FA-39461 / Tree accessibility / Open access

Asynchronous tree reveal path: Reveal readiness checks unrelated parent-child links · case 01

Reveal readiness checks unrelated parent-child links produces the wrong hierarchical widget state in a regression fixture.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The reveal-path contract is violated at `node not in d['children'].get(d['path'][i-1],[])` by replacing it with `node not in d['children'].get(node,[])`.

THE FAILURE

The reveal-path contract is violated at `node not in d['children'].get(d['path'][i-1],[])` by replacing it with `node not in d['children'].get(node,[])`.

Unsuccessful approach: The partial repair `node not in sum(d['children'].values(),[])` still violates a boundary or preservation case.

Case contract

Reveal consumes an ordered root-to-target path. Already loaded branches are opened in order until the first missing child link, then exactly one load is requested. Focus moves only when the target is visible and the request generation is current. A denied branch stops reveal before opening it.

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):
    current=d['generation']==d['request_generation']
    opened=set(d['opened']); request=None; blocked=None; reached=None
    if current:
        for i,node in enumerate(d['path']):
            if node in d['denied']:
                blocked=node; break
            if i and node not in d['children'].get(node,[]):
                request=d['path'][i-1]; break
            reached=node
            if i<len(d['path'])-1: opened.add(node)
    finished=current and bool(d['path']) and reached==d['path'][-1] and blocked is None and request is None
    focus=d['path'][-1] if finished else d['focus']
    pending=d['path'][d['path'].index(reached)+1:] if current and reached in d['path'] else (d['path'] if current else [])
    return [sorted(opened),request,blocked,finished,focus,pending]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [('complete reveal', {'generation': 1, 'request_generation': 1, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], None, None, True, 'c', []]), ('missing deep child', {'generation': 1, 'request_generation': 1, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': []}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]), ('wrong branch child', {'generation': 1, 'request_generation': 1, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a', 'b'], 'a': [], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], 'a', None, False, 'q', ['b', 'c']]), ('denied middle', {'generation': 1, 'request_generation': 1, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['b'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]), ('stale request', {'generation': 1, 'request_generation': 0, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('empty path', {'generation': 1, 'request_generation': 1, 'opened': ['q'], 'path': [], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('denied root', {'generation': 1, 'request_generation': 1, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['r'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']])], 2: [('complete reveal', {'generation': 2, 'request_generation': 2, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], None, None, True, 'c', []]), ('missing deep child', {'generation': 2, 'request_generation': 2, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': []}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]), ('wrong branch child', {'generation': 2, 'request_generation': 2, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a', 'b'], 'a': [], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], 'a', None, False, 'q', ['b', 'c']]), ('denied middle', {'generation': 2, 'request_generation': 2, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['b'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]), ('stale request', {'generation': 2, 'request_generation': 1, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('empty path', {'generation': 2, 'request_generation': 2, 'opened': ['q'], 'path': [], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('denied root', {'generation': 2, 'request_generation': 2, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['r'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']])], 3: [('complete reveal', {'generation': 3, 'request_generation': 3, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], None, None, True, 'c', []]), ('missing deep child', {'generation': 3, 'request_generation': 3, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': []}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]), ('wrong branch child', {'generation': 3, 'request_generation': 3, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a', 'b'], 'a': [], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], 'a', None, False, 'q', ['b', 'c']]), ('denied middle', {'generation': 3, 'request_generation': 3, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['b'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]), ('stale request', {'generation': 3, 'request_generation': 2, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('empty path', {'generation': 3, 'request_generation': 3, 'opened': ['q'], 'path': [], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('denied root', {'generation': 3, 'request_generation': 3, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['r'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']])], 4: [('complete reveal', {'generation': 4, 'request_generation': 4, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], None, None, True, 'c', []]), ('missing deep child', {'generation': 4, 'request_generation': 4, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': []}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]), ('wrong branch child', {'generation': 4, 'request_generation': 4, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a', 'b'], 'a': [], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], 'a', None, False, 'q', ['b', 'c']]), ('denied middle', {'generation': 4, 'request_generation': 4, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['b'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]), ('stale request', {'generation': 4, 'request_generation': 3, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('empty path', {'generation': 4, 'request_generation': 4, 'opened': ['q'], 'path': [], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('denied root', {'generation': 4, 'request_generation': 4, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['r'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']])], 5: [('complete reveal', {'generation': 5, 'request_generation': 5, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], None, None, True, 'c', []]), ('missing deep child', {'generation': 5, 'request_generation': 5, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': []}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]), ('wrong branch child', {'generation': 5, 'request_generation': 5, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a', 'b'], 'a': [], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], 'a', None, False, 'q', ['b', 'c']]), ('denied middle', {'generation': 5, 'request_generation': 5, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['b'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]), ('stale request', {'generation': 5, 'request_generation': 4, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('empty path', {'generation': 5, 'request_generation': 5, 'opened': ['q'], 'path': [], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('denied root', {'generation': 5, 'request_generation': 5, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['r'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']])]}
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
complete reveal	`[['q', 'r'], 'r', None, False, 'q', ['a', 'b', 'c']]`	`[['a', 'b', 'q', 'r'], None, None, True, 'c', []]`	Failed
missing deep child	`[['q', 'r'], 'r', None, False, 'q', ['a', 'b', 'c']]`	`[['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]`	Failed
wrong branch child	`[['q', 'r'], 'r', None, False, 'q', ['a', 'b', 'c']]`	`[['a', 'q', 'r'], 'a', None, False, 'q', ['b', 'c']]`	Failed
denied middle	`[['q', 'r'], 'r', None, False, 'q', ['a', 'b', 'c']]`	`[['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]`	Failed
stale request	`[['q'], None, None, False, 'q', []]`	`[['q'], None, None, False, 'q', []]`	Passed
empty path	`[['q'], None, None, False, 'q', []]`	`[['q'], None, None, False, 'q', []]`	Passed
denied root	`[['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']]`	`[['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']]`	Passed

SHA-256 / 874e92390b8ecf4f977f899059c2afdd0d86a1820b0d730c7c2d2d4b35c20d9d

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(d):
    current=d['generation']==d['request_generation']
    opened=set(d['opened']); request=None; blocked=None; reached=None
    if current:
        for i,node in enumerate(d['path']):
            if node in d['denied']:
                blocked=node; break
            if i and node not in sum(d['children'].values(),[]):
                request=d['path'][i-1]; break
            reached=node
            if i<len(d['path'])-1: opened.add(node)
    finished=current and bool(d['path']) and reached==d['path'][-1] and blocked is None and request is None
    focus=d['path'][-1] if finished else d['focus']
    pending=d['path'][d['path'].index(reached)+1:] if current and reached in d['path'] else (d['path'] if current else [])
    return [sorted(opened),request,blocked,finished,focus,pending]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [('complete reveal', {'generation': 1, 'request_generation': 1, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], None, None, True, 'c', []]), ('missing deep child', {'generation': 1, 'request_generation': 1, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': []}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]), ('wrong branch child', {'generation': 1, 'request_generation': 1, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a', 'b'], 'a': [], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], 'a', None, False, 'q', ['b', 'c']]), ('denied middle', {'generation': 1, 'request_generation': 1, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['b'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]), ('stale request', {'generation': 1, 'request_generation': 0, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('empty path', {'generation': 1, 'request_generation': 1, 'opened': ['q'], 'path': [], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('denied root', {'generation': 1, 'request_generation': 1, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['r'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']])], 2: [('complete reveal', {'generation': 2, 'request_generation': 2, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], None, None, True, 'c', []]), ('missing deep child', {'generation': 2, 'request_generation': 2, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': []}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]), ('wrong branch child', {'generation': 2, 'request_generation': 2, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a', 'b'], 'a': [], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], 'a', None, False, 'q', ['b', 'c']]), ('denied middle', {'generation': 2, 'request_generation': 2, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['b'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]), ('stale request', {'generation': 2, 'request_generation': 1, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('empty path', {'generation': 2, 'request_generation': 2, 'opened': ['q'], 'path': [], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('denied root', {'generation': 2, 'request_generation': 2, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['r'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']])], 3: [('complete reveal', {'generation': 3, 'request_generation': 3, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], None, None, True, 'c', []]), ('missing deep child', {'generation': 3, 'request_generation': 3, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': []}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]), ('wrong branch child', {'generation': 3, 'request_generation': 3, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a', 'b'], 'a': [], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], 'a', None, False, 'q', ['b', 'c']]), ('denied middle', {'generation': 3, 'request_generation': 3, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['b'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]), ('stale request', {'generation': 3, 'request_generation': 2, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('empty path', {'generation': 3, 'request_generation': 3, 'opened': ['q'], 'path': [], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('denied root', {'generation': 3, 'request_generation': 3, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['r'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']])], 4: [('complete reveal', {'generation': 4, 'request_generation': 4, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], None, None, True, 'c', []]), ('missing deep child', {'generation': 4, 'request_generation': 4, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': []}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]), ('wrong branch child', {'generation': 4, 'request_generation': 4, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a', 'b'], 'a': [], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], 'a', None, False, 'q', ['b', 'c']]), ('denied middle', {'generation': 4, 'request_generation': 4, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['b'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]), ('stale request', {'generation': 4, 'request_generation': 3, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('empty path', {'generation': 4, 'request_generation': 4, 'opened': ['q'], 'path': [], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('denied root', {'generation': 4, 'request_generation': 4, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['r'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']])], 5: [('complete reveal', {'generation': 5, 'request_generation': 5, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], None, None, True, 'c', []]), ('missing deep child', {'generation': 5, 'request_generation': 5, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': []}, 'focus': 'q'}, [['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]), ('wrong branch child', {'generation': 5, 'request_generation': 5, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a', 'b'], 'a': [], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], 'a', None, False, 'q', ['b', 'c']]), ('denied middle', {'generation': 5, 'request_generation': 5, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['b'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]), ('stale request', {'generation': 5, 'request_generation': 4, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('empty path', {'generation': 5, 'request_generation': 5, 'opened': ['q'], 'path': [], 'denied': [], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, None, False, 'q', []]), ('denied root', {'generation': 5, 'request_generation': 5, 'opened': ['q'], 'path': ['r', 'a', 'b', 'c'], 'denied': ['r'], 'children': {'r': ['a'], 'a': ['b'], 'b': ['c']}, 'focus': 'q'}, [['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']])]}
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
complete reveal	`[['a', 'b', 'q', 'r'], None, None, True, 'c', []]`	`[['a', 'b', 'q', 'r'], None, None, True, 'c', []]`	Passed
missing deep child	`[['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]`	`[['a', 'b', 'q', 'r'], 'b', None, False, 'q', ['c']]`	Passed
wrong branch child	`[['a', 'b', 'q', 'r'], None, None, True, 'c', []]`	`[['a', 'q', 'r'], 'a', None, False, 'q', ['b', 'c']]`	Failed
denied middle	`[['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]`	`[['a', 'q', 'r'], None, 'b', False, 'q', ['b', 'c']]`	Passed
stale request	`[['q'], None, None, False, 'q', []]`	`[['q'], None, None, False, 'q', []]`	Passed
empty path	`[['q'], None, None, False, 'q', []]`	`[['q'], None, None, False, 'q', []]`	Passed
denied root	`[['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']]`	`[['q'], None, 'r', False, 'q', ['r', 'a', 'b', 'c']]`	Passed

SHA-256 / f979f1929ae54e741407086b736f8a85bbdf22dfddf03a21a1817a45c14e542f

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 7 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 2026-09-29T14:43:21.693058+00:00.

Case digest / 7bf2b68fdb536581da30c82f0369258cc7ca85bfd27adc93c9b4a982c274cfde