FA-20836 / Assistive announcements / Open access
Emitted burst remains pending · case 01
The announcement trace violates the stated coalescing-window contract.
ROOT CAUSE
Fault site: row=pending.pop(k) is implemented as row=pending[k]
VERIFIED REPAIR
Restore the stated transition: row=pending.pop(k)
Unsuccessful approach: The attempted repair substitutes row=pending.pop(k); row[2]=1 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.pop(e[1],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[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]], [['z', 1, 'last', 2]], 1] | [[['z', 'last', 2]], [], 1] | Failed |
| trace-2 | [[], [['a', 6, 'x', 1]], 4] | [[], [['a', 6, 'x', 1]], 4] | Passed |
| trace-3 | [[['a', 'x', 1]], [['a', 6, 'x', 1]], 6] | [[['a', 'x', 1]], [], 6] | Failed |
| trace-4 | [[], [['a', 1, 'x', 1]], 0] | [[], [['a', 1, 'x', 1]], 0] | Passed |
| trace-5 | [[], [['a', 3, 'first', 1]], 0] | [[], [['a', 3, 'first', 1]], 0] | Passed |
| trace-6 | [[['a', 'y', 2]], [], 10] | [[['a', 'y', 2]], [], 10] | Passed |
| trace-7 | [[['z', 'early', 1], ['a', 'late', 1], ['z', 'early', 1], ['a', 'late', 1]], [['z', 1, 'early', 1], ['a', 3, 'late', 1]], 5] | [[['z', 'early', 1], ['a', 'late', 1]], [], 5] | Failed |
| trace-8 | [[], [], 0] | [[], [], 0] | Passed |
SHA-256 / 8a6c5218f3c582e2bd6fc2c00824c513c2f88e0f3c46e8aac5a2f90ed1e898e2
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(e[1],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); row[2]=1
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', 1]], [], 1] | [[['z', 'last', 2]], [], 1] | Failed |
| 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 | [[], [['a', 3, 'first', 1]], 0] | [[], [['a', 3, 'first', 1]], 0] | Passed |
| 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 / 986c8857c10c696aa21664974e741f633cedccaa14184ec70c1c5a7f7e3d0a47
3 / The verified repair
Exit 0"""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(e[1],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 | [[], [['a', 3, 'first', 1]], 0] | [[], [['a', 3, 'first', 1]], 0] | Passed |
| 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 / 23aa7e960877a8056cc277834bf39c2b10a7d46462d8899ba4604a4cc4a22365
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 / 0a97be64a2a56467610f509c988e6666d8070728877b0899d50597480fe41454