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Accordion open-panel state: Noncollapsible panels close on repeated activation · case 01

Noncollapsible panels close on repeated activation.

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

ROOT CAUSE

The collapse policy operation uses `if True: opened.remove(target)` where the contract requires `if collapsible: opened.remove(target)`.

THE FAILURE

The collapse policy operation uses `if True: opened.remove(target)` where the contract requires `if collapsible: opened.remove(target)`.

Unsuccessful approach: Disabling collapse universally breaks collapsible accordions.

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 True: 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']`	Failed
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 / ca1972bd7750a8f436646032726fb23128250c0902138bff2a9628d5062fcd03

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 False: 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	`['a']`	`[]`	Failed
multiple	`['a', 'b']`	`['a', 'b']`	Passed
single	`['b']`	`['b']`	Passed
parameterized panels	`[0, 1]`	`[0, 1]`	Passed
repeat single	`['b']`	`['b']`	Passed

SHA-256 / 97eee2227914b6969f787cdcc2d9b897531588d3cf69d4a3f8b93e5020d7253f

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.

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

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 / 6c302ea1fa112ba52c917e97872c0761f18d944a666d2b155ccfc23932526684