FA-53641 / Accessibility interaction semantics / Open access
Heading whitespace-only names create empty navigation entries · case 01
Heading whitespace-only names create empty navigation entries.
ROOT CAUSE
The text trim decision in the heading inventory adapter violates its declared contract.
VERIFIED REPAIR
Apply the exact contract at the text trim decision: text.strip(' \t\r\n')
Unsuccessful approach: The local repair substitutes text.strip(' ') but still mishandles the regression fixtures.
Case contract
A document heading inventory receives records [id,level,text,exposed,document,order] and requested document. Admit exposed level integers 1..6 (booleans are not levels), nonempty text after ASCII trimming, exact document. For duplicate IDs retain the earliest order record; ties retain first input. Output sorted by order with each heading's nearest preceding lower-level heading ID as parent. Skipped levels do not create synthetic headings. Output [id,level,trimmed_text,parent].
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):
records,document = data
chosen = {}
for ident,level,text,visible,doc,order in records:
if not visible or doc != document: continue
if type(level) is not int or not 1 <= level <= 6: continue
text = text
if not text: continue
if ident not in chosen or order < chosen[ident][0]: chosen[ident] = (order,level,text)
stack = []
result = []
for ident,(order,level,text) in sorted(chosen.items(),key=lambda pair:pair[1][0]):
while stack and stack[-1][1] >= level: stack.pop()
result.append([ident,level,text,stack[-1][0] if stack else None])
stack.append((ident,level))
return result
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('levels and sibling ancestry', solve([[['a',1,' '+'A'*N+' ',True,'d',0],['b',3,'B',True,'d',N],['c',3,'C',True,'d',N+1],['d',2,'D',True,'d',N+2],['e',1,'E',True,'d',N+3]],'d'],), [['a',1,'A'*N,None],['b',3,'B','a'],['c',3,'C','a'],['d',2,'D','a'],['e',1,'E',None]])
check('sort document order', solve([[['b',2,'B',True,'d',N+1],['a',1,'A',True,'d',N]],'d'],), [['a',1,'A',None],['b',2,'B','a']])
check('earliest duplicate', solve([[['a',2,'late',True,'d',N+1],['a',1,'first',True,'d',N],['a',3,'tie',True,'d',N]],'d'],), [['a',1,'first',None]])
check('visibility and document', solve([[['a',1,'A',False,'d',0],['b',1,'B',True,'e',1],['c',2,'C',True,'d',2]],'d'],), [['c',2,'C',None]])
check('level admission', solve([[['a',0,'A',True,'d',0],['b',7,'B',True,'d',1],['c',True,'C',True,'d',2],['z',6,'Z',True,'d',3]],'d'],), [['z',6,'Z',None]])
check('trim empty and NBSP', solve([[['a',1,' \t',True,'d',0],['b',2,'\u00a0',True,'d',1]],'d'],), [['b',2,'\u00a0',None]])
check('empty', solve([[],'d'],), [])
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 |
|---|---|---|---|
| levels and sibling ancestry | [['a', 1, ' A ', None], ['b', 3, 'B', 'a'], ['c', 3, 'C', 'a'], ['d', 2, 'D', 'a'], ['e', 1, 'E', None]] | [['a', 1, 'A', None], ['b', 3, 'B', 'a'], ['c', 3, 'C', 'a'], ['d', 2, 'D', 'a'], ['e', 1, 'E', None]] | Failed |
| sort document order | [['a', 1, 'A', None], ['b', 2, 'B', 'a']] | [['a', 1, 'A', None], ['b', 2, 'B', 'a']] | Passed |
| earliest duplicate | [['a', 1, 'first', None]] | [['a', 1, 'first', None]] | Passed |
| visibility and document | [['c', 2, 'C', None]] | [['c', 2, 'C', None]] | Passed |
| level admission | [['z', 6, 'Z', None]] | [['z', 6, 'Z', None]] | Passed |
| trim empty and NBSP | [['a', 1, ' \t', None], ['b', 2, '\xa0', 'a']] | [['b', 2, '\xa0', None]] | Failed |
| empty | [] | [] | Passed |
SHA-256 / 844f0c27db0c31dfa991d27905a347f5cc5d7bf18bd43b20665cf8bbe6f5b103
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(data):
records,document = data
chosen = {}
for ident,level,text,visible,doc,order in records:
if not visible or doc != document: continue
if type(level) is not int or not 1 <= level <= 6: continue
text = text.strip(' ')
if not text: continue
if ident not in chosen or order < chosen[ident][0]: chosen[ident] = (order,level,text)
stack = []
result = []
for ident,(order,level,text) in sorted(chosen.items(),key=lambda pair:pair[1][0]):
while stack and stack[-1][1] >= level: stack.pop()
result.append([ident,level,text,stack[-1][0] if stack else None])
stack.append((ident,level))
return result
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('levels and sibling ancestry', solve([[['a',1,' '+'A'*N+' ',True,'d',0],['b',3,'B',True,'d',N],['c',3,'C',True,'d',N+1],['d',2,'D',True,'d',N+2],['e',1,'E',True,'d',N+3]],'d'],), [['a',1,'A'*N,None],['b',3,'B','a'],['c',3,'C','a'],['d',2,'D','a'],['e',1,'E',None]])
check('sort document order', solve([[['b',2,'B',True,'d',N+1],['a',1,'A',True,'d',N]],'d'],), [['a',1,'A',None],['b',2,'B','a']])
check('earliest duplicate', solve([[['a',2,'late',True,'d',N+1],['a',1,'first',True,'d',N],['a',3,'tie',True,'d',N]],'d'],), [['a',1,'first',None]])
check('visibility and document', solve([[['a',1,'A',False,'d',0],['b',1,'B',True,'e',1],['c',2,'C',True,'d',2]],'d'],), [['c',2,'C',None]])
check('level admission', solve([[['a',0,'A',True,'d',0],['b',7,'B',True,'d',1],['c',True,'C',True,'d',2],['z',6,'Z',True,'d',3]],'d'],), [['z',6,'Z',None]])
check('trim empty and NBSP', solve([[['a',1,' \t',True,'d',0],['b',2,'\u00a0',True,'d',1]],'d'],), [['b',2,'\u00a0',None]])
check('empty', solve([[],'d'],), [])
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 |
|---|---|---|---|
| levels and sibling ancestry | [['a', 1, 'A', None], ['b', 3, 'B', 'a'], ['c', 3, 'C', 'a'], ['d', 2, 'D', 'a'], ['e', 1, 'E', None]] | [['a', 1, 'A', None], ['b', 3, 'B', 'a'], ['c', 3, 'C', 'a'], ['d', 2, 'D', 'a'], ['e', 1, 'E', None]] | Passed |
| sort document order | [['a', 1, 'A', None], ['b', 2, 'B', 'a']] | [['a', 1, 'A', None], ['b', 2, 'B', 'a']] | Passed |
| earliest duplicate | [['a', 1, 'first', None]] | [['a', 1, 'first', None]] | Passed |
| visibility and document | [['c', 2, 'C', None]] | [['c', 2, 'C', None]] | Passed |
| level admission | [['z', 6, 'Z', None]] | [['z', 6, 'Z', None]] | Passed |
| trim empty and NBSP | [['a', 1, '\t', None], ['b', 2, '\xa0', 'a']] | [['b', 2, '\xa0', None]] | Failed |
| empty | [] | [] | Passed |
SHA-256 / 12173b601c011a1b88bd0f566915b31482af9754f2ae012e6117e7a7c44e79dd
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(data):
records,document = data
chosen = {}
for ident,level,text,visible,doc,order in records:
if not visible or doc != document: continue
if type(level) is not int or not 1 <= level <= 6: continue
text = text.strip(' \t\r\n')
if not text: continue
if ident not in chosen or order < chosen[ident][0]: chosen[ident] = (order,level,text)
stack = []
result = []
for ident,(order,level,text) in sorted(chosen.items(),key=lambda pair:pair[1][0]):
while stack and stack[-1][1] >= level: stack.pop()
result.append([ident,level,text,stack[-1][0] if stack else None])
stack.append((ident,level))
return result
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('levels and sibling ancestry', solve([[['a',1,' '+'A'*N+' ',True,'d',0],['b',3,'B',True,'d',N],['c',3,'C',True,'d',N+1],['d',2,'D',True,'d',N+2],['e',1,'E',True,'d',N+3]],'d'],), [['a',1,'A'*N,None],['b',3,'B','a'],['c',3,'C','a'],['d',2,'D','a'],['e',1,'E',None]])
check('sort document order', solve([[['b',2,'B',True,'d',N+1],['a',1,'A',True,'d',N]],'d'],), [['a',1,'A',None],['b',2,'B','a']])
check('earliest duplicate', solve([[['a',2,'late',True,'d',N+1],['a',1,'first',True,'d',N],['a',3,'tie',True,'d',N]],'d'],), [['a',1,'first',None]])
check('visibility and document', solve([[['a',1,'A',False,'d',0],['b',1,'B',True,'e',1],['c',2,'C',True,'d',2]],'d'],), [['c',2,'C',None]])
check('level admission', solve([[['a',0,'A',True,'d',0],['b',7,'B',True,'d',1],['c',True,'C',True,'d',2],['z',6,'Z',True,'d',3]],'d'],), [['z',6,'Z',None]])
check('trim empty and NBSP', solve([[['a',1,' \t',True,'d',0],['b',2,'\u00a0',True,'d',1]],'d'],), [['b',2,'\u00a0',None]])
check('empty', solve([[],'d'],), [])
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 |
|---|---|---|---|
| levels and sibling ancestry | [['a', 1, 'A', None], ['b', 3, 'B', 'a'], ['c', 3, 'C', 'a'], ['d', 2, 'D', 'a'], ['e', 1, 'E', None]] | [['a', 1, 'A', None], ['b', 3, 'B', 'a'], ['c', 3, 'C', 'a'], ['d', 2, 'D', 'a'], ['e', 1, 'E', None]] | Passed |
| sort document order | [['a', 1, 'A', None], ['b', 2, 'B', 'a']] | [['a', 1, 'A', None], ['b', 2, 'B', 'a']] | Passed |
| earliest duplicate | [['a', 1, 'first', None]] | [['a', 1, 'first', None]] | Passed |
| visibility and document | [['c', 2, 'C', None]] | [['c', 2, 'C', None]] | Passed |
| level admission | [['z', 6, 'Z', None]] | [['z', 6, 'Z', None]] | Passed |
| trim empty and NBSP | [['b', 2, '\xa0', None]] | [['b', 2, '\xa0', None]] | Passed |
| empty | [] | [] | Passed |
SHA-256 / 8c98753824fc1057b2b43de480fcc719dee0580c9d0af8f24f69504f08370094
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 2026-09-29T14:45:40.837943+00:00.
Case digest / 841dfa7eb924c1852c546a1bd14f8ff41df41af6b31572fef75bb5d1eb2f54b1