FA-7941 / Selection controls / Open access
Hierarchical checkbox state: Clicking a checked child cannot deselect it · case 01
Clicking a checked child cannot deselect it.
ROOT CAUSE
The toggle operation uses `selected.add(child)` where the contract requires `selected.symmetric_difference_update({child})`.
VERIFIED REPAIR
Implement the toggle operation as `selected.symmetric_difference_update({child})`.
Unsuccessful approach: Always removing prevents unchecked children from being selected.
Case contract
Subtree actions preserve outside selections; toggle is symmetric; parent status depends only on selected descendants and distinguishes none, mixed and all.
Why this case matters
A deterministic model of hierarchical checkbox state; this isolates one interface invariant without requiring a browser.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(selected, children, event, child):
selected = set(selected)
children = set(children)
if event == 'all': selected |= children
elif event == 'none': selected -= children
elif event == 'toggle': selected.add(child)
visible = selected & children
state = 'none' if not visible else ('all' if visible == children else 'mixed')
return (sorted(selected), state)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('all keeps outside', solve(['x','a'], ['a','b'], 'all', None), (['a', 'b', 'x'], 'all'))
check('none keeps outside', solve(['x','a'], ['a','b'], 'none', None), (['x'], 'none'))
check('toggle off', solve(['a'], ['a','b'], 'toggle', 'a'), ([], 'none'))
check('toggle on', solve([], ['a','b'], 'toggle', 'a'), (['a'], 'mixed'))
check('outside only', solve(['x'], ['a','b'], 'read', None), (['x'], 'none'))
check('all', solve(['a','b'], ['a','b'], 'read', None), (['a', 'b'], 'all'))
check('parameterized checked subtree', solve(list(range(N)), list(range(N)), 'read', None), (list(range(N)), 'all'))
for repetition in range(N):
check('repeat all', solve(['a','b'], ['a','b'], 'read', None), (['a', 'b'], 'all'))
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 |
|---|---|---|---|
| all keeps outside | [['a', 'b', 'x'], 'all'] | [['a', 'b', 'x'], 'all'] | Passed |
| none keeps outside | [['x'], 'none'] | [['x'], 'none'] | Passed |
| toggle off | [['a'], 'mixed'] | [[], 'none'] | Failed |
| toggle on | [['a'], 'mixed'] | [['a'], 'mixed'] | Passed |
| outside only | [['x'], 'none'] | [['x'], 'none'] | Passed |
| all | [['a', 'b'], 'all'] | [['a', 'b'], 'all'] | Passed |
| parameterized checked subtree | [[0], 'all'] | [[0], 'all'] | Passed |
| repeat all | [['a', 'b'], 'all'] | [['a', 'b'], 'all'] | Passed |
SHA-256 / 988ef4f4ea9538dd3ca42edbdf98f53af31ebc174f86b6416cf69768c802e3bb
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(selected, children, event, child):
selected = set(selected)
children = set(children)
if event == 'all': selected |= children
elif event == 'none': selected -= children
elif event == 'toggle': selected.discard(child)
visible = selected & children
state = 'none' if not visible else ('all' if visible == children else 'mixed')
return (sorted(selected), state)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('all keeps outside', solve(['x','a'], ['a','b'], 'all', None), (['a', 'b', 'x'], 'all'))
check('none keeps outside', solve(['x','a'], ['a','b'], 'none', None), (['x'], 'none'))
check('toggle off', solve(['a'], ['a','b'], 'toggle', 'a'), ([], 'none'))
check('toggle on', solve([], ['a','b'], 'toggle', 'a'), (['a'], 'mixed'))
check('outside only', solve(['x'], ['a','b'], 'read', None), (['x'], 'none'))
check('all', solve(['a','b'], ['a','b'], 'read', None), (['a', 'b'], 'all'))
check('parameterized checked subtree', solve(list(range(N)), list(range(N)), 'read', None), (list(range(N)), 'all'))
for repetition in range(N):
check('repeat all', solve(['a','b'], ['a','b'], 'read', None), (['a', 'b'], 'all'))
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 |
|---|---|---|---|
| all keeps outside | [['a', 'b', 'x'], 'all'] | [['a', 'b', 'x'], 'all'] | Passed |
| none keeps outside | [['x'], 'none'] | [['x'], 'none'] | Passed |
| toggle off | [[], 'none'] | [[], 'none'] | Passed |
| toggle on | [[], 'none'] | [['a'], 'mixed'] | Failed |
| outside only | [['x'], 'none'] | [['x'], 'none'] | Passed |
| all | [['a', 'b'], 'all'] | [['a', 'b'], 'all'] | Passed |
| parameterized checked subtree | [[0], 'all'] | [[0], 'all'] | Passed |
| repeat all | [['a', 'b'], 'all'] | [['a', 'b'], 'all'] | Passed |
SHA-256 / 6670be4a9f548c3ca08325a89268d6c83cab0f36c9ed1be0793c8cab54f9bbeb
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(selected, children, event, child):
selected = set(selected)
children = set(children)
if event == 'all': selected |= children
elif event == 'none': selected -= children
elif event == 'toggle': selected.symmetric_difference_update({child})
visible = selected & children
state = 'none' if not visible else ('all' if visible == children else 'mixed')
return (sorted(selected), state)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('all keeps outside', solve(['x','a'], ['a','b'], 'all', None), (['a', 'b', 'x'], 'all'))
check('none keeps outside', solve(['x','a'], ['a','b'], 'none', None), (['x'], 'none'))
check('toggle off', solve(['a'], ['a','b'], 'toggle', 'a'), ([], 'none'))
check('toggle on', solve([], ['a','b'], 'toggle', 'a'), (['a'], 'mixed'))
check('outside only', solve(['x'], ['a','b'], 'read', None), (['x'], 'none'))
check('all', solve(['a','b'], ['a','b'], 'read', None), (['a', 'b'], 'all'))
check('parameterized checked subtree', solve(list(range(N)), list(range(N)), 'read', None), (list(range(N)), 'all'))
for repetition in range(N):
check('repeat all', solve(['a','b'], ['a','b'], 'read', None), (['a', 'b'], 'all'))
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 |
|---|---|---|---|
| all keeps outside | [['a', 'b', 'x'], 'all'] | [['a', 'b', 'x'], 'all'] | Passed |
| none keeps outside | [['x'], 'none'] | [['x'], 'none'] | Passed |
| toggle off | [[], 'none'] | [[], 'none'] | Passed |
| toggle on | [['a'], 'mixed'] | [['a'], 'mixed'] | Passed |
| outside only | [['x'], 'none'] | [['x'], 'none'] | Passed |
| all | [['a', 'b'], 'all'] | [['a', 'b'], 'all'] | Passed |
| parameterized checked subtree | [[0], 'all'] | [[0], 'all'] | Passed |
| repeat all | [['a', 'b'], 'all'] | [['a', 'b'], 'all'] | Passed |
SHA-256 / 8601b5edb6a2428e9f04dc68f017ac8fa14035179bf7c42f7b2dc6a5cc451f6a
Verification & scope
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 2026-09-29T14:38:16.786891+00:00.
Case digest / 11158c651d32b6facc81bf0bdb3e6d40c9f8e0f8e956721067f87d856eaab6a0