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FA-73446 / Rate limiter algorithms / Open access

Sliding-window log limiter: retry hint is always the full window · case 01

Clients back off longer than necessary.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The retry hint is the full window length instead of the time until the oldest entry expires.

THE FAILURE

The retry hint is the full window length instead of the time until the oldest entry expires.

Unsuccessful approach: Using the newest entry overstates the wait whenever more than one entry is logged.

Case contract

Input {limit, window_ms, requests [t]}. The limiter clock is now = max of all timestamps seen, so a late request is evaluated at now. Log entries with s <= now - W are pruned. Allow while fewer than limit entries remain and log now; denials are not logged and report retry = oldest + W - now. Return [[decision, retry]], final log].

Why this case matters

Sliding logs give exact rolling-window limits for login attempts and expensive endpoints; pruning and logging rules decide exactly when a client may retry.

1 / The failure

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

N = 1
observations = []
def solve(x):
    L = x['limit']
    W = x['window_ms']
    log = []
    now = None
    out = []
    for t in x['requests']:
        now = t if now is None else max(now, t)
        log = [s for s in log if s > now - W]
        if len(log) < L:
            log.append(now)
            out.append(['allow', 0])
        else:
            out.append(['deny', W])
    return [out, log]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[['exact expiry boundary',
   {'limit': 2, 'requests': [0, 10, 1000, 1011, 1012], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 988]], [1000, 1011]]],
  ['denied requests not logged',
   {'limit': 2, 'requests': [0, 100, 200, 300, 1051, 1150], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['deny', 800], ['deny', 700], ['allow', 0], ['allow', 0]],
    [1051, 1150]]],
  ['late timestamp uses monotonic now',
   {'limit': 2, 'requests': [400, 450, 101, 900, 905, 960], 'window_ms': 500},
   [[['allow', 0], ['allow', 0], ['deny', 450], ['allow', 0], ['deny', 45], ['allow', 0]],
    [900, 960]]],
  ['retry after oldest expires',
   {'limit': 3, 'requests': [0, 300, 600, 701, 999, 1000, 1001], 'window_ms': 1000},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 299],
     ['deny', 1],
     ['allow', 0],
     ['deny', 299]],
    [300, 600, 1000]]],
  ['random traffic',
   {'limit': 3,
    'requests': [737, 924, 1194, 1231, 1362, 1408, 1509, 1520, 1559, 1643, 1776, 2570],
    'window_ms': 800},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 306],
     ['deny', 175],
     ['deny', 129],
     ['deny', 28],
     ['deny', 17],
     ['allow', 0],
     ['deny', 81],
     ['allow', 0],
     ['allow', 0]],
    [1776, 2570]]],
  ['single slot',
   {'limit': 1, 'requests': [0, 50, 100, 151, 251], 'window_ms': 100},
   [[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 49], ['allow', 0]], [251]]]],
 [['exact expiry boundary',
   {'limit': 2, 'requests': [0, 10, 1000, 1012, 1013], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 987]], [1000, 1012]]],
  ['denied requests not logged',
   {'limit': 2, 'requests': [0, 100, 200, 300, 1052, 1150], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['deny', 800], ['deny', 700], ['allow', 0], ['allow', 0]],
    [1052, 1150]]],
  ['late timestamp uses monotonic now',
   {'limit': 2, 'requests': [400, 450, 102, 900, 905, 960], 'window_ms': 500},
   [[['allow', 0], ['allow', 0], ['deny', 450], ['allow', 0], ['deny', 45], ['allow', 0]],
    [900, 960]]],
  ['retry after oldest expires',
   {'limit': 3, 'requests': [0, 300, 600, 702, 999, 1000, 1001], 'window_ms': 1000},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 298],
     ['deny', 1],
     ['allow', 0],
     ['deny', 299]],
    [300, 600, 1000]]],
  ['random traffic',
   {'limit': 3,
    'requests': [203, 368, 954, 964, 1092, 1537, 1711, 1845, 1983, 2392, 2599, 2816],
    'window_ms': 800},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 39],
     ['allow', 0],
     ['allow', 0],
     ['deny', 43],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 46],
     ['allow', 0]],
    [2392, 2816]]],
  ['single slot',
   {'limit': 1, 'requests': [0, 50, 100, 152, 252], 'window_ms': 100},
   [[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 48], ['allow', 0]], [252]]]],
 [['exact expiry boundary',
   {'limit': 2, 'requests': [0, 10, 1000, 1013, 1014], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 986]], [1000, 1013]]],
  ['denied requests not logged',
   {'limit': 2, 'requests': [0, 100, 200, 300, 1053, 1150], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['deny', 800], ['deny', 700], ['allow', 0], ['allow', 0]],
    [1053, 1150]]],
  ['late timestamp uses monotonic now',
   {'limit': 2, 'requests': [400, 450, 103, 900, 905, 960], 'window_ms': 500},
   [[['allow', 0], ['allow', 0], ['deny', 450], ['allow', 0], ['deny', 45], ['allow', 0]],
    [900, 960]]],
  ['retry after oldest expires',
   {'limit': 3, 'requests': [0, 300, 600, 703, 999, 1000, 1001], 'window_ms': 1000},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 297],
     ['deny', 1],
     ['allow', 0],
     ['deny', 299]],
    [300, 600, 1000]]],
  ['random traffic',
   {'limit': 3,
    'requests': [659, 794, 1414, 1446, 1627, 2009, 2196, 2262, 2536, 2557, 2734, 2819],
    'window_ms': 800},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 13],
     ['allow', 0],
     ['allow', 0],
     ['deny', 18],
     ['allow', 0],
     ['allow', 0],
     ['deny', 252],
     ['deny', 75],
     ['allow', 0]],
    [2262, 2536, 2819]]],
  ['single slot',
   {'limit': 1, 'requests': [0, 50, 100, 153, 253], 'window_ms': 100},
   [[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 47], ['allow', 0]], [253]]]],
 [['exact expiry boundary',
   {'limit': 2, 'requests': [0, 10, 1000, 1014, 1015], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 985]], [1000, 1014]]],
  ['denied requests not logged',
   {'limit': 2, 'requests': [0, 100, 200, 300, 1054, 1150], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['deny', 800], ['deny', 700], ['allow', 0], ['allow', 0]],
    [1054, 1150]]],
  ['late timestamp uses monotonic now',
   {'limit': 2, 'requests': [400, 450, 104, 900, 905, 960], 'window_ms': 500},
   [[['allow', 0], ['allow', 0], ['deny', 450], ['allow', 0], ['deny', 45], ['allow', 0]],
    [900, 960]]],
  ['retry after oldest expires',
   {'limit': 3, 'requests': [0, 300, 600, 704, 999, 1000, 1001], 'window_ms': 1000},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 296],
     ['deny', 1],
     ['allow', 0],
     ['deny', 299]],
    [300, 600, 1000]]],
  ['random traffic',
   {'limit': 3,
    'requests': [81, 344, 553, 1450, 1591, 1736, 1934, 2492, 2556, 2664, 2677, 2831],
    'window_ms': 800},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 316],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 615],
     ['deny', 461]],
    [2492, 2556, 2664]]],
  ['single slot',
   {'limit': 1, 'requests': [0, 50, 100, 154, 254], 'window_ms': 100},
   [[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 46], ['allow', 0]], [254]]]],
 [['exact expiry boundary',
   {'limit': 2, 'requests': [0, 10, 1000, 1015, 1016], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 984]], [1000, 1015]]],
  ['denied requests not logged',
   {'limit': 2, 'requests': [0, 100, 200, 300, 1055, 1150], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['deny', 800], ['deny', 700], ['allow', 0], ['allow', 0]],
    [1055, 1150]]],
  ['late timestamp uses monotonic now',
   {'limit': 2, 'requests': [400, 450, 105, 900, 905, 960], 'window_ms': 500},
   [[['allow', 0], ['allow', 0], ['deny', 450], ['allow', 0], ['deny', 45], ['allow', 0]],
    [900, 960]]],
  ['retry after oldest expires',
   {'limit': 3, 'requests': [0, 300, 600, 705, 999, 1000, 1001], 'window_ms': 1000},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 295],
     ['deny', 1],
     ['allow', 0],
     ['deny', 299]],
    [300, 600, 1000]]],
  ['random traffic',
   {'limit': 3,
    'requests': [85, 117, 140, 309, 683, 1093, 2036, 2231, 2349, 2416, 2706, 2868],
    'window_ms': 800},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 576],
     ['deny', 202],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 420],
     ['deny', 130],
     ['allow', 0]],
    [2231, 2349, 2868]]],
  ['single slot',
   {'limit': 1, 'requests': [0, 50, 100, 155, 255], 'window_ms': 100},
   [[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 45], ['allow', 0]], [255]]]]]
for label, args, expected in cases[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 fixtureActualExpectedOutcome
exact expiry boundary[[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 1000]], [1000, 1011]][[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 988]], [1000, 1011]]Failed
denied requests not logged[[['allow', 0], ['allow', 0], ['deny', 1000], ['deny', 1000], ['allow', 0], ['allow', 0]], [1051, 1150]][[['allow', 0], ['allow', 0], ['deny', 800], ['deny', 700], ['allow', 0], ['allow', 0]], [1051, 1150]]Failed
late timestamp uses monotonic now[[['allow', 0], ['allow', 0], ['deny', 500], ['allow', 0], ['deny', 500], ['allow', 0]], [900, 960]][[['allow', 0], ['allow', 0], ['deny', 450], ['allow', 0], ['deny', 45], ['allow', 0]], [900, 960]]Failed
retry after oldest expires[[['allow', 0], ['allow', 0], ['allow', 0], ['deny', 1000], ['deny', 1000], ['allow', 0], ['deny', 1000]], [300, 600, 1000]][[['allow', 0], ['allow', 0], ['allow', 0], ['deny', 299], ['deny', 1], ['allow', 0], ['deny', 299]], [300, 600, 1000]]Failed
random traffic[[['allow', 0], ['allow', 0], ['allow', 0], ['deny', 800], ['deny', 800], ['deny', 800], ['deny', 800], ['deny', 800], ['allow', 0], ['deny', 800], ['allow', 0], ['allow', 0]], [1776, 2570]][[['allow', 0], ['allow', 0], ['allow', 0], ['deny', 306], ['deny', 175], ['deny', 129], ['deny', 28], ['deny', 17], ['allow', 0], ['deny', 81], ['allow', 0], ['allow', 0]], [1776, 2570]]Failed
single slot[[['allow', 0], ['deny', 100], ['allow', 0], ['deny', 100], ['allow', 0]], [251]][[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 49], ['allow', 0]], [251]]Failed

SHA-256 / ac62511074add25b80be8a392c26e30af3fc1d972fa2873a468e34233a672ce9

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(x):
    L = x['limit']
    W = x['window_ms']
    log = []
    now = None
    out = []
    for t in x['requests']:
        now = t if now is None else max(now, t)
        log = [s for s in log if s > now - W]
        if len(log) < L:
            log.append(now)
            out.append(['allow', 0])
        else:
            out.append(['deny', log[-1] + W - now])
    return [out, log]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[['exact expiry boundary',
   {'limit': 2, 'requests': [0, 10, 1000, 1011, 1012], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 988]], [1000, 1011]]],
  ['denied requests not logged',
   {'limit': 2, 'requests': [0, 100, 200, 300, 1051, 1150], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['deny', 800], ['deny', 700], ['allow', 0], ['allow', 0]],
    [1051, 1150]]],
  ['late timestamp uses monotonic now',
   {'limit': 2, 'requests': [400, 450, 101, 900, 905, 960], 'window_ms': 500},
   [[['allow', 0], ['allow', 0], ['deny', 450], ['allow', 0], ['deny', 45], ['allow', 0]],
    [900, 960]]],
  ['retry after oldest expires',
   {'limit': 3, 'requests': [0, 300, 600, 701, 999, 1000, 1001], 'window_ms': 1000},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 299],
     ['deny', 1],
     ['allow', 0],
     ['deny', 299]],
    [300, 600, 1000]]],
  ['random traffic',
   {'limit': 3,
    'requests': [737, 924, 1194, 1231, 1362, 1408, 1509, 1520, 1559, 1643, 1776, 2570],
    'window_ms': 800},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 306],
     ['deny', 175],
     ['deny', 129],
     ['deny', 28],
     ['deny', 17],
     ['allow', 0],
     ['deny', 81],
     ['allow', 0],
     ['allow', 0]],
    [1776, 2570]]],
  ['single slot',
   {'limit': 1, 'requests': [0, 50, 100, 151, 251], 'window_ms': 100},
   [[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 49], ['allow', 0]], [251]]]],
 [['exact expiry boundary',
   {'limit': 2, 'requests': [0, 10, 1000, 1012, 1013], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 987]], [1000, 1012]]],
  ['denied requests not logged',
   {'limit': 2, 'requests': [0, 100, 200, 300, 1052, 1150], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['deny', 800], ['deny', 700], ['allow', 0], ['allow', 0]],
    [1052, 1150]]],
  ['late timestamp uses monotonic now',
   {'limit': 2, 'requests': [400, 450, 102, 900, 905, 960], 'window_ms': 500},
   [[['allow', 0], ['allow', 0], ['deny', 450], ['allow', 0], ['deny', 45], ['allow', 0]],
    [900, 960]]],
  ['retry after oldest expires',
   {'limit': 3, 'requests': [0, 300, 600, 702, 999, 1000, 1001], 'window_ms': 1000},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 298],
     ['deny', 1],
     ['allow', 0],
     ['deny', 299]],
    [300, 600, 1000]]],
  ['random traffic',
   {'limit': 3,
    'requests': [203, 368, 954, 964, 1092, 1537, 1711, 1845, 1983, 2392, 2599, 2816],
    'window_ms': 800},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 39],
     ['allow', 0],
     ['allow', 0],
     ['deny', 43],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 46],
     ['allow', 0]],
    [2392, 2816]]],
  ['single slot',
   {'limit': 1, 'requests': [0, 50, 100, 152, 252], 'window_ms': 100},
   [[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 48], ['allow', 0]], [252]]]],
 [['exact expiry boundary',
   {'limit': 2, 'requests': [0, 10, 1000, 1013, 1014], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 986]], [1000, 1013]]],
  ['denied requests not logged',
   {'limit': 2, 'requests': [0, 100, 200, 300, 1053, 1150], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['deny', 800], ['deny', 700], ['allow', 0], ['allow', 0]],
    [1053, 1150]]],
  ['late timestamp uses monotonic now',
   {'limit': 2, 'requests': [400, 450, 103, 900, 905, 960], 'window_ms': 500},
   [[['allow', 0], ['allow', 0], ['deny', 450], ['allow', 0], ['deny', 45], ['allow', 0]],
    [900, 960]]],
  ['retry after oldest expires',
   {'limit': 3, 'requests': [0, 300, 600, 703, 999, 1000, 1001], 'window_ms': 1000},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 297],
     ['deny', 1],
     ['allow', 0],
     ['deny', 299]],
    [300, 600, 1000]]],
  ['random traffic',
   {'limit': 3,
    'requests': [659, 794, 1414, 1446, 1627, 2009, 2196, 2262, 2536, 2557, 2734, 2819],
    'window_ms': 800},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 13],
     ['allow', 0],
     ['allow', 0],
     ['deny', 18],
     ['allow', 0],
     ['allow', 0],
     ['deny', 252],
     ['deny', 75],
     ['allow', 0]],
    [2262, 2536, 2819]]],
  ['single slot',
   {'limit': 1, 'requests': [0, 50, 100, 153, 253], 'window_ms': 100},
   [[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 47], ['allow', 0]], [253]]]],
 [['exact expiry boundary',
   {'limit': 2, 'requests': [0, 10, 1000, 1014, 1015], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 985]], [1000, 1014]]],
  ['denied requests not logged',
   {'limit': 2, 'requests': [0, 100, 200, 300, 1054, 1150], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['deny', 800], ['deny', 700], ['allow', 0], ['allow', 0]],
    [1054, 1150]]],
  ['late timestamp uses monotonic now',
   {'limit': 2, 'requests': [400, 450, 104, 900, 905, 960], 'window_ms': 500},
   [[['allow', 0], ['allow', 0], ['deny', 450], ['allow', 0], ['deny', 45], ['allow', 0]],
    [900, 960]]],
  ['retry after oldest expires',
   {'limit': 3, 'requests': [0, 300, 600, 704, 999, 1000, 1001], 'window_ms': 1000},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 296],
     ['deny', 1],
     ['allow', 0],
     ['deny', 299]],
    [300, 600, 1000]]],
  ['random traffic',
   {'limit': 3,
    'requests': [81, 344, 553, 1450, 1591, 1736, 1934, 2492, 2556, 2664, 2677, 2831],
    'window_ms': 800},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 316],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 615],
     ['deny', 461]],
    [2492, 2556, 2664]]],
  ['single slot',
   {'limit': 1, 'requests': [0, 50, 100, 154, 254], 'window_ms': 100},
   [[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 46], ['allow', 0]], [254]]]],
 [['exact expiry boundary',
   {'limit': 2, 'requests': [0, 10, 1000, 1015, 1016], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 984]], [1000, 1015]]],
  ['denied requests not logged',
   {'limit': 2, 'requests': [0, 100, 200, 300, 1055, 1150], 'window_ms': 1000},
   [[['allow', 0], ['allow', 0], ['deny', 800], ['deny', 700], ['allow', 0], ['allow', 0]],
    [1055, 1150]]],
  ['late timestamp uses monotonic now',
   {'limit': 2, 'requests': [400, 450, 105, 900, 905, 960], 'window_ms': 500},
   [[['allow', 0], ['allow', 0], ['deny', 450], ['allow', 0], ['deny', 45], ['allow', 0]],
    [900, 960]]],
  ['retry after oldest expires',
   {'limit': 3, 'requests': [0, 300, 600, 705, 999, 1000, 1001], 'window_ms': 1000},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 295],
     ['deny', 1],
     ['allow', 0],
     ['deny', 299]],
    [300, 600, 1000]]],
  ['random traffic',
   {'limit': 3,
    'requests': [85, 117, 140, 309, 683, 1093, 2036, 2231, 2349, 2416, 2706, 2868],
    'window_ms': 800},
   [[['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 576],
     ['deny', 202],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['allow', 0],
     ['deny', 420],
     ['deny', 130],
     ['allow', 0]],
    [2231, 2349, 2868]]],
  ['single slot',
   {'limit': 1, 'requests': [0, 50, 100, 155, 255], 'window_ms': 100},
   [[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 45], ['allow', 0]], [255]]]]]
for label, args, expected in cases[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 fixtureActualExpectedOutcome
exact expiry boundary[[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 999]], [1000, 1011]][[['allow', 0], ['allow', 0], ['allow', 0], ['allow', 0], ['deny', 988]], [1000, 1011]]Failed
denied requests not logged[[['allow', 0], ['allow', 0], ['deny', 900], ['deny', 800], ['allow', 0], ['allow', 0]], [1051, 1150]][[['allow', 0], ['allow', 0], ['deny', 800], ['deny', 700], ['allow', 0], ['allow', 0]], [1051, 1150]]Failed
late timestamp uses monotonic now[[['allow', 0], ['allow', 0], ['deny', 500], ['allow', 0], ['deny', 495], ['allow', 0]], [900, 960]][[['allow', 0], ['allow', 0], ['deny', 450], ['allow', 0], ['deny', 45], ['allow', 0]], [900, 960]]Failed
retry after oldest expires[[['allow', 0], ['allow', 0], ['allow', 0], ['deny', 899], ['deny', 601], ['allow', 0], ['deny', 999]], [300, 600, 1000]][[['allow', 0], ['allow', 0], ['allow', 0], ['deny', 299], ['deny', 1], ['allow', 0], ['deny', 299]], [300, 600, 1000]]Failed
random traffic[[['allow', 0], ['allow', 0], ['allow', 0], ['deny', 763], ['deny', 632], ['deny', 586], ['deny', 485], ['deny', 474], ['allow', 0], ['deny', 716], ['allow', 0], ['allow', 0]], [1776, 2570]][[['allow', 0], ['allow', 0], ['allow', 0], ['deny', 306], ['deny', 175], ['deny', 129], ['deny', 28], ['deny', 17], ['allow', 0], ['deny', 81], ['allow', 0], ['allow', 0]], [1776, 2570]]Failed
single slot[[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 49], ['allow', 0]], [251]][[['allow', 0], ['deny', 50], ['allow', 0], ['deny', 49], ['allow', 0]], [251]]Passed

SHA-256 / 06511ae8ab3cb4ec55a73ec32471aba2c2c1d4559e54ce805ee0efc78d421164

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 6 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.

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Verification & scope

A deterministic, bounded teaching model with stipulated constants and pre-hashed or explicitly hashed inputs; it is not a production implementation and makes no claim of conformance to any library or paper beyond the stated contract. 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 2026-09-29T14:48:47.721092+00:00.

Case digest / d22760b6fd1c2aa8e2923c3312efe0a170e99767db3b8374fb249cfa54b4ab9c