FA-20811 / Assistive announcements / Open access
Canceling one burst discards other sources · case 01
The announcement trace violates the stated coalescing-window contract.
ROOT CAUSE
Fault site: elif e[0]=='cancel': pending.pop(e[1],None) is implemented as elif e[0]=='cancel': pending.clear()
THE FAILURE
Fault site: elif e[0]=='cancel': pending.pop(e[1],None) is implemented as elif e[0]=='cancel': pending.clear()
Unsuccessful approach: The attempted repair substitutes elif e[0]=='cancel': pending.pop(next(iter(pending)),None) if pending else None and still violates a regression oracle.
Case contract
Per-source announcements coalesce during an explicit tick window. First update opens [deadline=now+window,text,count]. Further updates replace text, increment count, and never slide deadline. Tick monotonically advances now and emits due sources by deadline then source insertion order as [source,text,count]. Force emits one source immediately. Cancel removes one source. Changing window affects future openings only. Return spoken, pending and now.
Why this case matters
Deterministic controlled model of assistive announcement delivery.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(events):
window=3; now=0; pending={}; spoken=[]
for e in events:
if e[0]=='window': window=max(1,e[1])
elif e[0]=='update':
if e[1] in pending:
pending[e[1]][1]=e[2]
pending[e[1]][2]+=1
else: pending[e[1]]=[now+window,e[2],1]
elif e[0]=='cancel': pending.clear()
elif e[0]=='force' and e[1] in pending:
row=pending.pop(e[1]); spoken.append([e[1],row[1],row[2]])
elif e[0]=='tick':
now=max(now,e[1])
ready=sorted([k for k,v in pending.items() if v[0]<=now],key=lambda k:pending[k][0])
for k in ready:
row=pending.pop(k)
spoken.append([k,row[1],row[2]])
return [spoken,[[k]+v for k,v in pending.items()],now]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['window',N],['update','z','first'],['update','z','last'*N],['tick',N]]", "[['tick',N+3],['window',2],['update','a','x'*N]]", "[['tick',N+3],['window',2],['update','a','x'*N],['tick',N+4],['tick',N+5]]", "[['window',0],['update','a','x'*N],['tick',0]]", "[['update','a','first'*N],['update','b','keep'],['cancel','b']]", "[['update','a','x'],['update','a','y'*N],['force','a'],['tick',10]]", "[['window',1],['update','z','early'*N],['window',3],['update','a','late'],['tick',N+4],['tick',0]]", '[]']
expected = {1: [[[['z', 'last', 2]], [], 1], [[], [['a', 6, 'x', 1]], 4], [[['a', 'x', 1]], [], 6], [[], [['a', 1, 'x', 1]], 0], [[], [['a', 3, 'first', 1]], 0], [[['a', 'y', 2]], [], 10], [[['z', 'early', 1], ['a', 'late', 1]], [], 5], [[], [], 0]], 2: [[[['z', 'lastlast', 2]], [], 2], [[], [['a', 7, 'xx', 1]], 5], [[['a', 'xx', 1]], [], 7], [[], [['a', 1, 'xx', 1]], 0], [[], [['a', 3, 'firstfirst', 1]], 0], [[['a', 'yy', 2]], [], 10], [[['z', 'earlyearly', 1], ['a', 'late', 1]], [], 6], [[], [], 0]], 3: [[[['z', 'lastlastlast', 2]], [], 3], [[], [['a', 8, 'xxx', 1]], 6], [[['a', 'xxx', 1]], [], 8], [[], [['a', 1, 'xxx', 1]], 0], [[], [['a', 3, 'firstfirstfirst', 1]], 0], [[['a', 'yyy', 2]], [], 10], [[['z', 'earlyearlyearly', 1], ['a', 'late', 1]], [], 7], [[], [], 0]], 4: [[[['z', 'lastlastlastlast', 2]], [], 4], [[], [['a', 9, 'xxxx', 1]], 7], [[['a', 'xxxx', 1]], [], 9], [[], [['a', 1, 'xxxx', 1]], 0], [[], [['a', 3, 'firstfirstfirstfirst', 1]], 0], [[['a', 'yyyy', 2]], [], 10], [[['z', 'earlyearlyearlyearly', 1], ['a', 'late', 1]], [], 8], [[], [], 0]], 5: [[[['z', 'lastlastlastlastlast', 2]], [], 5], [[], [['a', 10, 'xxxxx', 1]], 8], [[['a', 'xxxxx', 1]], [], 10], [[], [['a', 1, 'xxxxx', 1]], 0], [[], [['a', 3, 'firstfirstfirstfirstfirst', 1]], 0], [[['a', 'yyyyy', 2]], [], 10], [[['z', 'earlyearlyearlyearlyearly', 1], ['a', 'late', 1]], [], 9], [[], [], 0]]}[N]
for i, expression in enumerate(fixtures):
check("trace-"+str(i+1), solve(eval(expression)), expected[i])
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 |
|---|---|---|---|
| trace-1 | [[['z', 'last', 2]], [], 1] | [[['z', 'last', 2]], [], 1] | Passed |
| trace-2 | [[], [['a', 6, 'x', 1]], 4] | [[], [['a', 6, 'x', 1]], 4] | Passed |
| trace-3 | [[['a', 'x', 1]], [], 6] | [[['a', 'x', 1]], [], 6] | Passed |
| trace-4 | [[], [['a', 1, 'x', 1]], 0] | [[], [['a', 1, 'x', 1]], 0] | Passed |
| trace-5 | [[], [], 0] | [[], [['a', 3, 'first', 1]], 0] | Failed |
| trace-6 | [[['a', 'y', 2]], [], 10] | [[['a', 'y', 2]], [], 10] | Passed |
| trace-7 | [[['z', 'early', 1], ['a', 'late', 1]], [], 5] | [[['z', 'early', 1], ['a', 'late', 1]], [], 5] | Passed |
| trace-8 | [[], [], 0] | [[], [], 0] | Passed |
SHA-256 / 23556378b23e2ee2fb30ee965c2ef7373e83d9adcb34db09e85b58f3857f335b
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(events):
window=3; now=0; pending={}; spoken=[]
for e in events:
if e[0]=='window': window=max(1,e[1])
elif e[0]=='update':
if e[1] in pending:
pending[e[1]][1]=e[2]
pending[e[1]][2]+=1
else: pending[e[1]]=[now+window,e[2],1]
elif e[0]=='cancel': pending.pop(next(iter(pending)),None) if pending else None
elif e[0]=='force' and e[1] in pending:
row=pending.pop(e[1]); spoken.append([e[1],row[1],row[2]])
elif e[0]=='tick':
now=max(now,e[1])
ready=sorted([k for k,v in pending.items() if v[0]<=now],key=lambda k:pending[k][0])
for k in ready:
row=pending.pop(k)
spoken.append([k,row[1],row[2]])
return [spoken,[[k]+v for k,v in pending.items()],now]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['window',N],['update','z','first'],['update','z','last'*N],['tick',N]]", "[['tick',N+3],['window',2],['update','a','x'*N]]", "[['tick',N+3],['window',2],['update','a','x'*N],['tick',N+4],['tick',N+5]]", "[['window',0],['update','a','x'*N],['tick',0]]", "[['update','a','first'*N],['update','b','keep'],['cancel','b']]", "[['update','a','x'],['update','a','y'*N],['force','a'],['tick',10]]", "[['window',1],['update','z','early'*N],['window',3],['update','a','late'],['tick',N+4],['tick',0]]", '[]']
expected = {1: [[[['z', 'last', 2]], [], 1], [[], [['a', 6, 'x', 1]], 4], [[['a', 'x', 1]], [], 6], [[], [['a', 1, 'x', 1]], 0], [[], [['a', 3, 'first', 1]], 0], [[['a', 'y', 2]], [], 10], [[['z', 'early', 1], ['a', 'late', 1]], [], 5], [[], [], 0]], 2: [[[['z', 'lastlast', 2]], [], 2], [[], [['a', 7, 'xx', 1]], 5], [[['a', 'xx', 1]], [], 7], [[], [['a', 1, 'xx', 1]], 0], [[], [['a', 3, 'firstfirst', 1]], 0], [[['a', 'yy', 2]], [], 10], [[['z', 'earlyearly', 1], ['a', 'late', 1]], [], 6], [[], [], 0]], 3: [[[['z', 'lastlastlast', 2]], [], 3], [[], [['a', 8, 'xxx', 1]], 6], [[['a', 'xxx', 1]], [], 8], [[], [['a', 1, 'xxx', 1]], 0], [[], [['a', 3, 'firstfirstfirst', 1]], 0], [[['a', 'yyy', 2]], [], 10], [[['z', 'earlyearlyearly', 1], ['a', 'late', 1]], [], 7], [[], [], 0]], 4: [[[['z', 'lastlastlastlast', 2]], [], 4], [[], [['a', 9, 'xxxx', 1]], 7], [[['a', 'xxxx', 1]], [], 9], [[], [['a', 1, 'xxxx', 1]], 0], [[], [['a', 3, 'firstfirstfirstfirst', 1]], 0], [[['a', 'yyyy', 2]], [], 10], [[['z', 'earlyearlyearlyearly', 1], ['a', 'late', 1]], [], 8], [[], [], 0]], 5: [[[['z', 'lastlastlastlastlast', 2]], [], 5], [[], [['a', 10, 'xxxxx', 1]], 8], [[['a', 'xxxxx', 1]], [], 10], [[], [['a', 1, 'xxxxx', 1]], 0], [[], [['a', 3, 'firstfirstfirstfirstfirst', 1]], 0], [[['a', 'yyyyy', 2]], [], 10], [[['z', 'earlyearlyearlyearlyearly', 1], ['a', 'late', 1]], [], 9], [[], [], 0]]}[N]
for i, expression in enumerate(fixtures):
check("trace-"+str(i+1), solve(eval(expression)), expected[i])
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 |
|---|---|---|---|
| trace-1 | [[['z', 'last', 2]], [], 1] | [[['z', 'last', 2]], [], 1] | Passed |
| trace-2 | [[], [['a', 6, 'x', 1]], 4] | [[], [['a', 6, 'x', 1]], 4] | Passed |
| trace-3 | [[['a', 'x', 1]], [], 6] | [[['a', 'x', 1]], [], 6] | Passed |
| trace-4 | [[], [['a', 1, 'x', 1]], 0] | [[], [['a', 1, 'x', 1]], 0] | Passed |
| trace-5 | [[], [['b', 3, 'keep', 1]], 0] | [[], [['a', 3, 'first', 1]], 0] | Failed |
| trace-6 | [[['a', 'y', 2]], [], 10] | [[['a', 'y', 2]], [], 10] | Passed |
| trace-7 | [[['z', 'early', 1], ['a', 'late', 1]], [], 5] | [[['z', 'early', 1], ['a', 'late', 1]], [], 5] | Passed |
| trace-8 | [[], [], 0] | [[], [], 0] | Passed |
SHA-256 / 01a777a8af634136570dc805d430c011008f48f270a6b349a00ee37f4f2c8141
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.
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Sign in to the archive ↗Verification & scope
Stipulated bounded policy, not a browser, speech engine, platform API, or standards conformance claim. 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 2026-09-29T14:40:22.825258+00:00.
Case digest / 0d97cefeab9a6cb15ba75491f1a1cb6322b66748c3ffa32e7b94d6de8bf77b47