FA-76971 / Calendar recurrence rules / Open access

Merging RRULE instances with RDATE and EXDATE: count vs exdate · case 01

Excluding one instance of a COUNT=5 series pushes a sixth instance onto the calendar.

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ROOT CAUSE

COUNT is applied after EXDATE removal, so excluded instances are replaced by later ones.

VERIFIED REPAIR

At the count vs exdate decision use `[start + dt.timedelta(days=k * interval) for k in range(count)]`, leaving the other decision sites of the model unchanged.

Unsuccessful approach: The partial repair `[start + dt.timedelta(days=k * interval) for k in range(count + len(excluded))]` extends the rule by the number of EXDATE values even when they do not hit rule instances.

Case contract

All-day series: the rule yields exactly count instances dtstart + k*interval days (COUNT counts rule instances before exclusions; RDATEs never consume COUNT). The instance set is rule plus RDATE minus EXDATE; EXDATE also removes RDATEs. EXDATE values may carry a time part (YYYY-MM-DDTHH:MM:SS) and then exclude their calendar date. Return the unique dates sorted ascending.

Why this case matters

Recurring calendar series are expanded into concrete instances for display, reminders and conflict checks.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import datetime as dt
import calendar
N = 1
observations = []
def solve(dtstart, interval, count, rdates, exdates):
    start = dt.date.fromisoformat(dtstart)
    excluded = {dt.date.fromisoformat(x[:10]) for x in exdates}
    rule = [d for d in (start + dt.timedelta(days=k * interval) for k in range(count * 3 + 3)) if d not in excluded][:count]
    extra = [dt.date.fromisoformat(x) for x in rdates]
    rule = rule
    merged = [d for d in rule + extra if d not in excluded]
    result = sorted(set(merged))
    return [d.isoformat() for d in result]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: exdate does not extend count',
   ['2024-03-01', 1, 5, [], ['2024-03-03']],
   ['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']),
  ('timed exdate',
   ['2024-03-01', 2, 4, [], ['2024-03-05T09:30:00']],
   ['2024-03-01', '2024-03-03', '2024-03-07']),
  ('midnight exdate', ['2024-03-01', 1, 3, [], ['2024-03-02T00:00:00']], ['2024-03-01', '2024-03-03']),
  ('rdate equal to rule date',
   ['2024-01-01', 7, 3, ['2024-01-08'], []],
   ['2024-01-01', '2024-01-08', '2024-01-15']),
  ('rdate before dtstart',
   ['2024-01-10', 1, 3, ['2024-01-02'], []],
   ['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']),
  ('exdate removes rdate',
   ['2024-01-01', 1, 3, ['2024-02-01'], ['2024-02-01']],
   ['2024-01-01', '2024-01-02', '2024-01-03']),
  ('exdate outside rule',
   ['2024-01-01', 3, 3, [], ['2024-01-02']],
   ['2024-01-01', '2024-01-04', '2024-01-07'])],
 [('midnight exdate', ['2024-03-01', 1, 3, [], ['2024-03-02T00:00:00']], ['2024-03-01', '2024-03-03']),
  ('rdate equal to rule date',
   ['2024-01-01', 7, 3, ['2024-01-08'], []],
   ['2024-01-01', '2024-01-08', '2024-01-15']),
  ('rdate before dtstart',
   ['2024-01-10', 1, 3, ['2024-01-02'], []],
   ['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']),
  ('exdate removes rdate',
   ['2024-01-01', 1, 3, ['2024-02-01'], ['2024-02-01']],
   ['2024-01-01', '2024-01-02', '2024-01-03']),
  ('exdate outside rule',
   ['2024-01-01', 3, 3, [], ['2024-01-02']],
   ['2024-01-01', '2024-01-04', '2024-01-07']),
  ('rdate between instances',
   ['2024-05-01', 10, 3, ['2024-05-05', '2024-05-30'], ['2024-05-11']],
   ['2024-05-01', '2024-05-05', '2024-05-21', '2024-05-30']),
  ('count zero with rdate', ['2024-01-01', 1, 0, ['2024-01-03'], []], ['2024-01-03'])],
 [('rdate before dtstart',
   ['2024-01-10', 1, 3, ['2024-01-02'], []],
   ['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']),
  ('exdate removes rdate',
   ['2024-01-01', 1, 3, ['2024-02-01'], ['2024-02-01']],
   ['2024-01-01', '2024-01-02', '2024-01-03']),
  ('exdate outside rule',
   ['2024-01-01', 3, 3, [], ['2024-01-02']],
   ['2024-01-01', '2024-01-04', '2024-01-07']),
  ('rdate between instances',
   ['2024-05-01', 10, 3, ['2024-05-05', '2024-05-30'], ['2024-05-11']],
   ['2024-05-01', '2024-05-05', '2024-05-21', '2024-05-30']),
  ('count zero with rdate', ['2024-01-01', 1, 0, ['2024-01-03'], []], ['2024-01-03']),
  ('duplicate rdates and timed exdate',
   ['2024-02-27', 1, 4, ['2024-03-05', '2024-03-05'], ['2024-02-28T12:00:00']],
   ['2024-02-27', '2024-02-29', '2024-03-01', '2024-03-05']),
  ('all excluded', ['2024-07-01', 1, 2, [], ['2024-07-01', '2024-07-02']], [])],
 [('exdate outside rule',
   ['2024-01-01', 3, 3, [], ['2024-01-02']],
   ['2024-01-01', '2024-01-04', '2024-01-07']),
  ('rdate between instances',
   ['2024-05-01', 10, 3, ['2024-05-05', '2024-05-30'], ['2024-05-11']],
   ['2024-05-01', '2024-05-05', '2024-05-21', '2024-05-30']),
  ('count zero with rdate', ['2024-01-01', 1, 0, ['2024-01-03'], []], ['2024-01-03']),
  ('duplicate rdates and timed exdate',
   ['2024-02-27', 1, 4, ['2024-03-05', '2024-03-05'], ['2024-02-28T12:00:00']],
   ['2024-02-27', '2024-02-29', '2024-03-01', '2024-03-05']),
  ('all excluded', ['2024-07-01', 1, 2, [], ['2024-07-01', '2024-07-02']], []),
  ('regression: exdate does not extend count',
   ['2024-03-01', 1, 5, [], ['2024-03-03']],
   ['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']),
  ('timed exdate',
   ['2024-03-01', 2, 4, [], ['2024-03-05T09:30:00']],
   ['2024-03-01', '2024-03-03', '2024-03-07'])],
 [('count zero with rdate', ['2024-01-01', 1, 0, ['2024-01-03'], []], ['2024-01-03']),
  ('duplicate rdates and timed exdate',
   ['2024-02-27', 1, 4, ['2024-03-05', '2024-03-05'], ['2024-02-28T12:00:00']],
   ['2024-02-27', '2024-02-29', '2024-03-01', '2024-03-05']),
  ('all excluded', ['2024-07-01', 1, 2, [], ['2024-07-01', '2024-07-02']], []),
  ('regression: exdate does not extend count',
   ['2024-03-01', 1, 5, [], ['2024-03-03']],
   ['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']),
  ('timed exdate',
   ['2024-03-01', 2, 4, [], ['2024-03-05T09:30:00']],
   ['2024-03-01', '2024-03-03', '2024-03-07']),
  ('midnight exdate', ['2024-03-01', 1, 3, [], ['2024-03-02T00:00:00']], ['2024-03-01', '2024-03-03']),
  ('rdate equal to rule date',
   ['2024-01-01', 7, 3, ['2024-01-08'], []],
   ['2024-01-01', '2024-01-08', '2024-01-15'])]]
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 fixture	Actual	Expected	Outcome
regression: exdate does not extend count	`['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05', '2024-03-06']`	`['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']`	Failed
timed exdate	`['2024-03-01', '2024-03-03', '2024-03-07', '2024-03-09']`	`['2024-03-01', '2024-03-03', '2024-03-07']`	Failed
midnight exdate	`['2024-03-01', '2024-03-03', '2024-03-04']`	`['2024-03-01', '2024-03-03']`	Failed
rdate equal to rule date	`['2024-01-01', '2024-01-08', '2024-01-15']`	`['2024-01-01', '2024-01-08', '2024-01-15']`	Passed
rdate before dtstart	`['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']`	`['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']`	Passed
exdate removes rdate	`['2024-01-01', '2024-01-02', '2024-01-03']`	`['2024-01-01', '2024-01-02', '2024-01-03']`	Passed
exdate outside rule	`['2024-01-01', '2024-01-04', '2024-01-07']`	`['2024-01-01', '2024-01-04', '2024-01-07']`	Passed

SHA-256 / 975d95371dcdfdbe85eb0c8cedd5d18d7255cf2de06a1acaeddcba5bb68adb78

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import datetime as dt
import calendar
N = 1
observations = []
def solve(dtstart, interval, count, rdates, exdates):
    start = dt.date.fromisoformat(dtstart)
    excluded = {dt.date.fromisoformat(x[:10]) for x in exdates}
    rule = [start + dt.timedelta(days=k * interval) for k in range(count + len(excluded))]
    extra = [dt.date.fromisoformat(x) for x in rdates]
    rule = rule
    merged = [d for d in rule + extra if d not in excluded]
    result = sorted(set(merged))
    return [d.isoformat() for d in result]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: exdate does not extend count',
   ['2024-03-01', 1, 5, [], ['2024-03-03']],
   ['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']),
  ('timed exdate',
   ['2024-03-01', 2, 4, [], ['2024-03-05T09:30:00']],
   ['2024-03-01', '2024-03-03', '2024-03-07']),
  ('midnight exdate', ['2024-03-01', 1, 3, [], ['2024-03-02T00:00:00']], ['2024-03-01', '2024-03-03']),
  ('rdate equal to rule date',
   ['2024-01-01', 7, 3, ['2024-01-08'], []],
   ['2024-01-01', '2024-01-08', '2024-01-15']),
  ('rdate before dtstart',
   ['2024-01-10', 1, 3, ['2024-01-02'], []],
   ['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']),
  ('exdate removes rdate',
   ['2024-01-01', 1, 3, ['2024-02-01'], ['2024-02-01']],
   ['2024-01-01', '2024-01-02', '2024-01-03']),
  ('exdate outside rule',
   ['2024-01-01', 3, 3, [], ['2024-01-02']],
   ['2024-01-01', '2024-01-04', '2024-01-07'])],
 [('midnight exdate', ['2024-03-01', 1, 3, [], ['2024-03-02T00:00:00']], ['2024-03-01', '2024-03-03']),
  ('rdate equal to rule date',
   ['2024-01-01', 7, 3, ['2024-01-08'], []],
   ['2024-01-01', '2024-01-08', '2024-01-15']),
  ('rdate before dtstart',
   ['2024-01-10', 1, 3, ['2024-01-02'], []],
   ['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']),
  ('exdate removes rdate',
   ['2024-01-01', 1, 3, ['2024-02-01'], ['2024-02-01']],
   ['2024-01-01', '2024-01-02', '2024-01-03']),
  ('exdate outside rule',
   ['2024-01-01', 3, 3, [], ['2024-01-02']],
   ['2024-01-01', '2024-01-04', '2024-01-07']),
  ('rdate between instances',
   ['2024-05-01', 10, 3, ['2024-05-05', '2024-05-30'], ['2024-05-11']],
   ['2024-05-01', '2024-05-05', '2024-05-21', '2024-05-30']),
  ('count zero with rdate', ['2024-01-01', 1, 0, ['2024-01-03'], []], ['2024-01-03'])],
 [('rdate before dtstart',
   ['2024-01-10', 1, 3, ['2024-01-02'], []],
   ['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']),
  ('exdate removes rdate',
   ['2024-01-01', 1, 3, ['2024-02-01'], ['2024-02-01']],
   ['2024-01-01', '2024-01-02', '2024-01-03']),
  ('exdate outside rule',
   ['2024-01-01', 3, 3, [], ['2024-01-02']],
   ['2024-01-01', '2024-01-04', '2024-01-07']),
  ('rdate between instances',
   ['2024-05-01', 10, 3, ['2024-05-05', '2024-05-30'], ['2024-05-11']],
   ['2024-05-01', '2024-05-05', '2024-05-21', '2024-05-30']),
  ('count zero with rdate', ['2024-01-01', 1, 0, ['2024-01-03'], []], ['2024-01-03']),
  ('duplicate rdates and timed exdate',
   ['2024-02-27', 1, 4, ['2024-03-05', '2024-03-05'], ['2024-02-28T12:00:00']],
   ['2024-02-27', '2024-02-29', '2024-03-01', '2024-03-05']),
  ('all excluded', ['2024-07-01', 1, 2, [], ['2024-07-01', '2024-07-02']], [])],
 [('exdate outside rule',
   ['2024-01-01', 3, 3, [], ['2024-01-02']],
   ['2024-01-01', '2024-01-04', '2024-01-07']),
  ('rdate between instances',
   ['2024-05-01', 10, 3, ['2024-05-05', '2024-05-30'], ['2024-05-11']],
   ['2024-05-01', '2024-05-05', '2024-05-21', '2024-05-30']),
  ('count zero with rdate', ['2024-01-01', 1, 0, ['2024-01-03'], []], ['2024-01-03']),
  ('duplicate rdates and timed exdate',
   ['2024-02-27', 1, 4, ['2024-03-05', '2024-03-05'], ['2024-02-28T12:00:00']],
   ['2024-02-27', '2024-02-29', '2024-03-01', '2024-03-05']),
  ('all excluded', ['2024-07-01', 1, 2, [], ['2024-07-01', '2024-07-02']], []),
  ('regression: exdate does not extend count',
   ['2024-03-01', 1, 5, [], ['2024-03-03']],
   ['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']),
  ('timed exdate',
   ['2024-03-01', 2, 4, [], ['2024-03-05T09:30:00']],
   ['2024-03-01', '2024-03-03', '2024-03-07'])],
 [('count zero with rdate', ['2024-01-01', 1, 0, ['2024-01-03'], []], ['2024-01-03']),
  ('duplicate rdates and timed exdate',
   ['2024-02-27', 1, 4, ['2024-03-05', '2024-03-05'], ['2024-02-28T12:00:00']],
   ['2024-02-27', '2024-02-29', '2024-03-01', '2024-03-05']),
  ('all excluded', ['2024-07-01', 1, 2, [], ['2024-07-01', '2024-07-02']], []),
  ('regression: exdate does not extend count',
   ['2024-03-01', 1, 5, [], ['2024-03-03']],
   ['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']),
  ('timed exdate',
   ['2024-03-01', 2, 4, [], ['2024-03-05T09:30:00']],
   ['2024-03-01', '2024-03-03', '2024-03-07']),
  ('midnight exdate', ['2024-03-01', 1, 3, [], ['2024-03-02T00:00:00']], ['2024-03-01', '2024-03-03']),
  ('rdate equal to rule date',
   ['2024-01-01', 7, 3, ['2024-01-08'], []],
   ['2024-01-01', '2024-01-08', '2024-01-15'])]]
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 fixture	Actual	Expected	Outcome
regression: exdate does not extend count	`['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05', '2024-03-06']`	`['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']`	Failed
timed exdate	`['2024-03-01', '2024-03-03', '2024-03-07', '2024-03-09']`	`['2024-03-01', '2024-03-03', '2024-03-07']`	Failed
midnight exdate	`['2024-03-01', '2024-03-03', '2024-03-04']`	`['2024-03-01', '2024-03-03']`	Failed
rdate equal to rule date	`['2024-01-01', '2024-01-08', '2024-01-15']`	`['2024-01-01', '2024-01-08', '2024-01-15']`	Passed
rdate before dtstart	`['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']`	`['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']`	Passed
exdate removes rdate	`['2024-01-01', '2024-01-02', '2024-01-03', '2024-01-04']`	`['2024-01-01', '2024-01-02', '2024-01-03']`	Failed
exdate outside rule	`['2024-01-01', '2024-01-04', '2024-01-07', '2024-01-10']`	`['2024-01-01', '2024-01-04', '2024-01-07']`	Failed

SHA-256 / e72c5e99a2987623c1512784aedbdee31002461a8e35f3f7b797bf9f4fdccd74

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import datetime as dt
import calendar
N = 1
observations = []
def solve(dtstart, interval, count, rdates, exdates):
    start = dt.date.fromisoformat(dtstart)
    excluded = {dt.date.fromisoformat(x[:10]) for x in exdates}
    rule = [start + dt.timedelta(days=k * interval) for k in range(count)]
    extra = [dt.date.fromisoformat(x) for x in rdates]
    rule = rule
    merged = [d for d in rule + extra if d not in excluded]
    result = sorted(set(merged))
    return [d.isoformat() for d in result]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: exdate does not extend count',
   ['2024-03-01', 1, 5, [], ['2024-03-03']],
   ['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']),
  ('timed exdate',
   ['2024-03-01', 2, 4, [], ['2024-03-05T09:30:00']],
   ['2024-03-01', '2024-03-03', '2024-03-07']),
  ('midnight exdate', ['2024-03-01', 1, 3, [], ['2024-03-02T00:00:00']], ['2024-03-01', '2024-03-03']),
  ('rdate equal to rule date',
   ['2024-01-01', 7, 3, ['2024-01-08'], []],
   ['2024-01-01', '2024-01-08', '2024-01-15']),
  ('rdate before dtstart',
   ['2024-01-10', 1, 3, ['2024-01-02'], []],
   ['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']),
  ('exdate removes rdate',
   ['2024-01-01', 1, 3, ['2024-02-01'], ['2024-02-01']],
   ['2024-01-01', '2024-01-02', '2024-01-03']),
  ('exdate outside rule',
   ['2024-01-01', 3, 3, [], ['2024-01-02']],
   ['2024-01-01', '2024-01-04', '2024-01-07'])],
 [('midnight exdate', ['2024-03-01', 1, 3, [], ['2024-03-02T00:00:00']], ['2024-03-01', '2024-03-03']),
  ('rdate equal to rule date',
   ['2024-01-01', 7, 3, ['2024-01-08'], []],
   ['2024-01-01', '2024-01-08', '2024-01-15']),
  ('rdate before dtstart',
   ['2024-01-10', 1, 3, ['2024-01-02'], []],
   ['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']),
  ('exdate removes rdate',
   ['2024-01-01', 1, 3, ['2024-02-01'], ['2024-02-01']],
   ['2024-01-01', '2024-01-02', '2024-01-03']),
  ('exdate outside rule',
   ['2024-01-01', 3, 3, [], ['2024-01-02']],
   ['2024-01-01', '2024-01-04', '2024-01-07']),
  ('rdate between instances',
   ['2024-05-01', 10, 3, ['2024-05-05', '2024-05-30'], ['2024-05-11']],
   ['2024-05-01', '2024-05-05', '2024-05-21', '2024-05-30']),
  ('count zero with rdate', ['2024-01-01', 1, 0, ['2024-01-03'], []], ['2024-01-03'])],
 [('rdate before dtstart',
   ['2024-01-10', 1, 3, ['2024-01-02'], []],
   ['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']),
  ('exdate removes rdate',
   ['2024-01-01', 1, 3, ['2024-02-01'], ['2024-02-01']],
   ['2024-01-01', '2024-01-02', '2024-01-03']),
  ('exdate outside rule',
   ['2024-01-01', 3, 3, [], ['2024-01-02']],
   ['2024-01-01', '2024-01-04', '2024-01-07']),
  ('rdate between instances',
   ['2024-05-01', 10, 3, ['2024-05-05', '2024-05-30'], ['2024-05-11']],
   ['2024-05-01', '2024-05-05', '2024-05-21', '2024-05-30']),
  ('count zero with rdate', ['2024-01-01', 1, 0, ['2024-01-03'], []], ['2024-01-03']),
  ('duplicate rdates and timed exdate',
   ['2024-02-27', 1, 4, ['2024-03-05', '2024-03-05'], ['2024-02-28T12:00:00']],
   ['2024-02-27', '2024-02-29', '2024-03-01', '2024-03-05']),
  ('all excluded', ['2024-07-01', 1, 2, [], ['2024-07-01', '2024-07-02']], [])],
 [('exdate outside rule',
   ['2024-01-01', 3, 3, [], ['2024-01-02']],
   ['2024-01-01', '2024-01-04', '2024-01-07']),
  ('rdate between instances',
   ['2024-05-01', 10, 3, ['2024-05-05', '2024-05-30'], ['2024-05-11']],
   ['2024-05-01', '2024-05-05', '2024-05-21', '2024-05-30']),
  ('count zero with rdate', ['2024-01-01', 1, 0, ['2024-01-03'], []], ['2024-01-03']),
  ('duplicate rdates and timed exdate',
   ['2024-02-27', 1, 4, ['2024-03-05', '2024-03-05'], ['2024-02-28T12:00:00']],
   ['2024-02-27', '2024-02-29', '2024-03-01', '2024-03-05']),
  ('all excluded', ['2024-07-01', 1, 2, [], ['2024-07-01', '2024-07-02']], []),
  ('regression: exdate does not extend count',
   ['2024-03-01', 1, 5, [], ['2024-03-03']],
   ['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']),
  ('timed exdate',
   ['2024-03-01', 2, 4, [], ['2024-03-05T09:30:00']],
   ['2024-03-01', '2024-03-03', '2024-03-07'])],
 [('count zero with rdate', ['2024-01-01', 1, 0, ['2024-01-03'], []], ['2024-01-03']),
  ('duplicate rdates and timed exdate',
   ['2024-02-27', 1, 4, ['2024-03-05', '2024-03-05'], ['2024-02-28T12:00:00']],
   ['2024-02-27', '2024-02-29', '2024-03-01', '2024-03-05']),
  ('all excluded', ['2024-07-01', 1, 2, [], ['2024-07-01', '2024-07-02']], []),
  ('regression: exdate does not extend count',
   ['2024-03-01', 1, 5, [], ['2024-03-03']],
   ['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']),
  ('timed exdate',
   ['2024-03-01', 2, 4, [], ['2024-03-05T09:30:00']],
   ['2024-03-01', '2024-03-03', '2024-03-07']),
  ('midnight exdate', ['2024-03-01', 1, 3, [], ['2024-03-02T00:00:00']], ['2024-03-01', '2024-03-03']),
  ('rdate equal to rule date',
   ['2024-01-01', 7, 3, ['2024-01-08'], []],
   ['2024-01-01', '2024-01-08', '2024-01-15'])]]
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 fixture	Actual	Expected	Outcome
regression: exdate does not extend count	`['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']`	`['2024-03-01', '2024-03-02', '2024-03-04', '2024-03-05']`	Passed
timed exdate	`['2024-03-01', '2024-03-03', '2024-03-07']`	`['2024-03-01', '2024-03-03', '2024-03-07']`	Passed
midnight exdate	`['2024-03-01', '2024-03-03']`	`['2024-03-01', '2024-03-03']`	Passed
rdate equal to rule date	`['2024-01-01', '2024-01-08', '2024-01-15']`	`['2024-01-01', '2024-01-08', '2024-01-15']`	Passed
rdate before dtstart	`['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']`	`['2024-01-02', '2024-01-10', '2024-01-11', '2024-01-12']`	Passed
exdate removes rdate	`['2024-01-01', '2024-01-02', '2024-01-03']`	`['2024-01-01', '2024-01-02', '2024-01-03']`	Passed
exdate outside rule	`['2024-01-01', '2024-01-04', '2024-01-07']`	`['2024-01-01', '2024-01-04', '2024-01-07']`	Passed

SHA-256 / 2c6d08cf2a7c66086ab763b13b6553ecc1ccdcac2d472452c4bd9a2565e6126f

Verification & scope

Stipulated, bounded recurrence-expansion model evaluated offline on explicit fixtures; it is not a complete iCalendar implementation and makes no claim of standards conformance. 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 2026-09-29T14:49:21.242942+00:00.

Case digest / 9a2e2825f2e794c70cde0293a8821e0132d4774e8f6412b598ac854e4cabe46d