FAILURE MAP
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FA-20471 / Assistive announcements / Open access

Cancel retains a live chunk assembly · case 01

The announcement trace violates the stated chunk-assembly contract.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Fault site: elif e[0]=='cancel': pieces.clear(); opened=False is implemented as elif e[0]=='cancel': opened=False

VERIFIED REPAIR

Restore the stated transition: elif e[0]=='cancel': pieces.clear(); opened=False

Unsuccessful approach: The attempted repair substitutes elif e[0]=='cancel': pieces.clear() and still violates a regression oracle.

Case contract

Utterance chunks carry a sequence index. Begin sets expected count and clears previous chunks. Put accepts only in-range indices; last write wins. Seal emits only a contiguous complete set, in index order, joined by spaces. A successful seal clears pieces and closes the assembly. Cancel closes without speech; reopen starts a new assembly. Report emitted strings and pending indices.

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):
    count=0; pieces={}; opened=False; spoken=[]
    for e in events:
        if e[0]=='begin':
            count=e[1]
            pieces.clear()
            opened=True
        elif e[0]=='put':
            if not opened: continue
            if not 0<=e[1]<count: continue
            pieces[e[1]]=e[2]
        elif e[0]=='cancel': opened=False
        elif e[0]=='seal':
            if not opened: continue
            if len(pieces)!=count: continue
            if count: spoken.append(' '.join(pieces[i] for i in range(count)))
            pieces.clear(); opened=False
    return [spoken, sorted(pieces), opened]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['begin',2],['put',1,'two'*N],['put',0,'one'],['seal'],['seal']]", "[['begin',2],['put',0,'old'],['put',0,'new'*N],['put',1,'end'],['seal']]", "[['begin',2],['put',1,'old'],['begin',2],['put',0,'fresh'*N],['seal']]", "[['begin',1],['put',1,'outside'*N],['put',0,'inside'],['seal']]", "[['begin',N],['put',0,'x'],['cancel'],['put',0,'late']]", "[['begin',0],['seal'],['seal']]", "[['begin',1],['put',0,'x'*N],['seal']]", "[['begin',2],['put',0,'partial'*N],['seal']]"]
expected = {1: [[['one two'], [], False], [['new end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['x'], [], False], [[], [0], True]], 2: [[['one twotwo'], [], False], [['newnew end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['xx'], [], False], [[], [0], True]], 3: [[['one twotwotwo'], [], False], [['newnewnew end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['xxx'], [], False], [[], [0], True]], 4: [[['one twotwotwotwo'], [], False], [['newnewnewnew end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['xxxx'], [], False], [[], [0], True]], 5: [[['one twotwotwotwotwo'], [], False], [['newnewnewnewnew end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['xxxxx'], [], False], [[], [0], True]]}[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[['one two'], [], False][['one two'], [], False]Passed
trace-2[['new end'], [], False][['new end'], [], False]Passed
trace-3[[], [0], True][[], [0], True]Passed
trace-4[['inside'], [], False][['inside'], [], False]Passed
trace-5[[], [0], False][[], [], False]Failed
trace-6[[], [], False][[], [], False]Passed
trace-7[['x'], [], False][['x'], [], False]Passed
trace-8[[], [0], True][[], [0], True]Passed

SHA-256 / d4b34bdb174ec992649676c9be698aca5f7c403ff7a9e5f49319e9012c6ffd41

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(events):
    count=0; pieces={}; opened=False; spoken=[]
    for e in events:
        if e[0]=='begin':
            count=e[1]
            pieces.clear()
            opened=True
        elif e[0]=='put':
            if not opened: continue
            if not 0<=e[1]<count: continue
            pieces[e[1]]=e[2]
        elif e[0]=='cancel': pieces.clear()
        elif e[0]=='seal':
            if not opened: continue
            if len(pieces)!=count: continue
            if count: spoken.append(' '.join(pieces[i] for i in range(count)))
            pieces.clear(); opened=False
    return [spoken, sorted(pieces), opened]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['begin',2],['put',1,'two'*N],['put',0,'one'],['seal'],['seal']]", "[['begin',2],['put',0,'old'],['put',0,'new'*N],['put',1,'end'],['seal']]", "[['begin',2],['put',1,'old'],['begin',2],['put',0,'fresh'*N],['seal']]", "[['begin',1],['put',1,'outside'*N],['put',0,'inside'],['seal']]", "[['begin',N],['put',0,'x'],['cancel'],['put',0,'late']]", "[['begin',0],['seal'],['seal']]", "[['begin',1],['put',0,'x'*N],['seal']]", "[['begin',2],['put',0,'partial'*N],['seal']]"]
expected = {1: [[['one two'], [], False], [['new end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['x'], [], False], [[], [0], True]], 2: [[['one twotwo'], [], False], [['newnew end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['xx'], [], False], [[], [0], True]], 3: [[['one twotwotwo'], [], False], [['newnewnew end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['xxx'], [], False], [[], [0], True]], 4: [[['one twotwotwotwo'], [], False], [['newnewnewnew end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['xxxx'], [], False], [[], [0], True]], 5: [[['one twotwotwotwotwo'], [], False], [['newnewnewnewnew end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['xxxxx'], [], False], [[], [0], True]]}[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[['one two'], [], False][['one two'], [], False]Passed
trace-2[['new end'], [], False][['new end'], [], False]Passed
trace-3[[], [0], True][[], [0], True]Passed
trace-4[['inside'], [], False][['inside'], [], False]Passed
trace-5[[], [0], True][[], [], False]Failed
trace-6[[], [], False][[], [], False]Passed
trace-7[['x'], [], False][['x'], [], False]Passed
trace-8[[], [0], True][[], [0], True]Passed

SHA-256 / 2725b00eaa430dc4efc8e85d9fd1059a9c6719f7824153a67c30ee3f5debafba

3 / The verified repair

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

N = 1
observations = []
def solve(events):
    count=0; pieces={}; opened=False; spoken=[]
    for e in events:
        if e[0]=='begin':
            count=e[1]
            pieces.clear()
            opened=True
        elif e[0]=='put':
            if not opened: continue
            if not 0<=e[1]<count: continue
            pieces[e[1]]=e[2]
        elif e[0]=='cancel': pieces.clear(); opened=False
        elif e[0]=='seal':
            if not opened: continue
            if len(pieces)!=count: continue
            if count: spoken.append(' '.join(pieces[i] for i in range(count)))
            pieces.clear(); opened=False
    return [spoken, sorted(pieces), opened]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['begin',2],['put',1,'two'*N],['put',0,'one'],['seal'],['seal']]", "[['begin',2],['put',0,'old'],['put',0,'new'*N],['put',1,'end'],['seal']]", "[['begin',2],['put',1,'old'],['begin',2],['put',0,'fresh'*N],['seal']]", "[['begin',1],['put',1,'outside'*N],['put',0,'inside'],['seal']]", "[['begin',N],['put',0,'x'],['cancel'],['put',0,'late']]", "[['begin',0],['seal'],['seal']]", "[['begin',1],['put',0,'x'*N],['seal']]", "[['begin',2],['put',0,'partial'*N],['seal']]"]
expected = {1: [[['one two'], [], False], [['new end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['x'], [], False], [[], [0], True]], 2: [[['one twotwo'], [], False], [['newnew end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['xx'], [], False], [[], [0], True]], 3: [[['one twotwotwo'], [], False], [['newnewnew end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['xxx'], [], False], [[], [0], True]], 4: [[['one twotwotwotwo'], [], False], [['newnewnewnew end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['xxxx'], [], False], [[], [0], True]], 5: [[['one twotwotwotwotwo'], [], False], [['newnewnewnewnew end'], [], False], [[], [0], True], [['inside'], [], False], [[], [], False], [[], [], False], [['xxxxx'], [], False], [[], [0], True]]}[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[['one two'], [], False][['one two'], [], False]Passed
trace-2[['new end'], [], False][['new end'], [], False]Passed
trace-3[[], [0], True][[], [0], True]Passed
trace-4[['inside'], [], False][['inside'], [], False]Passed
trace-5[[], [], False][[], [], False]Passed
trace-6[[], [], False][[], [], False]Passed
trace-7[['x'], [], False][['x'], [], False]Passed
trace-8[[], [0], True][[], [0], True]Passed

SHA-256 / 487859558e9ea4f960034fbbe63d30f2c3627975329046abbffd800b5318da5f

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 2026-09-29T14:40:19.250420+00:00.

Case digest / 223408340e91b81924858ade1a32db8965191b876d2fcdbac68a7b1a157ce5b9