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FA-21791 / Assistive announcements / Open access

Speech-only mode waits for an impossible braille receipt · case 01

The announcement trace violates the stated dual-channel-barrier contract.

Verified by executionVariant 1 · 9 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Fault site: if e[0]=='submit': pending[e[1]]=[e[2],False,not braille] is implemented as if e[0]=='submit': pending[e[1]]=[e[2],False,False]

VERIFIED REPAIR

Restore the stated transition: if e[0]=='submit': pending[e[1]]=[e[2],False,not braille]

Unsuccessful approach: The attempted repair substitutes if e[0]=='submit': pending[e[1]]=[e[2],not braille,not braille] and still violates a regression oracle.

Case contract

An announcement delivery couples speech and braille with per-message receipts. Submit creates [text,speechDone=False,brailleDone=False]. Speech and braille ACK set only their channel. Commit emits completion once only when both acknowledged and removes message. Disable-braille marks pending braille complete and affects future submissions; enable only affects future submissions. Replace text resets both receipts according to current enabled channels. Cancel drops one pending item. Report completion text, pending receipts and braille enabled.

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):
    pending={}; braille=True; out=[]
    for e in events:
        if e[0]=='submit': pending[e[1]]=[e[2],False,False]
        elif e[0]=='disable-braille':
            braille=False
            for row in pending.values(): row[2]=True
        elif e[0]=='enable-braille': braille=True
        elif e[0]=='cancel': pending.pop(e[1],None)
        elif len(e)>1 and e[1] in pending:
            row=pending[e[1]]
            if e[0]=='speech': row[1]=True
            elif e[0]=='braille': row[2]=True
            elif e[0]=='replace': row[:]=[e[2],False,not braille]
            elif e[0]=='commit':
                if not(row[1] and row[2]): continue
                out.append(row[0])
                del pending[e[1]]
    return [out,[[k]+v for k,v in pending.items()],braille]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['submit','a','hello'*N],['speech','a'],['commit','a']]", "[['submit','a','hello'*N],['braille','a'],['commit','a']]", "[['submit','a','hello'*N],['speech','a'],['braille','a'],['submit','b','keep'],['commit','a'],['commit','a']]", "[['submit','a','old'],['speech','a'],['braille','a'],['replace','a','new'*N],['commit','a']]", "[['submit','a','pending'*N],['disable-braille'],['commit','a'],['submit','b','future'],['speech','b'],['commit','b'],['enable-braille']]", "[['disable-braille'],['submit','a','new'*N],['commit','a']]", "[['disable-braille'],['submit','a','old'],['replace','a','new'*N],['speech','a'],['commit','a']]", "[['submit','a','a'*N],['submit','b','b'],['cancel','a']]", '[]']
expected = {1: [[[], [['a', 'hello', True, False]], True], [[], [['a', 'hello', False, True]], True], [['hello'], [['b', 'keep', False, False]], True], [[], [['a', 'new', False, False]], True], [['future'], [['a', 'pending', False, True]], True], [[], [['a', 'new', False, True]], False], [['new'], [], False], [[], [['b', 'b', False, False]], True], [[], [], True]], 2: [[[], [['a', 'hellohello', True, False]], True], [[], [['a', 'hellohello', False, True]], True], [['hellohello'], [['b', 'keep', False, False]], True], [[], [['a', 'newnew', False, False]], True], [['future'], [['a', 'pendingpending', False, True]], True], [[], [['a', 'newnew', False, True]], False], [['newnew'], [], False], [[], [['b', 'b', False, False]], True], [[], [], True]], 3: [[[], [['a', 'hellohellohello', True, False]], True], [[], [['a', 'hellohellohello', False, True]], True], [['hellohellohello'], [['b', 'keep', False, False]], True], [[], [['a', 'newnewnew', False, False]], True], [['future'], [['a', 'pendingpendingpending', False, True]], True], [[], [['a', 'newnewnew', False, True]], False], [['newnewnew'], [], False], [[], [['b', 'b', False, False]], True], [[], [], True]], 4: [[[], [['a', 'hellohellohellohello', True, False]], True], [[], [['a', 'hellohellohellohello', False, True]], True], [['hellohellohellohello'], [['b', 'keep', False, False]], True], [[], [['a', 'newnewnewnew', False, False]], True], [['future'], [['a', 'pendingpendingpendingpending', False, True]], True], [[], [['a', 'newnewnewnew', False, True]], False], [['newnewnewnew'], [], False], [[], [['b', 'b', False, False]], True], [[], [], True]], 5: [[[], [['a', 'hellohellohellohellohello', True, False]], True], [[], [['a', 'hellohellohellohellohello', False, True]], True], [['hellohellohellohellohello'], [['b', 'keep', False, False]], True], [[], [['a', 'newnewnewnewnew', False, False]], True], [['future'], [['a', 'pendingpendingpendingpendingpending', False, True]], True], [[], [['a', 'newnewnewnewnew', False, True]], False], [['newnewnewnewnew'], [], False], [[], [['b', 'b', False, False]], True], [[], [], 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[[], [['a', 'hello', True, False]], True][[], [['a', 'hello', True, False]], True]Passed
trace-2[[], [['a', 'hello', False, True]], True][[], [['a', 'hello', False, True]], True]Passed
trace-3[['hello'], [['b', 'keep', False, False]], True][['hello'], [['b', 'keep', False, False]], True]Passed
trace-4[[], [['a', 'new', False, False]], True][[], [['a', 'new', False, False]], True]Passed
trace-5[[], [['a', 'pending', False, True], ['b', 'future', True, False]], True][['future'], [['a', 'pending', False, True]], True]Failed
trace-6[[], [['a', 'new', False, False]], False][[], [['a', 'new', False, True]], False]Failed
trace-7[['new'], [], False][['new'], [], False]Passed
trace-8[[], [['b', 'b', False, False]], True][[], [['b', 'b', False, False]], True]Passed
trace-9[[], [], True][[], [], True]Passed

SHA-256 / cb0e8be81500dcf7c3fc90969295f501ff3fabb774943fdc017e3a85ba000036

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(events):
    pending={}; braille=True; out=[]
    for e in events:
        if e[0]=='submit': pending[e[1]]=[e[2],not braille,not braille]
        elif e[0]=='disable-braille':
            braille=False
            for row in pending.values(): row[2]=True
        elif e[0]=='enable-braille': braille=True
        elif e[0]=='cancel': pending.pop(e[1],None)
        elif len(e)>1 and e[1] in pending:
            row=pending[e[1]]
            if e[0]=='speech': row[1]=True
            elif e[0]=='braille': row[2]=True
            elif e[0]=='replace': row[:]=[e[2],False,not braille]
            elif e[0]=='commit':
                if not(row[1] and row[2]): continue
                out.append(row[0])
                del pending[e[1]]
    return [out,[[k]+v for k,v in pending.items()],braille]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['submit','a','hello'*N],['speech','a'],['commit','a']]", "[['submit','a','hello'*N],['braille','a'],['commit','a']]", "[['submit','a','hello'*N],['speech','a'],['braille','a'],['submit','b','keep'],['commit','a'],['commit','a']]", "[['submit','a','old'],['speech','a'],['braille','a'],['replace','a','new'*N],['commit','a']]", "[['submit','a','pending'*N],['disable-braille'],['commit','a'],['submit','b','future'],['speech','b'],['commit','b'],['enable-braille']]", "[['disable-braille'],['submit','a','new'*N],['commit','a']]", "[['disable-braille'],['submit','a','old'],['replace','a','new'*N],['speech','a'],['commit','a']]", "[['submit','a','a'*N],['submit','b','b'],['cancel','a']]", '[]']
expected = {1: [[[], [['a', 'hello', True, False]], True], [[], [['a', 'hello', False, True]], True], [['hello'], [['b', 'keep', False, False]], True], [[], [['a', 'new', False, False]], True], [['future'], [['a', 'pending', False, True]], True], [[], [['a', 'new', False, True]], False], [['new'], [], False], [[], [['b', 'b', False, False]], True], [[], [], True]], 2: [[[], [['a', 'hellohello', True, False]], True], [[], [['a', 'hellohello', False, True]], True], [['hellohello'], [['b', 'keep', False, False]], True], [[], [['a', 'newnew', False, False]], True], [['future'], [['a', 'pendingpending', False, True]], True], [[], [['a', 'newnew', False, True]], False], [['newnew'], [], False], [[], [['b', 'b', False, False]], True], [[], [], True]], 3: [[[], [['a', 'hellohellohello', True, False]], True], [[], [['a', 'hellohellohello', False, True]], True], [['hellohellohello'], [['b', 'keep', False, False]], True], [[], [['a', 'newnewnew', False, False]], True], [['future'], [['a', 'pendingpendingpending', False, True]], True], [[], [['a', 'newnewnew', False, True]], False], [['newnewnew'], [], False], [[], [['b', 'b', False, False]], True], [[], [], True]], 4: [[[], [['a', 'hellohellohellohello', True, False]], True], [[], [['a', 'hellohellohellohello', False, True]], True], [['hellohellohellohello'], [['b', 'keep', False, False]], True], [[], [['a', 'newnewnewnew', False, False]], True], [['future'], [['a', 'pendingpendingpendingpending', False, True]], True], [[], [['a', 'newnewnewnew', False, True]], False], [['newnewnewnew'], [], False], [[], [['b', 'b', False, False]], True], [[], [], True]], 5: [[[], [['a', 'hellohellohellohellohello', True, False]], True], [[], [['a', 'hellohellohellohellohello', False, True]], True], [['hellohellohellohellohello'], [['b', 'keep', False, False]], True], [[], [['a', 'newnewnewnewnew', False, False]], True], [['future'], [['a', 'pendingpendingpendingpendingpending', False, True]], True], [[], [['a', 'newnewnewnewnew', False, True]], False], [['newnewnewnewnew'], [], False], [[], [['b', 'b', False, False]], True], [[], [], 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[[], [['a', 'hello', True, False]], True][[], [['a', 'hello', True, False]], True]Passed
trace-2[[], [['a', 'hello', False, True]], True][[], [['a', 'hello', False, True]], True]Passed
trace-3[['hello'], [['b', 'keep', False, False]], True][['hello'], [['b', 'keep', False, False]], True]Passed
trace-4[[], [['a', 'new', False, False]], True][[], [['a', 'new', False, False]], True]Passed
trace-5[['future'], [['a', 'pending', False, True]], True][['future'], [['a', 'pending', False, True]], True]Passed
trace-6[['new'], [], False][[], [['a', 'new', False, True]], False]Failed
trace-7[['new'], [], False][['new'], [], False]Passed
trace-8[[], [['b', 'b', False, False]], True][[], [['b', 'b', False, False]], True]Passed
trace-9[[], [], True][[], [], True]Passed

SHA-256 / 60959c8a8fafc93ffb6325e866b2808799c71e3466b6a39ad61f2b8c0223a87b

3 / The verified repair

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

N = 1
observations = []
def solve(events):
    pending={}; braille=True; out=[]
    for e in events:
        if e[0]=='submit': pending[e[1]]=[e[2],False,not braille]
        elif e[0]=='disable-braille':
            braille=False
            for row in pending.values(): row[2]=True
        elif e[0]=='enable-braille': braille=True
        elif e[0]=='cancel': pending.pop(e[1],None)
        elif len(e)>1 and e[1] in pending:
            row=pending[e[1]]
            if e[0]=='speech': row[1]=True
            elif e[0]=='braille': row[2]=True
            elif e[0]=='replace': row[:]=[e[2],False,not braille]
            elif e[0]=='commit':
                if not(row[1] and row[2]): continue
                out.append(row[0])
                del pending[e[1]]
    return [out,[[k]+v for k,v in pending.items()],braille]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['submit','a','hello'*N],['speech','a'],['commit','a']]", "[['submit','a','hello'*N],['braille','a'],['commit','a']]", "[['submit','a','hello'*N],['speech','a'],['braille','a'],['submit','b','keep'],['commit','a'],['commit','a']]", "[['submit','a','old'],['speech','a'],['braille','a'],['replace','a','new'*N],['commit','a']]", "[['submit','a','pending'*N],['disable-braille'],['commit','a'],['submit','b','future'],['speech','b'],['commit','b'],['enable-braille']]", "[['disable-braille'],['submit','a','new'*N],['commit','a']]", "[['disable-braille'],['submit','a','old'],['replace','a','new'*N],['speech','a'],['commit','a']]", "[['submit','a','a'*N],['submit','b','b'],['cancel','a']]", '[]']
expected = {1: [[[], [['a', 'hello', True, False]], True], [[], [['a', 'hello', False, True]], True], [['hello'], [['b', 'keep', False, False]], True], [[], [['a', 'new', False, False]], True], [['future'], [['a', 'pending', False, True]], True], [[], [['a', 'new', False, True]], False], [['new'], [], False], [[], [['b', 'b', False, False]], True], [[], [], True]], 2: [[[], [['a', 'hellohello', True, False]], True], [[], [['a', 'hellohello', False, True]], True], [['hellohello'], [['b', 'keep', False, False]], True], [[], [['a', 'newnew', False, False]], True], [['future'], [['a', 'pendingpending', False, True]], True], [[], [['a', 'newnew', False, True]], False], [['newnew'], [], False], [[], [['b', 'b', False, False]], True], [[], [], True]], 3: [[[], [['a', 'hellohellohello', True, False]], True], [[], [['a', 'hellohellohello', False, True]], True], [['hellohellohello'], [['b', 'keep', False, False]], True], [[], [['a', 'newnewnew', False, False]], True], [['future'], [['a', 'pendingpendingpending', False, True]], True], [[], [['a', 'newnewnew', False, True]], False], [['newnewnew'], [], False], [[], [['b', 'b', False, False]], True], [[], [], True]], 4: [[[], [['a', 'hellohellohellohello', True, False]], True], [[], [['a', 'hellohellohellohello', False, True]], True], [['hellohellohellohello'], [['b', 'keep', False, False]], True], [[], [['a', 'newnewnewnew', False, False]], True], [['future'], [['a', 'pendingpendingpendingpending', False, True]], True], [[], [['a', 'newnewnewnew', False, True]], False], [['newnewnewnew'], [], False], [[], [['b', 'b', False, False]], True], [[], [], True]], 5: [[[], [['a', 'hellohellohellohellohello', True, False]], True], [[], [['a', 'hellohellohellohellohello', False, True]], True], [['hellohellohellohellohello'], [['b', 'keep', False, False]], True], [[], [['a', 'newnewnewnewnew', False, False]], True], [['future'], [['a', 'pendingpendingpendingpendingpending', False, True]], True], [[], [['a', 'newnewnewnewnew', False, True]], False], [['newnewnewnewnew'], [], False], [[], [['b', 'b', False, False]], True], [[], [], 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[[], [['a', 'hello', True, False]], True][[], [['a', 'hello', True, False]], True]Passed
trace-2[[], [['a', 'hello', False, True]], True][[], [['a', 'hello', False, True]], True]Passed
trace-3[['hello'], [['b', 'keep', False, False]], True][['hello'], [['b', 'keep', False, False]], True]Passed
trace-4[[], [['a', 'new', False, False]], True][[], [['a', 'new', False, False]], True]Passed
trace-5[['future'], [['a', 'pending', False, True]], True][['future'], [['a', 'pending', False, True]], True]Passed
trace-6[[], [['a', 'new', False, True]], False][[], [['a', 'new', False, True]], False]Passed
trace-7[['new'], [], False][['new'], [], False]Passed
trace-8[[], [['b', 'b', False, False]], True][[], [['b', 'b', False, False]], True]Passed
trace-9[[], [], True][[], [], True]Passed

SHA-256 / fcc8db3bcf8f18aa25e464439e39158c579f6c98ec529b14bcf6c1f9a04e9e5e

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 2026-09-29T14:40:32.226102+00:00.

Case digest / fc717b5ae9b2b994d18cb0c5e5de31acc62f4aae586dcf54301503fc2aa32e98