FA-8101 / Disclosure widgets / Open access

Accordion open-panel state: Single-open accordions accumulate expanded panels · case 01

Single-open accordions accumulate expanded panels.

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

ROOT CAUSE

The single open operation uses `else: opened.add(target)` where the contract requires `else: opened = {target}`.

VERIFIED REPAIR

Implement the single open operation as `else: opened = {target}`.

Unsuccessful approach: Clearing the set opens no requested panel.

Case contract

Discard removed panels; ignore invalid targets; expanded panels close only when collapsible; multiple mode unions and single mode replaces.

Why this case matters

A deterministic model of accordion open-panel 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(panels, opened, target, multiple, collapsible):
    valid = set(panels)
    opened = set(opened) & valid
    if target not in valid: return sorted(opened)
    if target in opened:
        if collapsible: opened.remove(target)
    elif multiple: opened.add(target)
    else: opened.add(target)
    return sorted(opened)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('removed', solve(['a','b'], ['a','gone'], 'unknown', True, True), ['a'])
check('unknown', solve(['a','b'], ['a'], 'unknown', True, True), ['a'])
check('locked', solve(['a','b'], ['a'], 'a', False, False), ['a'])
check('collapse', solve(['a','b'], ['a'], 'a', False, True), [])
check('multiple', solve(['a','b'], ['a'], 'b', True, True), ['a', 'b'])
check('single', solve(['a','b'], ['a'], 'b', False, True), ['b'])
check('parameterized panels', solve(list(range(N+1)), [0], N, True, True), [0,N])
for repetition in range(N):
    check('repeat single', solve(['a','b'], ['a'], 'b', False, True), ['b'])
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
removed	`['a']`	`['a']`	Passed
unknown	`['a']`	`['a']`	Passed
locked	`['a']`	`['a']`	Passed
collapse	`[]`	`[]`	Passed
multiple	`['a', 'b']`	`['a', 'b']`	Passed
single	`['a', 'b']`	`['b']`	Failed
parameterized panels	`[0, 1]`	`[0, 1]`	Passed
repeat single	`['a', 'b']`	`['b']`	Failed

SHA-256 / 3b830f9c7df544e1d339c9cf84d4bee7b626f046bc75dd4b5e3ebea05bf36367

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(panels, opened, target, multiple, collapsible):
    valid = set(panels)
    opened = set(opened) & valid
    if target not in valid: return sorted(opened)
    if target in opened:
        if collapsible: opened.remove(target)
    elif multiple: opened.add(target)
    else: opened = set()
    return sorted(opened)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('removed', solve(['a','b'], ['a','gone'], 'unknown', True, True), ['a'])
check('unknown', solve(['a','b'], ['a'], 'unknown', True, True), ['a'])
check('locked', solve(['a','b'], ['a'], 'a', False, False), ['a'])
check('collapse', solve(['a','b'], ['a'], 'a', False, True), [])
check('multiple', solve(['a','b'], ['a'], 'b', True, True), ['a', 'b'])
check('single', solve(['a','b'], ['a'], 'b', False, True), ['b'])
check('parameterized panels', solve(list(range(N+1)), [0], N, True, True), [0,N])
for repetition in range(N):
    check('repeat single', solve(['a','b'], ['a'], 'b', False, True), ['b'])
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
removed	`['a']`	`['a']`	Passed
unknown	`['a']`	`['a']`	Passed
locked	`['a']`	`['a']`	Passed
collapse	`[]`	`[]`	Passed
multiple	`['a', 'b']`	`['a', 'b']`	Passed
single	`[]`	`['b']`	Failed
parameterized panels	`[0, 1]`	`[0, 1]`	Passed
repeat single	`[]`	`['b']`	Failed

SHA-256 / c0dcd1f4388fad88edf525396653c4e9133784729179a79d980c0b86036fdf23

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(panels, opened, target, multiple, collapsible):
    valid = set(panels)
    opened = set(opened) & valid
    if target not in valid: return sorted(opened)
    if target in opened:
        if collapsible: opened.remove(target)
    elif multiple: opened.add(target)
    else: opened = {target}
    return sorted(opened)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('removed', solve(['a','b'], ['a','gone'], 'unknown', True, True), ['a'])
check('unknown', solve(['a','b'], ['a'], 'unknown', True, True), ['a'])
check('locked', solve(['a','b'], ['a'], 'a', False, False), ['a'])
check('collapse', solve(['a','b'], ['a'], 'a', False, True), [])
check('multiple', solve(['a','b'], ['a'], 'b', True, True), ['a', 'b'])
check('single', solve(['a','b'], ['a'], 'b', False, True), ['b'])
check('parameterized panels', solve(list(range(N+1)), [0], N, True, True), [0,N])
for repetition in range(N):
    check('repeat single', solve(['a','b'], ['a'], 'b', False, True), ['b'])
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
removed	`['a']`	`['a']`	Passed
unknown	`['a']`	`['a']`	Passed
locked	`['a']`	`['a']`	Passed
collapse	`[]`	`[]`	Passed
multiple	`['a', 'b']`	`['a', 'b']`	Passed
single	`['b']`	`['b']`	Passed
parameterized panels	`[0, 1]`	`[0, 1]`	Passed
repeat single	`['b']`	`['b']`	Passed

SHA-256 / b8fe78cbde67bd47435fdfb2ceb8126435f2c64371760b474144ab9b1ae04f34

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 2026-09-29T14:38:18.132215+00:00.

Case digest / 462300fbf64fe2b98fd4a637336860713abecbc6eac55af05c72a085cb43b2b3