FA-53996 / Accessibility interaction semantics / Open access

An empty semantic patch fails to advance revision · case 01

An empty semantic patch fails to advance revision.

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

ROOT CAUSE

The no op revision decision in the property patch adapter violates its declared contract.

THE FAILURE

The no op revision decision in the property patch adapter violates its declared contract.

Unsuccessful approach: The local repair substitutes revision = nxt if any(v is not None for v in changes.values()) else revision 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 if changes else revision
    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	`[{}, 1, [False, 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 / 2ebd60087bd7fd9d98726538caa92c9a6bf1723fd5df07ef6ece39791965db6a

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 if any(v is not None for v in changes.values()) else revision
    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'}, 1, [True, False]]`	`[{'help': 'h'}, 2, [True, False]]`	Failed
contract fixture 3	`[{'id': 'x', 'role': 'image'}, 1, [False, False]]`	`[{'id': 'x', 'role': 'image'}, 1, [False, False]]`	Passed
contract fixture 4	`[{}, 1, [False, 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 / 3f89b4cac9af0edb569108f9c6ca8a84bd2c6ee17926486e479af6cfd2b7f63d

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 6 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.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

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 2026-09-29T14:45:44.317336+00:00.

Case digest / 729834a6779bfec2a4075aecceefd8462c64eaad7ad6b2f21b23384325d6ee26