FA-81856 / Poker hand evaluation / Open access

One pair hands leak into the two pair branch · case 01

A single pair of nines with three unpaired cards is labelled two pair.

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

ROOT CAUSE

The two pair test allows four distinct ranks, which is the one pair shape.

VERIFIED REPAIR

Require the count shape [2,2,1], i.e. exactly three distinct ranks with two pairs.

Unsuccessful approach: Testing whether any rank appears twice is just the one pair predicate again.

Case contract

Input: five distinct cards as rank+suit strings; ranks 2-9, T or 10, J, Q, K, A (case-insensitive), suits c/d/h/s (case-insensitive). Return the standard five-card category name in lower case; A-2-3-4-5 is a straight; royal flush is reported as "straight flush".

Why this case matters

Poker engines settle real money pots from these comparisons; a single misranked hand pays the wrong seat.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import collections
N = 1
observations = []
def solve(x):
    R='23456789TJQKA'
    vals=sorted((R.index('T' if c[:-1]=='10' else c[:-1].upper())+2 for c in x), reverse=True)
    suits=[c[-1].lower() for c in x]
    cnt=sorted(collections.Counter(vals).values(), reverse=True)
    flush=len(set(suits))==1
    uniq=sorted(set(vals))
    straight=False
    if len(uniq)==5:
        if uniq[4]-uniq[0]==4: straight=True
        elif uniq==[2,3,4,5,14]: straight=True
    if straight and flush: return 'straight flush'
    if cnt[0]==4: return 'four of a kind'
    if cnt==[3,2]: return 'full house'
    if flush: return 'flush'
    if straight: return 'straight'
    if cnt[0]==3: return 'three of a kind'
    if cnt[0]==2 and len(cnt)<=4: return 'two pair'
    if cnt[0]==2: return 'one pair'
    return 'high card'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('wheel straight', ['Ah', '2d', '3c', '4s', '5h'], 'straight'),
  ('wheel straight flush', ['As', '2s', '3s', '4s', '5s'], 'straight flush'),
  ('four to wheel plus nine', ['2h', '3d', '4c', '5s', '9h'], 'high card'),
  ('four to wheel plus king', ['2h', '3d', '4c', '5s', 'Kh'], 'high card'),
  ('plain flush', ['2h', '7h', '9h', 'Jh', 'Kh'], 'flush'),
  ('broadway', ['Th', 'Jd', 'Qc', 'Ks', 'Ah'], 'straight'),
  ('trips', ['7h', '7d', '7c', 'Ks', '2h'], 'three of a kind'),
  ('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair')],
 [('four to wheel plus king', ['2h', '3d', '4c', '5s', 'Kh'], 'high card'),
  ('plain flush', ['2h', '7h', '9h', 'Jh', 'Kh'], 'flush'),
  ('broadway', ['Th', 'Jd', 'Qc', 'Ks', 'Ah'], 'straight'),
  ('trips', ['7h', '7d', '7c', 'Ks', '2h'], 'three of a kind'),
  ('full house', ['7h', '7d', '7c', 'Ks', 'Kh'], 'full house'),
  ('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair'),
  ('two pair', ['9h', '9d', '4c', '4s', '2h'], 'two pair'),
  ('ten written as 10', ['10h', 'Jd', 'Qc', 'Ks', '9h'], 'straight')],
 [('trips', ['7h', '7d', '7c', 'Ks', '2h'], 'three of a kind'),
  ('full house', ['7h', '7d', '7c', 'Ks', 'Kh'], 'full house'),
  ('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair'),
  ('two pair', ['9h', '9d', '4c', '4s', '2h'], 'two pair'),
  ('ten written as 10', ['10h', 'Jd', 'Qc', 'Ks', '9h'], 'straight'),
  ('lower-case ranks', ['kd', 'kh', '3c', '3s', '8h'], 'two pair'),
  ('mixed-case suits flush', ['2H', '7h', '9h', 'JH', 'Kh'], 'flush'),
  ('four-flush only', ['2h', '7h', '9h', 'Jh', 'Ks'], 'high card')],
 [('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair'),
  ('ten written as 10', ['10h', 'Jd', 'Qc', 'Ks', '9h'], 'straight'),
  ('lower-case ranks', ['kd', 'kh', '3c', '3s', '8h'], 'two pair'),
  ('mixed-case suits flush', ['2H', '7h', '9h', 'JH', 'Kh'], 'flush'),
  ('four-flush only', ['2h', '7h', '9h', 'Jh', 'Ks'], 'high card'),
  ('quads', ['6h', '6d', '6c', '6s', '2h'], 'four of a kind'),
  ('high card', ['2h', '7d', '9c', 'Js', 'Kh'], 'high card'),
  ('straight flush middle', ['5d', '6d', '7d', '8d', '9d'], 'straight flush')],
 [('wheel straight', ['Ah', '2d', '3c', '4s', '5h'], 'straight'),
  ('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair'),
  ('four-flush only', ['2h', '7h', '9h', 'Jh', 'Ks'], 'high card'),
  ('quads', ['6h', '6d', '6c', '6s', '2h'], 'four of a kind'),
  ('high card', ['2h', '7d', '9c', 'Js', 'Kh'], 'high card'),
  ('straight flush middle', ['5d', '6d', '7d', '8d', '9d'], 'straight flush'),
  ('ten flush with 10 token', ['10c', '2c', '5c', '8c', 'Qc'], 'flush'),
  ('flush ends match only', ['2h', '7d', '9h', 'Jc', 'Kh'], 'high card')]]
for label, args, expected in fixtures[N-1]:
    try:
        actual = solve(args)
    except Exception as exc:
        actual = 'error:' + type(exc).__name__
    check(label, actual, 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
wheel straight	`straight`	`straight`	Passed
wheel straight flush	`straight flush`	`straight flush`	Passed
four to wheel plus nine	`high card`	`high card`	Passed
four to wheel plus king	`high card`	`high card`	Passed
plain flush	`flush`	`flush`	Passed
broadway	`straight`	`straight`	Passed
trips	`three of a kind`	`three of a kind`	Passed
one pair	`two pair`	`one pair`	Failed

SHA-256 / bde0ed45554547c6e9af02ec9a38c05b42803a1d8e418618782841d99c6fa76b

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import collections
N = 1
observations = []
def solve(x):
    R='23456789TJQKA'
    vals=sorted((R.index('T' if c[:-1]=='10' else c[:-1].upper())+2 for c in x), reverse=True)
    suits=[c[-1].lower() for c in x]
    cnt=sorted(collections.Counter(vals).values(), reverse=True)
    flush=len(set(suits))==1
    uniq=sorted(set(vals))
    straight=False
    if len(uniq)==5:
        if uniq[4]-uniq[0]==4: straight=True
        elif uniq==[2,3,4,5,14]: straight=True
    if straight and flush: return 'straight flush'
    if cnt[0]==4: return 'four of a kind'
    if cnt==[3,2]: return 'full house'
    if flush: return 'flush'
    if straight: return 'straight'
    if cnt[0]==3: return 'three of a kind'
    if 2 in cnt: return 'two pair'
    if cnt[0]==2: return 'one pair'
    return 'high card'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('wheel straight', ['Ah', '2d', '3c', '4s', '5h'], 'straight'),
  ('wheel straight flush', ['As', '2s', '3s', '4s', '5s'], 'straight flush'),
  ('four to wheel plus nine', ['2h', '3d', '4c', '5s', '9h'], 'high card'),
  ('four to wheel plus king', ['2h', '3d', '4c', '5s', 'Kh'], 'high card'),
  ('plain flush', ['2h', '7h', '9h', 'Jh', 'Kh'], 'flush'),
  ('broadway', ['Th', 'Jd', 'Qc', 'Ks', 'Ah'], 'straight'),
  ('trips', ['7h', '7d', '7c', 'Ks', '2h'], 'three of a kind'),
  ('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair')],
 [('four to wheel plus king', ['2h', '3d', '4c', '5s', 'Kh'], 'high card'),
  ('plain flush', ['2h', '7h', '9h', 'Jh', 'Kh'], 'flush'),
  ('broadway', ['Th', 'Jd', 'Qc', 'Ks', 'Ah'], 'straight'),
  ('trips', ['7h', '7d', '7c', 'Ks', '2h'], 'three of a kind'),
  ('full house', ['7h', '7d', '7c', 'Ks', 'Kh'], 'full house'),
  ('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair'),
  ('two pair', ['9h', '9d', '4c', '4s', '2h'], 'two pair'),
  ('ten written as 10', ['10h', 'Jd', 'Qc', 'Ks', '9h'], 'straight')],
 [('trips', ['7h', '7d', '7c', 'Ks', '2h'], 'three of a kind'),
  ('full house', ['7h', '7d', '7c', 'Ks', 'Kh'], 'full house'),
  ('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair'),
  ('two pair', ['9h', '9d', '4c', '4s', '2h'], 'two pair'),
  ('ten written as 10', ['10h', 'Jd', 'Qc', 'Ks', '9h'], 'straight'),
  ('lower-case ranks', ['kd', 'kh', '3c', '3s', '8h'], 'two pair'),
  ('mixed-case suits flush', ['2H', '7h', '9h', 'JH', 'Kh'], 'flush'),
  ('four-flush only', ['2h', '7h', '9h', 'Jh', 'Ks'], 'high card')],
 [('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair'),
  ('ten written as 10', ['10h', 'Jd', 'Qc', 'Ks', '9h'], 'straight'),
  ('lower-case ranks', ['kd', 'kh', '3c', '3s', '8h'], 'two pair'),
  ('mixed-case suits flush', ['2H', '7h', '9h', 'JH', 'Kh'], 'flush'),
  ('four-flush only', ['2h', '7h', '9h', 'Jh', 'Ks'], 'high card'),
  ('quads', ['6h', '6d', '6c', '6s', '2h'], 'four of a kind'),
  ('high card', ['2h', '7d', '9c', 'Js', 'Kh'], 'high card'),
  ('straight flush middle', ['5d', '6d', '7d', '8d', '9d'], 'straight flush')],
 [('wheel straight', ['Ah', '2d', '3c', '4s', '5h'], 'straight'),
  ('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair'),
  ('four-flush only', ['2h', '7h', '9h', 'Jh', 'Ks'], 'high card'),
  ('quads', ['6h', '6d', '6c', '6s', '2h'], 'four of a kind'),
  ('high card', ['2h', '7d', '9c', 'Js', 'Kh'], 'high card'),
  ('straight flush middle', ['5d', '6d', '7d', '8d', '9d'], 'straight flush'),
  ('ten flush with 10 token', ['10c', '2c', '5c', '8c', 'Qc'], 'flush'),
  ('flush ends match only', ['2h', '7d', '9h', 'Jc', 'Kh'], 'high card')]]
for label, args, expected in fixtures[N-1]:
    try:
        actual = solve(args)
    except Exception as exc:
        actual = 'error:' + type(exc).__name__
    check(label, actual, 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
wheel straight	`straight`	`straight`	Passed
wheel straight flush	`straight flush`	`straight flush`	Passed
four to wheel plus nine	`high card`	`high card`	Passed
four to wheel plus king	`high card`	`high card`	Passed
plain flush	`flush`	`flush`	Passed
broadway	`straight`	`straight`	Passed
trips	`three of a kind`	`three of a kind`	Passed
one pair	`two pair`	`one pair`	Failed

SHA-256 / 3eeb2b013d4a2e4349494fab4d086f1997772ca7068680e29b2d1ab32e939777

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import collections
N = 1
observations = []
def solve(x):
    R='23456789TJQKA'
    vals=sorted((R.index('T' if c[:-1]=='10' else c[:-1].upper())+2 for c in x), reverse=True)
    suits=[c[-1].lower() for c in x]
    cnt=sorted(collections.Counter(vals).values(), reverse=True)
    flush=len(set(suits))==1
    uniq=sorted(set(vals))
    straight=False
    if len(uniq)==5:
        if uniq[4]-uniq[0]==4: straight=True
        elif uniq==[2,3,4,5,14]: straight=True
    if straight and flush: return 'straight flush'
    if cnt[0]==4: return 'four of a kind'
    if cnt==[3,2]: return 'full house'
    if flush: return 'flush'
    if straight: return 'straight'
    if cnt[0]==3: return 'three of a kind'
    if cnt==[2,2,1]: return 'two pair'
    if cnt[0]==2: return 'one pair'
    return 'high card'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('wheel straight', ['Ah', '2d', '3c', '4s', '5h'], 'straight'),
  ('wheel straight flush', ['As', '2s', '3s', '4s', '5s'], 'straight flush'),
  ('four to wheel plus nine', ['2h', '3d', '4c', '5s', '9h'], 'high card'),
  ('four to wheel plus king', ['2h', '3d', '4c', '5s', 'Kh'], 'high card'),
  ('plain flush', ['2h', '7h', '9h', 'Jh', 'Kh'], 'flush'),
  ('broadway', ['Th', 'Jd', 'Qc', 'Ks', 'Ah'], 'straight'),
  ('trips', ['7h', '7d', '7c', 'Ks', '2h'], 'three of a kind'),
  ('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair')],
 [('four to wheel plus king', ['2h', '3d', '4c', '5s', 'Kh'], 'high card'),
  ('plain flush', ['2h', '7h', '9h', 'Jh', 'Kh'], 'flush'),
  ('broadway', ['Th', 'Jd', 'Qc', 'Ks', 'Ah'], 'straight'),
  ('trips', ['7h', '7d', '7c', 'Ks', '2h'], 'three of a kind'),
  ('full house', ['7h', '7d', '7c', 'Ks', 'Kh'], 'full house'),
  ('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair'),
  ('two pair', ['9h', '9d', '4c', '4s', '2h'], 'two pair'),
  ('ten written as 10', ['10h', 'Jd', 'Qc', 'Ks', '9h'], 'straight')],
 [('trips', ['7h', '7d', '7c', 'Ks', '2h'], 'three of a kind'),
  ('full house', ['7h', '7d', '7c', 'Ks', 'Kh'], 'full house'),
  ('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair'),
  ('two pair', ['9h', '9d', '4c', '4s', '2h'], 'two pair'),
  ('ten written as 10', ['10h', 'Jd', 'Qc', 'Ks', '9h'], 'straight'),
  ('lower-case ranks', ['kd', 'kh', '3c', '3s', '8h'], 'two pair'),
  ('mixed-case suits flush', ['2H', '7h', '9h', 'JH', 'Kh'], 'flush'),
  ('four-flush only', ['2h', '7h', '9h', 'Jh', 'Ks'], 'high card')],
 [('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair'),
  ('ten written as 10', ['10h', 'Jd', 'Qc', 'Ks', '9h'], 'straight'),
  ('lower-case ranks', ['kd', 'kh', '3c', '3s', '8h'], 'two pair'),
  ('mixed-case suits flush', ['2H', '7h', '9h', 'JH', 'Kh'], 'flush'),
  ('four-flush only', ['2h', '7h', '9h', 'Jh', 'Ks'], 'high card'),
  ('quads', ['6h', '6d', '6c', '6s', '2h'], 'four of a kind'),
  ('high card', ['2h', '7d', '9c', 'Js', 'Kh'], 'high card'),
  ('straight flush middle', ['5d', '6d', '7d', '8d', '9d'], 'straight flush')],
 [('wheel straight', ['Ah', '2d', '3c', '4s', '5h'], 'straight'),
  ('one pair', ['9h', '9d', '4c', 'Ks', '2h'], 'one pair'),
  ('four-flush only', ['2h', '7h', '9h', 'Jh', 'Ks'], 'high card'),
  ('quads', ['6h', '6d', '6c', '6s', '2h'], 'four of a kind'),
  ('high card', ['2h', '7d', '9c', 'Js', 'Kh'], 'high card'),
  ('straight flush middle', ['5d', '6d', '7d', '8d', '9d'], 'straight flush'),
  ('ten flush with 10 token', ['10c', '2c', '5c', '8c', 'Qc'], 'flush'),
  ('flush ends match only', ['2h', '7d', '9h', 'Jc', 'Kh'], 'high card')]]
for label, args, expected in fixtures[N-1]:
    try:
        actual = solve(args)
    except Exception as exc:
        actual = 'error:' + type(exc).__name__
    check(label, actual, 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
wheel straight	`straight`	`straight`	Passed
wheel straight flush	`straight flush`	`straight flush`	Passed
four to wheel plus nine	`high card`	`high card`	Passed
four to wheel plus king	`high card`	`high card`	Passed
plain flush	`flush`	`flush`	Passed
broadway	`straight`	`straight`	Passed
trips	`three of a kind`	`three of a kind`	Passed
one pair	`one pair`	`one pair`	Passed

SHA-256 / 03bdfdccf5251bc7a8a3fa6b1c5635e70502759a8f012532fee4caf043625db7

Verification & scope

A deterministic toy model with an explicitly stated contract; card strings are rank+suit (for example "As", "Td", "10h"); no claim of conformance to any casino or tournament rulebook. 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 2026-09-29T14:50:06.927530+00:00.

Case digest / a6badecd2fcbb35aeded33b56ad0c93e6df9e7e75b035c98cbc8cf626783e5a3