FAILURE MAP
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FA-93976 / Shift rostering labor rules / Open access

Merged callback restarts a fresh guarantee · case 01

Clustered callbacks are paid a new three-hour minimum each time.

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

ROOT CAUSE

A callback inside an open window extends the window by its own guarantee.

VERIFIED REPAIR

Inside an open window, extend only to the callback's actual end when later.

Unsuccessful approach: Setting the end to the callback end can shrink the window when the callback ends early.

Case contract

Callback work intervals [start, end] and a minimum guarantee in minutes. Sorted by start, each callback that does not start inside the current guarantee window opens a new window from its start to max(end, start + guarantee); a callback starting before the window end extends the window to its own end if later. Return [paid minutes as the sum of window lengths, window count].

Why this case matters

Callback and show-up minimum-pay rules routinely double pay or underpay when callbacks cluster.

1 / The failure

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

N = 1
observations = []
def solve(callbacks, guarantee):
    paid = 0
    windows = 0
    win_start = win_end = None
    for s, e in sorted(callbacks):
        if win_end is not None and s < win_end:
            win_end = max(win_end, s + guarantee)
        else:
            if win_end is not None:
                paid += win_end - win_start
            win_start, win_end = s, max(e, s + guarantee)
            windows += 1
    if win_end is not None:
        paid += win_end - win_start
    return [paid, windows]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: window extension restarts guarantee 1', [[[0, 30], [179, 200]], 180], [200, 1]),
  ('regression variant: window extension restarts guarantee 2', [[[360, 600], [0, 30], [181, 241]], 180],
   [599, 2]),
  ('partial repair guard 3', [[[280, 295], [880, 1120], [100, 340]], 120], [480, 2]),
  ('boundary control 4', [[[0, 240]], 180], [240, 1]),
  ('boundary control 5', [[[0, 30], [180, 200]], 180], [360, 2]),
  ('normal control 6', [[[0, 200], [240, 255]], 240], [480, 2]),
  ('normal control 7', [[[1400, 1520], [1579, 1594], [1758, 1878]], 180], [374, 2]),
  ('normal control 8', [[[2180, 2380], [1400, 1520], [1640, 1700], [1880, 2120]], 240], [960, 4])],
 [('regression: window extension restarts guarantee 1', [[[0, 30], [60, 400]], 180], [400, 1]),
  ('regression variant: window extension restarts guarantee 2', [[[371, 611], [100, 130], [190, 205]], 180],
   [420, 2]),
  ('partial repair guard 3', [[[1580, 1595], [1820, 1835], [1999, 2014], [1400, 1430]], 240], [480, 2]),
  ('boundary control 4', [[], 180], [0, 0]),
  ('normal control 5', [[[1640, 1700], [1730, 1850], [1400, 1520], [1820, 2060]], 120], [540, 2]),
  ('normal control 6', [[[309, 509], [130, 145], [549, 579], [100, 340]], 240], [649, 2]),
  ('normal control 7', [[[2030, 2270], [1400, 1430], [1430, 1550], [2180, 2300]], 180], [450, 2]),
  ('normal control 8', [[[580, 610], [400, 415], [490, 610], [100, 340]], 180], [450, 2])],
 [('regression: window extension restarts guarantee 1',
   [[[1550, 1580], [2180, 2210], [1580, 1780], [1400, 1520]], 120], [470, 3]),
  ('regression variant: window extension restarts guarantee 2', [[[430, 630], [340, 580], [100, 130]], 180],
   [470, 2]),
  ('partial repair guard 3', [[[1400, 1640], [1610, 1850], [1640, 1655], [1430, 1630]], 120], [450, 1]),
  ('boundary control 4', [[[0, 30], [179, 200]], 180], [200, 1]),
  ('boundary control 5', [[[0, 30]], 180], [180, 1]),
  ('normal control 6', [[[0, 15], [90, 290]], 240], [290, 1]),
  ('normal control 7', [[[1400, 1640]], 180], [240, 1]),
  ('normal control 8', [[[100, 220]], 240], [240, 1])],
 [('regression: window extension restarts guarantee 1', [[[1430, 1490], [1400, 1430]], 240], [240, 1]),
  ('regression variant: window extension restarts guarantee 2',
   [[[1671, 1911], [1400, 1415], [1490, 1610], [1701, 1761]], 240], [480, 2]),
  ('partial repair guard 3', [[[130, 370], [100, 340], [309, 369]], 120], [270, 1]),
  ('boundary control 4', [[[300, 330], [0, 30]], 180], [360, 2]),
  ('boundary control 5', [[[0, 240]], 180], [240, 1]),
  ('normal control 6', [[[100, 130], [130, 330], [430, 445]], 180], [410, 2]),
  ('normal control 7', [[[100, 300], [281, 521]], 240], [421, 1]),
  ('normal control 8', [[[0, 120], [150, 210], [450, 690]], 180], [450, 2])],
 [('regression: window extension restarts guarantee 1', [[[1490, 1550], [1400, 1600]], 240], [240, 1]),
  ('regression variant: window extension restarts guarantee 2',
   [[[1400, 1640], [1610, 1850], [1640, 1655], [1430, 1630]], 120], [450, 1]),
  ('partial repair guard 3', [[[250, 265], [100, 115]], 180], [180, 1]),
  ('boundary control 4', [[[0, 30], [180, 200]], 180], [360, 2]), ('boundary control 5', [[], 180], [0, 0]),
  ('normal control 6', [[[100, 300], [250, 265]], 180], [200, 1]),
  ('normal control 7', [[[1000, 1060], [250, 310], [100, 220], [400, 600]], 180], [590, 3]),
  ('normal control 8', [[[0, 120]], 180], [180, 1])]]
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 fixtureActualExpectedOutcome
regression: window extension restarts guarantee 1[359, 1][200, 1]Failed
regression variant: window extension restarts guarantee 2[539, 2][599, 2]Failed
partial repair guard 3[540, 2][480, 2]Failed
boundary control 4[240, 1][240, 1]Passed
boundary control 5[360, 2][360, 2]Passed
normal control 6[480, 2][480, 2]Passed
normal control 7[538, 1][374, 2]Failed
normal control 8[960, 4][960, 4]Passed

SHA-256 / 0031eec2815ac51bf12e329fc2d76457959d1c0b3532ca5d68843dfa74a4ea53

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(callbacks, guarantee):
    paid = 0
    windows = 0
    win_start = win_end = None
    for s, e in sorted(callbacks):
        if win_end is not None and s < win_end:
            win_end = e
        else:
            if win_end is not None:
                paid += win_end - win_start
            win_start, win_end = s, max(e, s + guarantee)
            windows += 1
    if win_end is not None:
        paid += win_end - win_start
    return [paid, windows]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: window extension restarts guarantee 1', [[[0, 30], [179, 200]], 180], [200, 1]),
  ('regression variant: window extension restarts guarantee 2', [[[360, 600], [0, 30], [181, 241]], 180],
   [599, 2]),
  ('partial repair guard 3', [[[280, 295], [880, 1120], [100, 340]], 120], [480, 2]),
  ('boundary control 4', [[[0, 240]], 180], [240, 1]),
  ('boundary control 5', [[[0, 30], [180, 200]], 180], [360, 2]),
  ('normal control 6', [[[0, 200], [240, 255]], 240], [480, 2]),
  ('normal control 7', [[[1400, 1520], [1579, 1594], [1758, 1878]], 180], [374, 2]),
  ('normal control 8', [[[2180, 2380], [1400, 1520], [1640, 1700], [1880, 2120]], 240], [960, 4])],
 [('regression: window extension restarts guarantee 1', [[[0, 30], [60, 400]], 180], [400, 1]),
  ('regression variant: window extension restarts guarantee 2', [[[371, 611], [100, 130], [190, 205]], 180],
   [420, 2]),
  ('partial repair guard 3', [[[1580, 1595], [1820, 1835], [1999, 2014], [1400, 1430]], 240], [480, 2]),
  ('boundary control 4', [[], 180], [0, 0]),
  ('normal control 5', [[[1640, 1700], [1730, 1850], [1400, 1520], [1820, 2060]], 120], [540, 2]),
  ('normal control 6', [[[309, 509], [130, 145], [549, 579], [100, 340]], 240], [649, 2]),
  ('normal control 7', [[[2030, 2270], [1400, 1430], [1430, 1550], [2180, 2300]], 180], [450, 2]),
  ('normal control 8', [[[580, 610], [400, 415], [490, 610], [100, 340]], 180], [450, 2])],
 [('regression: window extension restarts guarantee 1',
   [[[1550, 1580], [2180, 2210], [1580, 1780], [1400, 1520]], 120], [470, 3]),
  ('regression variant: window extension restarts guarantee 2', [[[430, 630], [340, 580], [100, 130]], 180],
   [470, 2]),
  ('partial repair guard 3', [[[1400, 1640], [1610, 1850], [1640, 1655], [1430, 1630]], 120], [450, 1]),
  ('boundary control 4', [[[0, 30], [179, 200]], 180], [200, 1]),
  ('boundary control 5', [[[0, 30]], 180], [180, 1]),
  ('normal control 6', [[[0, 15], [90, 290]], 240], [290, 1]),
  ('normal control 7', [[[1400, 1640]], 180], [240, 1]),
  ('normal control 8', [[[100, 220]], 240], [240, 1])],
 [('regression: window extension restarts guarantee 1', [[[1430, 1490], [1400, 1430]], 240], [240, 1]),
  ('regression variant: window extension restarts guarantee 2',
   [[[1671, 1911], [1400, 1415], [1490, 1610], [1701, 1761]], 240], [480, 2]),
  ('partial repair guard 3', [[[130, 370], [100, 340], [309, 369]], 120], [270, 1]),
  ('boundary control 4', [[[300, 330], [0, 30]], 180], [360, 2]),
  ('boundary control 5', [[[0, 240]], 180], [240, 1]),
  ('normal control 6', [[[100, 130], [130, 330], [430, 445]], 180], [410, 2]),
  ('normal control 7', [[[100, 300], [281, 521]], 240], [421, 1]),
  ('normal control 8', [[[0, 120], [150, 210], [450, 690]], 180], [450, 2])],
 [('regression: window extension restarts guarantee 1', [[[1490, 1550], [1400, 1600]], 240], [240, 1]),
  ('regression variant: window extension restarts guarantee 2',
   [[[1400, 1640], [1610, 1850], [1640, 1655], [1430, 1630]], 120], [450, 1]),
  ('partial repair guard 3', [[[250, 265], [100, 115]], 180], [180, 1]),
  ('boundary control 4', [[[0, 30], [180, 200]], 180], [360, 2]), ('boundary control 5', [[], 180], [0, 0]),
  ('normal control 6', [[[100, 300], [250, 265]], 180], [200, 1]),
  ('normal control 7', [[[1000, 1060], [250, 310], [100, 220], [400, 600]], 180], [590, 3]),
  ('normal control 8', [[[0, 120]], 180], [180, 1])]]
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 fixtureActualExpectedOutcome
regression: window extension restarts guarantee 1[200, 1][200, 1]Passed
regression variant: window extension restarts guarantee 2[599, 2][599, 2]Passed
partial repair guard 3[435, 2][480, 2]Failed
boundary control 4[240, 1][240, 1]Passed
boundary control 5[360, 2][360, 2]Passed
normal control 6[480, 2][480, 2]Passed
normal control 7[374, 2][374, 2]Passed
normal control 8[960, 4][960, 4]Passed

SHA-256 / 34bc8c8815f5974bb1badff557d32ab0501ecc0d04f4414ad21e1ba667e81141

3 / The verified repair

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

N = 1
observations = []
def solve(callbacks, guarantee):
    paid = 0
    windows = 0
    win_start = win_end = None
    for s, e in sorted(callbacks):
        if win_end is not None and s < win_end:
            win_end = max(win_end, e)
        else:
            if win_end is not None:
                paid += win_end - win_start
            win_start, win_end = s, max(e, s + guarantee)
            windows += 1
    if win_end is not None:
        paid += win_end - win_start
    return [paid, windows]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: window extension restarts guarantee 1', [[[0, 30], [179, 200]], 180], [200, 1]),
  ('regression variant: window extension restarts guarantee 2', [[[360, 600], [0, 30], [181, 241]], 180],
   [599, 2]),
  ('partial repair guard 3', [[[280, 295], [880, 1120], [100, 340]], 120], [480, 2]),
  ('boundary control 4', [[[0, 240]], 180], [240, 1]),
  ('boundary control 5', [[[0, 30], [180, 200]], 180], [360, 2]),
  ('normal control 6', [[[0, 200], [240, 255]], 240], [480, 2]),
  ('normal control 7', [[[1400, 1520], [1579, 1594], [1758, 1878]], 180], [374, 2]),
  ('normal control 8', [[[2180, 2380], [1400, 1520], [1640, 1700], [1880, 2120]], 240], [960, 4])],
 [('regression: window extension restarts guarantee 1', [[[0, 30], [60, 400]], 180], [400, 1]),
  ('regression variant: window extension restarts guarantee 2', [[[371, 611], [100, 130], [190, 205]], 180],
   [420, 2]),
  ('partial repair guard 3', [[[1580, 1595], [1820, 1835], [1999, 2014], [1400, 1430]], 240], [480, 2]),
  ('boundary control 4', [[], 180], [0, 0]),
  ('normal control 5', [[[1640, 1700], [1730, 1850], [1400, 1520], [1820, 2060]], 120], [540, 2]),
  ('normal control 6', [[[309, 509], [130, 145], [549, 579], [100, 340]], 240], [649, 2]),
  ('normal control 7', [[[2030, 2270], [1400, 1430], [1430, 1550], [2180, 2300]], 180], [450, 2]),
  ('normal control 8', [[[580, 610], [400, 415], [490, 610], [100, 340]], 180], [450, 2])],
 [('regression: window extension restarts guarantee 1',
   [[[1550, 1580], [2180, 2210], [1580, 1780], [1400, 1520]], 120], [470, 3]),
  ('regression variant: window extension restarts guarantee 2', [[[430, 630], [340, 580], [100, 130]], 180],
   [470, 2]),
  ('partial repair guard 3', [[[1400, 1640], [1610, 1850], [1640, 1655], [1430, 1630]], 120], [450, 1]),
  ('boundary control 4', [[[0, 30], [179, 200]], 180], [200, 1]),
  ('boundary control 5', [[[0, 30]], 180], [180, 1]),
  ('normal control 6', [[[0, 15], [90, 290]], 240], [290, 1]),
  ('normal control 7', [[[1400, 1640]], 180], [240, 1]),
  ('normal control 8', [[[100, 220]], 240], [240, 1])],
 [('regression: window extension restarts guarantee 1', [[[1430, 1490], [1400, 1430]], 240], [240, 1]),
  ('regression variant: window extension restarts guarantee 2',
   [[[1671, 1911], [1400, 1415], [1490, 1610], [1701, 1761]], 240], [480, 2]),
  ('partial repair guard 3', [[[130, 370], [100, 340], [309, 369]], 120], [270, 1]),
  ('boundary control 4', [[[300, 330], [0, 30]], 180], [360, 2]),
  ('boundary control 5', [[[0, 240]], 180], [240, 1]),
  ('normal control 6', [[[100, 130], [130, 330], [430, 445]], 180], [410, 2]),
  ('normal control 7', [[[100, 300], [281, 521]], 240], [421, 1]),
  ('normal control 8', [[[0, 120], [150, 210], [450, 690]], 180], [450, 2])],
 [('regression: window extension restarts guarantee 1', [[[1490, 1550], [1400, 1600]], 240], [240, 1]),
  ('regression variant: window extension restarts guarantee 2',
   [[[1400, 1640], [1610, 1850], [1640, 1655], [1430, 1630]], 120], [450, 1]),
  ('partial repair guard 3', [[[250, 265], [100, 115]], 180], [180, 1]),
  ('boundary control 4', [[[0, 30], [180, 200]], 180], [360, 2]), ('boundary control 5', [[], 180], [0, 0]),
  ('normal control 6', [[[100, 300], [250, 265]], 180], [200, 1]),
  ('normal control 7', [[[1000, 1060], [250, 310], [100, 220], [400, 600]], 180], [590, 3]),
  ('normal control 8', [[[0, 120]], 180], [180, 1])]]
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 fixtureActualExpectedOutcome
regression: window extension restarts guarantee 1[200, 1][200, 1]Passed
regression variant: window extension restarts guarantee 2[599, 2][599, 2]Passed
partial repair guard 3[480, 2][480, 2]Passed
boundary control 4[240, 1][240, 1]Passed
boundary control 5[360, 2][360, 2]Passed
normal control 6[480, 2][480, 2]Passed
normal control 7[374, 2][374, 2]Passed
normal control 8[960, 4][960, 4]Passed

SHA-256 / 4a80fca1b2ef877f06fc536bba1df52ff43ea20be75a1bdae8ee64a8abbdb409

Verification & scope

Stipulated toy labor rule for a bounded roster model; it is not legal advice and does not claim conformance with any jurisdiction, award, or collective agreement. 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 2026-09-29T14:52:00.032662+00:00.

Case digest / f3833c06c5ec33fee263f25c6b698aa655e8d65ac32021af0f9737265f3113ea