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FA-38341 / Tree accessibility / Open access

Visible tree range selection: Hidden range anchor loses its focused fallback · case 01

Hidden range anchor loses its focused fallback produces the wrong hierarchical widget state in a regression fixture.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The range-selection contract is violated at `anchor=d['anchor'] if d['anchor'] in rows else d['focus']` by replacing it with `anchor=d['anchor'] if d['anchor'] in rows else rows[0]`.

THE FAILURE

The range-selection contract is violated at `anchor=d['anchor'] if d['anchor'] in rows else d['focus']` by replacing it with `anchor=d['anchor'] if d['anchor'] in rows else rows[0]`.

Unsuccessful approach: The partial repair `anchor=d['anchor'] if d['anchor'] in rows else d['target']` still violates a boundary or preservation case.

Case contract

Selectable rows are the ordered visible preorder supplied in rows; disabled rows cannot be selected. A hidden anchor falls back to focus. Preserve outside selections only for additive ranges. Report focus, anchor, ordered selection, and branch coverage.

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):
    rows=d['rows']; blocked=set(d['disabled']); old=set(d['selected'])
    anchor=d['anchor'] if d['anchor'] in rows else rows[0]
    a=rows.index(anchor); b=rows.index(d['target'])
    span=rows[min(a,b):max(a,b)+1]
    eligible=[x for x in span if x not in blocked]
    kept=old if d['additive'] else set()
    selected=set(eligible)|kept
    ordered=[x for x in rows if x in selected]
    focus=d['target']
    next_anchor=anchor
    branch=[x for x in d['branch'] if x in rows and x not in blocked]
    covered=bool(branch) and all(x in selected for x in branch)
    return [ordered,focus,next_anchor,covered]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [('forward', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c2', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2'], 'c2', 'z', True]), ('reverse', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'a', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'a'], 'z', 'a', True]), ('additive', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c2', 'additive': True, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'a'], 'c2', 'z', True]), ('hidden anchor', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'hidden', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'z', 'c0', True]), ('empty branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c2', 'additive': False, 'branch': []}, [['z', 'c0', 'c2'], 'c2', 'z', False]), ('partial branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c2', 'additive': False, 'branch': ['a', 'z']}, [['z', 'c0', 'c2'], 'c2', 'z', False]), ('singleton', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'c0', 'focus': 'c0', 'target': 'c0', 'additive': False, 'branch': ['z', 'c0']}, [['c0'], 'c0', 'c0', False]), ('disabled target', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c1', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'c1', 'z', True])], 2: [('forward', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c3', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3'], 'c3', 'z', True]), ('reverse', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'a', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'a'], 'z', 'a', True]), ('additive', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c3', 'additive': True, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'a'], 'c3', 'z', True]), ('hidden anchor', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'hidden', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'z', 'c0', True]), ('empty branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c3', 'additive': False, 'branch': []}, [['z', 'c0', 'c2', 'c3'], 'c3', 'z', False]), ('partial branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c3', 'additive': False, 'branch': ['a', 'z']}, [['z', 'c0', 'c2', 'c3'], 'c3', 'z', False]), ('singleton', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'c0', 'focus': 'c0', 'target': 'c0', 'additive': False, 'branch': ['z', 'c0']}, [['c0'], 'c0', 'c0', False]), ('disabled target', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c1', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'c1', 'z', True])], 3: [('forward', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c4', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4'], 'c4', 'z', True]), ('reverse', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'a', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'a'], 'z', 'a', True]), ('additive', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c4', 'additive': True, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'a'], 'c4', 'z', True]), ('hidden anchor', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'hidden', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'z', 'c0', True]), ('empty branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c4', 'additive': False, 'branch': []}, [['z', 'c0', 'c2', 'c3', 'c4'], 'c4', 'z', False]), ('partial branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c4', 'additive': False, 'branch': ['a', 'z']}, [['z', 'c0', 'c2', 'c3', 'c4'], 'c4', 'z', False]), ('singleton', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'c0', 'focus': 'c0', 'target': 'c0', 'additive': False, 'branch': ['z', 'c0']}, [['c0'], 'c0', 'c0', False]), ('disabled target', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c1', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'c1', 'z', True])], 4: [('forward', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c5', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5'], 'c5', 'z', True]), ('reverse', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'a', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'a'], 'z', 'a', True]), ('additive', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c5', 'additive': True, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'a'], 'c5', 'z', True]), ('hidden anchor', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'hidden', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'z', 'c0', True]), ('empty branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c5', 'additive': False, 'branch': []}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5'], 'c5', 'z', False]), ('partial branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c5', 'additive': False, 'branch': ['a', 'z']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5'], 'c5', 'z', False]), ('singleton', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'c0', 'focus': 'c0', 'target': 'c0', 'additive': False, 'branch': ['z', 'c0']}, [['c0'], 'c0', 'c0', False]), ('disabled target', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c1', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'c1', 'z', True])], 5: [('forward', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c6', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'c6'], 'c6', 'z', True]), ('reverse', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'a', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'z', 'a', True]), ('additive', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c6', 'additive': True, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'c6', 'z', True]), ('hidden anchor', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'hidden', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'z', 'c0', True]), ('empty branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c6', 'additive': False, 'branch': []}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'c6'], 'c6', 'z', False]), ('partial branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c6', 'additive': False, 'branch': ['a', 'z']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'c6'], 'c6', 'z', False]), ('singleton', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'c0', 'focus': 'c0', 'target': 'c0', 'additive': False, 'branch': ['z', 'c0']}, [['c0'], 'c0', 'c0', False]), ('disabled target', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c1', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'c1', 'z', 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 fixtureActualExpectedOutcome
forward[['z', 'c0', 'c2'], 'c2', 'z', True][['z', 'c0', 'c2'], 'c2', 'z', True]Passed
reverse[['z', 'c0', 'c2', 'a'], 'z', 'a', True][['z', 'c0', 'c2', 'a'], 'z', 'a', True]Passed
additive[['z', 'c0', 'c2', 'a'], 'c2', 'z', True][['z', 'c0', 'c2', 'a'], 'c2', 'z', True]Passed
hidden anchor[['r', 'z'], 'z', 'r', False][['z', 'c0'], 'z', 'c0', True]Failed
empty branch[['z', 'c0', 'c2'], 'c2', 'z', False][['z', 'c0', 'c2'], 'c2', 'z', False]Passed
partial branch[['z', 'c0', 'c2'], 'c2', 'z', False][['z', 'c0', 'c2'], 'c2', 'z', False]Passed
singleton[['c0'], 'c0', 'c0', False][['c0'], 'c0', 'c0', False]Passed
disabled target[['z', 'c0'], 'c1', 'z', True][['z', 'c0'], 'c1', 'z', True]Passed

SHA-256 / 09277e863953eb81c3f0a1ed6a1f3368a71a4b663471b972aac017c685cf4a4e

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(d):
    rows=d['rows']; blocked=set(d['disabled']); old=set(d['selected'])
    anchor=d['anchor'] if d['anchor'] in rows else d['target']
    a=rows.index(anchor); b=rows.index(d['target'])
    span=rows[min(a,b):max(a,b)+1]
    eligible=[x for x in span if x not in blocked]
    kept=old if d['additive'] else set()
    selected=set(eligible)|kept
    ordered=[x for x in rows if x in selected]
    focus=d['target']
    next_anchor=anchor
    branch=[x for x in d['branch'] if x in rows and x not in blocked]
    covered=bool(branch) and all(x in selected for x in branch)
    return [ordered,focus,next_anchor,covered]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [('forward', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c2', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2'], 'c2', 'z', True]), ('reverse', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'a', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'a'], 'z', 'a', True]), ('additive', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c2', 'additive': True, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'a'], 'c2', 'z', True]), ('hidden anchor', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'hidden', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'z', 'c0', True]), ('empty branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c2', 'additive': False, 'branch': []}, [['z', 'c0', 'c2'], 'c2', 'z', False]), ('partial branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c2', 'additive': False, 'branch': ['a', 'z']}, [['z', 'c0', 'c2'], 'c2', 'z', False]), ('singleton', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'c0', 'focus': 'c0', 'target': 'c0', 'additive': False, 'branch': ['z', 'c0']}, [['c0'], 'c0', 'c0', False]), ('disabled target', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c1', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'c1', 'z', True])], 2: [('forward', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c3', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3'], 'c3', 'z', True]), ('reverse', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'a', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'a'], 'z', 'a', True]), ('additive', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c3', 'additive': True, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'a'], 'c3', 'z', True]), ('hidden anchor', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'hidden', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'z', 'c0', True]), ('empty branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c3', 'additive': False, 'branch': []}, [['z', 'c0', 'c2', 'c3'], 'c3', 'z', False]), ('partial branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c3', 'additive': False, 'branch': ['a', 'z']}, [['z', 'c0', 'c2', 'c3'], 'c3', 'z', False]), ('singleton', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'c0', 'focus': 'c0', 'target': 'c0', 'additive': False, 'branch': ['z', 'c0']}, [['c0'], 'c0', 'c0', False]), ('disabled target', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c1', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'c1', 'z', True])], 3: [('forward', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c4', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4'], 'c4', 'z', True]), ('reverse', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'a', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'a'], 'z', 'a', True]), ('additive', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c4', 'additive': True, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'a'], 'c4', 'z', True]), ('hidden anchor', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'hidden', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'z', 'c0', True]), ('empty branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c4', 'additive': False, 'branch': []}, [['z', 'c0', 'c2', 'c3', 'c4'], 'c4', 'z', False]), ('partial branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c4', 'additive': False, 'branch': ['a', 'z']}, [['z', 'c0', 'c2', 'c3', 'c4'], 'c4', 'z', False]), ('singleton', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'c0', 'focus': 'c0', 'target': 'c0', 'additive': False, 'branch': ['z', 'c0']}, [['c0'], 'c0', 'c0', False]), ('disabled target', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c1', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'c1', 'z', True])], 4: [('forward', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c5', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5'], 'c5', 'z', True]), ('reverse', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'a', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'a'], 'z', 'a', True]), ('additive', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c5', 'additive': True, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'a'], 'c5', 'z', True]), ('hidden anchor', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'hidden', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'z', 'c0', True]), ('empty branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c5', 'additive': False, 'branch': []}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5'], 'c5', 'z', False]), ('partial branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c5', 'additive': False, 'branch': ['a', 'z']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5'], 'c5', 'z', False]), ('singleton', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'c0', 'focus': 'c0', 'target': 'c0', 'additive': False, 'branch': ['z', 'c0']}, [['c0'], 'c0', 'c0', False]), ('disabled target', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c1', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'c1', 'z', True])], 5: [('forward', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c6', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'c6'], 'c6', 'z', True]), ('reverse', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'a', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'z', 'a', True]), ('additive', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c6', 'additive': True, 'branch': ['z', 'c0']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'c6', 'z', True]), ('hidden anchor', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'hidden', 'focus': 'c0', 'target': 'z', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'z', 'c0', True]), ('empty branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c6', 'additive': False, 'branch': []}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'c6'], 'c6', 'z', False]), ('partial branch', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c6', 'additive': False, 'branch': ['a', 'z']}, [['z', 'c0', 'c2', 'c3', 'c4', 'c5', 'c6'], 'c6', 'z', False]), ('singleton', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'c0', 'focus': 'c0', 'target': 'c0', 'additive': False, 'branch': ['z', 'c0']}, [['c0'], 'c0', 'c0', False]), ('disabled target', {'rows': ['r', 'z', 'c0', 'c1', 'c2', 'c3', 'c4', 'c5', 'c6', 'a'], 'disabled': ['c1'], 'selected': ['a'], 'anchor': 'z', 'focus': 'c0', 'target': 'c1', 'additive': False, 'branch': ['z', 'c0']}, [['z', 'c0'], 'c1', 'z', 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 fixtureActualExpectedOutcome
forward[['z', 'c0', 'c2'], 'c2', 'z', True][['z', 'c0', 'c2'], 'c2', 'z', True]Passed
reverse[['z', 'c0', 'c2', 'a'], 'z', 'a', True][['z', 'c0', 'c2', 'a'], 'z', 'a', True]Passed
additive[['z', 'c0', 'c2', 'a'], 'c2', 'z', True][['z', 'c0', 'c2', 'a'], 'c2', 'z', True]Passed
hidden anchor[['z'], 'z', 'z', False][['z', 'c0'], 'z', 'c0', True]Failed
empty branch[['z', 'c0', 'c2'], 'c2', 'z', False][['z', 'c0', 'c2'], 'c2', 'z', False]Passed
partial branch[['z', 'c0', 'c2'], 'c2', 'z', False][['z', 'c0', 'c2'], 'c2', 'z', False]Passed
singleton[['c0'], 'c0', 'c0', False][['c0'], 'c0', 'c0', False]Passed
disabled target[['z', 'c0'], 'c1', 'z', True][['z', 'c0'], 'c1', 'z', True]Passed

SHA-256 / 3f3c1ecd389ead188b88f054081fcbcc18554f919ed6c171cdf76418487d1b63

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 8 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.

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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 2026-09-29T14:43:10.693990+00:00.

Case digest / 6269761abe248c0f6466f401f78f89255c680f2d985099c989e2277401c9ef30