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FA-25126 / Filter interfaces / Open access

An empty page does not imply the end when a cursor remains · case 01

An empty page does not imply the end when a cursor remains is violated by the widget projection.

Verified by executionVariant 1 · 10 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The end-marker decision uses `not d['cursor']` instead of the stipulated facet-pagination projection.

THE FAILURE

The end-marker decision uses `not d['cursor']` instead of the stipulated facet-pagination projection.

Unsuccessful approach: The attempted correction `not d['page']` still violates the explicit contract fixtures.

Case contract

A paged facet picker merges option identities, respects continuation state, and keeps selected off-page options visible in a dedicated selection summary. This example checks: An empty page does not imply the end when a cursor remains.

Why this case matters

Filter-widget state and serialization must preserve user constraints while the view changes.

1 / The failure

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

N = 1
observations = []
def solve(d):
    return {'merge-order':(list(dict.fromkeys(d['old']+d['page']))), 'load-more':(d['cursor'] is not None and not d['loading']), 'off-page':([x for x in d['selected'] if x not in d['old']+d['page']]), 'end-marker':(not d['cursor']), 'replace-query':(list(d['page']) if d['changed'] else list(dict.fromkeys(d['old']+d['page']))), 'visible-total':(len(set(d['old']+d['page'])))}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = {1: [({'old': [], 'page': [], 'selected': [], 'cursor': '', 'loading': False, 'changed': False}, {'merge-order': [], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': [], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': [], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': None, 'loading': True, 'changed': True}, {'merge-order': [], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': True, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': [], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': ['a', 'c'], 'selected': [], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': None, 'loading': True, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': True, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': [], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': None, 'loading': True, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': True, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': False, 'replace-query': [], 'visible-total': 2})], 2: [({'old': [], 'page': [], 'selected': [], 'cursor': '', 'loading': False, 'changed': True}, {'merge-order': [], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': [], 'cursor': 'next', 'loading': True, 'changed': False}, {'merge-order': [], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': None, 'loading': True, 'changed': False}, {'merge-order': [], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': True, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': False}, {'merge-order': [], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': ['a', 'c'], 'selected': [], 'cursor': '', 'loading': True, 'changed': False}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': None, 'loading': True, 'changed': False}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': True, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': False}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': [], 'cursor': '', 'loading': True, 'changed': False}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': ['b', 'a'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': None, 'loading': True, 'changed': False}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': True, 'replace-query': ['b', 'a'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': False}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': False, 'replace-query': ['b', 'a'], 'visible-total': 2})], 3: [({'old': [], 'page': [], 'selected': [], 'cursor': '', 'loading': True, 'changed': False}, {'merge-order': [], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': '', 'loading': False, 'changed': True}, {'merge-order': [], 'load-more': True, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': False, 'changed': True}, {'merge-order': [], 'load-more': True, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': ['a', 'c'], 'selected': [], 'cursor': '', 'loading': False, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': None, 'loading': False, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': True, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': False, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': True, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': [], 'cursor': '', 'loading': False, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': None, 'loading': False, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': True, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': False, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': True, 'off-page': ['z'], 'end-marker': False, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': ['a', 'c'], 'selected': [], 'cursor': '', 'loading': False, 'changed': True}, {'merge-order': ['b', 'a', 'c'], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 3})], 4: [({'old': [], 'page': [], 'selected': [], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': [], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': False, 'changed': False}, {'merge-order': [], 'load-more': True, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': ['a', 'c'], 'selected': [], 'cursor': '', 'loading': False, 'changed': False}, {'merge-order': ['a', 'c'], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': None, 'loading': False, 'changed': False}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': True, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': False, 'changed': False}, {'merge-order': ['a', 'c'], 'load-more': True, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': [], 'cursor': '', 'loading': False, 'changed': False}, {'merge-order': ['b', 'a'], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': ['b', 'a'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': None, 'loading': False, 'changed': False}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': True, 'replace-query': ['b', 'a'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': False, 'changed': False}, {'merge-order': ['b', 'a'], 'load-more': True, 'off-page': ['z'], 'end-marker': False, 'replace-query': ['b', 'a'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': ['a', 'c'], 'selected': [], 'cursor': '', 'loading': False, 'changed': False}, {'merge-order': ['b', 'a', 'c'], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': ['b', 'a', 'c'], 'visible-total': 3}), ({'old': ['b', 'a'], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': None, 'loading': False, 'changed': False}, {'merge-order': ['b', 'a', 'c'], 'load-more': False, 'off-page': ['z'], 'end-marker': True, 'replace-query': ['b', 'a', 'c'], 'visible-total': 3})], 5: [({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': '', 'loading': False, 'changed': False}, {'merge-order': [], 'load-more': True, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': [], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': ['a', 'c'], 'selected': [], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': [], 'cursor': None, 'loading': True, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': [], 'end-marker': True, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': [], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': False, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': ['a', 'c'], 'selected': [], 'cursor': None, 'loading': True, 'changed': True}, {'merge-order': ['b', 'a', 'c'], 'load-more': False, 'off-page': [], 'end-marker': True, 'replace-query': ['a', 'c'], 'visible-total': 3}), ({'old': ['b', 'a'], 'page': ['a', 'c'], 'selected': [], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': ['b', 'a', 'c'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 3}), ({'old': ['b', 'a'], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': ['b', 'a', 'c'], 'load-more': False, 'off-page': ['z'], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 3})]}
for index, (data, expected) in enumerate(fixtures[N]):
    check("contract fixture " + str(index), solve(data), 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
contract fixture 0{'end-marker': True, 'load-more': True, 'merge-order': [], 'off-page': [], 'replace-query': [], 'visible-total': 0}{'end-marker': False, 'load-more': True, 'merge-order': [], 'off-page': [], 'replace-query': [], 'visible-total': 0}Failed
contract fixture 1{'end-marker': True, 'load-more': False, 'merge-order': [], 'off-page': [], 'replace-query': [], 'visible-total': 0}{'end-marker': False, 'load-more': False, 'merge-order': [], 'off-page': [], 'replace-query': [], 'visible-total': 0}Failed
contract fixture 2{'end-marker': True, 'load-more': False, 'merge-order': [], 'off-page': ['z', 'b'], 'replace-query': [], 'visible-total': 0}{'end-marker': True, 'load-more': False, 'merge-order': [], 'off-page': ['z', 'b'], 'replace-query': [], 'visible-total': 0}Passed
contract fixture 3{'end-marker': False, 'load-more': False, 'merge-order': [], 'off-page': ['z', 'b'], 'replace-query': [], 'visible-total': 0}{'end-marker': False, 'load-more': False, 'merge-order': [], 'off-page': ['z', 'b'], 'replace-query': [], 'visible-total': 0}Passed
contract fixture 4{'end-marker': True, 'load-more': False, 'merge-order': ['a', 'c'], 'off-page': [], 'replace-query': ['a', 'c'], 'visible-total': 2}{'end-marker': False, 'load-more': False, 'merge-order': ['a', 'c'], 'off-page': [], 'replace-query': ['a', 'c'], 'visible-total': 2}Failed
contract fixture 5{'end-marker': True, 'load-more': False, 'merge-order': ['a', 'c'], 'off-page': ['z', 'b'], 'replace-query': ['a', 'c'], 'visible-total': 2}{'end-marker': True, 'load-more': False, 'merge-order': ['a', 'c'], 'off-page': ['z', 'b'], 'replace-query': ['a', 'c'], 'visible-total': 2}Passed
contract fixture 6{'end-marker': False, 'load-more': False, 'merge-order': ['a', 'c'], 'off-page': ['z', 'b'], 'replace-query': ['a', 'c'], 'visible-total': 2}{'end-marker': False, 'load-more': False, 'merge-order': ['a', 'c'], 'off-page': ['z', 'b'], 'replace-query': ['a', 'c'], 'visible-total': 2}Passed
contract fixture 7{'end-marker': True, 'load-more': False, 'merge-order': ['b', 'a'], 'off-page': [], 'replace-query': [], 'visible-total': 2}{'end-marker': False, 'load-more': False, 'merge-order': ['b', 'a'], 'off-page': [], 'replace-query': [], 'visible-total': 2}Failed
contract fixture 8{'end-marker': True, 'load-more': False, 'merge-order': ['b', 'a'], 'off-page': ['z'], 'replace-query': [], 'visible-total': 2}{'end-marker': True, 'load-more': False, 'merge-order': ['b', 'a'], 'off-page': ['z'], 'replace-query': [], 'visible-total': 2}Passed
contract fixture 9{'end-marker': False, 'load-more': False, 'merge-order': ['b', 'a'], 'off-page': ['z'], 'replace-query': [], 'visible-total': 2}{'end-marker': False, 'load-more': False, 'merge-order': ['b', 'a'], 'off-page': ['z'], 'replace-query': [], 'visible-total': 2}Passed

SHA-256 / 4e44837b7d8638038603d8d023e7e6d4a04de1e5c52a3944c9508410493e9fc9

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(d):
    return {'merge-order':(list(dict.fromkeys(d['old']+d['page']))), 'load-more':(d['cursor'] is not None and not d['loading']), 'off-page':([x for x in d['selected'] if x not in d['old']+d['page']]), 'end-marker':(not d['page']), 'replace-query':(list(d['page']) if d['changed'] else list(dict.fromkeys(d['old']+d['page']))), 'visible-total':(len(set(d['old']+d['page'])))}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = {1: [({'old': [], 'page': [], 'selected': [], 'cursor': '', 'loading': False, 'changed': False}, {'merge-order': [], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': [], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': [], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': None, 'loading': True, 'changed': True}, {'merge-order': [], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': True, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': [], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': ['a', 'c'], 'selected': [], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': None, 'loading': True, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': True, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': [], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': None, 'loading': True, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': True, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': False, 'replace-query': [], 'visible-total': 2})], 2: [({'old': [], 'page': [], 'selected': [], 'cursor': '', 'loading': False, 'changed': True}, {'merge-order': [], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': [], 'cursor': 'next', 'loading': True, 'changed': False}, {'merge-order': [], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': None, 'loading': True, 'changed': False}, {'merge-order': [], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': True, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': False}, {'merge-order': [], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': ['a', 'c'], 'selected': [], 'cursor': '', 'loading': True, 'changed': False}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': None, 'loading': True, 'changed': False}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': True, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': False}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': [], 'cursor': '', 'loading': True, 'changed': False}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': ['b', 'a'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': None, 'loading': True, 'changed': False}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': True, 'replace-query': ['b', 'a'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': False}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': False, 'replace-query': ['b', 'a'], 'visible-total': 2})], 3: [({'old': [], 'page': [], 'selected': [], 'cursor': '', 'loading': True, 'changed': False}, {'merge-order': [], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': '', 'loading': False, 'changed': True}, {'merge-order': [], 'load-more': True, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': False, 'changed': True}, {'merge-order': [], 'load-more': True, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': ['a', 'c'], 'selected': [], 'cursor': '', 'loading': False, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': None, 'loading': False, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': True, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': False, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': True, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': [], 'cursor': '', 'loading': False, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': None, 'loading': False, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': True, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': False, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': True, 'off-page': ['z'], 'end-marker': False, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': ['a', 'c'], 'selected': [], 'cursor': '', 'loading': False, 'changed': True}, {'merge-order': ['b', 'a', 'c'], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 3})], 4: [({'old': [], 'page': [], 'selected': [], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': [], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': False, 'changed': False}, {'merge-order': [], 'load-more': True, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': ['a', 'c'], 'selected': [], 'cursor': '', 'loading': False, 'changed': False}, {'merge-order': ['a', 'c'], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': None, 'loading': False, 'changed': False}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': True, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': False, 'changed': False}, {'merge-order': ['a', 'c'], 'load-more': True, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': [], 'cursor': '', 'loading': False, 'changed': False}, {'merge-order': ['b', 'a'], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': ['b', 'a'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': None, 'loading': False, 'changed': False}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': True, 'replace-query': ['b', 'a'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': False, 'changed': False}, {'merge-order': ['b', 'a'], 'load-more': True, 'off-page': ['z'], 'end-marker': False, 'replace-query': ['b', 'a'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': ['a', 'c'], 'selected': [], 'cursor': '', 'loading': False, 'changed': False}, {'merge-order': ['b', 'a', 'c'], 'load-more': True, 'off-page': [], 'end-marker': False, 'replace-query': ['b', 'a', 'c'], 'visible-total': 3}), ({'old': ['b', 'a'], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': None, 'loading': False, 'changed': False}, {'merge-order': ['b', 'a', 'c'], 'load-more': False, 'off-page': ['z'], 'end-marker': True, 'replace-query': ['b', 'a', 'c'], 'visible-total': 3})], 5: [({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': '', 'loading': False, 'changed': False}, {'merge-order': [], 'load-more': True, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': [], 'selected': ['z', 'b'], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': [], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': [], 'visible-total': 0}), ({'old': [], 'page': ['a', 'c'], 'selected': [], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': [], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': ['a', 'c'], 'load-more': False, 'off-page': ['z', 'b'], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': [], 'cursor': None, 'loading': True, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': [], 'end-marker': True, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': [], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': [], 'selected': ['z', 'b'], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': ['b', 'a'], 'load-more': False, 'off-page': ['z'], 'end-marker': False, 'replace-query': [], 'visible-total': 2}), ({'old': ['b', 'a'], 'page': ['a', 'c'], 'selected': [], 'cursor': None, 'loading': True, 'changed': True}, {'merge-order': ['b', 'a', 'c'], 'load-more': False, 'off-page': [], 'end-marker': True, 'replace-query': ['a', 'c'], 'visible-total': 3}), ({'old': ['b', 'a'], 'page': ['a', 'c'], 'selected': [], 'cursor': 'next', 'loading': True, 'changed': True}, {'merge-order': ['b', 'a', 'c'], 'load-more': False, 'off-page': [], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 3}), ({'old': ['b', 'a'], 'page': ['a', 'c'], 'selected': ['z', 'b'], 'cursor': '', 'loading': True, 'changed': True}, {'merge-order': ['b', 'a', 'c'], 'load-more': False, 'off-page': ['z'], 'end-marker': False, 'replace-query': ['a', 'c'], 'visible-total': 3})]}
for index, (data, expected) in enumerate(fixtures[N]):
    check("contract fixture " + str(index), solve(data), 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
contract fixture 0{'end-marker': True, 'load-more': True, 'merge-order': [], 'off-page': [], 'replace-query': [], 'visible-total': 0}{'end-marker': False, 'load-more': True, 'merge-order': [], 'off-page': [], 'replace-query': [], 'visible-total': 0}Failed
contract fixture 1{'end-marker': True, 'load-more': False, 'merge-order': [], 'off-page': [], 'replace-query': [], 'visible-total': 0}{'end-marker': False, 'load-more': False, 'merge-order': [], 'off-page': [], 'replace-query': [], 'visible-total': 0}Failed
contract fixture 2{'end-marker': True, 'load-more': False, 'merge-order': [], 'off-page': ['z', 'b'], 'replace-query': [], 'visible-total': 0}{'end-marker': True, 'load-more': False, 'merge-order': [], 'off-page': ['z', 'b'], 'replace-query': [], 'visible-total': 0}Passed
contract fixture 3{'end-marker': True, 'load-more': False, 'merge-order': [], 'off-page': ['z', 'b'], 'replace-query': [], 'visible-total': 0}{'end-marker': False, 'load-more': False, 'merge-order': [], 'off-page': ['z', 'b'], 'replace-query': [], 'visible-total': 0}Failed
contract fixture 4{'end-marker': False, 'load-more': False, 'merge-order': ['a', 'c'], 'off-page': [], 'replace-query': ['a', 'c'], 'visible-total': 2}{'end-marker': False, 'load-more': False, 'merge-order': ['a', 'c'], 'off-page': [], 'replace-query': ['a', 'c'], 'visible-total': 2}Passed
contract fixture 5{'end-marker': False, 'load-more': False, 'merge-order': ['a', 'c'], 'off-page': ['z', 'b'], 'replace-query': ['a', 'c'], 'visible-total': 2}{'end-marker': True, 'load-more': False, 'merge-order': ['a', 'c'], 'off-page': ['z', 'b'], 'replace-query': ['a', 'c'], 'visible-total': 2}Failed
contract fixture 6{'end-marker': False, 'load-more': False, 'merge-order': ['a', 'c'], 'off-page': ['z', 'b'], 'replace-query': ['a', 'c'], 'visible-total': 2}{'end-marker': False, 'load-more': False, 'merge-order': ['a', 'c'], 'off-page': ['z', 'b'], 'replace-query': ['a', 'c'], 'visible-total': 2}Passed
contract fixture 7{'end-marker': True, 'load-more': False, 'merge-order': ['b', 'a'], 'off-page': [], 'replace-query': [], 'visible-total': 2}{'end-marker': False, 'load-more': False, 'merge-order': ['b', 'a'], 'off-page': [], 'replace-query': [], 'visible-total': 2}Failed
contract fixture 8{'end-marker': True, 'load-more': False, 'merge-order': ['b', 'a'], 'off-page': ['z'], 'replace-query': [], 'visible-total': 2}{'end-marker': True, 'load-more': False, 'merge-order': ['b', 'a'], 'off-page': ['z'], 'replace-query': [], 'visible-total': 2}Passed
contract fixture 9{'end-marker': True, 'load-more': False, 'merge-order': ['b', 'a'], 'off-page': ['z'], 'replace-query': [], 'visible-total': 2}{'end-marker': False, 'load-more': False, 'merge-order': ['b', 'a'], 'off-page': ['z'], 'replace-query': [], 'visible-total': 2}Failed

SHA-256 / f3b70b21bff8589e78d5098549ca5b90c61680ddc5a36faf40cb083ac5fe1286

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

This mechanism has 10 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.

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Verification & scope

Deterministic bounded UI-state model only; no browser, query engine, network, or production-standard conformance is claimed. 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 2026-09-29T14:41:03.836083+00:00.

Case digest / 366b81005b117c0921db5b85abacf4d6d20dbf1ec10b6cd8a6fbf8af22e707ff