FA-77896 / Subtitle cue timing / Open access

Partial subtitle resync from a point: dropped cue test · case 01

A cue that ends exactly at time zero after shifting survives as a zero-length cue.

Verified by executionVariant 1 · 9 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The drop test uses end<0, keeping cues whose shifted end is exactly zero.

VERIFIED REPAIR

Drop cues whose shifted end is at or before zero.

Unsuccessful approach: Testing for a non-positive duration before clamping never fires for shifted cues, keeping cues entirely before zero.

Case contract

Cues [start,end,text] (sorted by start) whose start is at or after from_ms are shifted by offset ms (start and end). A cue whose end becomes <= 0 is dropped; a negative start is clamped to 0 without moving its end. The result is re-sorted by (start,end) and numbered from 1 as [n,start,end,text].

Why this case matters

Subtitle timing defects shift, hide or overlap captions that viewers depend on for comprehension and accessibility.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(cues, offset, from_ms):
    out=[]
    for start,end,text in cues:
        if start>=from_ms:
            start+=offset
            end+=offset
        if end<0:
            continue
        if start<0:
            start=0
        out.append([start,end,text])
    out.sort(key=lambda c:(c[0],c[1]))
    return [[i+1]+c for i,c in enumerate(out)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: dropped cue test', [[[400, 1200, 'e']], -1200, 0], []), ('regression variant: dropped cue test', [[[1500, 3000, 'b'], [1500, 2300, 'a']], -3000, 0], []), ('partial repair probe: dropped cue test', [[[2050, 2850, 'c'], [2550, 4050, 'e'], [3000, 3001, 'c'], [4950, 5750, 'a']], -3000, 2050], [[1, 0, 1, 'c'], [2, 0, 1050, 'e'], [3, 1950, 2750, 'a']]), ('partial repair variant: dropped cue test', [[[800, 1000, 'a'], [2300, 2500, 'd'], [4100, 5600, 'e'], [4300, 5800, 'e']], -3000, 0], [[1, 1100, 2600, 'e'], [2, 1300, 2800, 'e']]), ('boundary control', [[[1000, 2000, 'a'], [3000, 4000, 'b']], -1500, 0], [[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]), ('boundary control', [[[0, 500, 'a'], [600, 900, 'b']], -500, 600], [[1, 0, 500, 'a'], [2, 100, 400, 'b']]), ('normal control', [[[100, 200, 'x']], 50, 100], [[1, 150, 250, 'x']]), ('normal control', [[[150, 151, 'd'], [200, 400, 'e']], 1000, 3319], [[1, 150, 151, 'd'], [2, 200, 400, 'e']]), ('normal control', [[[2500, 5500, 'e']], 4000, 2500], [[1, 6500, 9500, 'e']])], [('regression: dropped cue test', [[[100, 300, 'd'], [800, 2300, 'd'], [3300, 6300, 'c'], [3500, 6500, 'e'], [3700, 6700, 'e']], -300, 100], [[1, 500, 2000, 'd'], [2, 3000, 6000, 'c'], [3, 3200, 6200, 'e'], [4, 3400, 6400, 'e']]), ('regression variant: dropped cue test', [[[400, 1200, 'e']], -1200, 0], []), ('partial repair probe: dropped cue test', [[[-300, -299, 'b'], [150, 950, 'b'], [700, 3700, 'e'], [1950, 2750, 'e'], [2450, 5450, 'c']], -800, 5852], [[1, 150, 950, 'b'], [2, 700, 3700, 'e'], [3, 1950, 2750, 'e'], [4, 2450, 5450, 'c']]), ('partial repair variant: dropped cue test', [[[0, 200, 'd']], -1200, 0], []), ('boundary control', [[[0, 500, 'a'], [600, 900, 'b']], -500, 600], [[1, 0, 500, 'a'], [2, 100, 400, 'b']]), ('boundary control', [[[100, 200, 'x']], 50, 100], [[1, 150, 250, 'x']]), ('normal control', [[[400, 401, 'e'], [2900, 3700, 'd'], [5400, 5401, 'd'], [6600, 9600, 'e'], [8600, 8601, 'a']], 250, 1518], [[1, 400, 401, 'e'], [2, 3150, 3950, 'd'], [3, 5650, 5651, 'd'], [4, 6850, 9850, 'e'], [5, 8850, 8851, 'a']]), ('normal control', [[[500, 3500, 'b'], [3000, 4500, 'd'], [4400, 4600, 'a']], -1200, 500], [[1, 0, 2300, 'b'], [2, 1800, 3300, 'd'], [3, 3200, 3400, 'a']]), ('normal control', [[[1100, 1900, 'b'], [2650, 4150, 'c'], [2700, 2900, 'a'], [3100, 3300, 'e']], 4000, 1100], [[1, 5100, 5900, 'b'], [2, 6650, 8150, 'c'], [3, 6700, 6900, 'a'], [4, 7100, 7300, 'e']])], [('regression: dropped cue test', [[[1500, 3000, 'b'], [1500, 2300, 'a']], -3000, 0], []), ('regression variant: dropped cue test', [[[100, 300, 'd'], [800, 2300, 'd'], [3300, 6300, 'c'], [3500, 6500, 'e'], [3700, 6700, 'e']], -300, 100], [[1, 500, 2000, 'd'], [2, 3000, 6000, 'c'], [3, 3200, 6200, 'e'], [4, 3400, 6400, 'e']]), ('partial repair probe: dropped cue test', [[[0, 1500, 'c'], [300, 500, 'b'], [3200, 3201, 'e']], -800, 0], [[1, 0, 700, 'c'], [2, 2400, 2401, 'e']]), ('partial repair variant: dropped cue test', [[[300, 1100, 'c']], -3000, 300], []), ('boundary control', [[[100, 200, 'x']], 50, 100], [[1, 150, 250, 'x']]), ('boundary control', [[[1000, 2000, 'a'], [3000, 4000, 'b']], -1500, 0], [[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]), ('normal control', [[[400, 600, 'c'], [400, 1200, 'd'], [2900, 3100, 'b'], [5100, 5101, 'a']], -3000, 5100], [[1, 400, 600, 'c'], [2, 400, 1200, 'd'], [3, 2100, 2101, 'a'], [4, 2900, 3100, 'b']]), ('normal control', [[[2300, 3800, 'd'], [3550, 6550, 'a'], [4250, 7250, 'e'], [6450, 6650, 'e'], [9350, 10150, 'd']], -3000, 9350], [[1, 2300, 3800, 'd'], [2, 3550, 6550, 'a'], [3, 4250, 7250, 'e'], [4, 6350, 7150, 'd'], [5, 6450, 6650, 'e']]), ('normal control', [[[1100, 1300, 'c'], [3600, 3601, 'c']], -1200, 1100], [[1, 0, 100, 'c'], [2, 2400, 2401, 'c']])], [('regression: dropped cue test', [[[400, 1200, 'e']], -1200, 0], []), ('regression variant: dropped cue test', [[[1500, 3000, 'b'], [1500, 2300, 'a']], -3000, 0], []), ('partial repair probe: dropped cue test', [[[550, 551, 'e']], -3000, 0], []), ('partial repair variant: dropped cue test', [[[1800, 3300, 'e'], [1850, 2050, 'e'], [2000, 2001, 'b'], [4350, 4351, 'd'], [5600, 8600, 'd']], -3000, 0], [[1, 0, 300, 'e'], [2, 1350, 1351, 'd'], [3, 2600, 5600, 'd']]), ('boundary control', [[[1000, 2000, 'a'], [3000, 4000, 'b']], -1500, 0], [[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]), ('boundary control', [[[0, 500, 'a'], [600, 900, 'b']], -500, 600], [[1, 0, 500, 'a'], [2, 100, 400, 'b']]), ('normal control', [[[1000, 1200, 'a']], 250, 0], [[1, 1250, 1450, 'a']]), ('normal control', [[[400, 600, 'a'], [3300, 6300, 'b'], [3600, 4400, 'b']], -300, 0], [[1, 100, 300, 'a'], [2, 3000, 6000, 'b'], [3, 3300, 4100, 'b']]), ('normal control', [[[2500, 3300, 'a'], [4500, 6000, 'd'], [6700, 8200, 'a']], 1000, 0], [[1, 3500, 4300, 'a'], [2, 5500, 7000, 'd'], [3, 7700, 9200, 'a']])], [('regression: dropped cue test', [[[100, 300, 'd'], [800, 2300, 'd'], [3300, 6300, 'c'], [3500, 6500, 'e'], [3700, 6700, 'e']], -300, 100], [[1, 500, 2000, 'd'], [2, 3000, 6000, 'c'], [3, 3200, 6200, 'e'], [4, 3400, 6400, 'e']]), ('regression variant: dropped cue test', [[[400, 1200, 'e']], -1200, 0], []), ('partial repair probe: dropped cue test', [[[2600, 2800, 'a'], [5100, 5900, 'd'], [8600, 8601, 'd'], [8600, 8800, 'b'], [8800, 8801, 'e']], -3000, 2600], [[1, 2100, 2900, 'd'], [2, 5600, 5601, 'd'], [3, 5600, 5800, 'b'], [4, 5800, 5801, 'e']]), ('partial repair variant: dropped cue test', [[[0, 1500, 'c'], [1500, 2300, 'e']], -3000, 1500], [[1, 0, 1500, 'c']]), ('boundary control', [[[0, 500, 'a'], [600, 900, 'b']], -500, 600], [[1, 0, 500, 'a'], [2, 100, 400, 'b']]), ('boundary control', [[[100, 200, 'x']], 50, 100], [[1, 150, 250, 'x']]), ('normal control', [[[2050, 2051, 'c'], [2050, 2250, 'c']], -1200, 1309], [[1, 850, 851, 'c'], [2, 850, 1050, 'c']]), ('normal control', [[[500, 3500, 'c'], [3000, 3800, 'a'], [3050, 6050, 'c'], [3800, 4600, 'd'], [4250, 7250, 'd']], -3000, 6050], [[1, 500, 3500, 'c'], [2, 3000, 3800, 'a'], [3, 3050, 6050, 'c'], [4, 3800, 4600, 'd'], [5, 4250, 7250, 'd']]), ('normal control', [[[3000, 4500, 'c'], [3400, 4900, 'c']], -1200, 3000], [[1, 1800, 3300, 'c'], [2, 2200, 3700, 'c']])]]
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
regression: dropped cue test	`[[1, 0, 0, 'e']]`	`[]`	Failed
regression variant: dropped cue test	`[[1, 0, 0, 'b']]`	`[]`	Failed
partial repair probe: dropped cue test	`[[1, 0, 1, 'c'], [2, 0, 1050, 'e'], [3, 1950, 2750, 'a']]`	`[[1, 0, 1, 'c'], [2, 0, 1050, 'e'], [3, 1950, 2750, 'a']]`	Passed
partial repair variant: dropped cue test	`[[1, 1100, 2600, 'e'], [2, 1300, 2800, 'e']]`	`[[1, 1100, 2600, 'e'], [2, 1300, 2800, 'e']]`	Passed
boundary control	`[[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]`	`[[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]`	Passed
boundary control	`[[1, 0, 500, 'a'], [2, 100, 400, 'b']]`	`[[1, 0, 500, 'a'], [2, 100, 400, 'b']]`	Passed
normal control	`[[1, 150, 250, 'x']]`	`[[1, 150, 250, 'x']]`	Passed
normal control	`[[1, 150, 151, 'd'], [2, 200, 400, 'e']]`	`[[1, 150, 151, 'd'], [2, 200, 400, 'e']]`	Passed
normal control	`[[1, 6500, 9500, 'e']]`	`[[1, 6500, 9500, 'e']]`	Passed

SHA-256 / 39b73b7d40797ed1cae7a9020d2396b8cf5d1c53b6c564622f7e1ce689d085d1

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(cues, offset, from_ms):
    out=[]
    for start,end,text in cues:
        if start>=from_ms:
            start+=offset
            end+=offset
        if end-start<=0:
            continue
        if start<0:
            start=0
        out.append([start,end,text])
    out.sort(key=lambda c:(c[0],c[1]))
    return [[i+1]+c for i,c in enumerate(out)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: dropped cue test', [[[400, 1200, 'e']], -1200, 0], []), ('regression variant: dropped cue test', [[[1500, 3000, 'b'], [1500, 2300, 'a']], -3000, 0], []), ('partial repair probe: dropped cue test', [[[2050, 2850, 'c'], [2550, 4050, 'e'], [3000, 3001, 'c'], [4950, 5750, 'a']], -3000, 2050], [[1, 0, 1, 'c'], [2, 0, 1050, 'e'], [3, 1950, 2750, 'a']]), ('partial repair variant: dropped cue test', [[[800, 1000, 'a'], [2300, 2500, 'd'], [4100, 5600, 'e'], [4300, 5800, 'e']], -3000, 0], [[1, 1100, 2600, 'e'], [2, 1300, 2800, 'e']]), ('boundary control', [[[1000, 2000, 'a'], [3000, 4000, 'b']], -1500, 0], [[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]), ('boundary control', [[[0, 500, 'a'], [600, 900, 'b']], -500, 600], [[1, 0, 500, 'a'], [2, 100, 400, 'b']]), ('normal control', [[[100, 200, 'x']], 50, 100], [[1, 150, 250, 'x']]), ('normal control', [[[150, 151, 'd'], [200, 400, 'e']], 1000, 3319], [[1, 150, 151, 'd'], [2, 200, 400, 'e']]), ('normal control', [[[2500, 5500, 'e']], 4000, 2500], [[1, 6500, 9500, 'e']])], [('regression: dropped cue test', [[[100, 300, 'd'], [800, 2300, 'd'], [3300, 6300, 'c'], [3500, 6500, 'e'], [3700, 6700, 'e']], -300, 100], [[1, 500, 2000, 'd'], [2, 3000, 6000, 'c'], [3, 3200, 6200, 'e'], [4, 3400, 6400, 'e']]), ('regression variant: dropped cue test', [[[400, 1200, 'e']], -1200, 0], []), ('partial repair probe: dropped cue test', [[[-300, -299, 'b'], [150, 950, 'b'], [700, 3700, 'e'], [1950, 2750, 'e'], [2450, 5450, 'c']], -800, 5852], [[1, 150, 950, 'b'], [2, 700, 3700, 'e'], [3, 1950, 2750, 'e'], [4, 2450, 5450, 'c']]), ('partial repair variant: dropped cue test', [[[0, 200, 'd']], -1200, 0], []), ('boundary control', [[[0, 500, 'a'], [600, 900, 'b']], -500, 600], [[1, 0, 500, 'a'], [2, 100, 400, 'b']]), ('boundary control', [[[100, 200, 'x']], 50, 100], [[1, 150, 250, 'x']]), ('normal control', [[[400, 401, 'e'], [2900, 3700, 'd'], [5400, 5401, 'd'], [6600, 9600, 'e'], [8600, 8601, 'a']], 250, 1518], [[1, 400, 401, 'e'], [2, 3150, 3950, 'd'], [3, 5650, 5651, 'd'], [4, 6850, 9850, 'e'], [5, 8850, 8851, 'a']]), ('normal control', [[[500, 3500, 'b'], [3000, 4500, 'd'], [4400, 4600, 'a']], -1200, 500], [[1, 0, 2300, 'b'], [2, 1800, 3300, 'd'], [3, 3200, 3400, 'a']]), ('normal control', [[[1100, 1900, 'b'], [2650, 4150, 'c'], [2700, 2900, 'a'], [3100, 3300, 'e']], 4000, 1100], [[1, 5100, 5900, 'b'], [2, 6650, 8150, 'c'], [3, 6700, 6900, 'a'], [4, 7100, 7300, 'e']])], [('regression: dropped cue test', [[[1500, 3000, 'b'], [1500, 2300, 'a']], -3000, 0], []), ('regression variant: dropped cue test', [[[100, 300, 'd'], [800, 2300, 'd'], [3300, 6300, 'c'], [3500, 6500, 'e'], [3700, 6700, 'e']], -300, 100], [[1, 500, 2000, 'd'], [2, 3000, 6000, 'c'], [3, 3200, 6200, 'e'], [4, 3400, 6400, 'e']]), ('partial repair probe: dropped cue test', [[[0, 1500, 'c'], [300, 500, 'b'], [3200, 3201, 'e']], -800, 0], [[1, 0, 700, 'c'], [2, 2400, 2401, 'e']]), ('partial repair variant: dropped cue test', [[[300, 1100, 'c']], -3000, 300], []), ('boundary control', [[[100, 200, 'x']], 50, 100], [[1, 150, 250, 'x']]), ('boundary control', [[[1000, 2000, 'a'], [3000, 4000, 'b']], -1500, 0], [[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]), ('normal control', [[[400, 600, 'c'], [400, 1200, 'd'], [2900, 3100, 'b'], [5100, 5101, 'a']], -3000, 5100], [[1, 400, 600, 'c'], [2, 400, 1200, 'd'], [3, 2100, 2101, 'a'], [4, 2900, 3100, 'b']]), ('normal control', [[[2300, 3800, 'd'], [3550, 6550, 'a'], [4250, 7250, 'e'], [6450, 6650, 'e'], [9350, 10150, 'd']], -3000, 9350], [[1, 2300, 3800, 'd'], [2, 3550, 6550, 'a'], [3, 4250, 7250, 'e'], [4, 6350, 7150, 'd'], [5, 6450, 6650, 'e']]), ('normal control', [[[1100, 1300, 'c'], [3600, 3601, 'c']], -1200, 1100], [[1, 0, 100, 'c'], [2, 2400, 2401, 'c']])], [('regression: dropped cue test', [[[400, 1200, 'e']], -1200, 0], []), ('regression variant: dropped cue test', [[[1500, 3000, 'b'], [1500, 2300, 'a']], -3000, 0], []), ('partial repair probe: dropped cue test', [[[550, 551, 'e']], -3000, 0], []), ('partial repair variant: dropped cue test', [[[1800, 3300, 'e'], [1850, 2050, 'e'], [2000, 2001, 'b'], [4350, 4351, 'd'], [5600, 8600, 'd']], -3000, 0], [[1, 0, 300, 'e'], [2, 1350, 1351, 'd'], [3, 2600, 5600, 'd']]), ('boundary control', [[[1000, 2000, 'a'], [3000, 4000, 'b']], -1500, 0], [[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]), ('boundary control', [[[0, 500, 'a'], [600, 900, 'b']], -500, 600], [[1, 0, 500, 'a'], [2, 100, 400, 'b']]), ('normal control', [[[1000, 1200, 'a']], 250, 0], [[1, 1250, 1450, 'a']]), ('normal control', [[[400, 600, 'a'], [3300, 6300, 'b'], [3600, 4400, 'b']], -300, 0], [[1, 100, 300, 'a'], [2, 3000, 6000, 'b'], [3, 3300, 4100, 'b']]), ('normal control', [[[2500, 3300, 'a'], [4500, 6000, 'd'], [6700, 8200, 'a']], 1000, 0], [[1, 3500, 4300, 'a'], [2, 5500, 7000, 'd'], [3, 7700, 9200, 'a']])], [('regression: dropped cue test', [[[100, 300, 'd'], [800, 2300, 'd'], [3300, 6300, 'c'], [3500, 6500, 'e'], [3700, 6700, 'e']], -300, 100], [[1, 500, 2000, 'd'], [2, 3000, 6000, 'c'], [3, 3200, 6200, 'e'], [4, 3400, 6400, 'e']]), ('regression variant: dropped cue test', [[[400, 1200, 'e']], -1200, 0], []), ('partial repair probe: dropped cue test', [[[2600, 2800, 'a'], [5100, 5900, 'd'], [8600, 8601, 'd'], [8600, 8800, 'b'], [8800, 8801, 'e']], -3000, 2600], [[1, 2100, 2900, 'd'], [2, 5600, 5601, 'd'], [3, 5600, 5800, 'b'], [4, 5800, 5801, 'e']]), ('partial repair variant: dropped cue test', [[[0, 1500, 'c'], [1500, 2300, 'e']], -3000, 1500], [[1, 0, 1500, 'c']]), ('boundary control', [[[0, 500, 'a'], [600, 900, 'b']], -500, 600], [[1, 0, 500, 'a'], [2, 100, 400, 'b']]), ('boundary control', [[[100, 200, 'x']], 50, 100], [[1, 150, 250, 'x']]), ('normal control', [[[2050, 2051, 'c'], [2050, 2250, 'c']], -1200, 1309], [[1, 850, 851, 'c'], [2, 850, 1050, 'c']]), ('normal control', [[[500, 3500, 'c'], [3000, 3800, 'a'], [3050, 6050, 'c'], [3800, 4600, 'd'], [4250, 7250, 'd']], -3000, 6050], [[1, 500, 3500, 'c'], [2, 3000, 3800, 'a'], [3, 3050, 6050, 'c'], [4, 3800, 4600, 'd'], [5, 4250, 7250, 'd']]), ('normal control', [[[3000, 4500, 'c'], [3400, 4900, 'c']], -1200, 3000], [[1, 1800, 3300, 'c'], [2, 2200, 3700, 'c']])]]
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
regression: dropped cue test	`[[1, 0, 0, 'e']]`	`[]`	Failed
regression variant: dropped cue test	`[[1, 0, -700, 'a'], [2, 0, 0, 'b']]`	`[]`	Failed
partial repair probe: dropped cue test	`[[1, 0, -150, 'c'], [2, 0, 1, 'c'], [3, 0, 1050, 'e'], [4, 1950, 2750, 'a']]`	`[[1, 0, 1, 'c'], [2, 0, 1050, 'e'], [3, 1950, 2750, 'a']]`	Failed
partial repair variant: dropped cue test	`[[1, 0, -2000, 'a'], [2, 0, -500, 'd'], [3, 1100, 2600, 'e'], [4, 1300, 2800, 'e']]`	`[[1, 1100, 2600, 'e'], [2, 1300, 2800, 'e']]`	Failed
boundary control	`[[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]`	`[[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]`	Passed
boundary control	`[[1, 0, 500, 'a'], [2, 100, 400, 'b']]`	`[[1, 0, 500, 'a'], [2, 100, 400, 'b']]`	Passed
normal control	`[[1, 150, 250, 'x']]`	`[[1, 150, 250, 'x']]`	Passed
normal control	`[[1, 150, 151, 'd'], [2, 200, 400, 'e']]`	`[[1, 150, 151, 'd'], [2, 200, 400, 'e']]`	Passed
normal control	`[[1, 6500, 9500, 'e']]`	`[[1, 6500, 9500, 'e']]`	Passed

SHA-256 / da6f221445fe18c99ef8bc34a669f6a824fd91ca4373c7fbe3d7cddfd233f4f9

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(cues, offset, from_ms):
    out=[]
    for start,end,text in cues:
        if start>=from_ms:
            start+=offset
            end+=offset
        if end<=0:
            continue
        if start<0:
            start=0
        out.append([start,end,text])
    out.sort(key=lambda c:(c[0],c[1]))
    return [[i+1]+c for i,c in enumerate(out)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: dropped cue test', [[[400, 1200, 'e']], -1200, 0], []), ('regression variant: dropped cue test', [[[1500, 3000, 'b'], [1500, 2300, 'a']], -3000, 0], []), ('partial repair probe: dropped cue test', [[[2050, 2850, 'c'], [2550, 4050, 'e'], [3000, 3001, 'c'], [4950, 5750, 'a']], -3000, 2050], [[1, 0, 1, 'c'], [2, 0, 1050, 'e'], [3, 1950, 2750, 'a']]), ('partial repair variant: dropped cue test', [[[800, 1000, 'a'], [2300, 2500, 'd'], [4100, 5600, 'e'], [4300, 5800, 'e']], -3000, 0], [[1, 1100, 2600, 'e'], [2, 1300, 2800, 'e']]), ('boundary control', [[[1000, 2000, 'a'], [3000, 4000, 'b']], -1500, 0], [[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]), ('boundary control', [[[0, 500, 'a'], [600, 900, 'b']], -500, 600], [[1, 0, 500, 'a'], [2, 100, 400, 'b']]), ('normal control', [[[100, 200, 'x']], 50, 100], [[1, 150, 250, 'x']]), ('normal control', [[[150, 151, 'd'], [200, 400, 'e']], 1000, 3319], [[1, 150, 151, 'd'], [2, 200, 400, 'e']]), ('normal control', [[[2500, 5500, 'e']], 4000, 2500], [[1, 6500, 9500, 'e']])], [('regression: dropped cue test', [[[100, 300, 'd'], [800, 2300, 'd'], [3300, 6300, 'c'], [3500, 6500, 'e'], [3700, 6700, 'e']], -300, 100], [[1, 500, 2000, 'd'], [2, 3000, 6000, 'c'], [3, 3200, 6200, 'e'], [4, 3400, 6400, 'e']]), ('regression variant: dropped cue test', [[[400, 1200, 'e']], -1200, 0], []), ('partial repair probe: dropped cue test', [[[-300, -299, 'b'], [150, 950, 'b'], [700, 3700, 'e'], [1950, 2750, 'e'], [2450, 5450, 'c']], -800, 5852], [[1, 150, 950, 'b'], [2, 700, 3700, 'e'], [3, 1950, 2750, 'e'], [4, 2450, 5450, 'c']]), ('partial repair variant: dropped cue test', [[[0, 200, 'd']], -1200, 0], []), ('boundary control', [[[0, 500, 'a'], [600, 900, 'b']], -500, 600], [[1, 0, 500, 'a'], [2, 100, 400, 'b']]), ('boundary control', [[[100, 200, 'x']], 50, 100], [[1, 150, 250, 'x']]), ('normal control', [[[400, 401, 'e'], [2900, 3700, 'd'], [5400, 5401, 'd'], [6600, 9600, 'e'], [8600, 8601, 'a']], 250, 1518], [[1, 400, 401, 'e'], [2, 3150, 3950, 'd'], [3, 5650, 5651, 'd'], [4, 6850, 9850, 'e'], [5, 8850, 8851, 'a']]), ('normal control', [[[500, 3500, 'b'], [3000, 4500, 'd'], [4400, 4600, 'a']], -1200, 500], [[1, 0, 2300, 'b'], [2, 1800, 3300, 'd'], [3, 3200, 3400, 'a']]), ('normal control', [[[1100, 1900, 'b'], [2650, 4150, 'c'], [2700, 2900, 'a'], [3100, 3300, 'e']], 4000, 1100], [[1, 5100, 5900, 'b'], [2, 6650, 8150, 'c'], [3, 6700, 6900, 'a'], [4, 7100, 7300, 'e']])], [('regression: dropped cue test', [[[1500, 3000, 'b'], [1500, 2300, 'a']], -3000, 0], []), ('regression variant: dropped cue test', [[[100, 300, 'd'], [800, 2300, 'd'], [3300, 6300, 'c'], [3500, 6500, 'e'], [3700, 6700, 'e']], -300, 100], [[1, 500, 2000, 'd'], [2, 3000, 6000, 'c'], [3, 3200, 6200, 'e'], [4, 3400, 6400, 'e']]), ('partial repair probe: dropped cue test', [[[0, 1500, 'c'], [300, 500, 'b'], [3200, 3201, 'e']], -800, 0], [[1, 0, 700, 'c'], [2, 2400, 2401, 'e']]), ('partial repair variant: dropped cue test', [[[300, 1100, 'c']], -3000, 300], []), ('boundary control', [[[100, 200, 'x']], 50, 100], [[1, 150, 250, 'x']]), ('boundary control', [[[1000, 2000, 'a'], [3000, 4000, 'b']], -1500, 0], [[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]), ('normal control', [[[400, 600, 'c'], [400, 1200, 'd'], [2900, 3100, 'b'], [5100, 5101, 'a']], -3000, 5100], [[1, 400, 600, 'c'], [2, 400, 1200, 'd'], [3, 2100, 2101, 'a'], [4, 2900, 3100, 'b']]), ('normal control', [[[2300, 3800, 'd'], [3550, 6550, 'a'], [4250, 7250, 'e'], [6450, 6650, 'e'], [9350, 10150, 'd']], -3000, 9350], [[1, 2300, 3800, 'd'], [2, 3550, 6550, 'a'], [3, 4250, 7250, 'e'], [4, 6350, 7150, 'd'], [5, 6450, 6650, 'e']]), ('normal control', [[[1100, 1300, 'c'], [3600, 3601, 'c']], -1200, 1100], [[1, 0, 100, 'c'], [2, 2400, 2401, 'c']])], [('regression: dropped cue test', [[[400, 1200, 'e']], -1200, 0], []), ('regression variant: dropped cue test', [[[1500, 3000, 'b'], [1500, 2300, 'a']], -3000, 0], []), ('partial repair probe: dropped cue test', [[[550, 551, 'e']], -3000, 0], []), ('partial repair variant: dropped cue test', [[[1800, 3300, 'e'], [1850, 2050, 'e'], [2000, 2001, 'b'], [4350, 4351, 'd'], [5600, 8600, 'd']], -3000, 0], [[1, 0, 300, 'e'], [2, 1350, 1351, 'd'], [3, 2600, 5600, 'd']]), ('boundary control', [[[1000, 2000, 'a'], [3000, 4000, 'b']], -1500, 0], [[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]), ('boundary control', [[[0, 500, 'a'], [600, 900, 'b']], -500, 600], [[1, 0, 500, 'a'], [2, 100, 400, 'b']]), ('normal control', [[[1000, 1200, 'a']], 250, 0], [[1, 1250, 1450, 'a']]), ('normal control', [[[400, 600, 'a'], [3300, 6300, 'b'], [3600, 4400, 'b']], -300, 0], [[1, 100, 300, 'a'], [2, 3000, 6000, 'b'], [3, 3300, 4100, 'b']]), ('normal control', [[[2500, 3300, 'a'], [4500, 6000, 'd'], [6700, 8200, 'a']], 1000, 0], [[1, 3500, 4300, 'a'], [2, 5500, 7000, 'd'], [3, 7700, 9200, 'a']])], [('regression: dropped cue test', [[[100, 300, 'd'], [800, 2300, 'd'], [3300, 6300, 'c'], [3500, 6500, 'e'], [3700, 6700, 'e']], -300, 100], [[1, 500, 2000, 'd'], [2, 3000, 6000, 'c'], [3, 3200, 6200, 'e'], [4, 3400, 6400, 'e']]), ('regression variant: dropped cue test', [[[400, 1200, 'e']], -1200, 0], []), ('partial repair probe: dropped cue test', [[[2600, 2800, 'a'], [5100, 5900, 'd'], [8600, 8601, 'd'], [8600, 8800, 'b'], [8800, 8801, 'e']], -3000, 2600], [[1, 2100, 2900, 'd'], [2, 5600, 5601, 'd'], [3, 5600, 5800, 'b'], [4, 5800, 5801, 'e']]), ('partial repair variant: dropped cue test', [[[0, 1500, 'c'], [1500, 2300, 'e']], -3000, 1500], [[1, 0, 1500, 'c']]), ('boundary control', [[[0, 500, 'a'], [600, 900, 'b']], -500, 600], [[1, 0, 500, 'a'], [2, 100, 400, 'b']]), ('boundary control', [[[100, 200, 'x']], 50, 100], [[1, 150, 250, 'x']]), ('normal control', [[[2050, 2051, 'c'], [2050, 2250, 'c']], -1200, 1309], [[1, 850, 851, 'c'], [2, 850, 1050, 'c']]), ('normal control', [[[500, 3500, 'c'], [3000, 3800, 'a'], [3050, 6050, 'c'], [3800, 4600, 'd'], [4250, 7250, 'd']], -3000, 6050], [[1, 500, 3500, 'c'], [2, 3000, 3800, 'a'], [3, 3050, 6050, 'c'], [4, 3800, 4600, 'd'], [5, 4250, 7250, 'd']]), ('normal control', [[[3000, 4500, 'c'], [3400, 4900, 'c']], -1200, 3000], [[1, 1800, 3300, 'c'], [2, 2200, 3700, 'c']])]]
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
regression: dropped cue test	`[]`	`[]`	Passed
regression variant: dropped cue test	`[]`	`[]`	Passed
partial repair probe: dropped cue test	`[[1, 0, 1, 'c'], [2, 0, 1050, 'e'], [3, 1950, 2750, 'a']]`	`[[1, 0, 1, 'c'], [2, 0, 1050, 'e'], [3, 1950, 2750, 'a']]`	Passed
partial repair variant: dropped cue test	`[[1, 1100, 2600, 'e'], [2, 1300, 2800, 'e']]`	`[[1, 1100, 2600, 'e'], [2, 1300, 2800, 'e']]`	Passed
boundary control	`[[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]`	`[[1, 0, 500, 'a'], [2, 1500, 2500, 'b']]`	Passed
boundary control	`[[1, 0, 500, 'a'], [2, 100, 400, 'b']]`	`[[1, 0, 500, 'a'], [2, 100, 400, 'b']]`	Passed
normal control	`[[1, 150, 250, 'x']]`	`[[1, 150, 250, 'x']]`	Passed
normal control	`[[1, 150, 151, 'd'], [2, 200, 400, 'e']]`	`[[1, 150, 151, 'd'], [2, 200, 400, 'e']]`	Passed
normal control	`[[1, 6500, 9500, 'e']]`	`[[1, 6500, 9500, 'e']]`	Passed

SHA-256 / 8d263aab946e04d2acfa9b3e8093c5da19148bf06fa9d9af979d9796af3fa687

Verification & scope

A deterministic bounded teaching model with a stipulated toy contract; it does not claim conformance to any subtitle standard. 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 2026-09-29T14:49:30.067966+00:00.

Case digest / 489aae8fd7cef75cd87f053534f396ac92e8fa4401593a6d5e6030f34c073c5e