FA-53961 / Accessibility interaction semantics / Open access

Nonadvancing accessibility revisions are accepted · case 01

Nonadvancing accessibility revisions are accepted.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The monotonic revision decision in the property patch adapter violates its declared contract.

VERIFIED REPAIR

Apply the exact contract at the monotonic revision decision: nxt > base

Unsuccessful approach: The local repair substitutes nxt != base but still mishandles the regression fixtures.

Case contract

Input [initial,revision,updates]. Updates [base_revision,next_revision,changes] apply atomically only if base matches current and next is greater; updates cannot change immutable id or role. Allowed dynamic keys name,description,value,help,language; unknown keys reject whole update. None deletes a property, empty string is retained; values must be strings or None. Return [state,revision,accepted_flags]. Copy initial. Revision advances even for no-op changes.

Why this case matters

Offline accessibility bridge model with explicit policy; useful for testing semantic API adapters independently of browser implementations.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(data):
    initial,revision,updates = data
    state = dict(initial)
    accepted = []
    for base,nxt,changes in updates:
        valid = base == revision and nxt >= base
        valid = valid and all(k in {'name','description','value','help','language'} for k in changes)
        valid = valid and all(v is None or isinstance(v,str) for v in changes.values())
        accepted.append(valid)
        if not valid: continue
        for key,value in changes.items():
            if value is None: state.pop(key,None)
            else: state[key] = value
        revision = nxt
    return [state,revision,accepted]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('contract fixture 1', solve([{'id':'x','role':'image','name':'old'},N,[[N,N+1,{'name':'new','help':''}],[N,N+2,{'name':'stale'}]]],), [{'id':'x','role':'image','name':'new','help':''},N+1,[True,False]])
check('contract fixture 2', solve([{'name':'x','help':'h'},N,[[N,N+1,{'name':None}],[N+1,N+2,{'absent':'bad','help':'bad'}]]],), [{'help':'h'},N+1,[True,False]])
check('contract fixture 3', solve([{'id':'x','role':'image'},N,[[N,N+1,{'id':'y'}],[N,N+1,{'role':'button'}]]],), [{'id':'x','role':'image'},N,[False,False]])
check('contract fixture 4', solve([{},N,[[N,N,{'name':'bad'}],[N,N-1,{}],[N,N+1,{}]]],), [{},N+1,[False,False,True]])
check('contract fixture 5', solve([{'name':'x'},N,[[N,N+1,{'name':42,'help':'partial'}]]],), [{'name':'x'},N,[False]])
check('contract fixture 6', solve([{},N,[[N,N+1,{'name':None,'description':'D','value':'0','language':'en'}]]],), [{'description':'D','value':'0','language':'en'},N+1,[True]])
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
contract fixture 1	`[{'help': '', 'id': 'x', 'name': 'new', 'role': 'image'}, 2, [True, False]]`	`[{'help': '', 'id': 'x', 'name': 'new', 'role': 'image'}, 2, [True, False]]`	Passed
contract fixture 2	`[{'help': 'h'}, 2, [True, False]]`	`[{'help': 'h'}, 2, [True, False]]`	Passed
contract fixture 3	`[{'id': 'x', 'role': 'image'}, 1, [False, False]]`	`[{'id': 'x', 'role': 'image'}, 1, [False, False]]`	Passed
contract fixture 4	`[{'name': 'bad'}, 2, [True, False, True]]`	`[{}, 2, [False, False, True]]`	Failed
contract fixture 5	`[{'name': 'x'}, 1, [False]]`	`[{'name': 'x'}, 1, [False]]`	Passed
contract fixture 6	`[{'description': 'D', 'language': 'en', 'value': '0'}, 2, [True]]`	`[{'description': 'D', 'language': 'en', 'value': '0'}, 2, [True]]`	Passed

SHA-256 / 85d7aaa7230e1f4398b05828a6e78587d859fad02c72038000f15450e7678c4d

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(data):
    initial,revision,updates = data
    state = dict(initial)
    accepted = []
    for base,nxt,changes in updates:
        valid = base == revision and nxt != base
        valid = valid and all(k in {'name','description','value','help','language'} for k in changes)
        valid = valid and all(v is None or isinstance(v,str) for v in changes.values())
        accepted.append(valid)
        if not valid: continue
        for key,value in changes.items():
            if value is None: state.pop(key,None)
            else: state[key] = value
        revision = nxt
    return [state,revision,accepted]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('contract fixture 1', solve([{'id':'x','role':'image','name':'old'},N,[[N,N+1,{'name':'new','help':''}],[N,N+2,{'name':'stale'}]]],), [{'id':'x','role':'image','name':'new','help':''},N+1,[True,False]])
check('contract fixture 2', solve([{'name':'x','help':'h'},N,[[N,N+1,{'name':None}],[N+1,N+2,{'absent':'bad','help':'bad'}]]],), [{'help':'h'},N+1,[True,False]])
check('contract fixture 3', solve([{'id':'x','role':'image'},N,[[N,N+1,{'id':'y'}],[N,N+1,{'role':'button'}]]],), [{'id':'x','role':'image'},N,[False,False]])
check('contract fixture 4', solve([{},N,[[N,N,{'name':'bad'}],[N,N-1,{}],[N,N+1,{}]]],), [{},N+1,[False,False,True]])
check('contract fixture 5', solve([{'name':'x'},N,[[N,N+1,{'name':42,'help':'partial'}]]],), [{'name':'x'},N,[False]])
check('contract fixture 6', solve([{},N,[[N,N+1,{'name':None,'description':'D','value':'0','language':'en'}]]],), [{'description':'D','value':'0','language':'en'},N+1,[True]])
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
contract fixture 1	`[{'help': '', 'id': 'x', 'name': 'new', 'role': 'image'}, 2, [True, False]]`	`[{'help': '', 'id': 'x', 'name': 'new', 'role': 'image'}, 2, [True, False]]`	Passed
contract fixture 2	`[{'help': 'h'}, 2, [True, False]]`	`[{'help': 'h'}, 2, [True, False]]`	Passed
contract fixture 3	`[{'id': 'x', 'role': 'image'}, 1, [False, False]]`	`[{'id': 'x', 'role': 'image'}, 1, [False, False]]`	Passed
contract fixture 4	`[{}, 0, [False, True, False]]`	`[{}, 2, [False, False, True]]`	Failed
contract fixture 5	`[{'name': 'x'}, 1, [False]]`	`[{'name': 'x'}, 1, [False]]`	Passed
contract fixture 6	`[{'description': 'D', 'language': 'en', 'value': '0'}, 2, [True]]`	`[{'description': 'D', 'language': 'en', 'value': '0'}, 2, [True]]`	Passed

SHA-256 / efa401640724c503333f07b14c06272be75b51dc336cf2ce92f25c50d2b41305

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(data):
    initial,revision,updates = data
    state = dict(initial)
    accepted = []
    for base,nxt,changes in updates:
        valid = base == revision and nxt > base
        valid = valid and all(k in {'name','description','value','help','language'} for k in changes)
        valid = valid and all(v is None or isinstance(v,str) for v in changes.values())
        accepted.append(valid)
        if not valid: continue
        for key,value in changes.items():
            if value is None: state.pop(key,None)
            else: state[key] = value
        revision = nxt
    return [state,revision,accepted]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('contract fixture 1', solve([{'id':'x','role':'image','name':'old'},N,[[N,N+1,{'name':'new','help':''}],[N,N+2,{'name':'stale'}]]],), [{'id':'x','role':'image','name':'new','help':''},N+1,[True,False]])
check('contract fixture 2', solve([{'name':'x','help':'h'},N,[[N,N+1,{'name':None}],[N+1,N+2,{'absent':'bad','help':'bad'}]]],), [{'help':'h'},N+1,[True,False]])
check('contract fixture 3', solve([{'id':'x','role':'image'},N,[[N,N+1,{'id':'y'}],[N,N+1,{'role':'button'}]]],), [{'id':'x','role':'image'},N,[False,False]])
check('contract fixture 4', solve([{},N,[[N,N,{'name':'bad'}],[N,N-1,{}],[N,N+1,{}]]],), [{},N+1,[False,False,True]])
check('contract fixture 5', solve([{'name':'x'},N,[[N,N+1,{'name':42,'help':'partial'}]]],), [{'name':'x'},N,[False]])
check('contract fixture 6', solve([{},N,[[N,N+1,{'name':None,'description':'D','value':'0','language':'en'}]]],), [{'description':'D','value':'0','language':'en'},N+1,[True]])
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
contract fixture 1	`[{'help': '', 'id': 'x', 'name': 'new', 'role': 'image'}, 2, [True, False]]`	`[{'help': '', 'id': 'x', 'name': 'new', 'role': 'image'}, 2, [True, False]]`	Passed
contract fixture 2	`[{'help': 'h'}, 2, [True, False]]`	`[{'help': 'h'}, 2, [True, False]]`	Passed
contract fixture 3	`[{'id': 'x', 'role': 'image'}, 1, [False, False]]`	`[{'id': 'x', 'role': 'image'}, 1, [False, False]]`	Passed
contract fixture 4	`[{}, 2, [False, False, True]]`	`[{}, 2, [False, False, True]]`	Passed
contract fixture 5	`[{'name': 'x'}, 1, [False]]`	`[{'name': 'x'}, 1, [False]]`	Passed
contract fixture 6	`[{'description': 'D', 'language': 'en', 'value': '0'}, 2, [True]]`	`[{'description': 'D', 'language': 'en', 'value': '0'}, 2, [True]]`	Passed

SHA-256 / e836cfeb44c22eca60a1d6b283eda71036ee37515667f299af7e63105eb875ae

Verification & scope

Stipulated finite adapter contract, not a claim of platform accessibility or ARIA conformance. 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 2026-09-29T14:45:43.921276+00:00.

Case digest / f8cadc5bf4a45b4de7259d5c854224a5f57a79eb58d62f708bdcbc77787f870a