FA-78321 / Subtitle cue timing / Open access

Subtitle conform to an edit cut list: shift accumulation · case 01

Cues after two or more cuts are shifted by only the most recent cut.

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

ROOT CAUSE

The removed length replaces instead of accumulating.

VERIFIED REPAIR

Accumulate every removed length before the time.

Unsuccessful approach: Treating the cut end as inclusive under-shifts by one millisecond per cut.

Case contract

Cuts [a,b) are removed from the programme (they may overlap or be unsorted and are merged first). A time after a cut shifts left by the removed length; a time inside a cut maps to the cut point. Cues [start,end,text] are mapped and dropped when the mapped end is not after the mapped start.

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, cuts):
    merged=[]
    for a,b in sorted(cuts):
        if merged and a<=merged[-1][1]:
            merged[-1][1]=max(merged[-1][1],b)
        else:
            merged.append([a,b])
    def mapt(t):
        shift=0
        for a,b in merged:
            if t>=b:
                shift=b-a
            elif t>a:
                return a-shift
        return t-shift
    out=[]
    for s,e,txt in cues:
        ns,ne=mapt(s),mapt(e)
        if ne>ns:
            out.append([ns,ne,txt])
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: shift accumulation', [[[3000, 3500, 'a']], [[0, 500], [1000, 2000]]], [[1500, 2000, 'a']]), ('regression variant: shift accumulation', [[[4000, 4300, 'c0'], [1200, 3200, 'c1']], [[1500, 2000], [0, 100]]], [[3400, 3700, 'c0'], [1100, 2600, 'c1']]), ('partial repair probe: shift accumulation', [[[2000, 3000, 'x']], [[1000, 1500], [1200, 1800]]], [[1200, 2200, 'x']]), ('partial repair variant: shift accumulation', [[[3200, 5200, 'c0'], [200, 2200, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']], [[3000, 3100], [2000, 2100]]], [[3000, 5000, 'c0'], [200, 2100, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[200, 1000, 'c0'], [200, 2200, 'c1'], [0, 100, 'c2'], [200, 300, 'c3']], [[2000, 2500]]], [[200, 1000, 'c0'], [200, 2000, 'c1'], [0, 100, 'c2'], [200, 300, 'c3']]), ('normal control', [[[200, 300, 'c0'], [1600, 3600, 'c1'], [1200, 1500, 'c2'], [600, 900, 'c3']], [[3000, 4500]]], [[200, 300, 'c0'], [1600, 3000, 'c1'], [1200, 1500, 'c2'], [600, 900, 'c3']]), ('normal control', [[[0, 2000, 'c0'], [0, 300, 'c1']], []], [[0, 2000, 'c0'], [0, 300, 'c1']])], [('regression: shift accumulation', [[[2500, 2800, 'c0']], [[500, 600], [1000, 2500], [2000, 2500]]], [[900, 1200, 'c0']]), ('regression variant: shift accumulation', [[[1600, 2400, 'c0'], [0, 2000, 'c1']], [[0, 100], [500, 1000]]], [[1000, 1800, 'c0'], [0, 1400, 'c1']]), ('partial repair probe: shift accumulation', [[[600, 2600, 'c0'], [2500, 3300, 'c1'], [0, 2000, 'c2']], [[1000, 1100]]], [[600, 2500, 'c0'], [2400, 3200, 'c1'], [0, 1900, 'c2']]), ('partial repair variant: shift accumulation', [[[900, 1700, 'c0'], [2500, 3300, 'c1'], [1200, 2000, 'c2']], [[1000, 2500]]], [[900, 1000, 'c0'], [1000, 1800, 'c1']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[2500, 2800, 'c0'], [600, 1400, 'c1']], []], [[2500, 2800, 'c0'], [600, 1400, 'c1']]), ('normal control', [[[3200, 3300, 'c0'], [200, 500, 'c1'], [900, 2900, 'c2']], []], [[3200, 3300, 'c0'], [200, 500, 'c1'], [900, 2900, 'c2']]), ('normal control', [[[1200, 2000, 'c0'], [3200, 3300, 'c1'], [900, 1000, 'c2'], [1200, 1300, 'c3']], []], [[1200, 2000, 'c0'], [3200, 3300, 'c1'], [900, 1000, 'c2'], [1200, 1300, 'c3']])], [('regression: shift accumulation', [[[3200, 5200, 'c0'], [200, 2200, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']], [[3000, 3100], [2000, 2100]]], [[3000, 5000, 'c0'], [200, 2100, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']]), ('regression variant: shift accumulation', [[[2500, 4500, 'c0'], [1200, 1300, 'c1']], [[2000, 2500], [3000, 4000]]], [[2000, 3000, 'c0'], [1200, 1300, 'c1']]), ('partial repair probe: shift accumulation', [[[2500, 2800, 'c0']], [[500, 600], [1000, 2500], [2000, 2500]]], [[900, 1200, 'c0']]), ('partial repair variant: shift accumulation', [[[900, 1200, 'c0'], [2500, 3300, 'c1']], [[2000, 2500]]], [[900, 1200, 'c0'], [2000, 2800, 'c1']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[900, 2900, 'c0'], [3200, 3500, 'c1'], [2500, 2800, 'c2']], [[1500, 3000], [3000, 4000]]], [[900, 1500, 'c0']]), ('normal control', [[[200, 1000, 'c0']], [[500, 1000], [0, 1000], [1000, 1500]]], []), ('normal control', [[[900, 1200, 'c0'], [900, 1700, 'c1']], []], [[900, 1200, 'c0'], [900, 1700, 'c1']])], [('regression: shift accumulation', [[[2500, 3300, 'c0'], [200, 500, 'c1']], [[1500, 1600], [0, 1000], [1500, 3000]]], [[500, 800, 'c0']]), ('regression variant: shift accumulation', [[[0, 300, 'c0'], [200, 1000, 'c1'], [2500, 3300, 'c2']], [[2000, 2100], [1500, 1600], [500, 1500]]], [[0, 300, 'c0'], [200, 500, 'c1'], [1300, 2100, 'c2']]), ('partial repair probe: shift accumulation', [[[3200, 5200, 'c0'], [1200, 1300, 'c1']], [[500, 2000], [2000, 2100], [1500, 1600]]], [[1600, 3600, 'c0']]), ('partial repair variant: shift accumulation', [[[1600, 1900, 'c0'], [2500, 3300, 'c1'], [1600, 1900, 'c2'], [4000, 6000, 'c3']], [[500, 2000], [0, 1000]]], [[500, 1300, 'c1'], [2000, 4000, 'c3']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[200, 2200, 'c0'], [2500, 2800, 'c1'], [1200, 1500, 'c2'], [2500, 3300, 'c3']], []], [[200, 2200, 'c0'], [2500, 2800, 'c1'], [1200, 1500, 'c2'], [2500, 3300, 'c3']]), ('normal control', [[[1600, 1700, 'c0'], [1600, 2400, 'c1'], [1600, 1700, 'c2']], [[1500, 2500]]], []), ('normal control', [[[900, 2900, 'c0'], [200, 500, 'c1'], [1200, 1300, 'c2'], [200, 500, 'c3']], []], [[900, 2900, 'c0'], [200, 500, 'c1'], [1200, 1300, 'c2'], [200, 500, 'c3']])], [('regression: shift accumulation', [[[900, 1000, 'c0'], [600, 2600, 'c1'], [4000, 4100, 'c2'], [900, 2900, 'c3']], [[1000, 1500], [2000, 2100], [2000, 2500]]], [[900, 1000, 'c0'], [600, 1600, 'c1'], [3000, 3100, 'c2'], [900, 1900, 'c3']]), ('regression variant: shift accumulation', [[[4000, 4300, 'c0'], [4000, 4100, 'c1'], [4000, 4300, 'c2']], [[2000, 3000], [1000, 1100]]], [[2900, 3200, 'c0'], [2900, 3000, 'c1'], [2900, 3200, 'c2']]), ('partial repair probe: shift accumulation', [[[2500, 4500, 'c0'], [4000, 6000, 'c1'], [900, 2900, 'c2'], [200, 2200, 'c3']], [[500, 600], [500, 1000]]], [[2000, 4000, 'c0'], [3500, 5500, 'c1'], [500, 2400, 'c2'], [200, 1700, 'c3']]), ('partial repair variant: shift accumulation', [[[600, 700, 'c0'], [3200, 3500, 'c1'], [600, 1400, 'c2'], [200, 2200, 'c3']], [[1500, 2500]]], [[600, 700, 'c0'], [2200, 2500, 'c1'], [600, 1400, 'c2'], [200, 1500, 'c3']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[200, 300, 'c0'], [3200, 3500, 'c1'], [2500, 2600, 'c2']], []], [[200, 300, 'c0'], [3200, 3500, 'c1'], [2500, 2600, 'c2']]), ('normal control', [[[4000, 4300, 'c0']], [[3000, 3500], [3000, 4500], [500, 2000]]], []), ('normal control', [[[1200, 1500, 'c0']], [[1000, 1500], [1500, 2000]]], [])]]
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: shift accumulation	`[[2000, 2500, 'a']]`	`[[1500, 2000, 'a']]`	Failed
regression variant: shift accumulation	`[[3500, 3800, 'c0'], [1100, 2700, 'c1']]`	`[[3400, 3700, 'c0'], [1100, 2600, 'c1']]`	Failed
partial repair probe: shift accumulation	`[[1200, 2200, 'x']]`	`[[1200, 2200, 'x']]`	Passed
partial repair variant: shift accumulation	`[[3100, 5100, 'c0'], [200, 2100, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']]`	`[[3000, 5000, 'c0'], [200, 2100, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']]`	Failed
boundary control	`[]`	`[]`	Passed
normal control	`[[200, 1000, 'c0'], [200, 2000, 'c1'], [0, 100, 'c2'], [200, 300, 'c3']]`	`[[200, 1000, 'c0'], [200, 2000, 'c1'], [0, 100, 'c2'], [200, 300, 'c3']]`	Passed
normal control	`[[200, 300, 'c0'], [1600, 3000, 'c1'], [1200, 1500, 'c2'], [600, 900, 'c3']]`	`[[200, 300, 'c0'], [1600, 3000, 'c1'], [1200, 1500, 'c2'], [600, 900, 'c3']]`	Passed
normal control	`[[0, 2000, 'c0'], [0, 300, 'c1']]`	`[[0, 2000, 'c0'], [0, 300, 'c1']]`	Passed

SHA-256 / 8bab5c76360194d245bb275d934150a55a02ff10fbd862f462ddc3f4145e7626

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(cues, cuts):
    merged=[]
    for a,b in sorted(cuts):
        if merged and a<=merged[-1][1]:
            merged[-1][1]=max(merged[-1][1],b)
        else:
            merged.append([a,b])
    def mapt(t):
        shift=0
        for a,b in merged:
            if t>=b:
                shift+=b-a-1
            elif t>a:
                return a-shift
        return t-shift
    out=[]
    for s,e,txt in cues:
        ns,ne=mapt(s),mapt(e)
        if ne>ns:
            out.append([ns,ne,txt])
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: shift accumulation', [[[3000, 3500, 'a']], [[0, 500], [1000, 2000]]], [[1500, 2000, 'a']]), ('regression variant: shift accumulation', [[[4000, 4300, 'c0'], [1200, 3200, 'c1']], [[1500, 2000], [0, 100]]], [[3400, 3700, 'c0'], [1100, 2600, 'c1']]), ('partial repair probe: shift accumulation', [[[2000, 3000, 'x']], [[1000, 1500], [1200, 1800]]], [[1200, 2200, 'x']]), ('partial repair variant: shift accumulation', [[[3200, 5200, 'c0'], [200, 2200, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']], [[3000, 3100], [2000, 2100]]], [[3000, 5000, 'c0'], [200, 2100, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[200, 1000, 'c0'], [200, 2200, 'c1'], [0, 100, 'c2'], [200, 300, 'c3']], [[2000, 2500]]], [[200, 1000, 'c0'], [200, 2000, 'c1'], [0, 100, 'c2'], [200, 300, 'c3']]), ('normal control', [[[200, 300, 'c0'], [1600, 3600, 'c1'], [1200, 1500, 'c2'], [600, 900, 'c3']], [[3000, 4500]]], [[200, 300, 'c0'], [1600, 3000, 'c1'], [1200, 1500, 'c2'], [600, 900, 'c3']]), ('normal control', [[[0, 2000, 'c0'], [0, 300, 'c1']], []], [[0, 2000, 'c0'], [0, 300, 'c1']])], [('regression: shift accumulation', [[[2500, 2800, 'c0']], [[500, 600], [1000, 2500], [2000, 2500]]], [[900, 1200, 'c0']]), ('regression variant: shift accumulation', [[[1600, 2400, 'c0'], [0, 2000, 'c1']], [[0, 100], [500, 1000]]], [[1000, 1800, 'c0'], [0, 1400, 'c1']]), ('partial repair probe: shift accumulation', [[[600, 2600, 'c0'], [2500, 3300, 'c1'], [0, 2000, 'c2']], [[1000, 1100]]], [[600, 2500, 'c0'], [2400, 3200, 'c1'], [0, 1900, 'c2']]), ('partial repair variant: shift accumulation', [[[900, 1700, 'c0'], [2500, 3300, 'c1'], [1200, 2000, 'c2']], [[1000, 2500]]], [[900, 1000, 'c0'], [1000, 1800, 'c1']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[2500, 2800, 'c0'], [600, 1400, 'c1']], []], [[2500, 2800, 'c0'], [600, 1400, 'c1']]), ('normal control', [[[3200, 3300, 'c0'], [200, 500, 'c1'], [900, 2900, 'c2']], []], [[3200, 3300, 'c0'], [200, 500, 'c1'], [900, 2900, 'c2']]), ('normal control', [[[1200, 2000, 'c0'], [3200, 3300, 'c1'], [900, 1000, 'c2'], [1200, 1300, 'c3']], []], [[1200, 2000, 'c0'], [3200, 3300, 'c1'], [900, 1000, 'c2'], [1200, 1300, 'c3']])], [('regression: shift accumulation', [[[3200, 5200, 'c0'], [200, 2200, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']], [[3000, 3100], [2000, 2100]]], [[3000, 5000, 'c0'], [200, 2100, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']]), ('regression variant: shift accumulation', [[[2500, 4500, 'c0'], [1200, 1300, 'c1']], [[2000, 2500], [3000, 4000]]], [[2000, 3000, 'c0'], [1200, 1300, 'c1']]), ('partial repair probe: shift accumulation', [[[2500, 2800, 'c0']], [[500, 600], [1000, 2500], [2000, 2500]]], [[900, 1200, 'c0']]), ('partial repair variant: shift accumulation', [[[900, 1200, 'c0'], [2500, 3300, 'c1']], [[2000, 2500]]], [[900, 1200, 'c0'], [2000, 2800, 'c1']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[900, 2900, 'c0'], [3200, 3500, 'c1'], [2500, 2800, 'c2']], [[1500, 3000], [3000, 4000]]], [[900, 1500, 'c0']]), ('normal control', [[[200, 1000, 'c0']], [[500, 1000], [0, 1000], [1000, 1500]]], []), ('normal control', [[[900, 1200, 'c0'], [900, 1700, 'c1']], []], [[900, 1200, 'c0'], [900, 1700, 'c1']])], [('regression: shift accumulation', [[[2500, 3300, 'c0'], [200, 500, 'c1']], [[1500, 1600], [0, 1000], [1500, 3000]]], [[500, 800, 'c0']]), ('regression variant: shift accumulation', [[[0, 300, 'c0'], [200, 1000, 'c1'], [2500, 3300, 'c2']], [[2000, 2100], [1500, 1600], [500, 1500]]], [[0, 300, 'c0'], [200, 500, 'c1'], [1300, 2100, 'c2']]), ('partial repair probe: shift accumulation', [[[3200, 5200, 'c0'], [1200, 1300, 'c1']], [[500, 2000], [2000, 2100], [1500, 1600]]], [[1600, 3600, 'c0']]), ('partial repair variant: shift accumulation', [[[1600, 1900, 'c0'], [2500, 3300, 'c1'], [1600, 1900, 'c2'], [4000, 6000, 'c3']], [[500, 2000], [0, 1000]]], [[500, 1300, 'c1'], [2000, 4000, 'c3']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[200, 2200, 'c0'], [2500, 2800, 'c1'], [1200, 1500, 'c2'], [2500, 3300, 'c3']], []], [[200, 2200, 'c0'], [2500, 2800, 'c1'], [1200, 1500, 'c2'], [2500, 3300, 'c3']]), ('normal control', [[[1600, 1700, 'c0'], [1600, 2400, 'c1'], [1600, 1700, 'c2']], [[1500, 2500]]], []), ('normal control', [[[900, 2900, 'c0'], [200, 500, 'c1'], [1200, 1300, 'c2'], [200, 500, 'c3']], []], [[900, 2900, 'c0'], [200, 500, 'c1'], [1200, 1300, 'c2'], [200, 500, 'c3']])], [('regression: shift accumulation', [[[900, 1000, 'c0'], [600, 2600, 'c1'], [4000, 4100, 'c2'], [900, 2900, 'c3']], [[1000, 1500], [2000, 2100], [2000, 2500]]], [[900, 1000, 'c0'], [600, 1600, 'c1'], [3000, 3100, 'c2'], [900, 1900, 'c3']]), ('regression variant: shift accumulation', [[[4000, 4300, 'c0'], [4000, 4100, 'c1'], [4000, 4300, 'c2']], [[2000, 3000], [1000, 1100]]], [[2900, 3200, 'c0'], [2900, 3000, 'c1'], [2900, 3200, 'c2']]), ('partial repair probe: shift accumulation', [[[2500, 4500, 'c0'], [4000, 6000, 'c1'], [900, 2900, 'c2'], [200, 2200, 'c3']], [[500, 600], [500, 1000]]], [[2000, 4000, 'c0'], [3500, 5500, 'c1'], [500, 2400, 'c2'], [200, 1700, 'c3']]), ('partial repair variant: shift accumulation', [[[600, 700, 'c0'], [3200, 3500, 'c1'], [600, 1400, 'c2'], [200, 2200, 'c3']], [[1500, 2500]]], [[600, 700, 'c0'], [2200, 2500, 'c1'], [600, 1400, 'c2'], [200, 1500, 'c3']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[200, 300, 'c0'], [3200, 3500, 'c1'], [2500, 2600, 'c2']], []], [[200, 300, 'c0'], [3200, 3500, 'c1'], [2500, 2600, 'c2']]), ('normal control', [[[4000, 4300, 'c0']], [[3000, 3500], [3000, 4500], [500, 2000]]], []), ('normal control', [[[1200, 1500, 'c0']], [[1000, 1500], [1500, 2000]]], [])]]
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: shift accumulation	`[[1502, 2002, 'a']]`	`[[1500, 2000, 'a']]`	Failed
regression variant: shift accumulation	`[[3402, 3702, 'c0'], [1101, 2602, 'c1']]`	`[[3400, 3700, 'c0'], [1100, 2600, 'c1']]`	Failed
partial repair probe: shift accumulation	`[[1201, 2201, 'x']]`	`[[1200, 2200, 'x']]`	Failed
partial repair variant: shift accumulation	`[[3002, 5002, 'c0'], [200, 2101, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']]`	`[[3000, 5000, 'c0'], [200, 2100, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']]`	Failed
boundary control	`[]`	`[]`	Passed
normal control	`[[200, 1000, 'c0'], [200, 2000, 'c1'], [0, 100, 'c2'], [200, 300, 'c3']]`	`[[200, 1000, 'c0'], [200, 2000, 'c1'], [0, 100, 'c2'], [200, 300, 'c3']]`	Passed
normal control	`[[200, 300, 'c0'], [1600, 3000, 'c1'], [1200, 1500, 'c2'], [600, 900, 'c3']]`	`[[200, 300, 'c0'], [1600, 3000, 'c1'], [1200, 1500, 'c2'], [600, 900, 'c3']]`	Passed
normal control	`[[0, 2000, 'c0'], [0, 300, 'c1']]`	`[[0, 2000, 'c0'], [0, 300, 'c1']]`	Passed

SHA-256 / c80df9c61660e559cc7b2fafa1d9f7c107a705ce4f930efe695306bd11dcaed9

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(cues, cuts):
    merged=[]
    for a,b in sorted(cuts):
        if merged and a<=merged[-1][1]:
            merged[-1][1]=max(merged[-1][1],b)
        else:
            merged.append([a,b])
    def mapt(t):
        shift=0
        for a,b in merged:
            if t>=b:
                shift+=b-a
            elif t>a:
                return a-shift
        return t-shift
    out=[]
    for s,e,txt in cues:
        ns,ne=mapt(s),mapt(e)
        if ne>ns:
            out.append([ns,ne,txt])
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: shift accumulation', [[[3000, 3500, 'a']], [[0, 500], [1000, 2000]]], [[1500, 2000, 'a']]), ('regression variant: shift accumulation', [[[4000, 4300, 'c0'], [1200, 3200, 'c1']], [[1500, 2000], [0, 100]]], [[3400, 3700, 'c0'], [1100, 2600, 'c1']]), ('partial repair probe: shift accumulation', [[[2000, 3000, 'x']], [[1000, 1500], [1200, 1800]]], [[1200, 2200, 'x']]), ('partial repair variant: shift accumulation', [[[3200, 5200, 'c0'], [200, 2200, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']], [[3000, 3100], [2000, 2100]]], [[3000, 5000, 'c0'], [200, 2100, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[200, 1000, 'c0'], [200, 2200, 'c1'], [0, 100, 'c2'], [200, 300, 'c3']], [[2000, 2500]]], [[200, 1000, 'c0'], [200, 2000, 'c1'], [0, 100, 'c2'], [200, 300, 'c3']]), ('normal control', [[[200, 300, 'c0'], [1600, 3600, 'c1'], [1200, 1500, 'c2'], [600, 900, 'c3']], [[3000, 4500]]], [[200, 300, 'c0'], [1600, 3000, 'c1'], [1200, 1500, 'c2'], [600, 900, 'c3']]), ('normal control', [[[0, 2000, 'c0'], [0, 300, 'c1']], []], [[0, 2000, 'c0'], [0, 300, 'c1']])], [('regression: shift accumulation', [[[2500, 2800, 'c0']], [[500, 600], [1000, 2500], [2000, 2500]]], [[900, 1200, 'c0']]), ('regression variant: shift accumulation', [[[1600, 2400, 'c0'], [0, 2000, 'c1']], [[0, 100], [500, 1000]]], [[1000, 1800, 'c0'], [0, 1400, 'c1']]), ('partial repair probe: shift accumulation', [[[600, 2600, 'c0'], [2500, 3300, 'c1'], [0, 2000, 'c2']], [[1000, 1100]]], [[600, 2500, 'c0'], [2400, 3200, 'c1'], [0, 1900, 'c2']]), ('partial repair variant: shift accumulation', [[[900, 1700, 'c0'], [2500, 3300, 'c1'], [1200, 2000, 'c2']], [[1000, 2500]]], [[900, 1000, 'c0'], [1000, 1800, 'c1']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[2500, 2800, 'c0'], [600, 1400, 'c1']], []], [[2500, 2800, 'c0'], [600, 1400, 'c1']]), ('normal control', [[[3200, 3300, 'c0'], [200, 500, 'c1'], [900, 2900, 'c2']], []], [[3200, 3300, 'c0'], [200, 500, 'c1'], [900, 2900, 'c2']]), ('normal control', [[[1200, 2000, 'c0'], [3200, 3300, 'c1'], [900, 1000, 'c2'], [1200, 1300, 'c3']], []], [[1200, 2000, 'c0'], [3200, 3300, 'c1'], [900, 1000, 'c2'], [1200, 1300, 'c3']])], [('regression: shift accumulation', [[[3200, 5200, 'c0'], [200, 2200, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']], [[3000, 3100], [2000, 2100]]], [[3000, 5000, 'c0'], [200, 2100, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']]), ('regression variant: shift accumulation', [[[2500, 4500, 'c0'], [1200, 1300, 'c1']], [[2000, 2500], [3000, 4000]]], [[2000, 3000, 'c0'], [1200, 1300, 'c1']]), ('partial repair probe: shift accumulation', [[[2500, 2800, 'c0']], [[500, 600], [1000, 2500], [2000, 2500]]], [[900, 1200, 'c0']]), ('partial repair variant: shift accumulation', [[[900, 1200, 'c0'], [2500, 3300, 'c1']], [[2000, 2500]]], [[900, 1200, 'c0'], [2000, 2800, 'c1']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[900, 2900, 'c0'], [3200, 3500, 'c1'], [2500, 2800, 'c2']], [[1500, 3000], [3000, 4000]]], [[900, 1500, 'c0']]), ('normal control', [[[200, 1000, 'c0']], [[500, 1000], [0, 1000], [1000, 1500]]], []), ('normal control', [[[900, 1200, 'c0'], [900, 1700, 'c1']], []], [[900, 1200, 'c0'], [900, 1700, 'c1']])], [('regression: shift accumulation', [[[2500, 3300, 'c0'], [200, 500, 'c1']], [[1500, 1600], [0, 1000], [1500, 3000]]], [[500, 800, 'c0']]), ('regression variant: shift accumulation', [[[0, 300, 'c0'], [200, 1000, 'c1'], [2500, 3300, 'c2']], [[2000, 2100], [1500, 1600], [500, 1500]]], [[0, 300, 'c0'], [200, 500, 'c1'], [1300, 2100, 'c2']]), ('partial repair probe: shift accumulation', [[[3200, 5200, 'c0'], [1200, 1300, 'c1']], [[500, 2000], [2000, 2100], [1500, 1600]]], [[1600, 3600, 'c0']]), ('partial repair variant: shift accumulation', [[[1600, 1900, 'c0'], [2500, 3300, 'c1'], [1600, 1900, 'c2'], [4000, 6000, 'c3']], [[500, 2000], [0, 1000]]], [[500, 1300, 'c1'], [2000, 4000, 'c3']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[200, 2200, 'c0'], [2500, 2800, 'c1'], [1200, 1500, 'c2'], [2500, 3300, 'c3']], []], [[200, 2200, 'c0'], [2500, 2800, 'c1'], [1200, 1500, 'c2'], [2500, 3300, 'c3']]), ('normal control', [[[1600, 1700, 'c0'], [1600, 2400, 'c1'], [1600, 1700, 'c2']], [[1500, 2500]]], []), ('normal control', [[[900, 2900, 'c0'], [200, 500, 'c1'], [1200, 1300, 'c2'], [200, 500, 'c3']], []], [[900, 2900, 'c0'], [200, 500, 'c1'], [1200, 1300, 'c2'], [200, 500, 'c3']])], [('regression: shift accumulation', [[[900, 1000, 'c0'], [600, 2600, 'c1'], [4000, 4100, 'c2'], [900, 2900, 'c3']], [[1000, 1500], [2000, 2100], [2000, 2500]]], [[900, 1000, 'c0'], [600, 1600, 'c1'], [3000, 3100, 'c2'], [900, 1900, 'c3']]), ('regression variant: shift accumulation', [[[4000, 4300, 'c0'], [4000, 4100, 'c1'], [4000, 4300, 'c2']], [[2000, 3000], [1000, 1100]]], [[2900, 3200, 'c0'], [2900, 3000, 'c1'], [2900, 3200, 'c2']]), ('partial repair probe: shift accumulation', [[[2500, 4500, 'c0'], [4000, 6000, 'c1'], [900, 2900, 'c2'], [200, 2200, 'c3']], [[500, 600], [500, 1000]]], [[2000, 4000, 'c0'], [3500, 5500, 'c1'], [500, 2400, 'c2'], [200, 1700, 'c3']]), ('partial repair variant: shift accumulation', [[[600, 700, 'c0'], [3200, 3500, 'c1'], [600, 1400, 'c2'], [200, 2200, 'c3']], [[1500, 2500]]], [[600, 700, 'c0'], [2200, 2500, 'c1'], [600, 1400, 'c2'], [200, 1500, 'c3']]), ('boundary control', [[[1100, 1400, 'a']], [[1000, 1500]]], []), ('normal control', [[[200, 300, 'c0'], [3200, 3500, 'c1'], [2500, 2600, 'c2']], []], [[200, 300, 'c0'], [3200, 3500, 'c1'], [2500, 2600, 'c2']]), ('normal control', [[[4000, 4300, 'c0']], [[3000, 3500], [3000, 4500], [500, 2000]]], []), ('normal control', [[[1200, 1500, 'c0']], [[1000, 1500], [1500, 2000]]], [])]]
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: shift accumulation	`[[1500, 2000, 'a']]`	`[[1500, 2000, 'a']]`	Passed
regression variant: shift accumulation	`[[3400, 3700, 'c0'], [1100, 2600, 'c1']]`	`[[3400, 3700, 'c0'], [1100, 2600, 'c1']]`	Passed
partial repair probe: shift accumulation	`[[1200, 2200, 'x']]`	`[[1200, 2200, 'x']]`	Passed
partial repair variant: shift accumulation	`[[3000, 5000, 'c0'], [200, 2100, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']]`	`[[3000, 5000, 'c0'], [200, 2100, 'c1'], [200, 500, 'c2'], [1200, 1300, 'c3']]`	Passed
boundary control	`[]`	`[]`	Passed
normal control	`[[200, 1000, 'c0'], [200, 2000, 'c1'], [0, 100, 'c2'], [200, 300, 'c3']]`	`[[200, 1000, 'c0'], [200, 2000, 'c1'], [0, 100, 'c2'], [200, 300, 'c3']]`	Passed
normal control	`[[200, 300, 'c0'], [1600, 3000, 'c1'], [1200, 1500, 'c2'], [600, 900, 'c3']]`	`[[200, 300, 'c0'], [1600, 3000, 'c1'], [1200, 1500, 'c2'], [600, 900, 'c3']]`	Passed
normal control	`[[0, 2000, 'c0'], [0, 300, 'c1']]`	`[[0, 2000, 'c0'], [0, 300, 'c1']]`	Passed

SHA-256 / c1613182a670fab42e4f8ffb9d53f0fa76f6b289fed071705648dc99df77d330

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 2026-09-29T14:49:34.076459+00:00.

Case digest / 0550fa983f2741352f163070fd2d8850fe506e2b81d335c8582ae21c828d90eb