FA-38621 / Tree accessibility / Open access

Subtree deletion state cleanup: Deletion fallback priority skips surviving parent · case 01

Deletion fallback priority skips surviving parent produces the wrong hierarchical widget state in a regression fixture.

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

ROOT CAUSE

The delete-subtree contract is violated at `[nextrow,prevrow,d['parent']]+d['roots']` by replacing it with `[d['parent'],nextrow,prevrow]+d['roots']`.

THE FAILURE

The delete-subtree contract is violated at `[nextrow,prevrow,d['parent']]+d['roots']` by replacing it with `[d['parent'],nextrow,prevrow]+d['roots']`.

Unsuccessful approach: The partial repair `[nextrow,prevrow]+d['roots']` still violates a boundary or preservation case.

Case contract

Remove a supplied subtree closure atomically. Focus inside the deleted subtree recovers to surviving next sibling, previous sibling, then parent, then first root. Preserve unrelated state; clear only removed anchor, edits, expansion, selection and pending loads.

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):
    removed=set(d['removed'])
    rows=[x for x in d['rows'] if x not in removed]
    selected=[x for x in d['selected'] if x not in removed]
    expanded=[x for x in d['expanded'] if x not in removed]
    pending={x:v for x,v in d['pending'].items() if x not in removed}
    nextrow=next((x for x in d['next'] if x in rows),None)
    prevrow=next((x for x in reversed(d['previous']) if x in rows),None)
    fallback=next((x for x in [d['parent'],nextrow,prevrow]+d['roots'] if x in rows),None)
    focus=fallback if d['focus'] in removed else d['focus']
    anchor=None if d['anchor'] in removed else d['anchor']
    edit=None if d['edit'] in removed else d['edit']
    return [rows,selected,expanded,pending,focus,anchor,edit]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [('next recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'z', None, None]), ('previous recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'x', None, None]), ('parent recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['a'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'r', None, None]), ('unrelated focus', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'a', 'anchor': 'a', 'edit': 'a'}, [['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']), ('last root', {'removed': ['b', 'c'], 'rows': ['b', 'c'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [[], ['a'], ['r'], {'a': 1}, None, None, None]), ('stale neighbors', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c'], 'previous': ['a', 'c', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'x', None, None])], 2: [('next recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1'], ['a'], ['r'], {'a': 1}, 'z', None, None]), ('previous recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1'], ['a'], ['r'], {'a': 1}, 'x', None, None]), ('parent recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['a'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1'], ['a'], ['r'], {'a': 1}, 'r', None, None]), ('unrelated focus', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'a', 'anchor': 'a', 'edit': 'a'}, [['r', 'a', 'x', 'z', 'q0', 'q1'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']), ('last root', {'removed': ['b', 'c'], 'rows': ['b', 'c'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [[], ['a'], ['r'], {'a': 1}, None, None, None]), ('stale neighbors', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c'], 'previous': ['a', 'c', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1'], ['a'], ['r'], {'a': 1}, 'x', None, None])], 3: [('next recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1', 'q2'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2'], ['a'], ['r'], {'a': 1}, 'z', None, None]), ('previous recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2'], ['a'], ['r'], {'a': 1}, 'x', None, None]), ('parent recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['a'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2'], ['a'], ['r'], {'a': 1}, 'r', None, None]), ('unrelated focus', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1', 'q2'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'a', 'anchor': 'a', 'edit': 'a'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']), ('last root', {'removed': ['b', 'c'], 'rows': ['b', 'c'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [[], ['a'], ['r'], {'a': 1}, None, None, None]), ('stale neighbors', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c'], 'previous': ['a', 'c', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2'], ['a'], ['r'], {'a': 1}, 'x', None, None])], 4: [('next recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1', 'q2', 'q3'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3'], ['a'], ['r'], {'a': 1}, 'z', None, None]), ('previous recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3'], ['a'], ['r'], {'a': 1}, 'x', None, None]), ('parent recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['a'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3'], ['a'], ['r'], {'a': 1}, 'r', None, None]), ('unrelated focus', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1', 'q2', 'q3'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'a', 'anchor': 'a', 'edit': 'a'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']), ('last root', {'removed': ['b', 'c'], 'rows': ['b', 'c'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [[], ['a'], ['r'], {'a': 1}, None, None, None]), ('stale neighbors', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c'], 'previous': ['a', 'c', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3'], ['a'], ['r'], {'a': 1}, 'x', None, None])], 5: [('next recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], ['a'], ['r'], {'a': 1}, 'z', None, None]), ('previous recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], ['a'], ['r'], {'a': 1}, 'x', None, None]), ('parent recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['a'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], ['a'], ['r'], {'a': 1}, 'r', None, None]), ('unrelated focus', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'a', 'anchor': 'a', 'edit': 'a'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']), ('last root', {'removed': ['b', 'c'], 'rows': ['b', 'c'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [[], ['a'], ['r'], {'a': 1}, None, None, None]), ('stale neighbors', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c'], 'previous': ['a', 'c', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], ['a'], ['r'], {'a': 1}, 'x', None, None])]}
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
next recovery	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'r', None, None]`	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'z', None, None]`	Failed
previous recovery	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'r', None, None]`	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'x', None, None]`	Failed
parent recovery	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'r', None, None]`	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'r', None, None]`	Passed
unrelated focus	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']`	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']`	Passed
last root	`[[], ['a'], ['r'], {'a': 1}, None, None, None]`	`[[], ['a'], ['r'], {'a': 1}, None, None, None]`	Passed
stale neighbors	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'r', None, None]`	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'x', None, None]`	Failed

SHA-256 / 01ae573aeb6340b610e56c540e86b86558acab10ef0f9d381997f00458735874

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(d):
    removed=set(d['removed'])
    rows=[x for x in d['rows'] if x not in removed]
    selected=[x for x in d['selected'] if x not in removed]
    expanded=[x for x in d['expanded'] if x not in removed]
    pending={x:v for x,v in d['pending'].items() if x not in removed}
    nextrow=next((x for x in d['next'] if x in rows),None)
    prevrow=next((x for x in reversed(d['previous']) if x in rows),None)
    fallback=next((x for x in [nextrow,prevrow]+d['roots'] if x in rows),None)
    focus=fallback if d['focus'] in removed else d['focus']
    anchor=None if d['anchor'] in removed else d['anchor']
    edit=None if d['edit'] in removed else d['edit']
    return [rows,selected,expanded,pending,focus,anchor,edit]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [('next recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'z', None, None]), ('previous recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'x', None, None]), ('parent recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['a'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'r', None, None]), ('unrelated focus', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'a', 'anchor': 'a', 'edit': 'a'}, [['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']), ('last root', {'removed': ['b', 'c'], 'rows': ['b', 'c'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [[], ['a'], ['r'], {'a': 1}, None, None, None]), ('stale neighbors', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c'], 'previous': ['a', 'c', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'x', None, None])], 2: [('next recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1'], ['a'], ['r'], {'a': 1}, 'z', None, None]), ('previous recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1'], ['a'], ['r'], {'a': 1}, 'x', None, None]), ('parent recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['a'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1'], ['a'], ['r'], {'a': 1}, 'r', None, None]), ('unrelated focus', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'a', 'anchor': 'a', 'edit': 'a'}, [['r', 'a', 'x', 'z', 'q0', 'q1'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']), ('last root', {'removed': ['b', 'c'], 'rows': ['b', 'c'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [[], ['a'], ['r'], {'a': 1}, None, None, None]), ('stale neighbors', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c'], 'previous': ['a', 'c', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1'], ['a'], ['r'], {'a': 1}, 'x', None, None])], 3: [('next recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1', 'q2'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2'], ['a'], ['r'], {'a': 1}, 'z', None, None]), ('previous recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2'], ['a'], ['r'], {'a': 1}, 'x', None, None]), ('parent recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['a'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2'], ['a'], ['r'], {'a': 1}, 'r', None, None]), ('unrelated focus', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1', 'q2'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'a', 'anchor': 'a', 'edit': 'a'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']), ('last root', {'removed': ['b', 'c'], 'rows': ['b', 'c'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [[], ['a'], ['r'], {'a': 1}, None, None, None]), ('stale neighbors', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c'], 'previous': ['a', 'c', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2'], ['a'], ['r'], {'a': 1}, 'x', None, None])], 4: [('next recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1', 'q2', 'q3'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3'], ['a'], ['r'], {'a': 1}, 'z', None, None]), ('previous recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3'], ['a'], ['r'], {'a': 1}, 'x', None, None]), ('parent recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['a'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3'], ['a'], ['r'], {'a': 1}, 'r', None, None]), ('unrelated focus', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1', 'q2', 'q3'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'a', 'anchor': 'a', 'edit': 'a'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']), ('last root', {'removed': ['b', 'c'], 'rows': ['b', 'c'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [[], ['a'], ['r'], {'a': 1}, None, None, None]), ('stale neighbors', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c'], 'previous': ['a', 'c', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3'], ['a'], ['r'], {'a': 1}, 'x', None, None])], 5: [('next recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], ['a'], ['r'], {'a': 1}, 'z', None, None]), ('previous recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], ['a'], ['r'], {'a': 1}, 'x', None, None]), ('parent recovery', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['a'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], ['a'], ['r'], {'a': 1}, 'r', None, None]), ('unrelated focus', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'previous': ['a', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'a', 'anchor': 'a', 'edit': 'a'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']), ('last root', {'removed': ['b', 'c'], 'rows': ['b', 'c'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': [], 'previous': [], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [[], ['a'], ['r'], {'a': 1}, None, None, None]), ('stale neighbors', {'removed': ['b', 'c'], 'rows': ['r', 'a', 'x', 'b', 'c', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], 'selected': ['a', 'c'], 'expanded': ['r', 'b'], 'pending': {'a': 1, 'c': 2}, 'next': ['c'], 'previous': ['a', 'c', 'x'], 'parent': 'r', 'roots': ['r'], 'focus': 'c', 'anchor': 'c', 'edit': 'c'}, [['r', 'a', 'x', 'z', 'q0', 'q1', 'q2', 'q3', 'q4'], ['a'], ['r'], {'a': 1}, 'x', None, None])]}
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
next recovery	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'z', None, None]`	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'z', None, None]`	Passed
previous recovery	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'x', None, None]`	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'x', None, None]`	Passed
parent recovery	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'a', None, None]`	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'r', None, None]`	Failed
unrelated focus	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']`	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'a', 'a', 'a']`	Passed
last root	`[[], ['a'], ['r'], {'a': 1}, None, None, None]`	`[[], ['a'], ['r'], {'a': 1}, None, None, None]`	Passed
stale neighbors	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'x', None, None]`	`[['r', 'a', 'x', 'z', 'q0'], ['a'], ['r'], {'a': 1}, 'x', None, None]`	Passed

SHA-256 / 1685fa7b6c65017ef53f68c460385925354cb30ce0bca190c903ebcfb45291a3

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.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

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 2026-09-29T14:43:13.226036+00:00.

Case digest / 8b2dd7f1cf049e35a2a78838b12d5963d335abbe53b91ae38848f458e16ef6c1