FA-20601 / Assistive announcements / Open access
Cancel removes unrelated pending speech · case 01
The announcement trace violates the stated deadline-scheduler contract.
ROOT CAUSE
Fault site: elif e[0]=='cancel': q=[x for x in q if x[0]!=e[1]] is implemented as elif e[0]=='cancel': q=[]
VERIFIED REPAIR
Restore the stated transition: elif e[0]=='cancel': q=[x for x in q if x[0]!=e[1]]
Unsuccessful approach: The attempted repair substitutes elif e[0]=='cancel': q=q[1:] and still violates a regression oracle.
Case contract
Enqueue [id,text,ready,expiry,priority]. Cancel removes all matching IDs. Tick sets monotonic clock; dispatch at most one eligible unexpired item, highest priority then earliest enqueue. Expiry is exclusive. Future items remain. Expired items are purged even without ready work. Successful dispatch removes precisely that entry. Clock reset clears queue. Report spoken IDs/text, pending IDs and clock.
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):
q=[]; spoken=[]; now=0; seq=0
for e in events:
if e[0]=='enqueue':
seq+=1
q.append([e[1],e[2],e[3],e[4],e[5],seq])
elif e[0]=='cancel': q=[]
elif e[0]=='reset': now=0; q.clear()
elif e[0]=='tick':
now=max(now,e[1])
q=[x for x in q if x[3]>now]
eligible=[x for x in q if x[2]<=now]
if eligible:
chosen=min(eligible,key=lambda x:(-x[4],x[5]))
spoken.append(chosen[:2])
q.remove(chosen)
return [spoken,[x[0] for x in q],now]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['enqueue','a','a'*N,0,100,1],['enqueue','b','b'*N,0,100,3],['enqueue','c','c',0,100,3],['tick',N],['tick',N],['tick',N]]", "[['enqueue','a','wait'*N,N+1,N+5,1],['tick',N]]", "[['enqueue','a','wait'*N,N+1,N+5,1],['tick',N],['tick',N+1]]", "[['enqueue','a','expired'*N,0,N,1],['tick',N]]", "[['enqueue','a','gone',0,100,1],['enqueue','b','keep'*N,0,100,2],['cancel','missing'],['cancel','a'],['tick',N]]", "[['tick',N+5],['tick',N]]", "[['tick',N+5],['tick',N],['enqueue','a','old',0,100,1],['reset']]", '[]', "[['enqueue','r','first',N,100,1],['enqueue','s','second',0,100,1],['tick',N]]", "[['enqueue','z','first',0,100,1],['enqueue','a','second'*N,0,100,1],['tick',N]]"]
expected = {1: [[[['b', 'b'], ['c', 'c'], ['a', 'a']], [], 1], [[], ['a'], 1], [[['a', 'wait']], [], 2], [[], [], 1], [[['b', 'keep']], [], 1], [[], [], 6], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 1], [[['z', 'first']], ['a'], 1]], 2: [[[['b', 'bb'], ['c', 'c'], ['a', 'aa']], [], 2], [[], ['a'], 2], [[['a', 'waitwait']], [], 3], [[], [], 2], [[['b', 'keepkeep']], [], 2], [[], [], 7], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 2], [[['z', 'first']], ['a'], 2]], 3: [[[['b', 'bbb'], ['c', 'c'], ['a', 'aaa']], [], 3], [[], ['a'], 3], [[['a', 'waitwaitwait']], [], 4], [[], [], 3], [[['b', 'keepkeepkeep']], [], 3], [[], [], 8], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 3], [[['z', 'first']], ['a'], 3]], 4: [[[['b', 'bbbb'], ['c', 'c'], ['a', 'aaaa']], [], 4], [[], ['a'], 4], [[['a', 'waitwaitwaitwait']], [], 5], [[], [], 4], [[['b', 'keepkeepkeepkeep']], [], 4], [[], [], 9], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 4], [[['z', 'first']], ['a'], 4]], 5: [[[['b', 'bbbbb'], ['c', 'c'], ['a', 'aaaaa']], [], 5], [[], ['a'], 5], [[['a', 'waitwaitwaitwaitwait']], [], 6], [[], [], 5], [[['b', 'keepkeepkeepkeepkeep']], [], 5], [[], [], 10], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 5], [[['z', 'first']], ['a'], 5]]}[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 | [[['b', 'b'], ['c', 'c'], ['a', 'a']], [], 1] | [[['b', 'b'], ['c', 'c'], ['a', 'a']], [], 1] | Passed |
| trace-2 | [[], ['a'], 1] | [[], ['a'], 1] | Passed |
| trace-3 | [[['a', 'wait']], [], 2] | [[['a', 'wait']], [], 2] | Passed |
| trace-4 | [[], [], 1] | [[], [], 1] | Passed |
| trace-5 | [[], [], 1] | [[['b', 'keep']], [], 1] | Failed |
| trace-6 | [[], [], 6] | [[], [], 6] | Passed |
| trace-7 | [[], [], 0] | [[], [], 0] | Passed |
| trace-8 | [[], [], 0] | [[], [], 0] | Passed |
| trace-9 | [[['r', 'first']], ['s'], 1] | [[['r', 'first']], ['s'], 1] | Passed |
| trace-10 | [[['z', 'first']], ['a'], 1] | [[['z', 'first']], ['a'], 1] | Passed |
SHA-256 / a595a7b4fd3e8902c9e7ec0405f5c9e8d5caddda1e3b7b4d9a4f16d69aa242e6
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(events):
q=[]; spoken=[]; now=0; seq=0
for e in events:
if e[0]=='enqueue':
seq+=1
q.append([e[1],e[2],e[3],e[4],e[5],seq])
elif e[0]=='cancel': q=q[1:]
elif e[0]=='reset': now=0; q.clear()
elif e[0]=='tick':
now=max(now,e[1])
q=[x for x in q if x[3]>now]
eligible=[x for x in q if x[2]<=now]
if eligible:
chosen=min(eligible,key=lambda x:(-x[4],x[5]))
spoken.append(chosen[:2])
q.remove(chosen)
return [spoken,[x[0] for x in q],now]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['enqueue','a','a'*N,0,100,1],['enqueue','b','b'*N,0,100,3],['enqueue','c','c',0,100,3],['tick',N],['tick',N],['tick',N]]", "[['enqueue','a','wait'*N,N+1,N+5,1],['tick',N]]", "[['enqueue','a','wait'*N,N+1,N+5,1],['tick',N],['tick',N+1]]", "[['enqueue','a','expired'*N,0,N,1],['tick',N]]", "[['enqueue','a','gone',0,100,1],['enqueue','b','keep'*N,0,100,2],['cancel','missing'],['cancel','a'],['tick',N]]", "[['tick',N+5],['tick',N]]", "[['tick',N+5],['tick',N],['enqueue','a','old',0,100,1],['reset']]", '[]', "[['enqueue','r','first',N,100,1],['enqueue','s','second',0,100,1],['tick',N]]", "[['enqueue','z','first',0,100,1],['enqueue','a','second'*N,0,100,1],['tick',N]]"]
expected = {1: [[[['b', 'b'], ['c', 'c'], ['a', 'a']], [], 1], [[], ['a'], 1], [[['a', 'wait']], [], 2], [[], [], 1], [[['b', 'keep']], [], 1], [[], [], 6], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 1], [[['z', 'first']], ['a'], 1]], 2: [[[['b', 'bb'], ['c', 'c'], ['a', 'aa']], [], 2], [[], ['a'], 2], [[['a', 'waitwait']], [], 3], [[], [], 2], [[['b', 'keepkeep']], [], 2], [[], [], 7], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 2], [[['z', 'first']], ['a'], 2]], 3: [[[['b', 'bbb'], ['c', 'c'], ['a', 'aaa']], [], 3], [[], ['a'], 3], [[['a', 'waitwaitwait']], [], 4], [[], [], 3], [[['b', 'keepkeepkeep']], [], 3], [[], [], 8], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 3], [[['z', 'first']], ['a'], 3]], 4: [[[['b', 'bbbb'], ['c', 'c'], ['a', 'aaaa']], [], 4], [[], ['a'], 4], [[['a', 'waitwaitwaitwait']], [], 5], [[], [], 4], [[['b', 'keepkeepkeepkeep']], [], 4], [[], [], 9], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 4], [[['z', 'first']], ['a'], 4]], 5: [[[['b', 'bbbbb'], ['c', 'c'], ['a', 'aaaaa']], [], 5], [[], ['a'], 5], [[['a', 'waitwaitwaitwaitwait']], [], 6], [[], [], 5], [[['b', 'keepkeepkeepkeepkeep']], [], 5], [[], [], 10], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 5], [[['z', 'first']], ['a'], 5]]}[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 | [[['b', 'b'], ['c', 'c'], ['a', 'a']], [], 1] | [[['b', 'b'], ['c', 'c'], ['a', 'a']], [], 1] | Passed |
| trace-2 | [[], ['a'], 1] | [[], ['a'], 1] | Passed |
| trace-3 | [[['a', 'wait']], [], 2] | [[['a', 'wait']], [], 2] | Passed |
| trace-4 | [[], [], 1] | [[], [], 1] | Passed |
| trace-5 | [[], [], 1] | [[['b', 'keep']], [], 1] | Failed |
| trace-6 | [[], [], 6] | [[], [], 6] | Passed |
| trace-7 | [[], [], 0] | [[], [], 0] | Passed |
| trace-8 | [[], [], 0] | [[], [], 0] | Passed |
| trace-9 | [[['r', 'first']], ['s'], 1] | [[['r', 'first']], ['s'], 1] | Passed |
| trace-10 | [[['z', 'first']], ['a'], 1] | [[['z', 'first']], ['a'], 1] | Passed |
SHA-256 / 9b288f4b65a51d198f69af26c3c4ed1adb1f937de07ccd610b72c3978a0e5dc8
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(events):
q=[]; spoken=[]; now=0; seq=0
for e in events:
if e[0]=='enqueue':
seq+=1
q.append([e[1],e[2],e[3],e[4],e[5],seq])
elif e[0]=='cancel': q=[x for x in q if x[0]!=e[1]]
elif e[0]=='reset': now=0; q.clear()
elif e[0]=='tick':
now=max(now,e[1])
q=[x for x in q if x[3]>now]
eligible=[x for x in q if x[2]<=now]
if eligible:
chosen=min(eligible,key=lambda x:(-x[4],x[5]))
spoken.append(chosen[:2])
q.remove(chosen)
return [spoken,[x[0] for x in q],now]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['enqueue','a','a'*N,0,100,1],['enqueue','b','b'*N,0,100,3],['enqueue','c','c',0,100,3],['tick',N],['tick',N],['tick',N]]", "[['enqueue','a','wait'*N,N+1,N+5,1],['tick',N]]", "[['enqueue','a','wait'*N,N+1,N+5,1],['tick',N],['tick',N+1]]", "[['enqueue','a','expired'*N,0,N,1],['tick',N]]", "[['enqueue','a','gone',0,100,1],['enqueue','b','keep'*N,0,100,2],['cancel','missing'],['cancel','a'],['tick',N]]", "[['tick',N+5],['tick',N]]", "[['tick',N+5],['tick',N],['enqueue','a','old',0,100,1],['reset']]", '[]', "[['enqueue','r','first',N,100,1],['enqueue','s','second',0,100,1],['tick',N]]", "[['enqueue','z','first',0,100,1],['enqueue','a','second'*N,0,100,1],['tick',N]]"]
expected = {1: [[[['b', 'b'], ['c', 'c'], ['a', 'a']], [], 1], [[], ['a'], 1], [[['a', 'wait']], [], 2], [[], [], 1], [[['b', 'keep']], [], 1], [[], [], 6], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 1], [[['z', 'first']], ['a'], 1]], 2: [[[['b', 'bb'], ['c', 'c'], ['a', 'aa']], [], 2], [[], ['a'], 2], [[['a', 'waitwait']], [], 3], [[], [], 2], [[['b', 'keepkeep']], [], 2], [[], [], 7], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 2], [[['z', 'first']], ['a'], 2]], 3: [[[['b', 'bbb'], ['c', 'c'], ['a', 'aaa']], [], 3], [[], ['a'], 3], [[['a', 'waitwaitwait']], [], 4], [[], [], 3], [[['b', 'keepkeepkeep']], [], 3], [[], [], 8], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 3], [[['z', 'first']], ['a'], 3]], 4: [[[['b', 'bbbb'], ['c', 'c'], ['a', 'aaaa']], [], 4], [[], ['a'], 4], [[['a', 'waitwaitwaitwait']], [], 5], [[], [], 4], [[['b', 'keepkeepkeepkeep']], [], 4], [[], [], 9], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 4], [[['z', 'first']], ['a'], 4]], 5: [[[['b', 'bbbbb'], ['c', 'c'], ['a', 'aaaaa']], [], 5], [[], ['a'], 5], [[['a', 'waitwaitwaitwaitwait']], [], 6], [[], [], 5], [[['b', 'keepkeepkeepkeepkeep']], [], 5], [[], [], 10], [[], [], 0], [[], [], 0], [[['r', 'first']], ['s'], 5], [[['z', 'first']], ['a'], 5]]}[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 | [[['b', 'b'], ['c', 'c'], ['a', 'a']], [], 1] | [[['b', 'b'], ['c', 'c'], ['a', 'a']], [], 1] | Passed |
| trace-2 | [[], ['a'], 1] | [[], ['a'], 1] | Passed |
| trace-3 | [[['a', 'wait']], [], 2] | [[['a', 'wait']], [], 2] | Passed |
| trace-4 | [[], [], 1] | [[], [], 1] | Passed |
| trace-5 | [[['b', 'keep']], [], 1] | [[['b', 'keep']], [], 1] | Passed |
| trace-6 | [[], [], 6] | [[], [], 6] | Passed |
| trace-7 | [[], [], 0] | [[], [], 0] | Passed |
| trace-8 | [[], [], 0] | [[], [], 0] | Passed |
| trace-9 | [[['r', 'first']], ['s'], 1] | [[['r', 'first']], ['s'], 1] | Passed |
| trace-10 | [[['z', 'first']], ['a'], 1] | [[['z', 'first']], ['a'], 1] | Passed |
SHA-256 / b9de4f8d705c0de1a01c39bc7dcf2c74b8ce4c89b1d6dd6f18f12208ca9d3979
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 2026-09-29T14:40:20.543639+00:00.
Case digest / 19befb0d6a026c73b4197fd583416f956af6da76fefd45e42c31184d0ab1f3bc