FA-38471 / Tree accessibility / Open access

Virtual tree sibling metadata: Active row follows viewport position · case 01

Active row follows viewport position produces the wrong hierarchical widget state in a regression fixture.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The virtual-siblings contract is violated at `r['id']==d['active']` by replacing it with `d['slot']==d['active']`.

THE FAILURE

The virtual-siblings contract is violated at `r['id']==d['active']` by replacing it with `d['slot']==d['active']`.

Unsuccessful approach: The partial repair `bool(d['active'])` still violates a boundary or preservation case.

Case contract

Rows carry id,parent,logical sibling index,known sibling count,depth. The viewport must expose global sibling positions and counts, one-based depth, root ownership, expandable state only for branches, and stable identity independent of recycled slots.

Why this case matters

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.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(d):
    r=d['row']
    position=r['index']+1
    size=r['count'] if r['known'] else -1
    level=r['depth']+1
    owner=r['parent'] if r['parent'] is not None else d['tree']
    expanded=r['open'] if r['branch'] else None
    selected=r['id'] in d['selected']
    active=d['slot']==d['active']
    dom=d['tree']+':'+r['id']
    rowindex=d['offset']+d['slot']+1
    busy=r['loading'] and r['branch']
    return [position,size,level,owner,expanded,selected,active,dom,rowindex,busy]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [('branch', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 3, 'count': 9, 'known': True, 'depth': 1, 'open': True, 'branch': True, 'loading': True}, 'selected': ['b'], 'active': 'b', 'offset': 3, 'slot': 1, 'mounted': 3}, [4, 9, 2, 'p', True, True, True, 'tree:b', 5, True]), ('root', {'tree': 'tree', 'row': {'id': 'b', 'parent': None, 'index': 3, 'count': 9, 'known': True, 'depth': 1, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'x', 'offset': 3, 'slot': 1, 'mounted': 3}, [4, 9, 2, 'tree', True, False, False, 'tree:b', 5, True]), ('leaf', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 3, 'count': 9, 'known': True, 'depth': 1, 'open': True, 'branch': False, 'loading': True}, 'selected': ['b'], 'active': 'x', 'offset': 3, 'slot': 1, 'mounted': 3}, [4, 9, 2, 'p', None, True, False, 'tree:b', 5, False]), ('unknown', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 3, 'count': 9, 'known': False, 'depth': 1, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'b', 'offset': 3, 'slot': 1, 'mounted': 3}, [4, -1, 2, 'p', True, False, True, 'tree:b', 5, True]), ('idle', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 3, 'count': 9, 'known': True, 'depth': 1, 'open': True, 'branch': True, 'loading': False}, 'selected': ['x'], 'active': 'x', 'offset': 3, 'slot': 1, 'mounted': 3}, [4, 9, 2, 'p', True, False, False, 'tree:b', 5, False]), ('collapsed', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 0, 'count': 9, 'known': True, 'depth': 0, 'open': False, 'branch': True, 'loading': True}, 'selected': ['x'], 'active': 'b', 'offset': 3, 'slot': 1, 'mounted': 3}, [1, 9, 1, 'p', False, False, True, 'tree:b', 5, True])], 2: [('branch', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 4, 'count': 10, 'known': True, 'depth': 2, 'open': True, 'branch': True, 'loading': True}, 'selected': ['b'], 'active': 'b', 'offset': 6, 'slot': 1, 'mounted': 3}, [5, 10, 3, 'p', True, True, True, 'tree:b', 8, True]), ('root', {'tree': 'tree', 'row': {'id': 'b', 'parent': None, 'index': 4, 'count': 10, 'known': True, 'depth': 2, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'x', 'offset': 6, 'slot': 1, 'mounted': 3}, [5, 10, 3, 'tree', True, False, False, 'tree:b', 8, True]), ('leaf', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 4, 'count': 10, 'known': True, 'depth': 2, 'open': True, 'branch': False, 'loading': True}, 'selected': ['b'], 'active': 'x', 'offset': 6, 'slot': 1, 'mounted': 3}, [5, 10, 3, 'p', None, True, False, 'tree:b', 8, False]), ('unknown', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 4, 'count': 10, 'known': False, 'depth': 2, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'b', 'offset': 6, 'slot': 1, 'mounted': 3}, [5, -1, 3, 'p', True, False, True, 'tree:b', 8, True]), ('idle', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 4, 'count': 10, 'known': True, 'depth': 2, 'open': True, 'branch': True, 'loading': False}, 'selected': ['x'], 'active': 'x', 'offset': 6, 'slot': 1, 'mounted': 3}, [5, 10, 3, 'p', True, False, False, 'tree:b', 8, False]), ('collapsed', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 0, 'count': 10, 'known': True, 'depth': 0, 'open': False, 'branch': True, 'loading': True}, 'selected': ['x'], 'active': 'b', 'offset': 6, 'slot': 1, 'mounted': 3}, [1, 10, 1, 'p', False, False, True, 'tree:b', 8, True])], 3: [('branch', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 5, 'count': 11, 'known': True, 'depth': 3, 'open': True, 'branch': True, 'loading': True}, 'selected': ['b'], 'active': 'b', 'offset': 9, 'slot': 1, 'mounted': 3}, [6, 11, 4, 'p', True, True, True, 'tree:b', 11, True]), ('root', {'tree': 'tree', 'row': {'id': 'b', 'parent': None, 'index': 5, 'count': 11, 'known': True, 'depth': 3, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'x', 'offset': 9, 'slot': 1, 'mounted': 3}, [6, 11, 4, 'tree', True, False, False, 'tree:b', 11, True]), ('leaf', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 5, 'count': 11, 'known': True, 'depth': 3, 'open': True, 'branch': False, 'loading': True}, 'selected': ['b'], 'active': 'x', 'offset': 9, 'slot': 1, 'mounted': 3}, [6, 11, 4, 'p', None, True, False, 'tree:b', 11, False]), ('unknown', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 5, 'count': 11, 'known': False, 'depth': 3, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'b', 'offset': 9, 'slot': 1, 'mounted': 3}, [6, -1, 4, 'p', True, False, True, 'tree:b', 11, True]), ('idle', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 5, 'count': 11, 'known': True, 'depth': 3, 'open': True, 'branch': True, 'loading': False}, 'selected': ['x'], 'active': 'x', 'offset': 9, 'slot': 1, 'mounted': 3}, [6, 11, 4, 'p', True, False, False, 'tree:b', 11, False]), ('collapsed', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 0, 'count': 11, 'known': True, 'depth': 0, 'open': False, 'branch': True, 'loading': True}, 'selected': ['x'], 'active': 'b', 'offset': 9, 'slot': 1, 'mounted': 3}, [1, 11, 1, 'p', False, False, True, 'tree:b', 11, True])], 4: [('branch', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 6, 'count': 12, 'known': True, 'depth': 4, 'open': True, 'branch': True, 'loading': True}, 'selected': ['b'], 'active': 'b', 'offset': 12, 'slot': 1, 'mounted': 3}, [7, 12, 5, 'p', True, True, True, 'tree:b', 14, True]), ('root', {'tree': 'tree', 'row': {'id': 'b', 'parent': None, 'index': 6, 'count': 12, 'known': True, 'depth': 4, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'x', 'offset': 12, 'slot': 1, 'mounted': 3}, [7, 12, 5, 'tree', True, False, False, 'tree:b', 14, True]), ('leaf', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 6, 'count': 12, 'known': True, 'depth': 4, 'open': True, 'branch': False, 'loading': True}, 'selected': ['b'], 'active': 'x', 'offset': 12, 'slot': 1, 'mounted': 3}, [7, 12, 5, 'p', None, True, False, 'tree:b', 14, False]), ('unknown', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 6, 'count': 12, 'known': False, 'depth': 4, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'b', 'offset': 12, 'slot': 1, 'mounted': 3}, [7, -1, 5, 'p', True, False, True, 'tree:b', 14, True]), ('idle', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 6, 'count': 12, 'known': True, 'depth': 4, 'open': True, 'branch': True, 'loading': False}, 'selected': ['x'], 'active': 'x', 'offset': 12, 'slot': 1, 'mounted': 3}, [7, 12, 5, 'p', True, False, False, 'tree:b', 14, False]), ('collapsed', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 0, 'count': 12, 'known': True, 'depth': 0, 'open': False, 'branch': True, 'loading': True}, 'selected': ['x'], 'active': 'b', 'offset': 12, 'slot': 1, 'mounted': 3}, [1, 12, 1, 'p', False, False, True, 'tree:b', 14, True])], 5: [('branch', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 7, 'count': 13, 'known': True, 'depth': 5, 'open': True, 'branch': True, 'loading': True}, 'selected': ['b'], 'active': 'b', 'offset': 15, 'slot': 1, 'mounted': 3}, [8, 13, 6, 'p', True, True, True, 'tree:b', 17, True]), ('root', {'tree': 'tree', 'row': {'id': 'b', 'parent': None, 'index': 7, 'count': 13, 'known': True, 'depth': 5, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'x', 'offset': 15, 'slot': 1, 'mounted': 3}, [8, 13, 6, 'tree', True, False, False, 'tree:b', 17, True]), ('leaf', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 7, 'count': 13, 'known': True, 'depth': 5, 'open': True, 'branch': False, 'loading': True}, 'selected': ['b'], 'active': 'x', 'offset': 15, 'slot': 1, 'mounted': 3}, [8, 13, 6, 'p', None, True, False, 'tree:b', 17, False]), ('unknown', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 7, 'count': 13, 'known': False, 'depth': 5, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'b', 'offset': 15, 'slot': 1, 'mounted': 3}, [8, -1, 6, 'p', True, False, True, 'tree:b', 17, True]), ('idle', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 7, 'count': 13, 'known': True, 'depth': 5, 'open': True, 'branch': True, 'loading': False}, 'selected': ['x'], 'active': 'x', 'offset': 15, 'slot': 1, 'mounted': 3}, [8, 13, 6, 'p', True, False, False, 'tree:b', 17, False]), ('collapsed', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 0, 'count': 13, 'known': True, 'depth': 0, 'open': False, 'branch': True, 'loading': True}, 'selected': ['x'], 'active': 'b', 'offset': 15, 'slot': 1, 'mounted': 3}, [1, 13, 1, 'p', False, False, True, 'tree:b', 17, True])]}
for label, data, expected in cases[N]:
    check(label, 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 fixture	Actual	Expected	Outcome
branch	`[4, 9, 2, 'p', True, True, False, 'tree:b', 5, True]`	`[4, 9, 2, 'p', True, True, True, 'tree:b', 5, True]`	Failed
root	`[4, 9, 2, 'tree', True, False, False, 'tree:b', 5, True]`	`[4, 9, 2, 'tree', True, False, False, 'tree:b', 5, True]`	Passed
leaf	`[4, 9, 2, 'p', None, True, False, 'tree:b', 5, False]`	`[4, 9, 2, 'p', None, True, False, 'tree:b', 5, False]`	Passed
unknown	`[4, -1, 2, 'p', True, False, False, 'tree:b', 5, True]`	`[4, -1, 2, 'p', True, False, True, 'tree:b', 5, True]`	Failed
idle	`[4, 9, 2, 'p', True, False, False, 'tree:b', 5, False]`	`[4, 9, 2, 'p', True, False, False, 'tree:b', 5, False]`	Passed
collapsed	`[1, 9, 1, 'p', False, False, False, 'tree:b', 5, True]`	`[1, 9, 1, 'p', False, False, True, 'tree:b', 5, True]`	Failed

SHA-256 / bb67d60da12663b98dfe2535ecec81ea9fb408afe5b3953738112bb74c219115

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(d):
    r=d['row']
    position=r['index']+1
    size=r['count'] if r['known'] else -1
    level=r['depth']+1
    owner=r['parent'] if r['parent'] is not None else d['tree']
    expanded=r['open'] if r['branch'] else None
    selected=r['id'] in d['selected']
    active=bool(d['active'])
    dom=d['tree']+':'+r['id']
    rowindex=d['offset']+d['slot']+1
    busy=r['loading'] and r['branch']
    return [position,size,level,owner,expanded,selected,active,dom,rowindex,busy]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [('branch', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 3, 'count': 9, 'known': True, 'depth': 1, 'open': True, 'branch': True, 'loading': True}, 'selected': ['b'], 'active': 'b', 'offset': 3, 'slot': 1, 'mounted': 3}, [4, 9, 2, 'p', True, True, True, 'tree:b', 5, True]), ('root', {'tree': 'tree', 'row': {'id': 'b', 'parent': None, 'index': 3, 'count': 9, 'known': True, 'depth': 1, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'x', 'offset': 3, 'slot': 1, 'mounted': 3}, [4, 9, 2, 'tree', True, False, False, 'tree:b', 5, True]), ('leaf', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 3, 'count': 9, 'known': True, 'depth': 1, 'open': True, 'branch': False, 'loading': True}, 'selected': ['b'], 'active': 'x', 'offset': 3, 'slot': 1, 'mounted': 3}, [4, 9, 2, 'p', None, True, False, 'tree:b', 5, False]), ('unknown', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 3, 'count': 9, 'known': False, 'depth': 1, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'b', 'offset': 3, 'slot': 1, 'mounted': 3}, [4, -1, 2, 'p', True, False, True, 'tree:b', 5, True]), ('idle', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 3, 'count': 9, 'known': True, 'depth': 1, 'open': True, 'branch': True, 'loading': False}, 'selected': ['x'], 'active': 'x', 'offset': 3, 'slot': 1, 'mounted': 3}, [4, 9, 2, 'p', True, False, False, 'tree:b', 5, False]), ('collapsed', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 0, 'count': 9, 'known': True, 'depth': 0, 'open': False, 'branch': True, 'loading': True}, 'selected': ['x'], 'active': 'b', 'offset': 3, 'slot': 1, 'mounted': 3}, [1, 9, 1, 'p', False, False, True, 'tree:b', 5, True])], 2: [('branch', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 4, 'count': 10, 'known': True, 'depth': 2, 'open': True, 'branch': True, 'loading': True}, 'selected': ['b'], 'active': 'b', 'offset': 6, 'slot': 1, 'mounted': 3}, [5, 10, 3, 'p', True, True, True, 'tree:b', 8, True]), ('root', {'tree': 'tree', 'row': {'id': 'b', 'parent': None, 'index': 4, 'count': 10, 'known': True, 'depth': 2, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'x', 'offset': 6, 'slot': 1, 'mounted': 3}, [5, 10, 3, 'tree', True, False, False, 'tree:b', 8, True]), ('leaf', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 4, 'count': 10, 'known': True, 'depth': 2, 'open': True, 'branch': False, 'loading': True}, 'selected': ['b'], 'active': 'x', 'offset': 6, 'slot': 1, 'mounted': 3}, [5, 10, 3, 'p', None, True, False, 'tree:b', 8, False]), ('unknown', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 4, 'count': 10, 'known': False, 'depth': 2, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'b', 'offset': 6, 'slot': 1, 'mounted': 3}, [5, -1, 3, 'p', True, False, True, 'tree:b', 8, True]), ('idle', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 4, 'count': 10, 'known': True, 'depth': 2, 'open': True, 'branch': True, 'loading': False}, 'selected': ['x'], 'active': 'x', 'offset': 6, 'slot': 1, 'mounted': 3}, [5, 10, 3, 'p', True, False, False, 'tree:b', 8, False]), ('collapsed', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 0, 'count': 10, 'known': True, 'depth': 0, 'open': False, 'branch': True, 'loading': True}, 'selected': ['x'], 'active': 'b', 'offset': 6, 'slot': 1, 'mounted': 3}, [1, 10, 1, 'p', False, False, True, 'tree:b', 8, True])], 3: [('branch', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 5, 'count': 11, 'known': True, 'depth': 3, 'open': True, 'branch': True, 'loading': True}, 'selected': ['b'], 'active': 'b', 'offset': 9, 'slot': 1, 'mounted': 3}, [6, 11, 4, 'p', True, True, True, 'tree:b', 11, True]), ('root', {'tree': 'tree', 'row': {'id': 'b', 'parent': None, 'index': 5, 'count': 11, 'known': True, 'depth': 3, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'x', 'offset': 9, 'slot': 1, 'mounted': 3}, [6, 11, 4, 'tree', True, False, False, 'tree:b', 11, True]), ('leaf', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 5, 'count': 11, 'known': True, 'depth': 3, 'open': True, 'branch': False, 'loading': True}, 'selected': ['b'], 'active': 'x', 'offset': 9, 'slot': 1, 'mounted': 3}, [6, 11, 4, 'p', None, True, False, 'tree:b', 11, False]), ('unknown', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 5, 'count': 11, 'known': False, 'depth': 3, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'b', 'offset': 9, 'slot': 1, 'mounted': 3}, [6, -1, 4, 'p', True, False, True, 'tree:b', 11, True]), ('idle', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 5, 'count': 11, 'known': True, 'depth': 3, 'open': True, 'branch': True, 'loading': False}, 'selected': ['x'], 'active': 'x', 'offset': 9, 'slot': 1, 'mounted': 3}, [6, 11, 4, 'p', True, False, False, 'tree:b', 11, False]), ('collapsed', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 0, 'count': 11, 'known': True, 'depth': 0, 'open': False, 'branch': True, 'loading': True}, 'selected': ['x'], 'active': 'b', 'offset': 9, 'slot': 1, 'mounted': 3}, [1, 11, 1, 'p', False, False, True, 'tree:b', 11, True])], 4: [('branch', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 6, 'count': 12, 'known': True, 'depth': 4, 'open': True, 'branch': True, 'loading': True}, 'selected': ['b'], 'active': 'b', 'offset': 12, 'slot': 1, 'mounted': 3}, [7, 12, 5, 'p', True, True, True, 'tree:b', 14, True]), ('root', {'tree': 'tree', 'row': {'id': 'b', 'parent': None, 'index': 6, 'count': 12, 'known': True, 'depth': 4, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'x', 'offset': 12, 'slot': 1, 'mounted': 3}, [7, 12, 5, 'tree', True, False, False, 'tree:b', 14, True]), ('leaf', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 6, 'count': 12, 'known': True, 'depth': 4, 'open': True, 'branch': False, 'loading': True}, 'selected': ['b'], 'active': 'x', 'offset': 12, 'slot': 1, 'mounted': 3}, [7, 12, 5, 'p', None, True, False, 'tree:b', 14, False]), ('unknown', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 6, 'count': 12, 'known': False, 'depth': 4, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'b', 'offset': 12, 'slot': 1, 'mounted': 3}, [7, -1, 5, 'p', True, False, True, 'tree:b', 14, True]), ('idle', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 6, 'count': 12, 'known': True, 'depth': 4, 'open': True, 'branch': True, 'loading': False}, 'selected': ['x'], 'active': 'x', 'offset': 12, 'slot': 1, 'mounted': 3}, [7, 12, 5, 'p', True, False, False, 'tree:b', 14, False]), ('collapsed', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 0, 'count': 12, 'known': True, 'depth': 0, 'open': False, 'branch': True, 'loading': True}, 'selected': ['x'], 'active': 'b', 'offset': 12, 'slot': 1, 'mounted': 3}, [1, 12, 1, 'p', False, False, True, 'tree:b', 14, True])], 5: [('branch', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 7, 'count': 13, 'known': True, 'depth': 5, 'open': True, 'branch': True, 'loading': True}, 'selected': ['b'], 'active': 'b', 'offset': 15, 'slot': 1, 'mounted': 3}, [8, 13, 6, 'p', True, True, True, 'tree:b', 17, True]), ('root', {'tree': 'tree', 'row': {'id': 'b', 'parent': None, 'index': 7, 'count': 13, 'known': True, 'depth': 5, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'x', 'offset': 15, 'slot': 1, 'mounted': 3}, [8, 13, 6, 'tree', True, False, False, 'tree:b', 17, True]), ('leaf', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 7, 'count': 13, 'known': True, 'depth': 5, 'open': True, 'branch': False, 'loading': True}, 'selected': ['b'], 'active': 'x', 'offset': 15, 'slot': 1, 'mounted': 3}, [8, 13, 6, 'p', None, True, False, 'tree:b', 17, False]), ('unknown', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 7, 'count': 13, 'known': False, 'depth': 5, 'open': True, 'branch': True, 'loading': True}, 'selected': [], 'active': 'b', 'offset': 15, 'slot': 1, 'mounted': 3}, [8, -1, 6, 'p', True, False, True, 'tree:b', 17, True]), ('idle', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 7, 'count': 13, 'known': True, 'depth': 5, 'open': True, 'branch': True, 'loading': False}, 'selected': ['x'], 'active': 'x', 'offset': 15, 'slot': 1, 'mounted': 3}, [8, 13, 6, 'p', True, False, False, 'tree:b', 17, False]), ('collapsed', {'tree': 'tree', 'row': {'id': 'b', 'parent': 'p', 'index': 0, 'count': 13, 'known': True, 'depth': 0, 'open': False, 'branch': True, 'loading': True}, 'selected': ['x'], 'active': 'b', 'offset': 15, 'slot': 1, 'mounted': 3}, [1, 13, 1, 'p', False, False, True, 'tree:b', 17, True])]}
for label, data, expected in cases[N]:
    check(label, 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 fixture	Actual	Expected	Outcome
branch	`[4, 9, 2, 'p', True, True, True, 'tree:b', 5, True]`	`[4, 9, 2, 'p', True, True, True, 'tree:b', 5, True]`	Passed
root	`[4, 9, 2, 'tree', True, False, True, 'tree:b', 5, True]`	`[4, 9, 2, 'tree', True, False, False, 'tree:b', 5, True]`	Failed
leaf	`[4, 9, 2, 'p', None, True, True, 'tree:b', 5, False]`	`[4, 9, 2, 'p', None, True, False, 'tree:b', 5, False]`	Failed
unknown	`[4, -1, 2, 'p', True, False, True, 'tree:b', 5, True]`	`[4, -1, 2, 'p', True, False, True, 'tree:b', 5, True]`	Passed
idle	`[4, 9, 2, 'p', True, False, True, 'tree:b', 5, False]`	`[4, 9, 2, 'p', True, False, False, 'tree:b', 5, False]`	Failed
collapsed	`[1, 9, 1, 'p', False, False, True, 'tree:b', 5, True]`	`[1, 9, 1, 'p', False, False, True, 'tree:b', 5, True]`	Passed

SHA-256 / cefc7aaa2ab972db1df441321d70766db4fe013b4b2b85791a46dc503a0aad5a

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 6 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

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.

Observations recorded using Python 3.12.14 at 2026-09-29T14:43:11.695838+00:00.

Case digest / 9ec2f0c141cd6902831e202da89e007b7df76bf5922adc47e6b23bf4a2ed6737