FA-53836 / Accessibility interaction semantics / Open access

Object starts are measured after the replacement is appended · case 01

Object starts are measured after the replacement is appended.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The object start decision in the embedded text objects adapter violates its declared contract.

THE FAILURE

The object start decision in the embedded text objects adapter violates its declared contract.

Unsuccessful approach: The local repair substitutes [index,start+1,len(text),value] but still mishandles the regression fixtures.

Case contract

Input [tokens,alt_mode] where tokens are [kind,text,exposed], kinds text, object, break, decoration. Ignore unexposed or decoration tokens. Text is copied exactly; break becomes LF; object becomes U+FFFC unless alt_mode, when nonempty alternative text is used and empty alternative falls back to U+FFFC. Return [flattened,objects] with objects [token_index,start,end,alternative]. All offsets are codepoints in output; ordinary text does not add object mappings. Adjacent objects remain separate; zero-length text has no effect.

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):
    tokens,alt_mode = data
    text = ''
    objects = []
    for index,(kind,value,exposed) in enumerate(tokens):
        if not exposed or kind == 'decoration': continue
        start = len(text)
        if kind == 'text': text += value
        elif kind == 'break': text += '\n'
        elif kind == 'object':
            text += value if alt_mode and value else '\ufffc'
            objects.append([index,len(text),len(text),value])
    return [text,objects]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('contract fixture 1', solve([[['text','A'*N,True],['object','Cat',True],['text','Z',True]],False],), ['A'*N+'Z',[[1,N,N+1,'Cat']]])
check('contract fixture 2', solve([[['text','A'*N,True],['object','Cat',True],['object','',True]],True],), ['A'*N+'Cat',[[1,N,N+3,'Cat'],[2,N+3,N+4,'']]])
check('contract fixture 3', solve([[['decoration','*',True],['object','Hidden',False],['text','X',True]],False],), ['X',[]])
check('contract fixture 4', solve([[['text','A',True],['break','ignored',True],['text','B',True]],False],), ['A\nB',[]])
check('contract fixture 5', solve([[['object','A',True],['object','B',True]],False],), ['',[[0,0,1,'A'],[1,1,2,'B']]])
check('contract fixture 6', solve([[['text','',True]],True],), ['',[]])
check('contract fixture 7', solve([[['text',' A ',True]],False],), [' A ',[]])
check('contract fixture 8', solve([[],False],), ['',[]])
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	`['AZ', [[1, 2, 2, 'Cat']]]`	`['AZ', [[1, 1, 2, 'Cat']]]`	Failed
contract fixture 2	`['ACat', [[1, 4, 4, 'Cat'], [2, 5, 5, '']]]`	`['ACat', [[1, 1, 4, 'Cat'], [2, 4, 5, '']]]`	Failed
contract fixture 3	`['X', []]`	`['X', []]`	Passed
contract fixture 4	`['A\nB', []]`	`['A\nB', []]`	Passed
contract fixture 5	`['', [[0, 1, 1, 'A'], [1, 2, 2, 'B']]]`	`['', [[0, 0, 1, 'A'], [1, 1, 2, 'B']]]`	Failed
contract fixture 6	`['', []]`	`['', []]`	Passed
contract fixture 7	`[' A ', []]`	`[' A ', []]`	Passed
contract fixture 8	`['', []]`	`['', []]`	Passed

SHA-256 / 85350f98c8fc46e378809036e8304ad28f3de9687fa5bf102b05a3d0a397402e

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(data):
    tokens,alt_mode = data
    text = ''
    objects = []
    for index,(kind,value,exposed) in enumerate(tokens):
        if not exposed or kind == 'decoration': continue
        start = len(text)
        if kind == 'text': text += value
        elif kind == 'break': text += '\n'
        elif kind == 'object':
            text += value if alt_mode and value else '\ufffc'
            objects.append([index,start+1,len(text),value])
    return [text,objects]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('contract fixture 1', solve([[['text','A'*N,True],['object','Cat',True],['text','Z',True]],False],), ['A'*N+'Z',[[1,N,N+1,'Cat']]])
check('contract fixture 2', solve([[['text','A'*N,True],['object','Cat',True],['object','',True]],True],), ['A'*N+'Cat',[[1,N,N+3,'Cat'],[2,N+3,N+4,'']]])
check('contract fixture 3', solve([[['decoration','*',True],['object','Hidden',False],['text','X',True]],False],), ['X',[]])
check('contract fixture 4', solve([[['text','A',True],['break','ignored',True],['text','B',True]],False],), ['A\nB',[]])
check('contract fixture 5', solve([[['object','A',True],['object','B',True]],False],), ['',[[0,0,1,'A'],[1,1,2,'B']]])
check('contract fixture 6', solve([[['text','',True]],True],), ['',[]])
check('contract fixture 7', solve([[['text',' A ',True]],False],), [' A ',[]])
check('contract fixture 8', solve([[],False],), ['',[]])
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	`['AZ', [[1, 2, 2, 'Cat']]]`	`['AZ', [[1, 1, 2, 'Cat']]]`	Failed
contract fixture 2	`['ACat', [[1, 2, 4, 'Cat'], [2, 5, 5, '']]]`	`['ACat', [[1, 1, 4, 'Cat'], [2, 4, 5, '']]]`	Failed
contract fixture 3	`['X', []]`	`['X', []]`	Passed
contract fixture 4	`['A\nB', []]`	`['A\nB', []]`	Passed
contract fixture 5	`['', [[0, 1, 1, 'A'], [1, 2, 2, 'B']]]`	`['', [[0, 0, 1, 'A'], [1, 1, 2, 'B']]]`	Failed
contract fixture 6	`['', []]`	`['', []]`	Passed
contract fixture 7	`[' A ', []]`	`[' A ', []]`	Passed
contract fixture 8	`['', []]`	`['', []]`	Passed

SHA-256 / e37591fffa9cc8686445b46cc7f925e2f448cc052ff2b4f9461fce17eb0bab40

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 8 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 2026-09-29T14:45:42.814812+00:00.

Case digest / 31eabbfbdd08070b683515db558afa9db4f45de023bf8568851fae103adadfaa