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FAILURE MAP
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FA-62271 / Currency rounding and FX conversion / Open access

A target involving USD itself looks up a USDUSD quote · case 01

USDJPY and JPYUSD targets fail with ERR:no-quote.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

USD has no special case, so its leg is searched as 'USDUSD'.

THE FAILURE

USD has no special case, so its leg is searched as 'USDUSD'.

Unsuccessful approach: Special-casing USD only in the quote position still fails targets with USD as base.

Case contract

solve(quotes, target): quotes maps six-letter pairs to rates (QUOTE units per BASE unit). For currency c, units per USD are: 1 for USD; quotes['USD'+c] if present (authoritative when both orientations exist); else 1/quotes[c+'USD']; else unknown. The target BBBQQQ rate = (QQQ per USD)/(BBB per USD), rounded half-even to 6 decimals and returned as a string; an unknown leg returns 'ERR:no-quote'.

Why this case matters

Currency amounts must be rounded at the right stage and in the right unit, or ledgers, quotes and settlements drift by minor units.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
from decimal import Decimal, ROUND_HALF_EVEN, ROUND_HALF_UP, ROUND_FLOOR, ROUND_CEILING, ROUND_DOWN, ROUND_UP, ROUND_HALF_DOWN
N = 1
observations = []
def solve(quotes, target):
    def per_usd(c):
        pass
        if 'USD' + c in quotes: return Decimal(quotes['USD' + c])
        if c + 'USD' in quotes: return 1 / Decimal(quotes[c + 'USD'])
        return None
    b, q = target[:3], target[3:]
    pb, pq = per_usd(b), per_usd(q)
    if pb is None or pq is None: return 'ERR:no-quote'
    return format((pq / pb).quantize(Decimal('0.000001'), rounding=ROUND_HALF_EVEN), 'f')
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('regression usd-leg 1',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'USDJPY'),
   '151.370000'),
  ('regression usd-leg 2',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'JPYUSD'),
   '0.006606'),
  ('partial repair guard 2',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'USDEUR'),
   '0.922935'),
  ('control: euro yen',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'EURJPY'),
   '164.009395'),
  ('control: sterling euro',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'GBPEUR'),
   '1.167513'),
  ('control: missing leg',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'EURSEK'),
   'ERR:no-quote'),
  ('control: franc aussie',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'CHFAUD'),
   '1.718443')],
 [('regression usd-leg 1',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'USDEUR'),
   '0.922935'),
  ('regression usd-leg 2',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577'},
    'USDGBP'),
   '0.790514'),
  ('partial repair guard 2',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'USDEUR': '0.9231'},
    'USDCAD'),
   '1.357700'),
  ('control: usd quote',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'JPYUSD'),
   '0.006606'),
  ('control: missing leg',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'EURSEK'),
   'ERR:no-quote'),
  ('control: franc aussie',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'CHFAUD'),
   '1.718443'),
  ('control: both orientations',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDEUR': '0.9231'},
    'EURCHF'),
   '0.953418')],
 [('regression usd-leg 1',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'USDEUR': '0.9231'},
    'USDCAD'),
   '1.357700'),
  ('regression usd-leg 2',
   ({'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'JPYUSD': '0.006610',
     'USDEUR': '0.9231'},
    'EURUSD'),
   '1.083306'),
  ('partial repair guard 1',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'USDEUR': '0.9231'},
    'USDCHF'),
   '0.880100'),
  ('partial repair guard 2',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'JPYUSD': '0.006610',
     'USDEUR': '0.9231'},
    'USDGBP'),
   '0.790514'),
  ('control: both orientations',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDEUR': '0.9231'},
    'EURCHF'),
   '0.953418'),
  ('control: usd to euro',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'USDEUR'),
   '0.922935'),
  ('control: euro yen',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'EURJPY'),
   '164.009395'),
  ('control: sterling euro',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'GBPEUR'),
   '1.167513')],
 [('regression usd-leg 1',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'USDEUR': '0.9231'},
    'USDCHF'),
   '0.880100'),
  ('regression usd-leg 2',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'JPYUSD': '0.006610'},
    'EURUSD'),
   '1.083500'),
  ('partial repair guard 1',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577'},
    'USDCAD'),
   '1.357700'),
  ('partial repair guard 2',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'USDEUR': '0.9231'},
    'USDEUR'),
   '0.923100'),
  ('control: sterling euro',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'GBPEUR'),
   '1.167513'),
  ('control: direct usd base',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'USDJPY'),
   '151.370000'),
  ('control: usd quote',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'JPYUSD'),
   '0.006606'),
  ('control: missing leg',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'EURSEK'),
   'ERR:no-quote')],
 [('regression usd-leg 1',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'JPYUSD': '0.006610'},
    'CADUSD'),
   '0.736540'),
  ('regression usd-leg 2',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'CHFUSD'),
   '1.136235'),
  ('partial repair guard 1',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'JPYUSD': '0.006610'},
    'USDCHF'),
   '0.880100'),
  ('partial repair guard 2',
   ({'USDJPY': '151.37',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'JPYUSD': '0.006610'},
    'USDJPY'),
   '151.370000'),
  ('control: missing leg',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'EURSEK'),
   'ERR:no-quote'),
  ('control: franc aussie',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'CHFAUD'),
   '1.718443'),
  ('control: both orientations',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDEUR': '0.9231'},
    'EURCHF'),
   '0.953418'),
  ('control: usd to euro',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'USDEUR'),
   '0.922935')]]
for label, args, expected in cases[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 usd-leg 1ERR:no-quote151.370000Failed
regression usd-leg 2ERR:no-quote0.006606Failed
partial repair guard 2ERR:no-quote0.922935Failed
control: euro yen164.009395164.009395Passed
control: sterling euro1.1675131.167513Passed
control: missing legERR:no-quoteERR:no-quotePassed
control: franc aussie1.7184431.718443Passed

SHA-256 / 0c547cec804a404bf1889a06d110f34aca323a05b7039f5a9099788f723ada7b

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
from decimal import Decimal, ROUND_HALF_EVEN, ROUND_HALF_UP, ROUND_FLOOR, ROUND_CEILING, ROUND_DOWN, ROUND_UP, ROUND_HALF_DOWN
N = 1
observations = []
def solve(quotes, target):
    def per_usd(c):
        if c == 'USD' and c == q: return Decimal(1)
        if 'USD' + c in quotes: return Decimal(quotes['USD' + c])
        if c + 'USD' in quotes: return 1 / Decimal(quotes[c + 'USD'])
        return None
    b, q = target[:3], target[3:]
    pb, pq = per_usd(b), per_usd(q)
    if pb is None or pq is None: return 'ERR:no-quote'
    return format((pq / pb).quantize(Decimal('0.000001'), rounding=ROUND_HALF_EVEN), 'f')
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('regression usd-leg 1',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'USDJPY'),
   '151.370000'),
  ('regression usd-leg 2',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'JPYUSD'),
   '0.006606'),
  ('partial repair guard 2',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'USDEUR'),
   '0.922935'),
  ('control: euro yen',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'EURJPY'),
   '164.009395'),
  ('control: sterling euro',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'GBPEUR'),
   '1.167513'),
  ('control: missing leg',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'EURSEK'),
   'ERR:no-quote'),
  ('control: franc aussie',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'CHFAUD'),
   '1.718443')],
 [('regression usd-leg 1',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'USDEUR'),
   '0.922935'),
  ('regression usd-leg 2',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577'},
    'USDGBP'),
   '0.790514'),
  ('partial repair guard 2',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'USDEUR': '0.9231'},
    'USDCAD'),
   '1.357700'),
  ('control: usd quote',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'JPYUSD'),
   '0.006606'),
  ('control: missing leg',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'EURSEK'),
   'ERR:no-quote'),
  ('control: franc aussie',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'CHFAUD'),
   '1.718443'),
  ('control: both orientations',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDEUR': '0.9231'},
    'EURCHF'),
   '0.953418')],
 [('regression usd-leg 1',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'USDEUR': '0.9231'},
    'USDCAD'),
   '1.357700'),
  ('regression usd-leg 2',
   ({'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'JPYUSD': '0.006610',
     'USDEUR': '0.9231'},
    'EURUSD'),
   '1.083306'),
  ('partial repair guard 1',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'USDEUR': '0.9231'},
    'USDCHF'),
   '0.880100'),
  ('partial repair guard 2',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'JPYUSD': '0.006610',
     'USDEUR': '0.9231'},
    'USDGBP'),
   '0.790514'),
  ('control: both orientations',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDEUR': '0.9231'},
    'EURCHF'),
   '0.953418'),
  ('control: usd to euro',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'USDEUR'),
   '0.922935'),
  ('control: euro yen',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'EURJPY'),
   '164.009395'),
  ('control: sterling euro',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'GBPEUR'),
   '1.167513')],
 [('regression usd-leg 1',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'USDEUR': '0.9231'},
    'USDCHF'),
   '0.880100'),
  ('regression usd-leg 2',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'JPYUSD': '0.006610'},
    'EURUSD'),
   '1.083500'),
  ('partial repair guard 1',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577'},
    'USDCAD'),
   '1.357700'),
  ('partial repair guard 2',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'USDEUR': '0.9231'},
    'USDEUR'),
   '0.923100'),
  ('control: sterling euro',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'GBPEUR'),
   '1.167513'),
  ('control: direct usd base',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'USDJPY'),
   '151.370000'),
  ('control: usd quote',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'JPYUSD'),
   '0.006606'),
  ('control: missing leg',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'EURSEK'),
   'ERR:no-quote')],
 [('regression usd-leg 1',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'JPYUSD': '0.006610'},
    'CADUSD'),
   '0.736540'),
  ('regression usd-leg 2',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'CHFUSD'),
   '1.136235'),
  ('partial repair guard 1',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'JPYUSD': '0.006610'},
    'USDCHF'),
   '0.880100'),
  ('partial repair guard 2',
   ({'USDJPY': '151.37',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDCAD': '1.3577',
     'JPYUSD': '0.006610'},
    'USDJPY'),
   '151.370000'),
  ('control: missing leg',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'EURSEK'),
   'ERR:no-quote'),
  ('control: franc aussie',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'CHFAUD'),
   '1.718443'),
  ('control: both orientations',
   ({'USDJPY': '151.37',
     'EURUSD': '1.0835',
     'GBPUSD': '1.2650',
     'USDCHF': '0.8801',
     'AUDUSD': '0.6612',
     'USDEUR': '0.9231'},
    'EURCHF'),
   '0.953418'),
  ('control: usd to euro',
   ({'USDJPY': '151.37', 'EURUSD': '1.0835', 'GBPUSD': '1.2650', 'USDCHF': '0.8801', 'AUDUSD': '0.6612'}, 'USDEUR'),
   '0.922935')]]
for label, args, expected in cases[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 usd-leg 1ERR:no-quote151.370000Failed
regression usd-leg 20.0066060.006606Passed
partial repair guard 2ERR:no-quote0.922935Failed
control: euro yen164.009395164.009395Passed
control: sterling euro1.1675131.167513Passed
control: missing legERR:no-quoteERR:no-quotePassed
control: franc aussie1.7184431.718443Passed

SHA-256 / dd94d558c5bcb8ff05421e23513656d20bd0b921b60918a0b40705fc390fd212

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 7 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

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Verification & scope

A deterministic, bounded teaching model with a stipulated toy contract; it makes no claim of conformance to any real regulation, standard, or institution's rules. 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 2026-09-29T14:47:03.059998+00:00.

Case digest / a98d1d5fe6b054b0d259209edea9ed4c1b0967343ebc70f66f4f997d65169e56