FA-8406 / Assistive announcements / Open access
Live-region announcement scheduling: Repeated identical status changes are queued again · case 01
Repeated identical status changes are queued again.
ROOT CAUSE
The duplicate operation uses `if text == current: return (queue + [text], current)` where the contract requires `if text == current: return (queue, current)`.
VERIFIED REPAIR
Implement the duplicate operation as `if text == current: return (queue, current)`.
Unsuccessful approach: Clearing the queue drops unrelated pending announcements.
Case contract
Suppress identical and off updates; busy queues preserve order; assertive updates supersede pending work; atomic reads full content and incremental mode reads appended content.
Why this case matters
A deterministic model of live-region announcement scheduling; 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(queue, current, text, priority, busy, atomic):
queue = list(queue)
if text == current: return (queue + [text], current)
if priority == 'off': return (queue, current)
if busy: return (queue + [text], current)
if priority == 'assertive': return ([], text)
if atomic: return (queue, text)
return (queue, text[len(current):] if text.startswith(current) else text)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('duplicate', solve(['later'], 'done', 'done', 'polite', False, True), (['later'], 'done'))
check('off', solve(['later'], 'old', 'new', 'off', False, True), (['later'], 'old'))
check('busy', solve(['first'], 'old', 'new', 'polite', True, True), (['first', 'new'], 'old'))
check('urgent', solve(['old pending'], 'old', 'urgent', 'assertive', False, True), ([], 'urgent'))
check('atomic', solve([], '2 of ', '2 of 5', 'polite', False, True), ([], '2 of 5'))
check('incremental', solve([], '2 of ', '2 of 5', 'polite', False, False), ([], '5'))
check('parameterized atomic content', solve([], '', 'status'+str(N), 'polite', False, True), ([], 'status'+str(N)))
for repetition in range(N):
check('repeat incremental', solve([], '2 of ', '2 of 5', 'polite', False, False), ([], '5'))
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 |
|---|---|---|---|
| duplicate | [['later', 'done'], 'done'] | [['later'], 'done'] | Failed |
| off | [['later'], 'old'] | [['later'], 'old'] | Passed |
| busy | [['first', 'new'], 'old'] | [['first', 'new'], 'old'] | Passed |
| urgent | [[], 'urgent'] | [[], 'urgent'] | Passed |
| atomic | [[], '2 of 5'] | [[], '2 of 5'] | Passed |
| incremental | [[], '5'] | [[], '5'] | Passed |
| parameterized atomic content | [[], 'status1'] | [[], 'status1'] | Passed |
| repeat incremental | [[], '5'] | [[], '5'] | Passed |
SHA-256 / 4f1e07d492e42bffe5e0838718e5a7aecb64205fb491fb8e1c08cdc66879b1d5
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(queue, current, text, priority, busy, atomic):
queue = list(queue)
if text == current: return ([], current)
if priority == 'off': return (queue, current)
if busy: return (queue + [text], current)
if priority == 'assertive': return ([], text)
if atomic: return (queue, text)
return (queue, text[len(current):] if text.startswith(current) else text)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('duplicate', solve(['later'], 'done', 'done', 'polite', False, True), (['later'], 'done'))
check('off', solve(['later'], 'old', 'new', 'off', False, True), (['later'], 'old'))
check('busy', solve(['first'], 'old', 'new', 'polite', True, True), (['first', 'new'], 'old'))
check('urgent', solve(['old pending'], 'old', 'urgent', 'assertive', False, True), ([], 'urgent'))
check('atomic', solve([], '2 of ', '2 of 5', 'polite', False, True), ([], '2 of 5'))
check('incremental', solve([], '2 of ', '2 of 5', 'polite', False, False), ([], '5'))
check('parameterized atomic content', solve([], '', 'status'+str(N), 'polite', False, True), ([], 'status'+str(N)))
for repetition in range(N):
check('repeat incremental', solve([], '2 of ', '2 of 5', 'polite', False, False), ([], '5'))
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 |
|---|---|---|---|
| duplicate | [[], 'done'] | [['later'], 'done'] | Failed |
| off | [['later'], 'old'] | [['later'], 'old'] | Passed |
| busy | [['first', 'new'], 'old'] | [['first', 'new'], 'old'] | Passed |
| urgent | [[], 'urgent'] | [[], 'urgent'] | Passed |
| atomic | [[], '2 of 5'] | [[], '2 of 5'] | Passed |
| incremental | [[], '5'] | [[], '5'] | Passed |
| parameterized atomic content | [[], 'status1'] | [[], 'status1'] | Passed |
| repeat incremental | [[], '5'] | [[], '5'] | Passed |
SHA-256 / 689ea621782e3977f905aaf2bc50ec980279fcbf13af1555a208797d894595ed
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(queue, current, text, priority, busy, atomic):
queue = list(queue)
if text == current: return (queue, current)
if priority == 'off': return (queue, current)
if busy: return (queue + [text], current)
if priority == 'assertive': return ([], text)
if atomic: return (queue, text)
return (queue, text[len(current):] if text.startswith(current) else text)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('duplicate', solve(['later'], 'done', 'done', 'polite', False, True), (['later'], 'done'))
check('off', solve(['later'], 'old', 'new', 'off', False, True), (['later'], 'old'))
check('busy', solve(['first'], 'old', 'new', 'polite', True, True), (['first', 'new'], 'old'))
check('urgent', solve(['old pending'], 'old', 'urgent', 'assertive', False, True), ([], 'urgent'))
check('atomic', solve([], '2 of ', '2 of 5', 'polite', False, True), ([], '2 of 5'))
check('incremental', solve([], '2 of ', '2 of 5', 'polite', False, False), ([], '5'))
check('parameterized atomic content', solve([], '', 'status'+str(N), 'polite', False, True), ([], 'status'+str(N)))
for repetition in range(N):
check('repeat incremental', solve([], '2 of ', '2 of 5', 'polite', False, False), ([], '5'))
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 |
|---|---|---|---|
| duplicate | [['later'], 'done'] | [['later'], 'done'] | Passed |
| off | [['later'], 'old'] | [['later'], 'old'] | Passed |
| busy | [['first', 'new'], 'old'] | [['first', 'new'], 'old'] | Passed |
| urgent | [[], 'urgent'] | [[], 'urgent'] | Passed |
| atomic | [[], '2 of 5'] | [[], '2 of 5'] | Passed |
| incremental | [[], '5'] | [[], '5'] | Passed |
| parameterized atomic content | [[], 'status1'] | [[], 'status1'] | Passed |
| repeat incremental | [[], '5'] | [[], '5'] | Passed |
SHA-256 / 1d08f40e03d5830fe3875eaf5b80614c19ae995cf26ba3402a2654b3bc440d6d
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 2026-09-29T14:38:21.142649+00:00.
Case digest / 8e1e95431dcb791fe3b0ed76c1dae85a988e0baf9cb8a6649115bd356617fc1f