FA-54311 / Accessibility interaction semantics / Open access
Role replacement delta repeats the old role · case 01
Role replacement delta repeats the old role.
ROOT CAUSE
The new role decision in the snapshot delta adapter violates its declared contract.
VERIFIED REPAIR
Apply the exact contract at the new role decision: ['replace-role',ident,new['role']]
Unsuccessful approach: The local repair substitutes ['replace-role',ident,'generic'] but still mishandles the regression fixtures.
Case contract
Input [before,after] maps stable object ID to {role,name,parent,order}. Return delta operations in phases: removed IDs sorted lexical; added IDs sorted by after order then ID; common IDs sorted lexical get role-replace if role differs, otherwise name-set if name differs; parent/order changes append move even after role-replace. Removed values use old role, added records preserve complete new record, name-set preserves empty names. Same ID is never remove+add just for role changes. Return operations lists.
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):
before,after = data
result = []
for ident in sorted(set(before)-set(after)): result.append(['remove',ident,before[ident]['role']])
for ident in sorted(set(after)-set(before),key=lambda x:(after[x]['order'],x)): result.append(['add',ident,after[ident]])
for ident in sorted(set(before)&set(after)):
old,new = before[ident],after[ident]
if old['role'] != new['role']: result.append(['replace-role',ident,old['role']])
elif old['name'] != new['name']: result.append(['set-name',ident,new['name']])
if old['parent'] != new['parent'] or old['order'] != new['order']: result.append(['move',ident,new['parent'],new['order']])
return result
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('contract fixture 1', solve([{'x':{'role':'image','name':'old','parent':'a','order':N}},{'x':{'role':'button','name':'new','parent':'b','order':N+1}}],), [['replace-role','x','button'],['move','x','b',N+1]])
check('contract fixture 2', solve([{'x':{'role':'image','name':'old','parent':None,'order':0}},{'x':{'role':'image','name':'','parent':None,'order':0}}],), [['set-name','x','']])
check('contract fixture 3', solve([{'z':{'role':'image','name':'Z','parent':None,'order':0},'a':{'role':'group','name':'A','parent':None,'order':1}},{}],), [['remove','a','group'],['remove','z','image']])
check('contract fixture 4', solve([{}, {'z':{'role':'image','name':'Z','parent':None,'order':0},'a':{'role':'group','name':'A','parent':None,'order':1}}],), [['add','z',{'role':'image','name':'Z','parent':None,'order':0}],['add','a',{'role':'group','name':'A','parent':None,'order':1}]])
check('contract fixture 5', solve([{'x':{'role':'image','name':'X','parent':'a','order':0}},{'x':{'role':'image','name':'X','parent':'a','order':N}}],), [['move','x','a',N]])
check('contract fixture 6', solve([{'x':{'role':'image','name':'X','parent':'a','order':0}},{'x':{'role':'image','name':'X','parent':'b','order':0}}],), [['move','x','b',0]])
check('contract fixture 7', solve([{},{}],), [])
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 | [['replace-role', 'x', 'image'], ['move', 'x', 'b', 2]] | [['replace-role', 'x', 'button'], ['move', 'x', 'b', 2]] | Failed |
| contract fixture 2 | [['set-name', 'x', '']] | [['set-name', 'x', '']] | Passed |
| contract fixture 3 | [['remove', 'a', 'group'], ['remove', 'z', 'image']] | [['remove', 'a', 'group'], ['remove', 'z', 'image']] | Passed |
| contract fixture 4 | [['add', 'z', {'name': 'Z', 'order': 0, 'parent': None, 'role': 'image'}], ['add', 'a', {'name': 'A', 'order': 1, 'parent': None, 'role': 'group'}]] | [['add', 'z', {'name': 'Z', 'order': 0, 'parent': None, 'role': 'image'}], ['add', 'a', {'name': 'A', 'order': 1, 'parent': None, 'role': 'group'}]] | Passed |
| contract fixture 5 | [['move', 'x', 'a', 1]] | [['move', 'x', 'a', 1]] | Passed |
| contract fixture 6 | [['move', 'x', 'b', 0]] | [['move', 'x', 'b', 0]] | Passed |
| contract fixture 7 | [] | [] | Passed |
SHA-256 / 5b4768f6eaa68c0e98f6667f1312f697e7f8a54ec59c09011e98afbaa21c2298
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(data):
before,after = data
result = []
for ident in sorted(set(before)-set(after)): result.append(['remove',ident,before[ident]['role']])
for ident in sorted(set(after)-set(before),key=lambda x:(after[x]['order'],x)): result.append(['add',ident,after[ident]])
for ident in sorted(set(before)&set(after)):
old,new = before[ident],after[ident]
if old['role'] != new['role']: result.append(['replace-role',ident,'generic'])
elif old['name'] != new['name']: result.append(['set-name',ident,new['name']])
if old['parent'] != new['parent'] or old['order'] != new['order']: result.append(['move',ident,new['parent'],new['order']])
return result
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('contract fixture 1', solve([{'x':{'role':'image','name':'old','parent':'a','order':N}},{'x':{'role':'button','name':'new','parent':'b','order':N+1}}],), [['replace-role','x','button'],['move','x','b',N+1]])
check('contract fixture 2', solve([{'x':{'role':'image','name':'old','parent':None,'order':0}},{'x':{'role':'image','name':'','parent':None,'order':0}}],), [['set-name','x','']])
check('contract fixture 3', solve([{'z':{'role':'image','name':'Z','parent':None,'order':0},'a':{'role':'group','name':'A','parent':None,'order':1}},{}],), [['remove','a','group'],['remove','z','image']])
check('contract fixture 4', solve([{}, {'z':{'role':'image','name':'Z','parent':None,'order':0},'a':{'role':'group','name':'A','parent':None,'order':1}}],), [['add','z',{'role':'image','name':'Z','parent':None,'order':0}],['add','a',{'role':'group','name':'A','parent':None,'order':1}]])
check('contract fixture 5', solve([{'x':{'role':'image','name':'X','parent':'a','order':0}},{'x':{'role':'image','name':'X','parent':'a','order':N}}],), [['move','x','a',N]])
check('contract fixture 6', solve([{'x':{'role':'image','name':'X','parent':'a','order':0}},{'x':{'role':'image','name':'X','parent':'b','order':0}}],), [['move','x','b',0]])
check('contract fixture 7', solve([{},{}],), [])
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 | [['replace-role', 'x', 'generic'], ['move', 'x', 'b', 2]] | [['replace-role', 'x', 'button'], ['move', 'x', 'b', 2]] | Failed |
| contract fixture 2 | [['set-name', 'x', '']] | [['set-name', 'x', '']] | Passed |
| contract fixture 3 | [['remove', 'a', 'group'], ['remove', 'z', 'image']] | [['remove', 'a', 'group'], ['remove', 'z', 'image']] | Passed |
| contract fixture 4 | [['add', 'z', {'name': 'Z', 'order': 0, 'parent': None, 'role': 'image'}], ['add', 'a', {'name': 'A', 'order': 1, 'parent': None, 'role': 'group'}]] | [['add', 'z', {'name': 'Z', 'order': 0, 'parent': None, 'role': 'image'}], ['add', 'a', {'name': 'A', 'order': 1, 'parent': None, 'role': 'group'}]] | Passed |
| contract fixture 5 | [['move', 'x', 'a', 1]] | [['move', 'x', 'a', 1]] | Passed |
| contract fixture 6 | [['move', 'x', 'b', 0]] | [['move', 'x', 'b', 0]] | Passed |
| contract fixture 7 | [] | [] | Passed |
SHA-256 / d39a7114a602d7f81ad664bee7a5e229df174d797a8c72a86da8a875f67c3f2e
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(data):
before,after = data
result = []
for ident in sorted(set(before)-set(after)): result.append(['remove',ident,before[ident]['role']])
for ident in sorted(set(after)-set(before),key=lambda x:(after[x]['order'],x)): result.append(['add',ident,after[ident]])
for ident in sorted(set(before)&set(after)):
old,new = before[ident],after[ident]
if old['role'] != new['role']: result.append(['replace-role',ident,new['role']])
elif old['name'] != new['name']: result.append(['set-name',ident,new['name']])
if old['parent'] != new['parent'] or old['order'] != new['order']: result.append(['move',ident,new['parent'],new['order']])
return result
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('contract fixture 1', solve([{'x':{'role':'image','name':'old','parent':'a','order':N}},{'x':{'role':'button','name':'new','parent':'b','order':N+1}}],), [['replace-role','x','button'],['move','x','b',N+1]])
check('contract fixture 2', solve([{'x':{'role':'image','name':'old','parent':None,'order':0}},{'x':{'role':'image','name':'','parent':None,'order':0}}],), [['set-name','x','']])
check('contract fixture 3', solve([{'z':{'role':'image','name':'Z','parent':None,'order':0},'a':{'role':'group','name':'A','parent':None,'order':1}},{}],), [['remove','a','group'],['remove','z','image']])
check('contract fixture 4', solve([{}, {'z':{'role':'image','name':'Z','parent':None,'order':0},'a':{'role':'group','name':'A','parent':None,'order':1}}],), [['add','z',{'role':'image','name':'Z','parent':None,'order':0}],['add','a',{'role':'group','name':'A','parent':None,'order':1}]])
check('contract fixture 5', solve([{'x':{'role':'image','name':'X','parent':'a','order':0}},{'x':{'role':'image','name':'X','parent':'a','order':N}}],), [['move','x','a',N]])
check('contract fixture 6', solve([{'x':{'role':'image','name':'X','parent':'a','order':0}},{'x':{'role':'image','name':'X','parent':'b','order':0}}],), [['move','x','b',0]])
check('contract fixture 7', solve([{},{}],), [])
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 | [['replace-role', 'x', 'button'], ['move', 'x', 'b', 2]] | [['replace-role', 'x', 'button'], ['move', 'x', 'b', 2]] | Passed |
| contract fixture 2 | [['set-name', 'x', '']] | [['set-name', 'x', '']] | Passed |
| contract fixture 3 | [['remove', 'a', 'group'], ['remove', 'z', 'image']] | [['remove', 'a', 'group'], ['remove', 'z', 'image']] | Passed |
| contract fixture 4 | [['add', 'z', {'name': 'Z', 'order': 0, 'parent': None, 'role': 'image'}], ['add', 'a', {'name': 'A', 'order': 1, 'parent': None, 'role': 'group'}]] | [['add', 'z', {'name': 'Z', 'order': 0, 'parent': None, 'role': 'image'}], ['add', 'a', {'name': 'A', 'order': 1, 'parent': None, 'role': 'group'}]] | Passed |
| contract fixture 5 | [['move', 'x', 'a', 1]] | [['move', 'x', 'a', 1]] | Passed |
| contract fixture 6 | [['move', 'x', 'b', 0]] | [['move', 'x', 'b', 0]] | Passed |
| contract fixture 7 | [] | [] | Passed |
SHA-256 / 9354be8a55177f12917ccdb77fbde6bed5abc6e05a83b2081b5ca1d202d92629
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 2026-09-29T14:45:47.201343+00:00.
Case digest / 8b11c14b27c82561f8350cdf844f6bef9192ad55b6c480beb4a7ddcca2e56e08