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Team-draft interleaving credit: Clicks credit every ranker containing the document · case 01

Clicks on documents both rankers returned count for both, masking real preferences.

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

ROOT CAUSE

Credit checks whether the clicked document appears in each ranking rather than who placed it.

VERIFIED REPAIR

Credit only the team recorded for that position.

Unsuccessful approach: Crediting only documents exclusive to one ranking ignores the team that actually placed shared ones.

Case contract

Build an interleaved list of up to length documents. Each round both teams skip documents already placed; when both teams have the same number of picks, the next coin (cycled, consumed only on ties) chooses A on 0 and B on 1; otherwise the team with fewer picks goes. An exhausted team yields to the other. Clicks are positions; each credits the team that placed that document. Return [documents, teams, winner A/B/tie].

Why this case matters

Interleaving compares ranking algorithms with far fewer users than an A/B test, if credit is fair.

1 / The failure

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

N = 1
observations = []
def solve(rank_a, rank_b, coins, clicks, length):
    out, team = [], []
    ia = ib = ci = 0
    while len(out) < length:
        while ia < len(rank_a) and rank_a[ia] in out:
            ia += 1
        while ib < len(rank_b) and rank_b[ib] in out:
            ib += 1
        has_a, has_b = ia < len(rank_a), ib < len(rank_b)
        if not has_a and not has_b:
            break
        na, nb = team.count('A'), team.count('B')
        if na == nb:
            pick_a = coins[ci % len(coins)] == 0
            ci += 1
        else:
            pick_a = na < nb
        if pick_a and not has_a:
            pick_a = False
        elif not pick_a and not has_b:
            pick_a = True
        if pick_a:
            out.append(rank_a[ia])
            team.append('A')
        else:
            out.append(rank_b[ib])
            team.append('B')
    credit_a = sum(1 for i in clicks if i < len(out) and out[i] in rank_a)
    credit_b = sum(1 for i in clicks if i < len(out) and out[i] in rank_b)
    winner = 'A' if credit_a > credit_b else 'B' if credit_b > credit_a else 'tie'
    return [out, team, winner]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('shared top document is placed once',
   [['d1', 'd2', 'd3'], ['d1', 'd3', 'd4'], [0, 1], [1], 4],
   [['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']),
  ('coins are consumed only on ties',
   [['d1', 'd2', 'd3'], ['d4', 'd5', 'd6'], [1, 0], [0, 3], 6],
   [['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']),
  ('team behind picks next',
   [['d1', 'd2'], ['d3', 'd4'], [0], [2], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']),
  ('shared document credits the team that placed it',
   [['d1', 'd2'], ['d2', 'd1'], [1], [0], 2],
   [['d2', 'd1'], ['B', 'A'], 'B']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('query sample 1',
   [['d4', 'd3', 'd2'], ['d5', 'd6'], [0], [], 6],
   [['d4', 'd5', 'd3', 'd6', 'd2'], ['A', 'B', 'A', 'B', 'A'], 'tie']),
  ('query sample 2',
   [['d6', 'd5', 'd1', 'd2'], ['d6', 'd5'], [1, 1, 1], [], 4],
   [['d6', 'd5', 'd1', 'd2'], ['B', 'A', 'A', 'A'], 'tie']),
  ('query sample 3',
   [['d5', 'd4'], ['d6', 'd3', 'd5', 'd1'], [0], [], 5],
   [['d5', 'd6', 'd4', 'd3', 'd1'], ['A', 'B', 'A', 'B', 'B'], 'tie'])],
 [('coins are consumed only on ties',
   [['d1', 'd2', 'd3'], ['d4', 'd5', 'd6'], [1, 0], [0, 3], 6],
   [['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']),
  ('team behind picks next',
   [['d1', 'd2'], ['d3', 'd4'], [0], [2], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']),
  ('shared document credits the team that placed it',
   [['d1', 'd2'], ['d2', 'd1'], [1], [0], 2],
   [['d2', 'd1'], ['B', 'A'], 'B']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('no clicks is a tie', [['d1', 'd2'], ['d3'], [1], [], 3], [['d3', 'd1', 'd2'], ['B', 'A', 'A'], 'tie']),
  ('query sample 6',
   [['d1', 'd4', 'd5'], ['d5', 'd3', 'd2'], [0], [1], 6],
   [['d1', 'd5', 'd4', 'd3', 'd2'], ['A', 'B', 'A', 'B', 'B'], 'B']),
  ('query sample 7',
   [['d4', 'd1', 'd6'], ['d1', 'd6', 'd2', 'd4', 'd3'], [0, 0, 1], [4, 5], 5],
   [['d4', 'd1', 'd6', 'd2', 'd3'], ['A', 'B', 'A', 'B', 'B'], 'B']),
  ('query sample 31',
   [['d2', 'd4', 'd5', 'd6', 'd3'], ['d1', 'd3'], [1], [2, 5], 5],
   [['d1', 'd2', 'd3', 'd4', 'd5'], ['B', 'A', 'B', 'A', 'A'], 'B'])],
 [('shared top document is placed once',
   [['d1', 'd2', 'd3'], ['d1', 'd3', 'd4'], [0, 1], [1], 4],
   [['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']),
  ('team behind picks next',
   [['d1', 'd2'], ['d3', 'd4'], [0], [2], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']),
  ('shared document credits the team that placed it',
   [['d1', 'd2'], ['d2', 'd1'], [1], [0], 2],
   [['d2', 'd1'], ['B', 'A'], 'B']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('no clicks is a tie', [['d1', 'd2'], ['d3'], [1], [], 3], [['d3', 'd1', 'd2'], ['B', 'A', 'A'], 'tie']),
  ('query sample 6',
   [['d1', 'd4', 'd5'], ['d5', 'd3', 'd2'], [0], [1], 6],
   [['d1', 'd5', 'd4', 'd3', 'd2'], ['A', 'B', 'A', 'B', 'B'], 'B']),
  ('query sample 11',
   [['d4', 'd2', 'd5'], ['d5', 'd2', 'd1', 'd6'], [1, 0], [], 6],
   [['d5', 'd4', 'd2', 'd1', 'd6'], ['B', 'A', 'A', 'B', 'B'], 'tie']),
  ('query sample 12',
   [['d1', 'd4', 'd5', 'd6', 'd2'], ['d6', 'd2', 'd5'], [0, 1, 0], [], 3],
   [['d1', 'd6', 'd2'], ['A', 'B', 'B'], 'tie'])],
 [('shared top document is placed once',
   [['d1', 'd2', 'd3'], ['d1', 'd3', 'd4'], [0, 1], [1], 4],
   [['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']),
  ('coins are consumed only on ties',
   [['d1', 'd2', 'd3'], ['d4', 'd5', 'd6'], [1, 0], [0, 3], 6],
   [['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']),
  ('shared document credits the team that placed it',
   [['d1', 'd2'], ['d2', 'd1'], [1], [0], 2],
   [['d2', 'd1'], ['B', 'A'], 'B']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('no clicks is a tie', [['d1', 'd2'], ['d3'], [1], [], 3], [['d3', 'd1', 'd2'], ['B', 'A', 'A'], 'tie']),
  ('query sample 16',
   [['d1', 'd3', 'd4', 'd2'], ['d3', 'd2', 'd1', 'd5'], [0, 1, 1], [], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'B', 'A'], 'tie']),
  ('query sample 17',
   [['d4', 'd2'], ['d3', 'd5', 'd6', 'd4', 'd2'], [1, 1], [], 5],
   [['d3', 'd4', 'd5', 'd2', 'd6'], ['B', 'A', 'B', 'A', 'B'], 'tie']),
  ('query sample 45',
   [['d4', 'd1'], ['d5', 'd2', 'd3', 'd4'], [0, 1], [0, 5], 4],
   [['d4', 'd5', 'd2', 'd1'], ['A', 'B', 'B', 'A'], 'A'])],
 [('shared top document is placed once',
   [['d1', 'd2', 'd3'], ['d1', 'd3', 'd4'], [0, 1], [1], 4],
   [['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']),
  ('coins are consumed only on ties',
   [['d1', 'd2', 'd3'], ['d4', 'd5', 'd6'], [1, 0], [0, 3], 6],
   [['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']),
  ('team behind picks next',
   [['d1', 'd2'], ['d3', 'd4'], [0], [2], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('no clicks is a tie', [['d1', 'd2'], ['d3'], [1], [], 3], [['d3', 'd1', 'd2'], ['B', 'A', 'A'], 'tie']),
  ('query sample 21',
   [['d5', 'd3'], ['d2', 'd3', 'd6', 'd4', 'd5'], [1, 1], [], 5],
   [['d2', 'd5', 'd3', 'd6', 'd4'], ['B', 'A', 'B', 'B', 'B'], 'tie']),
  ('query sample 22',
   [['d1', 'd4'], ['d1', 'd6', 'd3', 'd5', 'd2'], [0], [4], 4],
   [['d1', 'd6', 'd4', 'd3'], ['A', 'B', 'A', 'B'], 'tie']),
  ('query sample 25',
   [['d5', 'd3', 'd2'], ['d2', 'd3', 'd4'], [1], [0, 2], 5],
   [['d2', 'd5', 'd3', 'd4'], ['B', 'A', 'B', 'B'], 'B'])]]
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
shared top document is placed once[['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'tie'][['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']Failed
coins are consumed only on ties[['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B'][['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']Passed
team behind picks next[['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A'][['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']Passed
shared document credits the team that placed it[['d2', 'd1'], ['B', 'A'], 'tie'][['d2', 'd1'], ['B', 'A'], 'B']Failed
exhausted ranking yields[['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B'][['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']Passed
query sample 1[['d4', 'd5', 'd3', 'd6', 'd2'], ['A', 'B', 'A', 'B', 'A'], 'tie'][['d4', 'd5', 'd3', 'd6', 'd2'], ['A', 'B', 'A', 'B', 'A'], 'tie']Passed
query sample 2[['d6', 'd5', 'd1', 'd2'], ['B', 'A', 'A', 'A'], 'tie'][['d6', 'd5', 'd1', 'd2'], ['B', 'A', 'A', 'A'], 'tie']Passed
query sample 3[['d5', 'd6', 'd4', 'd3', 'd1'], ['A', 'B', 'A', 'B', 'B'], 'tie'][['d5', 'd6', 'd4', 'd3', 'd1'], ['A', 'B', 'A', 'B', 'B'], 'tie']Passed

SHA-256 / 7f70b9a14b1771f850fddd07b1955f46fc9ca0cbf1db16ec5ca73d14073875a1

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(rank_a, rank_b, coins, clicks, length):
    out, team = [], []
    ia = ib = ci = 0
    while len(out) < length:
        while ia < len(rank_a) and rank_a[ia] in out:
            ia += 1
        while ib < len(rank_b) and rank_b[ib] in out:
            ib += 1
        has_a, has_b = ia < len(rank_a), ib < len(rank_b)
        if not has_a and not has_b:
            break
        na, nb = team.count('A'), team.count('B')
        if na == nb:
            pick_a = coins[ci % len(coins)] == 0
            ci += 1
        else:
            pick_a = na < nb
        if pick_a and not has_a:
            pick_a = False
        elif not pick_a and not has_b:
            pick_a = True
        if pick_a:
            out.append(rank_a[ia])
            team.append('A')
        else:
            out.append(rank_b[ib])
            team.append('B')
    credit_a = sum(1 for i in clicks if i < len(out) and out[i] in rank_a and out[i] not in rank_b)
    credit_b = sum(1 for i in clicks if i < len(out) and out[i] in rank_b and out[i] not in rank_a)
    winner = 'A' if credit_a > credit_b else 'B' if credit_b > credit_a else 'tie'
    return [out, team, winner]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('shared top document is placed once',
   [['d1', 'd2', 'd3'], ['d1', 'd3', 'd4'], [0, 1], [1], 4],
   [['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']),
  ('coins are consumed only on ties',
   [['d1', 'd2', 'd3'], ['d4', 'd5', 'd6'], [1, 0], [0, 3], 6],
   [['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']),
  ('team behind picks next',
   [['d1', 'd2'], ['d3', 'd4'], [0], [2], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']),
  ('shared document credits the team that placed it',
   [['d1', 'd2'], ['d2', 'd1'], [1], [0], 2],
   [['d2', 'd1'], ['B', 'A'], 'B']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('query sample 1',
   [['d4', 'd3', 'd2'], ['d5', 'd6'], [0], [], 6],
   [['d4', 'd5', 'd3', 'd6', 'd2'], ['A', 'B', 'A', 'B', 'A'], 'tie']),
  ('query sample 2',
   [['d6', 'd5', 'd1', 'd2'], ['d6', 'd5'], [1, 1, 1], [], 4],
   [['d6', 'd5', 'd1', 'd2'], ['B', 'A', 'A', 'A'], 'tie']),
  ('query sample 3',
   [['d5', 'd4'], ['d6', 'd3', 'd5', 'd1'], [0], [], 5],
   [['d5', 'd6', 'd4', 'd3', 'd1'], ['A', 'B', 'A', 'B', 'B'], 'tie'])],
 [('coins are consumed only on ties',
   [['d1', 'd2', 'd3'], ['d4', 'd5', 'd6'], [1, 0], [0, 3], 6],
   [['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']),
  ('team behind picks next',
   [['d1', 'd2'], ['d3', 'd4'], [0], [2], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']),
  ('shared document credits the team that placed it',
   [['d1', 'd2'], ['d2', 'd1'], [1], [0], 2],
   [['d2', 'd1'], ['B', 'A'], 'B']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('no clicks is a tie', [['d1', 'd2'], ['d3'], [1], [], 3], [['d3', 'd1', 'd2'], ['B', 'A', 'A'], 'tie']),
  ('query sample 6',
   [['d1', 'd4', 'd5'], ['d5', 'd3', 'd2'], [0], [1], 6],
   [['d1', 'd5', 'd4', 'd3', 'd2'], ['A', 'B', 'A', 'B', 'B'], 'B']),
  ('query sample 7',
   [['d4', 'd1', 'd6'], ['d1', 'd6', 'd2', 'd4', 'd3'], [0, 0, 1], [4, 5], 5],
   [['d4', 'd1', 'd6', 'd2', 'd3'], ['A', 'B', 'A', 'B', 'B'], 'B']),
  ('query sample 31',
   [['d2', 'd4', 'd5', 'd6', 'd3'], ['d1', 'd3'], [1], [2, 5], 5],
   [['d1', 'd2', 'd3', 'd4', 'd5'], ['B', 'A', 'B', 'A', 'A'], 'B'])],
 [('shared top document is placed once',
   [['d1', 'd2', 'd3'], ['d1', 'd3', 'd4'], [0, 1], [1], 4],
   [['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']),
  ('team behind picks next',
   [['d1', 'd2'], ['d3', 'd4'], [0], [2], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']),
  ('shared document credits the team that placed it',
   [['d1', 'd2'], ['d2', 'd1'], [1], [0], 2],
   [['d2', 'd1'], ['B', 'A'], 'B']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('no clicks is a tie', [['d1', 'd2'], ['d3'], [1], [], 3], [['d3', 'd1', 'd2'], ['B', 'A', 'A'], 'tie']),
  ('query sample 6',
   [['d1', 'd4', 'd5'], ['d5', 'd3', 'd2'], [0], [1], 6],
   [['d1', 'd5', 'd4', 'd3', 'd2'], ['A', 'B', 'A', 'B', 'B'], 'B']),
  ('query sample 11',
   [['d4', 'd2', 'd5'], ['d5', 'd2', 'd1', 'd6'], [1, 0], [], 6],
   [['d5', 'd4', 'd2', 'd1', 'd6'], ['B', 'A', 'A', 'B', 'B'], 'tie']),
  ('query sample 12',
   [['d1', 'd4', 'd5', 'd6', 'd2'], ['d6', 'd2', 'd5'], [0, 1, 0], [], 3],
   [['d1', 'd6', 'd2'], ['A', 'B', 'B'], 'tie'])],
 [('shared top document is placed once',
   [['d1', 'd2', 'd3'], ['d1', 'd3', 'd4'], [0, 1], [1], 4],
   [['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']),
  ('coins are consumed only on ties',
   [['d1', 'd2', 'd3'], ['d4', 'd5', 'd6'], [1, 0], [0, 3], 6],
   [['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']),
  ('shared document credits the team that placed it',
   [['d1', 'd2'], ['d2', 'd1'], [1], [0], 2],
   [['d2', 'd1'], ['B', 'A'], 'B']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('no clicks is a tie', [['d1', 'd2'], ['d3'], [1], [], 3], [['d3', 'd1', 'd2'], ['B', 'A', 'A'], 'tie']),
  ('query sample 16',
   [['d1', 'd3', 'd4', 'd2'], ['d3', 'd2', 'd1', 'd5'], [0, 1, 1], [], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'B', 'A'], 'tie']),
  ('query sample 17',
   [['d4', 'd2'], ['d3', 'd5', 'd6', 'd4', 'd2'], [1, 1], [], 5],
   [['d3', 'd4', 'd5', 'd2', 'd6'], ['B', 'A', 'B', 'A', 'B'], 'tie']),
  ('query sample 45',
   [['d4', 'd1'], ['d5', 'd2', 'd3', 'd4'], [0, 1], [0, 5], 4],
   [['d4', 'd5', 'd2', 'd1'], ['A', 'B', 'B', 'A'], 'A'])],
 [('shared top document is placed once',
   [['d1', 'd2', 'd3'], ['d1', 'd3', 'd4'], [0, 1], [1], 4],
   [['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']),
  ('coins are consumed only on ties',
   [['d1', 'd2', 'd3'], ['d4', 'd5', 'd6'], [1, 0], [0, 3], 6],
   [['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']),
  ('team behind picks next',
   [['d1', 'd2'], ['d3', 'd4'], [0], [2], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('no clicks is a tie', [['d1', 'd2'], ['d3'], [1], [], 3], [['d3', 'd1', 'd2'], ['B', 'A', 'A'], 'tie']),
  ('query sample 21',
   [['d5', 'd3'], ['d2', 'd3', 'd6', 'd4', 'd5'], [1, 1], [], 5],
   [['d2', 'd5', 'd3', 'd6', 'd4'], ['B', 'A', 'B', 'B', 'B'], 'tie']),
  ('query sample 22',
   [['d1', 'd4'], ['d1', 'd6', 'd3', 'd5', 'd2'], [0], [4], 4],
   [['d1', 'd6', 'd4', 'd3'], ['A', 'B', 'A', 'B'], 'tie']),
  ('query sample 25',
   [['d5', 'd3', 'd2'], ['d2', 'd3', 'd4'], [1], [0, 2], 5],
   [['d2', 'd5', 'd3', 'd4'], ['B', 'A', 'B', 'B'], 'B'])]]
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
shared top document is placed once[['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'tie'][['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']Failed
coins are consumed only on ties[['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B'][['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']Passed
team behind picks next[['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A'][['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']Passed
shared document credits the team that placed it[['d2', 'd1'], ['B', 'A'], 'tie'][['d2', 'd1'], ['B', 'A'], 'B']Failed
exhausted ranking yields[['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B'][['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']Passed
query sample 1[['d4', 'd5', 'd3', 'd6', 'd2'], ['A', 'B', 'A', 'B', 'A'], 'tie'][['d4', 'd5', 'd3', 'd6', 'd2'], ['A', 'B', 'A', 'B', 'A'], 'tie']Passed
query sample 2[['d6', 'd5', 'd1', 'd2'], ['B', 'A', 'A', 'A'], 'tie'][['d6', 'd5', 'd1', 'd2'], ['B', 'A', 'A', 'A'], 'tie']Passed
query sample 3[['d5', 'd6', 'd4', 'd3', 'd1'], ['A', 'B', 'A', 'B', 'B'], 'tie'][['d5', 'd6', 'd4', 'd3', 'd1'], ['A', 'B', 'A', 'B', 'B'], 'tie']Passed

SHA-256 / 9abcd321f8454ec839361a4f43663fb9956e9703a3de0744d1bae3f8bb821651

3 / The verified repair

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

N = 1
observations = []
def solve(rank_a, rank_b, coins, clicks, length):
    out, team = [], []
    ia = ib = ci = 0
    while len(out) < length:
        while ia < len(rank_a) and rank_a[ia] in out:
            ia += 1
        while ib < len(rank_b) and rank_b[ib] in out:
            ib += 1
        has_a, has_b = ia < len(rank_a), ib < len(rank_b)
        if not has_a and not has_b:
            break
        na, nb = team.count('A'), team.count('B')
        if na == nb:
            pick_a = coins[ci % len(coins)] == 0
            ci += 1
        else:
            pick_a = na < nb
        if pick_a and not has_a:
            pick_a = False
        elif not pick_a and not has_b:
            pick_a = True
        if pick_a:
            out.append(rank_a[ia])
            team.append('A')
        else:
            out.append(rank_b[ib])
            team.append('B')
    credit_a = sum(1 for i in clicks if i < len(out) and team[i] == 'A')
    credit_b = sum(1 for i in clicks if i < len(out) and team[i] == 'B')
    winner = 'A' if credit_a > credit_b else 'B' if credit_b > credit_a else 'tie'
    return [out, team, winner]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('shared top document is placed once',
   [['d1', 'd2', 'd3'], ['d1', 'd3', 'd4'], [0, 1], [1], 4],
   [['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']),
  ('coins are consumed only on ties',
   [['d1', 'd2', 'd3'], ['d4', 'd5', 'd6'], [1, 0], [0, 3], 6],
   [['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']),
  ('team behind picks next',
   [['d1', 'd2'], ['d3', 'd4'], [0], [2], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']),
  ('shared document credits the team that placed it',
   [['d1', 'd2'], ['d2', 'd1'], [1], [0], 2],
   [['d2', 'd1'], ['B', 'A'], 'B']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('query sample 1',
   [['d4', 'd3', 'd2'], ['d5', 'd6'], [0], [], 6],
   [['d4', 'd5', 'd3', 'd6', 'd2'], ['A', 'B', 'A', 'B', 'A'], 'tie']),
  ('query sample 2',
   [['d6', 'd5', 'd1', 'd2'], ['d6', 'd5'], [1, 1, 1], [], 4],
   [['d6', 'd5', 'd1', 'd2'], ['B', 'A', 'A', 'A'], 'tie']),
  ('query sample 3',
   [['d5', 'd4'], ['d6', 'd3', 'd5', 'd1'], [0], [], 5],
   [['d5', 'd6', 'd4', 'd3', 'd1'], ['A', 'B', 'A', 'B', 'B'], 'tie'])],
 [('coins are consumed only on ties',
   [['d1', 'd2', 'd3'], ['d4', 'd5', 'd6'], [1, 0], [0, 3], 6],
   [['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']),
  ('team behind picks next',
   [['d1', 'd2'], ['d3', 'd4'], [0], [2], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']),
  ('shared document credits the team that placed it',
   [['d1', 'd2'], ['d2', 'd1'], [1], [0], 2],
   [['d2', 'd1'], ['B', 'A'], 'B']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('no clicks is a tie', [['d1', 'd2'], ['d3'], [1], [], 3], [['d3', 'd1', 'd2'], ['B', 'A', 'A'], 'tie']),
  ('query sample 6',
   [['d1', 'd4', 'd5'], ['d5', 'd3', 'd2'], [0], [1], 6],
   [['d1', 'd5', 'd4', 'd3', 'd2'], ['A', 'B', 'A', 'B', 'B'], 'B']),
  ('query sample 7',
   [['d4', 'd1', 'd6'], ['d1', 'd6', 'd2', 'd4', 'd3'], [0, 0, 1], [4, 5], 5],
   [['d4', 'd1', 'd6', 'd2', 'd3'], ['A', 'B', 'A', 'B', 'B'], 'B']),
  ('query sample 31',
   [['d2', 'd4', 'd5', 'd6', 'd3'], ['d1', 'd3'], [1], [2, 5], 5],
   [['d1', 'd2', 'd3', 'd4', 'd5'], ['B', 'A', 'B', 'A', 'A'], 'B'])],
 [('shared top document is placed once',
   [['d1', 'd2', 'd3'], ['d1', 'd3', 'd4'], [0, 1], [1], 4],
   [['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']),
  ('team behind picks next',
   [['d1', 'd2'], ['d3', 'd4'], [0], [2], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']),
  ('shared document credits the team that placed it',
   [['d1', 'd2'], ['d2', 'd1'], [1], [0], 2],
   [['d2', 'd1'], ['B', 'A'], 'B']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('no clicks is a tie', [['d1', 'd2'], ['d3'], [1], [], 3], [['d3', 'd1', 'd2'], ['B', 'A', 'A'], 'tie']),
  ('query sample 6',
   [['d1', 'd4', 'd5'], ['d5', 'd3', 'd2'], [0], [1], 6],
   [['d1', 'd5', 'd4', 'd3', 'd2'], ['A', 'B', 'A', 'B', 'B'], 'B']),
  ('query sample 11',
   [['d4', 'd2', 'd5'], ['d5', 'd2', 'd1', 'd6'], [1, 0], [], 6],
   [['d5', 'd4', 'd2', 'd1', 'd6'], ['B', 'A', 'A', 'B', 'B'], 'tie']),
  ('query sample 12',
   [['d1', 'd4', 'd5', 'd6', 'd2'], ['d6', 'd2', 'd5'], [0, 1, 0], [], 3],
   [['d1', 'd6', 'd2'], ['A', 'B', 'B'], 'tie'])],
 [('shared top document is placed once',
   [['d1', 'd2', 'd3'], ['d1', 'd3', 'd4'], [0, 1], [1], 4],
   [['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']),
  ('coins are consumed only on ties',
   [['d1', 'd2', 'd3'], ['d4', 'd5', 'd6'], [1, 0], [0, 3], 6],
   [['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']),
  ('shared document credits the team that placed it',
   [['d1', 'd2'], ['d2', 'd1'], [1], [0], 2],
   [['d2', 'd1'], ['B', 'A'], 'B']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('no clicks is a tie', [['d1', 'd2'], ['d3'], [1], [], 3], [['d3', 'd1', 'd2'], ['B', 'A', 'A'], 'tie']),
  ('query sample 16',
   [['d1', 'd3', 'd4', 'd2'], ['d3', 'd2', 'd1', 'd5'], [0, 1, 1], [], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'B', 'A'], 'tie']),
  ('query sample 17',
   [['d4', 'd2'], ['d3', 'd5', 'd6', 'd4', 'd2'], [1, 1], [], 5],
   [['d3', 'd4', 'd5', 'd2', 'd6'], ['B', 'A', 'B', 'A', 'B'], 'tie']),
  ('query sample 45',
   [['d4', 'd1'], ['d5', 'd2', 'd3', 'd4'], [0, 1], [0, 5], 4],
   [['d4', 'd5', 'd2', 'd1'], ['A', 'B', 'B', 'A'], 'A'])],
 [('shared top document is placed once',
   [['d1', 'd2', 'd3'], ['d1', 'd3', 'd4'], [0, 1], [1], 4],
   [['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']),
  ('coins are consumed only on ties',
   [['d1', 'd2', 'd3'], ['d4', 'd5', 'd6'], [1, 0], [0, 3], 6],
   [['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']),
  ('team behind picks next',
   [['d1', 'd2'], ['d3', 'd4'], [0], [2], 4],
   [['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']),
  ('exhausted ranking yields',
   [['d1'], ['d2', 'd3', 'd4'], [0], [3], 4],
   [['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']),
  ('no clicks is a tie', [['d1', 'd2'], ['d3'], [1], [], 3], [['d3', 'd1', 'd2'], ['B', 'A', 'A'], 'tie']),
  ('query sample 21',
   [['d5', 'd3'], ['d2', 'd3', 'd6', 'd4', 'd5'], [1, 1], [], 5],
   [['d2', 'd5', 'd3', 'd6', 'd4'], ['B', 'A', 'B', 'B', 'B'], 'tie']),
  ('query sample 22',
   [['d1', 'd4'], ['d1', 'd6', 'd3', 'd5', 'd2'], [0], [4], 4],
   [['d1', 'd6', 'd4', 'd3'], ['A', 'B', 'A', 'B'], 'tie']),
  ('query sample 25',
   [['d5', 'd3', 'd2'], ['d2', 'd3', 'd4'], [1], [0, 2], 5],
   [['d2', 'd5', 'd3', 'd4'], ['B', 'A', 'B', 'B'], 'B'])]]
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
shared top document is placed once[['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B'][['d1', 'd3', 'd4', 'd2'], ['A', 'B', 'B', 'A'], 'B']Passed
coins are consumed only on ties[['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B'][['d4', 'd1', 'd2', 'd5', 'd6', 'd3'], ['B', 'A', 'A', 'B', 'B', 'A'], 'B']Passed
team behind picks next[['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A'][['d1', 'd3', 'd2', 'd4'], ['A', 'B', 'A', 'B'], 'A']Passed
shared document credits the team that placed it[['d2', 'd1'], ['B', 'A'], 'B'][['d2', 'd1'], ['B', 'A'], 'B']Passed
exhausted ranking yields[['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B'][['d1', 'd2', 'd3', 'd4'], ['A', 'B', 'B', 'B'], 'B']Passed
query sample 1[['d4', 'd5', 'd3', 'd6', 'd2'], ['A', 'B', 'A', 'B', 'A'], 'tie'][['d4', 'd5', 'd3', 'd6', 'd2'], ['A', 'B', 'A', 'B', 'A'], 'tie']Passed
query sample 2[['d6', 'd5', 'd1', 'd2'], ['B', 'A', 'A', 'A'], 'tie'][['d6', 'd5', 'd1', 'd2'], ['B', 'A', 'A', 'A'], 'tie']Passed
query sample 3[['d5', 'd6', 'd4', 'd3', 'd1'], ['A', 'B', 'A', 'B', 'B'], 'tie'][['d5', 'd6', 'd4', 'd3', 'd1'], ['A', 'B', 'A', 'B', 'B'], 'tie']Passed

SHA-256 / afa31581831271dcff445b66bf7f1cab674fc6fab2f19df7b93da800f20aca3f

Verification & scope

A deterministic toy experiment-analysis model with a stipulated contract; results are rounded and are not a substitute for a validated statistics package. 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 2026-09-29T14:48:59.851164+00:00.

Case digest / 5f2036c702e93516ea8349e608e7511ab689c0ee84c45d43b553638a83f60118