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FA-21516 / Assistive announcements / Open access

Committed handoff leaves pending speech on previous device · case 01

The announcement trace violates the stated device-handoff contract.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Fault site: q=[[current if route==old else route,text] for route,text in q] is implemented as q=list(q)

VERIFIED REPAIR

Restore the stated transition: q=[[current if route==old else route,text] for route,text in q]

Unsuccessful approach: The attempted repair substitutes q=[[current,text[:1]] for route,text in q] and still violates a regression oracle.

Case contract

Output routes start at local device. Queue snapshots requested route and utterance text. Begin-handoff sets a target while retaining current route. Commit switches current route and migrates only pending items on old route; cancel-handoff leaves queue unchanged. Device removal drops queued output to that device and chooses local if current removed. Send requires route available and sends one queued item; unavailable items remain. Add makes device available. Return [device,text] output and pending routes.

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):
    current='local'; target=None; devices={'local'}; q=[]; out=[]
    for e in events:
        if e[0]=='add': devices.add(e[1])
        elif e[0]=='queue': q.append([current,e[1]])
        elif e[0]=='begin': target=e[1]
        elif e[0]=='cancel': target=None
        elif e[0]=='commit' and target in devices:
            old=current; current=target
            q=list(q)
            target=None
        elif e[0]=='remove':
            devices.discard(e[1])
            q=[x for x in q if x[0]!=e[1]]
            if current==e[1]: current='local'
        elif e[0]=='send' and q:
            index=next((i for i,x in enumerate(q) if x[0] in devices),None)
            if index is not None: out.append(q.pop(index))
    return [out,q,current,target,sorted(devices)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['add','Headset'],['queue','hello'*N],['begin','Headset'],['queue','before'],['commit'],['queue','after'],['send']]", "[['queue','keep'*N],['begin','missing'],['commit']]", "[['queue','keep'*N],['begin','remote'],['queue','during'*N],['cancel'],['send']]", "[['add','head'],['begin','head'],['commit'],['queue','remote'*N],['remove','head']]", "[['add','head'],['begin','head'],['commit'],['queue','keep'*N],['remove','unused']]", "[['add','remote'],['queue','local'*N],['remove','remote'],['send']]", '[]']
expected = {1: [[[['Headset', 'hello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keep']], 'local', 'missing', ['local']], [[['local', 'keep']], [['local', 'during']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keep']], 'head', None, ['head', 'local']], [[['local', 'local']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]], 2: [[[['Headset', 'hellohello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keepkeep']], 'local', 'missing', ['local']], [[['local', 'keepkeep']], [['local', 'duringduring']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keepkeep']], 'head', None, ['head', 'local']], [[['local', 'locallocal']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]], 3: [[[['Headset', 'hellohellohello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keepkeepkeep']], 'local', 'missing', ['local']], [[['local', 'keepkeepkeep']], [['local', 'duringduringduring']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keepkeepkeep']], 'head', None, ['head', 'local']], [[['local', 'locallocallocal']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]], 4: [[[['Headset', 'hellohellohellohello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keepkeepkeepkeep']], 'local', 'missing', ['local']], [[['local', 'keepkeepkeepkeep']], [['local', 'duringduringduringduring']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keepkeepkeepkeep']], 'head', None, ['head', 'local']], [[['local', 'locallocallocallocal']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]], 5: [[[['Headset', 'hellohellohellohellohello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keepkeepkeepkeepkeep']], 'local', 'missing', ['local']], [[['local', 'keepkeepkeepkeepkeep']], [['local', 'duringduringduringduringduring']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keepkeepkeepkeepkeep']], 'head', None, ['head', 'local']], [[['local', 'locallocallocallocallocal']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]]}[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[[['local', 'hello']], [['local', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']][[['Headset', 'hello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']]Failed
trace-2[[], [['local', 'keep']], 'local', 'missing', ['local']][[], [['local', 'keep']], 'local', 'missing', ['local']]Passed
trace-3[[['local', 'keep']], [['local', 'during']], 'local', None, ['local']][[['local', 'keep']], [['local', 'during']], 'local', None, ['local']]Passed
trace-4[[], [], 'local', None, ['local']][[], [], 'local', None, ['local']]Passed
trace-5[[], [['head', 'keep']], 'head', None, ['head', 'local']][[], [['head', 'keep']], 'head', None, ['head', 'local']]Passed
trace-6[[['local', 'local']], [], 'local', None, ['local']][[['local', 'local']], [], 'local', None, ['local']]Passed
trace-7[[], [], 'local', None, ['local']][[], [], 'local', None, ['local']]Passed

SHA-256 / c42aedb0f341aaa9499eee0a783b9dc488053ba8650ba993968bc1aaf5d4c99b

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(events):
    current='local'; target=None; devices={'local'}; q=[]; out=[]
    for e in events:
        if e[0]=='add': devices.add(e[1])
        elif e[0]=='queue': q.append([current,e[1]])
        elif e[0]=='begin': target=e[1]
        elif e[0]=='cancel': target=None
        elif e[0]=='commit' and target in devices:
            old=current; current=target
            q=[[current,text[:1]] for route,text in q]
            target=None
        elif e[0]=='remove':
            devices.discard(e[1])
            q=[x for x in q if x[0]!=e[1]]
            if current==e[1]: current='local'
        elif e[0]=='send' and q:
            index=next((i for i,x in enumerate(q) if x[0] in devices),None)
            if index is not None: out.append(q.pop(index))
    return [out,q,current,target,sorted(devices)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['add','Headset'],['queue','hello'*N],['begin','Headset'],['queue','before'],['commit'],['queue','after'],['send']]", "[['queue','keep'*N],['begin','missing'],['commit']]", "[['queue','keep'*N],['begin','remote'],['queue','during'*N],['cancel'],['send']]", "[['add','head'],['begin','head'],['commit'],['queue','remote'*N],['remove','head']]", "[['add','head'],['begin','head'],['commit'],['queue','keep'*N],['remove','unused']]", "[['add','remote'],['queue','local'*N],['remove','remote'],['send']]", '[]']
expected = {1: [[[['Headset', 'hello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keep']], 'local', 'missing', ['local']], [[['local', 'keep']], [['local', 'during']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keep']], 'head', None, ['head', 'local']], [[['local', 'local']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]], 2: [[[['Headset', 'hellohello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keepkeep']], 'local', 'missing', ['local']], [[['local', 'keepkeep']], [['local', 'duringduring']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keepkeep']], 'head', None, ['head', 'local']], [[['local', 'locallocal']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]], 3: [[[['Headset', 'hellohellohello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keepkeepkeep']], 'local', 'missing', ['local']], [[['local', 'keepkeepkeep']], [['local', 'duringduringduring']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keepkeepkeep']], 'head', None, ['head', 'local']], [[['local', 'locallocallocal']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]], 4: [[[['Headset', 'hellohellohellohello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keepkeepkeepkeep']], 'local', 'missing', ['local']], [[['local', 'keepkeepkeepkeep']], [['local', 'duringduringduringduring']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keepkeepkeepkeep']], 'head', None, ['head', 'local']], [[['local', 'locallocallocallocal']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]], 5: [[[['Headset', 'hellohellohellohellohello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keepkeepkeepkeepkeep']], 'local', 'missing', ['local']], [[['local', 'keepkeepkeepkeepkeep']], [['local', 'duringduringduringduringduring']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keepkeepkeepkeepkeep']], 'head', None, ['head', 'local']], [[['local', 'locallocallocallocallocal']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]]}[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[[['Headset', 'h']], [['Headset', 'b'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']][[['Headset', 'hello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']]Failed
trace-2[[], [['local', 'keep']], 'local', 'missing', ['local']][[], [['local', 'keep']], 'local', 'missing', ['local']]Passed
trace-3[[['local', 'keep']], [['local', 'during']], 'local', None, ['local']][[['local', 'keep']], [['local', 'during']], 'local', None, ['local']]Passed
trace-4[[], [], 'local', None, ['local']][[], [], 'local', None, ['local']]Passed
trace-5[[], [['head', 'keep']], 'head', None, ['head', 'local']][[], [['head', 'keep']], 'head', None, ['head', 'local']]Passed
trace-6[[['local', 'local']], [], 'local', None, ['local']][[['local', 'local']], [], 'local', None, ['local']]Passed
trace-7[[], [], 'local', None, ['local']][[], [], 'local', None, ['local']]Passed

SHA-256 / 7ca5f2224a5f69620f649e77fc44ef8d2205618aeeb6d4ba2e874a781d33bde0

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(events):
    current='local'; target=None; devices={'local'}; q=[]; out=[]
    for e in events:
        if e[0]=='add': devices.add(e[1])
        elif e[0]=='queue': q.append([current,e[1]])
        elif e[0]=='begin': target=e[1]
        elif e[0]=='cancel': target=None
        elif e[0]=='commit' and target in devices:
            old=current; current=target
            q=[[current if route==old else route,text] for route,text in q]
            target=None
        elif e[0]=='remove':
            devices.discard(e[1])
            q=[x for x in q if x[0]!=e[1]]
            if current==e[1]: current='local'
        elif e[0]=='send' and q:
            index=next((i for i,x in enumerate(q) if x[0] in devices),None)
            if index is not None: out.append(q.pop(index))
    return [out,q,current,target,sorted(devices)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['add','Headset'],['queue','hello'*N],['begin','Headset'],['queue','before'],['commit'],['queue','after'],['send']]", "[['queue','keep'*N],['begin','missing'],['commit']]", "[['queue','keep'*N],['begin','remote'],['queue','during'*N],['cancel'],['send']]", "[['add','head'],['begin','head'],['commit'],['queue','remote'*N],['remove','head']]", "[['add','head'],['begin','head'],['commit'],['queue','keep'*N],['remove','unused']]", "[['add','remote'],['queue','local'*N],['remove','remote'],['send']]", '[]']
expected = {1: [[[['Headset', 'hello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keep']], 'local', 'missing', ['local']], [[['local', 'keep']], [['local', 'during']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keep']], 'head', None, ['head', 'local']], [[['local', 'local']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]], 2: [[[['Headset', 'hellohello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keepkeep']], 'local', 'missing', ['local']], [[['local', 'keepkeep']], [['local', 'duringduring']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keepkeep']], 'head', None, ['head', 'local']], [[['local', 'locallocal']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]], 3: [[[['Headset', 'hellohellohello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keepkeepkeep']], 'local', 'missing', ['local']], [[['local', 'keepkeepkeep']], [['local', 'duringduringduring']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keepkeepkeep']], 'head', None, ['head', 'local']], [[['local', 'locallocallocal']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]], 4: [[[['Headset', 'hellohellohellohello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keepkeepkeepkeep']], 'local', 'missing', ['local']], [[['local', 'keepkeepkeepkeep']], [['local', 'duringduringduringduring']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keepkeepkeepkeep']], 'head', None, ['head', 'local']], [[['local', 'locallocallocallocal']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]], 5: [[[['Headset', 'hellohellohellohellohello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']], [[], [['local', 'keepkeepkeepkeepkeep']], 'local', 'missing', ['local']], [[['local', 'keepkeepkeepkeepkeep']], [['local', 'duringduringduringduringduring']], 'local', None, ['local']], [[], [], 'local', None, ['local']], [[], [['head', 'keepkeepkeepkeepkeep']], 'head', None, ['head', 'local']], [[['local', 'locallocallocallocallocal']], [], 'local', None, ['local']], [[], [], 'local', None, ['local']]]}[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[[['Headset', 'hello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']][[['Headset', 'hello']], [['Headset', 'before'], ['Headset', 'after']], 'Headset', None, ['Headset', 'local']]Passed
trace-2[[], [['local', 'keep']], 'local', 'missing', ['local']][[], [['local', 'keep']], 'local', 'missing', ['local']]Passed
trace-3[[['local', 'keep']], [['local', 'during']], 'local', None, ['local']][[['local', 'keep']], [['local', 'during']], 'local', None, ['local']]Passed
trace-4[[], [], 'local', None, ['local']][[], [], 'local', None, ['local']]Passed
trace-5[[], [['head', 'keep']], 'head', None, ['head', 'local']][[], [['head', 'keep']], 'head', None, ['head', 'local']]Passed
trace-6[[['local', 'local']], [], 'local', None, ['local']][[['local', 'local']], [], 'local', None, ['local']]Passed
trace-7[[], [], 'local', None, ['local']][[], [], 'local', None, ['local']]Passed

SHA-256 / 0f629dda7fbbc8588a75fbc148c0b0edd2dc5d28ac23e4234d16e0e58ef87579

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 2026-09-29T14:40:29.576447+00:00.

Case digest / e05d7f3ee56378a0289d7bb333fafaafe379de3ffb5b97f072595e4bfd8803b4