [429, 1000]]}, []), ('normal control', {'start': 677, 'end': 1042, 'initial': 5000, 'changes': [[1042, 5000], [1042, 5000]]}, []), ('normal control', {'start': 849, 'end': 879, 'initial': 5000, 'changes': [[879, 7238], [846, 4596], [846, 5000], [863, 2000]]}, [-2667, 1067]), ('normal control', {'start': 358, 'end': 388, 'initial': 5000, 'changes': [[355, 4064], [386, 5000], [373, 2000]]}, [-2500, 1000, -133, 333])]]
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 fixture	Actual	Expected	Outcome
regression 0	`[-1008, 2521]`	`[-1008, 3529]`	Failed
regression 1	`[-5000, 1000, -516, 1933]`	`[-5000, 1000, -516, 1032]`	Failed
partial-repair probe 2	`[]`	`[-3226, 1290, -1161, 2903]`	Failed
partial-repair probe 3	`[-1733, 4040, -2486, 1067]`	`[-1733, 4040, -2486, 3733]`	Failed
normal control 4	`[]`	`[]`	Passed
normal control 5	`[-903, 2258, -161, 128]`	`[-903, 2258, -161, 128]`	Passed
normal control 6	`[-355, 1774]`	`[-355, 1774]`	Passed
normal control 7	`[]`	`[]`	Passed

SHA-256 / 058373d8f34a567fe89954b5f8bc9b8af89f94287345c862614df696e729212f

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(x):
    span = x['end'] - x['start']
    ch = sorted(x['changes'], key=lambda c: c[0])
    dedup = []
    for t, p in ch:
        if dedup and dedup[-1][0] == t:
            dedup[-1] = [t, p]
        else:
            dedup.append([t, p])
    cur = x['initial']
    lines = []
    for t, p in dedup:
        if t < x['start'] or t >= x['end'] or p == cur:
            continue
        left = x['end'] - t
        lines.append(-((cur * left * 2 + span) // (2 * span)))
        lines.append((p * left * 2 + span) // (2 * span))
        cur = p
    return lines
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression', {'start': 983, 'end': 1348, 'initial': 2000, 'changes': [[1164, 5000], [1164, 7000]]}, [-1008, 3529]), ('regression', {'start': 791, 'end': 822, 'initial': 5000, 'changes': [[791, 1000], [806, 3745], [806, 2000]]}, [-5000, 1000, -516, 1032]), ('partial-repair probe', {'start': 3, 'end': 34, 'initial': 5000, 'changes': [[34, 2000], [14, 5000], [14, 2000], [16, 5000]]}, [-3226, 1290, -1161, 2903]), ('partial-repair probe', {'start': 818, 'end': 848, 'initial': 2000, 'changes': [[822, 4662], [848, 5000], [815, 5000], [832, 2000], [832, 7000]]}, [-1733, 4040, -2486, 3733]), ('normal control', {'start': 925, 'end': 955, 'initial': 1000, 'changes': [[940, 1000], [922, 5000]]}, []), ('normal control', {'start': 984, 'end': 1015, 'initial': 2000, 'changes': [[1001, 5000], [1014, 3956], [981, 1000]]}, [-903, 2258, -161, 128]), ('normal control', {'start': 605, 'end': 636, 'initial': 1000, 'changes': [[610, 1000], [625, 5000], [602, 1000], [602, 2000]]}, [-355, 1774]), ('normal control', {'start': 446, 'end': 811, 'initial': 2000, 'changes': [[443, 5000]]}, [])], [('regression', {'start': 791, 'end': 822, 'initial': 5000, 'changes': [[791, 1000], [806, 3745], [806, 2000]]}, [-5000, 1000, -516, 1032]), ('regression', {'start': 818, 'end': 848, 'initial': 2000, 'changes': [[822, 4662], [848, 5000], [815, 5000], [832, 2000], [832, 7000]]}, [-1733, 4040, -2486, 3733]), ('partial-repair probe', {'start': 314, 'end': 345, 'initial': 5000, 'changes': [[345, 5000], [311, 2000], [337, 1000], [340, 768], [340, 7000]]}, [-1290, 258, -161, 1129]), ('partial-repair probe', {'start': 707, 'end': 737, 'initial': 1000, 'changes': [[704, 1000], [716, 3529], [710, 2000], [735, 1000], [735, 2000]]}, [-900, 1800, -1400, 2470, -235, 133]), ('normal control', {'start': 526, 'end': 557, 'initial': 5000, 'changes': []}, []), ('normal control', {'start': 534, 'end': 565, 'initial': 5000, 'changes': [[565, 1007], [565, 1000], [539, 1000], [537, 2000]]}, [-4516, 1806, -1677, 839]), ('normal control', {'start': 670, 'end': 700, 'initial': 2000, 'changes': [[678, 520], [700, 1000], [691, 5000]]}, [-1467, 381, -156, 1500]), ('normal control', {'start': 968, 'end': 1333, 'initial': 1000, 'changes': [[1333, 1000], [965, 5000], [1171, 2000]]}, [-444, 888])], [('regression', {'start': 818, 'end': 848, 'initial': 2000, 'changes': [[822, 4662], [848, 5000], [815, 5000], [832, 2000], [832, 7000]]}, [-1733, 4040, -2486, 3733]), ('regression', {'start': 314, 'end': 345, 'initial': 5000, 'changes': [[345, 5000], [311, 2000], [337, 1000], [340, 768], [340, 7000]]}, [-1290, 258, -161, 1129]), ('partial-repair probe', {'start': 707, 'end': 737, 'initial': 1000, 'changes': [[704, 1000], [716, 3529], [710, 2000], [735, 1000], [735, 2000]]}, [-900, 1800, -1400, 2470, -235, 133]), ('partial-repair probe', {'start': 263, 'end': 293, 'initial': 2000, 'changes': [[283, 3865], [283, 1000]]}, [-667, 333]), ('normal control', {'start': 796, 'end': 827, 'initial': 2000, 'changes': [[819, 2000], [827, 2383], [799, 1000], [827, 1000]]}, [-1806, 903, -258, 516]), ('normal control', {'start': 918, 'end': 948, 'initial': 1000, 'changes': [[920, 4137], [928, 1000], [948, 1000], [948, 7000]]}, [-933, 3861, -2758, 667]), ('normal control', {'start': 198, 'end': 563, 'initial': 1000, 'changes': [[263, 5000], [461, 2011], [195, 5000], [493, 1242]]}, [-822, 4110, -1397, 562, -386, 238]), ('normal control', {'start': 597, 'end': 627, 'initial': 2000, 'changes': [[594, 4502], [594, 7000]]}, [])], [('regression', {'start': 314, 'end': 345, 'initial': 5000, 'changes': [[345, 5000], [311, 2000], [337, 1000], [340, 768], [340, 7000]]}, [-1290, 258, -161, 1129]), ('regression', {'start': 707, 'end': 737, 'initial': 1000, 'changes': [[704, 1000], [716, 3529], [710, 2000], [735, 1000], [735, 2000]]}, [-900, 1800, -1400, 2470, -235, 133]), ('partial-repair probe', {'start': 263, 'end': 293, 'initial': 2000, 'changes': [[283, 3865], [283, 1000]]}, [-667, 333]), ('partial-repair probe', {'start': 268, 'end': 299, 'initial': 2000, 'changes': [[265, 1000], [277, 7070], [277, 1000]]}, [-1419, 710]), ('normal control', {'start': 903, 'end': 1268, 'initial': 1000, 'changes': [[900, 3996]]}, []), ('normal control', {'start': 925, 'end': 956, 'initial': 2000, 'changes': [[935, 95], [925, 5000], [956, 1000], [956, 1000]]}, [-2000, 5000, -3387, 64]), ('normal control', {'start': 382, 'end': 747, 'initial': 2000, 'changes': [[508, 5000]]}, [-1310, 3274]), ('normal control', {'start': 414, 'end': 445, 'initial': 2000, 'changes': [[445, 1000], [434, 1000], [431, 8555]]}, [-903, 3864, -3036, 355])], [('regression', {'start': 707, 'end': 737, 'initial': 1000, 'changes': [[704, 1000], [716, 3529], [710, 2000], [735, 1000], [735, 2000]]}, [-900, 1800, -1400, 2470, -235, 133]), ('regression', {'start': 263, 'end': 293, 'initial': 2000, 'changes': [[283, 3865], [283, 1000]]}, [-667, 333]), ('partial-repair probe', {'start': 140, 'end': 170, 'initial': 2000, 'changes': [[137, 5000], [158, 1000], [157, 2000], [157, 1000]]}, [-867, 433]), ('partial-repair probe', {'start': 479, 'end': 509, 'initial': 2000, 'changes': [[476, 5319], [484, 5000], [505, 5000], [507, 5000], [507, 1000]]}, [-1667, 4167, -333, 67]), ('normal control', {'start': 398, 'end': 429, 'initial': 5000, 'changes': [[429, 4572], [429, 1000]]}, []), ('normal control', {'start': 677, 'end': 1042, 'initial': 5000, 'changes': [[1042, 5000], [1042, 5000]]}, []), ('normal control', {'start': 849, 'end': 879, 'initial': 5000, 'changes': [[879, 7238], [846, 4596], [846, 5000], [863, 2000]]}, [-2667, 1067]), ('normal control', {'start': 358, 'end': 388, 'initial': 5000, 'changes': [[355, 4064], [386, 5000], [373, 2000]]}, [-2500, 1000, -133, 333])]]
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 fixture	Actual	Expected	Outcome
regression 0	`[-1008, 3529]`	`[-1008, 3529]`	Passed
regression 1	`[-5000, 1000, -516, 1032]`	`[-5000, 1000, -516, 1032]`	Passed
partial-repair probe 2	`[-3226, 1290, -1161, 2903]`	`[-3226, 1290, -1161, 2903]`	Passed
partial-repair probe 3	`[-1733, 4040, -2486, 3733]`	`[-1733, 4040, -2486, 3733]`	Passed
normal control 4	`[]`	`[]`	Passed
normal control 5	`[-903, 2258, -161, 128]`	`[-903, 2258, -161, 128]`	Passed
normal control 6	`[-355, 1774]`	`[-355, 1774]`	Passed
normal control 7	`[]`	`[]`	Passed

SHA-256 / c8fd27085877bfb2dbd22f85b6d3ca5f98df73a9720f125251f64a27a2b5d152

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 2026-09-29T14:46:37.851529+00:00.

Case digest / 4c30db2d0e97646154c0d5fe73222b38c34fc250b3b111c82a55489d1daf69c2