{"abstract":"Mounted row lookup confuses recycled slot with logical ID produces the wrong hierarchical widget state in a regression fixture.","category":"Tree accessibility","checks":8,"contract":"A virtualized active row keeps its identity while offscreen. Expose an active descendant only after a matching mount generation acknowledges the row; scrolling requests mount without changing selection. A recycled slot must not satisfy an old lease. Collapse repairs the logical active row to the closest visible ancestor before mounting.","evaluation_group":"s3-tree-virtual-focus-lease","failed_approach":"The partial repair `row==d['active']` still violates a boundary or preservation case.","family":"s3-tree_accessibility-virtual-focus-lease-03","id":"FA-39101","implementations":{"attempt":{"sha256":"59752a6f95ffff8b2afa721ea0c687489e47baffb1f9c7fe5ce2cf1c5e43e8e7","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(d):\n    visible=d['visible']\n    logical=d['active'] if d['active'] in visible else next((a for a in reversed(d['ancestors']) if a in visible),(visible[0] if visible else None))\n    slot=next((slot for slot,row in d['slots'].items() if row==d['active']),None)\n    ack=slot is not None and d['acks'].get(slot)==[logical,d['generation']]\n    aria=(d['tree']+':'+logical) if ack else None\n    request=logical if logical is not None and not ack else None\n    scroll=visible.index(logical) if logical in visible and slot is None else None\n    selection=d['selection']\n    lease=[logical,d['generation']] if request is not None else None\n    pinned=[logical] if ack else []\n    return [logical,aria,request,scroll,selection,lease,pinned]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = {1: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 0]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 1], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 1], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 1], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 1], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 1], []])], 2: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 1]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 2], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 2], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 2], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 2], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 2], []])], 3: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 2]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 3], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 3], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 3], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 3], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 3], []])], 4: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 3]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 4], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 4], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 4], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 4], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 4], []])], 5: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 4]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 5], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 5], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 5], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 5], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 5], []])]}\nfor label, data, expected in cases[N]:\n    check(label, solve(data), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"620f23059fd6c4606bed86a40e253b378f1a0f6f4a15ac044980e66700ecebde","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(d):\n    visible=d['visible']\n    logical=d['active'] if d['active'] in visible else next((a for a in reversed(d['ancestors']) if a in visible),(visible[0] if visible else None))\n    slot=next((slot for slot,row in d['slots'].items() if slot==logical),None)\n    ack=slot is not None and d['acks'].get(slot)==[logical,d['generation']]\n    aria=(d['tree']+':'+logical) if ack else None\n    request=logical if logical is not None and not ack else None\n    scroll=visible.index(logical) if logical in visible and slot is None else None\n    selection=d['selection']\n    lease=[logical,d['generation']] if request is not None else None\n    pinned=[logical] if ack else []\n    return [logical,aria,request,scroll,selection,lease,pinned]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = {1: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 0]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 1], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 1], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 1], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 1], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 1], []])], 2: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 1]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 2], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 2], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 2], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 2], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 2], []])], 3: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 2]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 3], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 3], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 3], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 3], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 3], []])], 4: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 3]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 4], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 4], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 4], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 4], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 4], []])], 5: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 4]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 5], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 5], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 5], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 5], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 5], []])]}\nfor label, data, expected in cases[N]:\n    check(label, solve(data), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"fixed":{"sha256":"3c7cd20b733546b54a016d1b01122f7cf354a1d29a4c6142582405ed7b37b39d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(d):\n    visible=d['visible']\n    logical=d['active'] if d['active'] in visible else next((a for a in reversed(d['ancestors']) if a in visible),(visible[0] if visible else None))\n    slot=next((slot for slot,row in d['slots'].items() if row==logical),None)\n    ack=slot is not None and d['acks'].get(slot)==[logical,d['generation']]\n    aria=(d['tree']+':'+logical) if ack else None\n    request=logical if logical is not None and not ack else None\n    scroll=visible.index(logical) if logical in visible and slot is None else None\n    selection=d['selection']\n    lease=[logical,d['generation']] if request is not None else None\n    pinned=[logical] if ack else []\n    return [logical,aria,request,scroll,selection,lease,pinned]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncases = {1: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 0]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 1], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 1], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 1], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 1], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 1], 'slot1': ['b', 1]}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 1, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 1], []])], 2: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 1]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 2], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 2], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 2], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 2], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 2], 'slot1': ['b', 2]}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0', 'x1'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 2, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 2], []])], 3: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 2]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 3], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 3], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 3], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 3], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 3], 'slot1': ['b', 3]}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 3, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 3], []])], 4: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 3]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 4], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 4], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 4], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 4], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 4], 'slot1': ['b', 4]}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 4, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 4], []])], 5: [('mounted lease', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', 'tree:b', None, None, ['a'], None, ['b']]), ('old ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['b', 4]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 5], []]), ('recycled ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot1': ['gone', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 5], []]), ('offscreen', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'r'}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', 2, ['a'], ['b', 5], []]), ('collapse', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['a', 'tree:a', None, None, ['a'], None, ['a']]), ('collapse offscreen', {'visible': ['r', 'a'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['a', None, 'a', 1, ['a'], ['a', 5], []]), ('empty tree', {'visible': [], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {}, 'acks': {'slot0': ['a', 5], 'slot1': ['b', 5]}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, [None, None, None, None, ['a'], None, []]), ('no ack', {'visible': ['r', 'a', 'b', 'x0', 'x1', 'x2', 'x3', 'x4'], 'active': 'b', 'ancestors': ['r', 'a'], 'slots': {'slot0': 'a', 'slot1': 'b'}, 'acks': {}, 'generation': 5, 'tree': 'tree', 'selection': ['a']}, ['b', None, 'b', None, ['a'], ['b', 5], []])]}\nfor label, data, expected in cases[N]:\n    check(label, solve(data), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"Synthetic deterministic hierarchical-widget data contract; not an implementation of a browser accessibility tree. 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.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"s3-tree_accessibility-virtual-focus-lease-03","generated_at":"2026-09-29T14:43:17.921902+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Offline executable model of a hierarchical accessibility interaction; inputs are bounded and valid as stipulated. No browser, assistive technology, or normative ARIA conformance is claimed.","repair":"Restore `row==logical` at this fault site while retaining the other tree state decisions.","root_cause":"The virtual-focus-lease contract is violated at `row==logical` by replacing it with `slot==logical`.","sha256":"c1d40322eb26c8ec673f092b97006c9d2cdf95066092dfd2810322d7578c6b4a","title":"Virtual tree active-descendant lease: Mounted row lookup confuses recycled slot with logical ID · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":43.224,"exit_code":1,"observations":[{"actual":["b","tree:b",null,null,["a"],null,["b"]],"check":"mounted lease","expected":["b","tree:b",null,null,["a"],null,["b"]],"passed":true},{"actual":["b",null,"b",null,["a"],["b",1],[]],"check":"old ack","expected":["b",null,"b",null,["a"],["b",1],[]],"passed":true},{"actual":["b",null,"b",null,["a"],["b",1],[]],"check":"recycled 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