FA-62166 / Currency rounding and FX conversion / Open access

The value date may fall on a USD holiday · case 01

EURUSD spot is set on a US holiday when dollars cannot settle.

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

ROOT CAUSE

The final day is checked only against the non-USD calendars.

VERIFIED REPAIR

The value date must be a business day in both currencies.

Unsuccessful approach: Checking only the quote currency's calendar on the final day misses base-currency holidays.

Case contract

solve(trade, pair, holidays): stipulated spot value-date rule. USDCAD/CADUSD settle T+1, every other pair T+2. Count forward from the trade date: a day before the final one counts only if it is a weekday and not a holiday of the non-USD currencies of the pair; the value date itself must be a weekday that is a holiday in neither currency. holidays maps currency to ISO date strings. Return the ISO value date.

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 datetime import date, timedelta
N = 1
observations = []
def solve(trade, pair, holidays):
    d = date.fromisoformat(trade)
    base, quote = pair[:3], pair[3:]
    def good(x, ccys):
        return x.weekday() < 5 and all(x.isoformat() not in holidays.get(c, []) for c in ccys)
    lag = 1 if {base, quote} == {'USD', 'CAD'} else 2
    non_usd = [c for c in (base, quote) if c != 'USD']
    x, n = d, 0
    while n < lag:
        x += timedelta(days=1)
        if good(x, non_usd):
            n += 1
    return x.isoformat()
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('regression value-date-both-calendars 1', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-04']}), '2026-03-05'),
  ('regression value-date-both-calendars 2', ('2026-03-06', 'CADUSD', {'USD': ['2026-03-09']}), '2026-03-10'),
  ('partial repair guard 1', ('2026-03-02', 'EURUSD', {'EUR': ['2026-03-04']}), '2026-03-05'),
  ('partial repair guard 2', ('2026-07-17', 'CADUSD', {'EUR': ['2026-07-20', '2026-07-22'], 'CAD': ['2026-07-20']}),
   '2026-07-21'),
  ('control: plain t+2', ('2026-03-02', 'EURUSD', {}), '2026-03-04'),
  ('control: over weekend', ('2026-03-05', 'EURUSD', {}), '2026-03-09'),
  ('control: usd holiday t+1', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-03']}), '2026-03-04'),
  ('control: cad t+1', ('2026-03-02', 'USDCAD', {}), '2026-03-03')],
 [('regression value-date-both-calendars 1',
   ('2026-05-26', 'CADUSD',
    {'USD': ['2026-05-28', '2026-05-29'],
     'JPY': ['2026-05-28'],
     'EUR': ['2026-05-27', '2026-05-31'],
     'CAD': ['2026-05-27', '2026-05-28', '2026-05-31']}),
   '2026-06-01'),
  ('regression value-date-both-calendars 2',
   ('2026-02-09', 'USDCAD', {'USD': ['2026-02-10', '2026-02-12'], 'JPY': [], 'CAD': ['2026-02-11']}), '2026-02-13'),
  ('control: usd holiday on spot', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-04']}), '2026-03-05'),
  ('control: cad t+1', ('2026-03-02', 'USDCAD', {}), '2026-03-03'),
  ('control: euro holiday t+1', ('2026-03-02', 'EURUSD', {'EUR': ['2026-03-03']}), '2026-03-05'),
  ('control: cross with cad', ('2026-03-02', 'EURCAD', {}), '2026-03-04')],
 [('regression value-date-both-calendars 1',
   ('2026-03-30', 'CADUSD',
    {'USD': ['2026-03-31'],
     'JPY': ['2026-04-01', '2026-04-03', '2026-04-04'],
     'CAD': ['2026-04-01', '2026-04-03'],
     'GBP': ['2026-03-31']}),
   '2026-04-02'),
  ('regression value-date-both-calendars 2',
   ('2026-01-12', 'EURUSD', {'USD': ['2026-01-14', '2026-01-15'], 'CAD': ['2026-01-15', '2026-01-17']}), '2026-01-16'),
  ('partial repair guard 1',
   ('2026-09-17', 'CADUSD',
    {'JPY': ['2026-09-22'], 'CAD': ['2026-09-18', '2026-09-20'], 'GBP': ['2026-09-20', '2026-09-21']}),
   '2026-09-21'),
  ('control: cross with cad', ('2026-03-02', 'EURCAD', {}), '2026-03-04'),
  ('control: cad usd holiday', ('2026-03-06', 'CADUSD', {'USD': ['2026-03-09']}), '2026-03-10'),
  ('control: yen cross', ('2026-04-28', 'GBPJPY', {'JPY': ['2026-04-29', '2026-04-30']}), '2026-05-04'),
  ('control: plain t+2', ('2026-03-02', 'EURUSD', {}), '2026-03-04')],
 [('regression value-date-both-calendars 1',
   ('2026-10-12', 'CADUSD',
    {'USD': ['2026-10-14', '2026-10-17'], 'JPY': ['2026-10-16'], 'CAD': ['2026-10-13', '2026-10-15']}),
   '2026-10-16'),
  ('regression value-date-both-calendars 2',
   ('2026-10-19', 'EURUSD',
    {'USD': ['2026-10-21'],
     'EUR': ['2026-10-22'],
     'CAD': ['2026-10-20', '2026-10-22', '2026-10-23', '2026-10-24'],
     'GBP': []}),
   '2026-10-23'),
  ('partial repair guard 2',
   ('2026-07-13', 'GBPJPY',
    {'USD': ['2026-07-18'],
     'JPY': ['2026-07-18'],
     'EUR': ['2026-07-14', '2026-07-16'],
     'CAD': ['2026-07-15'],
     'GBP': ['2026-07-15']}),
   '2026-07-16'),
  ('control: plain t+2', ('2026-03-02', 'EURUSD', {}), '2026-03-04'),
  ('control: over weekend', ('2026-03-05', 'EURUSD', {}), '2026-03-09'),
  ('control: usd holiday t+1', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-03']}), '2026-03-04'),
  ('control: usd holiday on spot', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-04']}), '2026-03-05')],
 [('regression value-date-both-calendars 1', ('2026-05-04', 'CADUSD', {'USD': ['2026-05-05', '2026-05-06'], 'EUR': []}),
   '2026-05-07'),
  ('regression value-date-both-calendars 2',
   ('2026-09-07', 'USDCAD',
    {'USD': ['2026-09-09', '2026-09-10'],
     'EUR': ['2026-09-09', '2026-09-11', '2026-09-12'],
     'CAD': ['2026-09-08'],
     'GBP': ['2026-09-09', '2026-09-10', '2026-09-11']}),
   '2026-09-11'),
  ('partial repair guard 1',
   ('2026-05-18', 'EURUSD', {'USD': ['2026-05-22'], 'JPY': ['2026-05-19'], 'EUR': ['2026-05-20', '2026-05-23']}),
   '2026-05-21'),
  ('partial repair guard 2',
   ('2026-10-19', 'EURUSD',
    {'USD': ['2026-10-21'],
     'EUR': ['2026-10-22'],
     'CAD': ['2026-10-20', '2026-10-22', '2026-10-23', '2026-10-24'],
     'GBP': []}),
   '2026-10-23'),
  ('control: usd holiday on spot', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-04']}), '2026-03-05'),
  ('control: cad t+1', ('2026-03-02', 'USDCAD', {}), '2026-03-03'),
  ('control: euro holiday t+1', ('2026-03-02', 'EURUSD', {'EUR': ['2026-03-03']}), '2026-03-05'),
  ('control: cross with cad', ('2026-03-02', 'EURCAD', {}), '2026-03-04')]]
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 fixture	Actual	Expected	Outcome
regression value-date-both-calendars 1	`2026-03-04`	`2026-03-05`	Failed
regression value-date-both-calendars 2	`2026-03-09`	`2026-03-10`	Failed
partial repair guard 1	`2026-03-05`	`2026-03-05`	Passed
partial repair guard 2	`2026-07-21`	`2026-07-21`	Passed
control: plain t+2	`2026-03-04`	`2026-03-04`	Passed
control: over weekend	`2026-03-09`	`2026-03-09`	Passed
control: usd holiday t+1	`2026-03-04`	`2026-03-04`	Passed
control: cad t+1	`2026-03-03`	`2026-03-03`	Passed

SHA-256 / 8435792ea846bca8a7e1c3858fa9a1f4571ffd7b60453e0137da46f87b0ffe74

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
from datetime import date, timedelta
N = 1
observations = []
def solve(trade, pair, holidays):
    d = date.fromisoformat(trade)
    base, quote = pair[:3], pair[3:]
    def good(x, ccys):
        return x.weekday() < 5 and all(x.isoformat() not in holidays.get(c, []) for c in ccys)
    lag = 1 if {base, quote} == {'USD', 'CAD'} else 2
    non_usd = [c for c in (base, quote) if c != 'USD']
    x, n = d, 0
    while n < lag:
        x += timedelta(days=1)
        if good(x, non_usd if n < lag - 1 else [quote]):
            n += 1
    return x.isoformat()
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('regression value-date-both-calendars 1', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-04']}), '2026-03-05'),
  ('regression value-date-both-calendars 2', ('2026-03-06', 'CADUSD', {'USD': ['2026-03-09']}), '2026-03-10'),
  ('partial repair guard 1', ('2026-03-02', 'EURUSD', {'EUR': ['2026-03-04']}), '2026-03-05'),
  ('partial repair guard 2', ('2026-07-17', 'CADUSD', {'EUR': ['2026-07-20', '2026-07-22'], 'CAD': ['2026-07-20']}),
   '2026-07-21'),
  ('control: plain t+2', ('2026-03-02', 'EURUSD', {}), '2026-03-04'),
  ('control: over weekend', ('2026-03-05', 'EURUSD', {}), '2026-03-09'),
  ('control: usd holiday t+1', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-03']}), '2026-03-04'),
  ('control: cad t+1', ('2026-03-02', 'USDCAD', {}), '2026-03-03')],
 [('regression value-date-both-calendars 1',
   ('2026-05-26', 'CADUSD',
    {'USD': ['2026-05-28', '2026-05-29'],
     'JPY': ['2026-05-28'],
     'EUR': ['2026-05-27', '2026-05-31'],
     'CAD': ['2026-05-27', '2026-05-28', '2026-05-31']}),
   '2026-06-01'),
  ('regression value-date-both-calendars 2',
   ('2026-02-09', 'USDCAD', {'USD': ['2026-02-10', '2026-02-12'], 'JPY': [], 'CAD': ['2026-02-11']}), '2026-02-13'),
  ('control: usd holiday on spot', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-04']}), '2026-03-05'),
  ('control: cad t+1', ('2026-03-02', 'USDCAD', {}), '2026-03-03'),
  ('control: euro holiday t+1', ('2026-03-02', 'EURUSD', {'EUR': ['2026-03-03']}), '2026-03-05'),
  ('control: cross with cad', ('2026-03-02', 'EURCAD', {}), '2026-03-04')],
 [('regression value-date-both-calendars 1',
   ('2026-03-30', 'CADUSD',
    {'USD': ['2026-03-31'],
     'JPY': ['2026-04-01', '2026-04-03', '2026-04-04'],
     'CAD': ['2026-04-01', '2026-04-03'],
     'GBP': ['2026-03-31']}),
   '2026-04-02'),
  ('regression value-date-both-calendars 2',
   ('2026-01-12', 'EURUSD', {'USD': ['2026-01-14', '2026-01-15'], 'CAD': ['2026-01-15', '2026-01-17']}), '2026-01-16'),
  ('partial repair guard 1',
   ('2026-09-17', 'CADUSD',
    {'JPY': ['2026-09-22'], 'CAD': ['2026-09-18', '2026-09-20'], 'GBP': ['2026-09-20', '2026-09-21']}),
   '2026-09-21'),
  ('control: cross with cad', ('2026-03-02', 'EURCAD', {}), '2026-03-04'),
  ('control: cad usd holiday', ('2026-03-06', 'CADUSD', {'USD': ['2026-03-09']}), '2026-03-10'),
  ('control: yen cross', ('2026-04-28', 'GBPJPY', {'JPY': ['2026-04-29', '2026-04-30']}), '2026-05-04'),
  ('control: plain t+2', ('2026-03-02', 'EURUSD', {}), '2026-03-04')],
 [('regression value-date-both-calendars 1',
   ('2026-10-12', 'CADUSD',
    {'USD': ['2026-10-14', '2026-10-17'], 'JPY': ['2026-10-16'], 'CAD': ['2026-10-13', '2026-10-15']}),
   '2026-10-16'),
  ('regression value-date-both-calendars 2',
   ('2026-10-19', 'EURUSD',
    {'USD': ['2026-10-21'],
     'EUR': ['2026-10-22'],
     'CAD': ['2026-10-20', '2026-10-22', '2026-10-23', '2026-10-24'],
     'GBP': []}),
   '2026-10-23'),
  ('partial repair guard 2',
   ('2026-07-13', 'GBPJPY',
    {'USD': ['2026-07-18'],
     'JPY': ['2026-07-18'],
     'EUR': ['2026-07-14', '2026-07-16'],
     'CAD': ['2026-07-15'],
     'GBP': ['2026-07-15']}),
   '2026-07-16'),
  ('control: plain t+2', ('2026-03-02', 'EURUSD', {}), '2026-03-04'),
  ('control: over weekend', ('2026-03-05', 'EURUSD', {}), '2026-03-09'),
  ('control: usd holiday t+1', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-03']}), '2026-03-04'),
  ('control: usd holiday on spot', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-04']}), '2026-03-05')],
 [('regression value-date-both-calendars 1', ('2026-05-04', 'CADUSD', {'USD': ['2026-05-05', '2026-05-06'], 'EUR': []}),
   '2026-05-07'),
  ('regression value-date-both-calendars 2',
   ('2026-09-07', 'USDCAD',
    {'USD': ['2026-09-09', '2026-09-10'],
     'EUR': ['2026-09-09', '2026-09-11', '2026-09-12'],
     'CAD': ['2026-09-08'],
     'GBP': ['2026-09-09', '2026-09-10', '2026-09-11']}),
   '2026-09-11'),
  ('partial repair guard 1',
   ('2026-05-18', 'EURUSD', {'USD': ['2026-05-22'], 'JPY': ['2026-05-19'], 'EUR': ['2026-05-20', '2026-05-23']}),
   '2026-05-21'),
  ('partial repair guard 2',
   ('2026-10-19', 'EURUSD',
    {'USD': ['2026-10-21'],
     'EUR': ['2026-10-22'],
     'CAD': ['2026-10-20', '2026-10-22', '2026-10-23', '2026-10-24'],
     'GBP': []}),
   '2026-10-23'),
  ('control: usd holiday on spot', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-04']}), '2026-03-05'),
  ('control: cad t+1', ('2026-03-02', 'USDCAD', {}), '2026-03-03'),
  ('control: euro holiday t+1', ('2026-03-02', 'EURUSD', {'EUR': ['2026-03-03']}), '2026-03-05'),
  ('control: cross with cad', ('2026-03-02', 'EURCAD', {}), '2026-03-04')]]
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 fixture	Actual	Expected	Outcome
regression value-date-both-calendars 1	`2026-03-05`	`2026-03-05`	Passed
regression value-date-both-calendars 2	`2026-03-10`	`2026-03-10`	Passed
partial repair guard 1	`2026-03-04`	`2026-03-05`	Failed
partial repair guard 2	`2026-07-20`	`2026-07-21`	Failed
control: plain t+2	`2026-03-04`	`2026-03-04`	Passed
control: over weekend	`2026-03-09`	`2026-03-09`	Passed
control: usd holiday t+1	`2026-03-04`	`2026-03-04`	Passed
control: cad t+1	`2026-03-03`	`2026-03-03`	Passed

SHA-256 / 731c0d5937aa93e2c370978f823bfc8be3e7f0e3630017de7aa26f50dd811c58

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
from datetime import date, timedelta
N = 1
observations = []
def solve(trade, pair, holidays):
    d = date.fromisoformat(trade)
    base, quote = pair[:3], pair[3:]
    def good(x, ccys):
        return x.weekday() < 5 and all(x.isoformat() not in holidays.get(c, []) for c in ccys)
    lag = 1 if {base, quote} == {'USD', 'CAD'} else 2
    non_usd = [c for c in (base, quote) if c != 'USD']
    x, n = d, 0
    while n < lag:
        x += timedelta(days=1)
        if good(x, non_usd if n < lag - 1 else [base, quote]):
            n += 1
    return x.isoformat()
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('regression value-date-both-calendars 1', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-04']}), '2026-03-05'),
  ('regression value-date-both-calendars 2', ('2026-03-06', 'CADUSD', {'USD': ['2026-03-09']}), '2026-03-10'),
  ('partial repair guard 1', ('2026-03-02', 'EURUSD', {'EUR': ['2026-03-04']}), '2026-03-05'),
  ('partial repair guard 2', ('2026-07-17', 'CADUSD', {'EUR': ['2026-07-20', '2026-07-22'], 'CAD': ['2026-07-20']}),
   '2026-07-21'),
  ('control: plain t+2', ('2026-03-02', 'EURUSD', {}), '2026-03-04'),
  ('control: over weekend', ('2026-03-05', 'EURUSD', {}), '2026-03-09'),
  ('control: usd holiday t+1', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-03']}), '2026-03-04'),
  ('control: cad t+1', ('2026-03-02', 'USDCAD', {}), '2026-03-03')],
 [('regression value-date-both-calendars 1',
   ('2026-05-26', 'CADUSD',
    {'USD': ['2026-05-28', '2026-05-29'],
     'JPY': ['2026-05-28'],
     'EUR': ['2026-05-27', '2026-05-31'],
     'CAD': ['2026-05-27', '2026-05-28', '2026-05-31']}),
   '2026-06-01'),
  ('regression value-date-both-calendars 2',
   ('2026-02-09', 'USDCAD', {'USD': ['2026-02-10', '2026-02-12'], 'JPY': [], 'CAD': ['2026-02-11']}), '2026-02-13'),
  ('control: usd holiday on spot', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-04']}), '2026-03-05'),
  ('control: cad t+1', ('2026-03-02', 'USDCAD', {}), '2026-03-03'),
  ('control: euro holiday t+1', ('2026-03-02', 'EURUSD', {'EUR': ['2026-03-03']}), '2026-03-05'),
  ('control: cross with cad', ('2026-03-02', 'EURCAD', {}), '2026-03-04')],
 [('regression value-date-both-calendars 1',
   ('2026-03-30', 'CADUSD',
    {'USD': ['2026-03-31'],
     'JPY': ['2026-04-01', '2026-04-03', '2026-04-04'],
     'CAD': ['2026-04-01', '2026-04-03'],
     'GBP': ['2026-03-31']}),
   '2026-04-02'),
  ('regression value-date-both-calendars 2',
   ('2026-01-12', 'EURUSD', {'USD': ['2026-01-14', '2026-01-15'], 'CAD': ['2026-01-15', '2026-01-17']}), '2026-01-16'),
  ('partial repair guard 1',
   ('2026-09-17', 'CADUSD',
    {'JPY': ['2026-09-22'], 'CAD': ['2026-09-18', '2026-09-20'], 'GBP': ['2026-09-20', '2026-09-21']}),
   '2026-09-21'),
  ('control: cross with cad', ('2026-03-02', 'EURCAD', {}), '2026-03-04'),
  ('control: cad usd holiday', ('2026-03-06', 'CADUSD', {'USD': ['2026-03-09']}), '2026-03-10'),
  ('control: yen cross', ('2026-04-28', 'GBPJPY', {'JPY': ['2026-04-29', '2026-04-30']}), '2026-05-04'),
  ('control: plain t+2', ('2026-03-02', 'EURUSD', {}), '2026-03-04')],
 [('regression value-date-both-calendars 1',
   ('2026-10-12', 'CADUSD',
    {'USD': ['2026-10-14', '2026-10-17'], 'JPY': ['2026-10-16'], 'CAD': ['2026-10-13', '2026-10-15']}),
   '2026-10-16'),
  ('regression value-date-both-calendars 2',
   ('2026-10-19', 'EURUSD',
    {'USD': ['2026-10-21'],
     'EUR': ['2026-10-22'],
     'CAD': ['2026-10-20', '2026-10-22', '2026-10-23', '2026-10-24'],
     'GBP': []}),
   '2026-10-23'),
  ('partial repair guard 2',
   ('2026-07-13', 'GBPJPY',
    {'USD': ['2026-07-18'],
     'JPY': ['2026-07-18'],
     'EUR': ['2026-07-14', '2026-07-16'],
     'CAD': ['2026-07-15'],
     'GBP': ['2026-07-15']}),
   '2026-07-16'),
  ('control: plain t+2', ('2026-03-02', 'EURUSD', {}), '2026-03-04'),
  ('control: over weekend', ('2026-03-05', 'EURUSD', {}), '2026-03-09'),
  ('control: usd holiday t+1', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-03']}), '2026-03-04'),
  ('control: usd holiday on spot', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-04']}), '2026-03-05')],
 [('regression value-date-both-calendars 1', ('2026-05-04', 'CADUSD', {'USD': ['2026-05-05', '2026-05-06'], 'EUR': []}),
   '2026-05-07'),
  ('regression value-date-both-calendars 2',
   ('2026-09-07', 'USDCAD',
    {'USD': ['2026-09-09', '2026-09-10'],
     'EUR': ['2026-09-09', '2026-09-11', '2026-09-12'],
     'CAD': ['2026-09-08'],
     'GBP': ['2026-09-09', '2026-09-10', '2026-09-11']}),
   '2026-09-11'),
  ('partial repair guard 1',
   ('2026-05-18', 'EURUSD', {'USD': ['2026-05-22'], 'JPY': ['2026-05-19'], 'EUR': ['2026-05-20', '2026-05-23']}),
   '2026-05-21'),
  ('partial repair guard 2',
   ('2026-10-19', 'EURUSD',
    {'USD': ['2026-10-21'],
     'EUR': ['2026-10-22'],
     'CAD': ['2026-10-20', '2026-10-22', '2026-10-23', '2026-10-24'],
     'GBP': []}),
   '2026-10-23'),
  ('control: usd holiday on spot', ('2026-03-02', 'EURUSD', {'USD': ['2026-03-04']}), '2026-03-05'),
  ('control: cad t+1', ('2026-03-02', 'USDCAD', {}), '2026-03-03'),
  ('control: euro holiday t+1', ('2026-03-02', 'EURUSD', {'EUR': ['2026-03-03']}), '2026-03-05'),
  ('control: cross with cad', ('2026-03-02', 'EURCAD', {}), '2026-03-04')]]
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 fixture	Actual	Expected	Outcome
regression value-date-both-calendars 1	`2026-03-05`	`2026-03-05`	Passed
regression value-date-both-calendars 2	`2026-03-10`	`2026-03-10`	Passed
partial repair guard 1	`2026-03-05`	`2026-03-05`	Passed
partial repair guard 2	`2026-07-21`	`2026-07-21`	Passed
control: plain t+2	`2026-03-04`	`2026-03-04`	Passed
control: over weekend	`2026-03-09`	`2026-03-09`	Passed
control: usd holiday t+1	`2026-03-04`	`2026-03-04`	Passed
control: cad t+1	`2026-03-03`	`2026-03-03`	Passed

SHA-256 / f2b8fc634b2a518b853a43af37539b732ae39a4d879abf7c53d9f034f7c71f5f

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 2026-09-29T14:47:02.045981+00:00.

Case digest / f47a47a2d3568947c6e2dba6984c99d8d571aebc8303d6a7a275fc6d79fb2a8b