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FA-8421 / Assistive announcements / Open access

Live-region announcement scheduling: Urgent announcements wait behind polite messages · case 01

Urgent announcements wait behind polite messages.

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

ROOT CAUSE

The assertive operation uses `if priority == 'assertive': return (queue + [text], current)` where the contract requires `if priority == 'assertive': return ([], text)`.

VERIFIED REPAIR

Implement the assertive operation as `if priority == 'assertive': return ([], text)`.

Unsuccessful approach: Leaving the old queue intact replays superseded announcements.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, current)
    if priority == 'off': return (queue, current)
    if busy: return (queue + [text], current)
    if priority == 'assertive': return (queue + [text], current)
    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 fixtureActualExpectedOutcome
duplicate[['later'], 'done'][['later'], 'done']Passed
off[['later'], 'old'][['later'], 'old']Passed
busy[['first', 'new'], 'old'][['first', 'new'], 'old']Passed
urgent[['old pending', 'urgent'], 'old'][[], 'urgent']Failed
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 / eb1415b8d9f420fb9a534ca53113d9be796c75db480553dfdec5f076e85bc463

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 (queue, current)
    if priority == 'off': return (queue, current)
    if busy: return (queue + [text], current)
    if priority == 'assertive': return (queue, 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 fixtureActualExpectedOutcome
duplicate[['later'], 'done'][['later'], 'done']Passed
off[['later'], 'old'][['later'], 'old']Passed
busy[['first', 'new'], 'old'][['first', 'new'], 'old']Passed
urgent[['old pending'], 'urgent'][[], 'urgent']Failed
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 / b09582b3e8ce7bd546974049865a6a84f1c332f21fa616743adbaee65674ee5c

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 fixtureActualExpectedOutcome
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 2026-09-29T14:38:21.262491+00:00.

Case digest / 8ec2e2f40c2b41648e355113504df4c90b183bad9e2afb1588a05557ce4db7d6