FAILURE MAP
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FA-20611 / Assistive announcements / Open access

Late timer moves announcement time backward · case 01

The announcement trace violates the stated deadline-scheduler contract.

Verified by executionVariant 1 · 10 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Fault site: now=max(now,e[1]) is implemented as now=e[1]

THE FAILURE

Fault site: now=max(now,e[1]) is implemented as now=e[1]

Unsuccessful approach: The attempted repair substitutes now+=e[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=[x for x in q if x[0]!=e[1]]
        elif e[0]=='reset': now=0; q.clear()
        elif e[0]=='tick':
            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 fixtureActualExpectedOutcome
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[[], [], 1][[], [], 6]Failed
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 / 5fc52191b3ae38833a8110c7f0cf245ddea32a07aa56b37744953c172b4964cf

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=[x for x in q if x[0]!=e[1]]
        elif e[0]=='reset': now=0; q.clear()
        elif e[0]=='tick':
            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 fixtureActualExpectedOutcome
trace-1[[['b', 'b'], ['c', 'c'], ['a', 'a']], [], 3][[['b', 'b'], ['c', 'c'], ['a', 'a']], [], 1]Failed
trace-2[[], ['a'], 1][[], ['a'], 1]Passed
trace-3[[['a', 'wait']], [], 3][[['a', 'wait']], [], 2]Failed
trace-4[[], [], 1][[], [], 1]Passed
trace-5[[['b', 'keep']], [], 1][[['b', 'keep']], [], 1]Passed
trace-6[[], [], 7][[], [], 6]Failed
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 / 7bf39273a34485638f58f412c7cee0581842fb35c6cc6475ece2e355a491a07a

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 10 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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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 2026-09-29T14:40:20.858621+00:00.

Case digest / 56f7987c993bdaec4800f5c8b1d7644f0f92b9b4b1845ba6d0890b7fd7424562