FAILURE MAP
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FA-78291 / Subtitle cue timing / Open access

Active cue lookup with prefix maximum ends: bisect side · case 01

A cue starting exactly at the query time is not shown.

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

ROOT CAUSE

bisect_left excludes cues whose start equals t.

VERIFIED REPAIR

Use bisect_right so cues starting at t are candidates.

Unsuccessful approach: Adding zero to the query leaves the same left-bisect exclusion.

Case contract

cues [start,end] are sorted by start. Return the ascending indices of cues active at t (start <= t < end). The search bisects the starts and walks backwards while the running maximum end of the prefix exceeds t.

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
import bisect
N = 1
observations = []
def solve(cues, t):
    starts=[c[0] for c in cues]
    hi=bisect.bisect_left(starts,t)
    maxend=[]
    run=0
    for c in cues:
        run=max(run,c[1])
        maxend.append(run)
    res=[]
    i=hi-1
    while i>=0 and maxend[i]>t:
        if cues[i][1]>t:
            res.append(i)
        i-=1
    return sorted(res)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: bisect side', [[[0, 100], [100, 200]], 100], [1]), ('regression variant: bisect side', [[[100, 400], [300, 350], [500, 550]], 300], [0, 1]), ('partial repair probe: bisect side', [[[100, 400], [400, 500], [500, 550], [500, 600]], 100], [0]), ('partial repair variant: bisect side', [[[100, 150], [100, 200], [400, 450]], 100], [0, 1]), ('boundary control', [[[0, 1000], [100, 200], [300, 400]], 350], [0, 2]), ('boundary control', [[[0, 100]], 100], []), ('normal control', [[[0, 50], [0, 500], [200, 250]], 300], [1]), ('normal control', [[[0, 100], [100, 1100], [200, 300], [200, 500]], 50], [0]), ('normal control', [[[400, 500], [500, 1500]], 0], [])], [('regression: bisect side', [[[100, 400], [300, 400], [300, 400], [300, 350], [400, 500], [500, 800]], 300], [0, 1, 2, 3]), ('regression variant: bisect side', [[[0, 1000], [100, 1100], [200, 500], [200, 500]], 200], [0, 1, 2, 3]), ('partial repair probe: bisect side', [[[0, 1000], [200, 300], [400, 450]], 200], [0, 1]), ('partial repair variant: bisect side', [[[0, 300], [0, 50], [100, 200], [200, 500], [400, 500]], 100], [0, 2]), ('boundary control', [[[0, 100]], 100], []), ('boundary control', [[[0, 50], [0, 500], [200, 250]], 300], [1]), ('normal control', [[[100, 200], [200, 250]], 0], []), ('normal control', [[[0, 100], [0, 1000], [400, 500], [500, 600], [500, 1500], [500, 550]], 600], [1, 4]), ('normal control', [[[0, 300], [500, 550]], 50], [0])], [('regression: bisect side', [[[100, 400], [400, 500], [500, 550], [500, 600]], 100], [0]), ('regression variant: bisect side', [[[0, 300], [100, 1100], [200, 250], [500, 550]], 100], [0, 1]), ('partial repair probe: bisect side', [[[100, 1100], [200, 1200], [300, 1300], [400, 450], [400, 500], [400, 500]], 300], [0, 1, 2]), ('partial repair variant: bisect side', [[[0, 300], [100, 150], [100, 150], [100, 200], [400, 700], [500, 1500]], 0], [0]), ('boundary control', [[[0, 50], [0, 500], [200, 250]], 300], [1]), ('boundary control', [[[0, 1000], [100, 200], [300, 400]], 350], [0, 2]), ('normal control', [[[0, 100], [0, 1000], [300, 1300]], 500], [1, 2]), ('normal control', [[[0, 100], [200, 1200], [300, 400], [500, 800]], 600], [1, 3]), ('normal control', [[[200, 500], [200, 1200], [500, 600]], 400], [0, 1])], [('regression: bisect side', [[[0, 1000], [200, 300], [400, 450]], 200], [0, 1]), ('regression variant: bisect side', [[[100, 1100], [100, 1100], [400, 500], [400, 700], [400, 450], [500, 550]], 500], [0, 1, 3, 5]), ('partial repair probe: bisect side', [[[100, 400], [300, 350], [500, 550]], 300], [0, 1]), ('partial repair variant: bisect side', [[[0, 300], [100, 150], [200, 250]], 100], [0, 1]), ('boundary control', [[[0, 1000], [100, 200], [300, 400]], 350], [0, 2]), ('boundary control', [[[0, 100]], 100], []), ('normal control', [[[200, 500]], 500], []), ('normal control', [[[500, 550]], 50], []), ('normal control', [[[200, 1200], [200, 250]], 1499], [])], [('regression: bisect side', [[[100, 1100], [200, 1200], [300, 1300], [400, 450], [400, 500], [400, 500]], 300], [0, 1, 2]), ('regression variant: bisect side', [[[100, 150], [100, 200], [400, 450]], 100], [0, 1]), ('partial repair probe: bisect side', [[[0, 1000], [100, 1100], [200, 500], [200, 500]], 200], [0, 1, 2, 3]), ('partial repair variant: bisect side', [[[200, 500], [300, 350], [500, 600], [500, 600]], 200], [0]), ('boundary control', [[[0, 100]], 100], []), ('boundary control', [[[0, 50], [0, 500], [200, 250]], 300], [1]), ('normal control', [[[400, 450]], 150], []), ('normal control', [[[200, 300]], 150], []), ('normal control', [[[0, 1000], [0, 300], [100, 1100], [100, 150], [100, 150], [400, 500]], 200], [0, 1, 2])]]
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: bisect side[][1]Failed
regression variant: bisect side[0][0, 1]Failed
partial repair probe: bisect side[][0]Failed
partial repair variant: bisect side[][0, 1]Failed
boundary control[0, 2][0, 2]Passed
boundary control[][]Passed
normal control[1][1]Passed
normal control[0][0]Passed
normal control[][]Passed

SHA-256 / f0bd778c453de39a71d5c5e08ea9016bedc22abe4aa06c04b6e539a53fe21693

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import bisect
N = 1
observations = []
def solve(cues, t):
    starts=[c[0] for c in cues]
    hi=bisect.bisect_left(starts,t+0)
    maxend=[]
    run=0
    for c in cues:
        run=max(run,c[1])
        maxend.append(run)
    res=[]
    i=hi-1
    while i>=0 and maxend[i]>t:
        if cues[i][1]>t:
            res.append(i)
        i-=1
    return sorted(res)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: bisect side', [[[0, 100], [100, 200]], 100], [1]), ('regression variant: bisect side', [[[100, 400], [300, 350], [500, 550]], 300], [0, 1]), ('partial repair probe: bisect side', [[[100, 400], [400, 500], [500, 550], [500, 600]], 100], [0]), ('partial repair variant: bisect side', [[[100, 150], [100, 200], [400, 450]], 100], [0, 1]), ('boundary control', [[[0, 1000], [100, 200], [300, 400]], 350], [0, 2]), ('boundary control', [[[0, 100]], 100], []), ('normal control', [[[0, 50], [0, 500], [200, 250]], 300], [1]), ('normal control', [[[0, 100], [100, 1100], [200, 300], [200, 500]], 50], [0]), ('normal control', [[[400, 500], [500, 1500]], 0], [])], [('regression: bisect side', [[[100, 400], [300, 400], [300, 400], [300, 350], [400, 500], [500, 800]], 300], [0, 1, 2, 3]), ('regression variant: bisect side', [[[0, 1000], [100, 1100], [200, 500], [200, 500]], 200], [0, 1, 2, 3]), ('partial repair probe: bisect side', [[[0, 1000], [200, 300], [400, 450]], 200], [0, 1]), ('partial repair variant: bisect side', [[[0, 300], [0, 50], [100, 200], [200, 500], [400, 500]], 100], [0, 2]), ('boundary control', [[[0, 100]], 100], []), ('boundary control', [[[0, 50], [0, 500], [200, 250]], 300], [1]), ('normal control', [[[100, 200], [200, 250]], 0], []), ('normal control', [[[0, 100], [0, 1000], [400, 500], [500, 600], [500, 1500], [500, 550]], 600], [1, 4]), ('normal control', [[[0, 300], [500, 550]], 50], [0])], [('regression: bisect side', [[[100, 400], [400, 500], [500, 550], [500, 600]], 100], [0]), ('regression variant: bisect side', [[[0, 300], [100, 1100], [200, 250], [500, 550]], 100], [0, 1]), ('partial repair probe: bisect side', [[[100, 1100], [200, 1200], [300, 1300], [400, 450], [400, 500], [400, 500]], 300], [0, 1, 2]), ('partial repair variant: bisect side', [[[0, 300], [100, 150], [100, 150], [100, 200], [400, 700], [500, 1500]], 0], [0]), ('boundary control', [[[0, 50], [0, 500], [200, 250]], 300], [1]), ('boundary control', [[[0, 1000], [100, 200], [300, 400]], 350], [0, 2]), ('normal control', [[[0, 100], [0, 1000], [300, 1300]], 500], [1, 2]), ('normal control', [[[0, 100], [200, 1200], [300, 400], [500, 800]], 600], [1, 3]), ('normal control', [[[200, 500], [200, 1200], [500, 600]], 400], [0, 1])], [('regression: bisect side', [[[0, 1000], [200, 300], [400, 450]], 200], [0, 1]), ('regression variant: bisect side', [[[100, 1100], [100, 1100], [400, 500], [400, 700], [400, 450], [500, 550]], 500], [0, 1, 3, 5]), ('partial repair probe: bisect side', [[[100, 400], [300, 350], [500, 550]], 300], [0, 1]), ('partial repair variant: bisect side', [[[0, 300], [100, 150], [200, 250]], 100], [0, 1]), ('boundary control', [[[0, 1000], [100, 200], [300, 400]], 350], [0, 2]), ('boundary control', [[[0, 100]], 100], []), ('normal control', [[[200, 500]], 500], []), ('normal control', [[[500, 550]], 50], []), ('normal control', [[[200, 1200], [200, 250]], 1499], [])], [('regression: bisect side', [[[100, 1100], [200, 1200], [300, 1300], [400, 450], [400, 500], [400, 500]], 300], [0, 1, 2]), ('regression variant: bisect side', [[[100, 150], [100, 200], [400, 450]], 100], [0, 1]), ('partial repair probe: bisect side', [[[0, 1000], [100, 1100], [200, 500], [200, 500]], 200], [0, 1, 2, 3]), ('partial repair variant: bisect side', [[[200, 500], [300, 350], [500, 600], [500, 600]], 200], [0]), ('boundary control', [[[0, 100]], 100], []), ('boundary control', [[[0, 50], [0, 500], [200, 250]], 300], [1]), ('normal control', [[[400, 450]], 150], []), ('normal control', [[[200, 300]], 150], []), ('normal control', [[[0, 1000], [0, 300], [100, 1100], [100, 150], [100, 150], [400, 500]], 200], [0, 1, 2])]]
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: bisect side[][1]Failed
regression variant: bisect side[0][0, 1]Failed
partial repair probe: bisect side[][0]Failed
partial repair variant: bisect side[][0, 1]Failed
boundary control[0, 2][0, 2]Passed
boundary control[][]Passed
normal control[1][1]Passed
normal control[0][0]Passed
normal control[][]Passed

SHA-256 / e6634de1e765d85b9854e5ad4873bf1b85cd27db456514ddbfcba0dc2e929e8e

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json
import bisect
N = 1
observations = []
def solve(cues, t):
    starts=[c[0] for c in cues]
    hi=bisect.bisect_right(starts,t)
    maxend=[]
    run=0
    for c in cues:
        run=max(run,c[1])
        maxend.append(run)
    res=[]
    i=hi-1
    while i>=0 and maxend[i]>t:
        if cues[i][1]>t:
            res.append(i)
        i-=1
    return sorted(res)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: bisect side', [[[0, 100], [100, 200]], 100], [1]), ('regression variant: bisect side', [[[100, 400], [300, 350], [500, 550]], 300], [0, 1]), ('partial repair probe: bisect side', [[[100, 400], [400, 500], [500, 550], [500, 600]], 100], [0]), ('partial repair variant: bisect side', [[[100, 150], [100, 200], [400, 450]], 100], [0, 1]), ('boundary control', [[[0, 1000], [100, 200], [300, 400]], 350], [0, 2]), ('boundary control', [[[0, 100]], 100], []), ('normal control', [[[0, 50], [0, 500], [200, 250]], 300], [1]), ('normal control', [[[0, 100], [100, 1100], [200, 300], [200, 500]], 50], [0]), ('normal control', [[[400, 500], [500, 1500]], 0], [])], [('regression: bisect side', [[[100, 400], [300, 400], [300, 400], [300, 350], [400, 500], [500, 800]], 300], [0, 1, 2, 3]), ('regression variant: bisect side', [[[0, 1000], [100, 1100], [200, 500], [200, 500]], 200], [0, 1, 2, 3]), ('partial repair probe: bisect side', [[[0, 1000], [200, 300], [400, 450]], 200], [0, 1]), ('partial repair variant: bisect side', [[[0, 300], [0, 50], [100, 200], [200, 500], [400, 500]], 100], [0, 2]), ('boundary control', [[[0, 100]], 100], []), ('boundary control', [[[0, 50], [0, 500], [200, 250]], 300], [1]), ('normal control', [[[100, 200], [200, 250]], 0], []), ('normal control', [[[0, 100], [0, 1000], [400, 500], [500, 600], [500, 1500], [500, 550]], 600], [1, 4]), ('normal control', [[[0, 300], [500, 550]], 50], [0])], [('regression: bisect side', [[[100, 400], [400, 500], [500, 550], [500, 600]], 100], [0]), ('regression variant: bisect side', [[[0, 300], [100, 1100], [200, 250], [500, 550]], 100], [0, 1]), ('partial repair probe: bisect side', [[[100, 1100], [200, 1200], [300, 1300], [400, 450], [400, 500], [400, 500]], 300], [0, 1, 2]), ('partial repair variant: bisect side', [[[0, 300], [100, 150], [100, 150], [100, 200], [400, 700], [500, 1500]], 0], [0]), ('boundary control', [[[0, 50], [0, 500], [200, 250]], 300], [1]), ('boundary control', [[[0, 1000], [100, 200], [300, 400]], 350], [0, 2]), ('normal control', [[[0, 100], [0, 1000], [300, 1300]], 500], [1, 2]), ('normal control', [[[0, 100], [200, 1200], [300, 400], [500, 800]], 600], [1, 3]), ('normal control', [[[200, 500], [200, 1200], [500, 600]], 400], [0, 1])], [('regression: bisect side', [[[0, 1000], [200, 300], [400, 450]], 200], [0, 1]), ('regression variant: bisect side', [[[100, 1100], [100, 1100], [400, 500], [400, 700], [400, 450], [500, 550]], 500], [0, 1, 3, 5]), ('partial repair probe: bisect side', [[[100, 400], [300, 350], [500, 550]], 300], [0, 1]), ('partial repair variant: bisect side', [[[0, 300], [100, 150], [200, 250]], 100], [0, 1]), ('boundary control', [[[0, 1000], [100, 200], [300, 400]], 350], [0, 2]), ('boundary control', [[[0, 100]], 100], []), ('normal control', [[[200, 500]], 500], []), ('normal control', [[[500, 550]], 50], []), ('normal control', [[[200, 1200], [200, 250]], 1499], [])], [('regression: bisect side', [[[100, 1100], [200, 1200], [300, 1300], [400, 450], [400, 500], [400, 500]], 300], [0, 1, 2]), ('regression variant: bisect side', [[[100, 150], [100, 200], [400, 450]], 100], [0, 1]), ('partial repair probe: bisect side', [[[0, 1000], [100, 1100], [200, 500], [200, 500]], 200], [0, 1, 2, 3]), ('partial repair variant: bisect side', [[[200, 500], [300, 350], [500, 600], [500, 600]], 200], [0]), ('boundary control', [[[0, 100]], 100], []), ('boundary control', [[[0, 50], [0, 500], [200, 250]], 300], [1]), ('normal control', [[[400, 450]], 150], []), ('normal control', [[[200, 300]], 150], []), ('normal control', [[[0, 1000], [0, 300], [100, 1100], [100, 150], [100, 150], [400, 500]], 200], [0, 1, 2])]]
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: bisect side[1][1]Passed
regression variant: bisect side[0, 1][0, 1]Passed
partial repair probe: bisect side[0][0]Passed
partial repair variant: bisect side[0, 1][0, 1]Passed
boundary control[0, 2][0, 2]Passed
boundary control[][]Passed
normal control[1][1]Passed
normal control[0][0]Passed
normal control[][]Passed

SHA-256 / bdfe02a5a17e4c64a4e1443edd17086c9d5baf3719a424dd34d517b9c21d649a

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 2026-09-29T14:49:34.030480+00:00.

Case digest / 8ae071df801050fba1132dbdd4ea1519419b4fd0b439f3663d4d6ed0ae27ee94