{"abstract":"Hidden controls enter the focus sequence.","category":"Keyboard accessibility","checks":9,"contract":"Visit visible enabled nonnegative tabindex controls; positive tabindex precedes zero; ties retain document order and navigation wraps.","contract_signature":"items, current, direction","evaluation_group":"xi-tab-stop","failed_approach":"Inverting visibility excludes every visible control.","family":"xi-tab-stop-hidden","id":"FA-7831","implementations":{"attempt":{"sha256":"e1f90a143be0186485a8673de8b5b5012d41067c0769e59ce0504d5d844d3c74","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(items, current, direction):\n    eligible = [i for i, item in enumerate(items) if not item['visible'] and not item['disabled'] and item['tab'] >= 0]\n    eligible.sort(key=lambda i: (items[i]['tab'] == 0, items[i]['tab'] if items[i]['tab'] > 0 else 0, i))\n    if not eligible: return None\n    if current not in eligible: return eligible[0] if direction > 0 else eligible[-1]\n    return eligible[(eligible.index(current) + direction) % len(eligible)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('hidden', solve([dict(visible=False, disabled=False, tab=0),dict(visible=True,disabled=False,tab=0)], None, 1), 1)\ncheck('disabled', solve([dict(visible=True,disabled=True,tab=0),dict(visible=True,disabled=False,tab=0)], None, 1), 1)\ncheck('negative', solve([dict(visible=True,disabled=False,tab=-1),dict(visible=True,disabled=False,tab=0)], None, 1), 1)\ncheck('priority', solve([dict(visible=True,disabled=False,tab=0),dict(visible=True,disabled=False,tab=2)], None, 1), 1)\ncheck('reverse', solve([dict(visible=True,disabled=False,tab=0)]*3, 1, -1), 0)\ncheck('forward', solve([dict(visible=True,disabled=False,tab=0)]*3, 1, 1), 2)\ncheck('empty', solve([], None, 1), None)\ncheck('parameterized focus sequence', solve([dict(visible=True, disabled=False, tab=0)]*(N+2), N, 1), N+1)\nfor repetition in range(N):\n    check('repeat empty', solve([], None, 1), None)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"7fddbd0bc1c44851fc10d06cfd1ee6374f2993521f471a1682bce4a9686e68b2","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(items, current, direction):\n    eligible = [i for i, item in enumerate(items) if  not item['disabled'] and item['tab'] >= 0]\n    eligible.sort(key=lambda i: (items[i]['tab'] == 0, items[i]['tab'] if items[i]['tab'] > 0 else 0, i))\n    if not eligible: return None\n    if current not in eligible: return eligible[0] if direction > 0 else eligible[-1]\n    return eligible[(eligible.index(current) + direction) % len(eligible)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('hidden', solve([dict(visible=False, disabled=False, tab=0),dict(visible=True,disabled=False,tab=0)], None, 1), 1)\ncheck('disabled', solve([dict(visible=True,disabled=True,tab=0),dict(visible=True,disabled=False,tab=0)], None, 1), 1)\ncheck('negative', solve([dict(visible=True,disabled=False,tab=-1),dict(visible=True,disabled=False,tab=0)], None, 1), 1)\ncheck('priority', solve([dict(visible=True,disabled=False,tab=0),dict(visible=True,disabled=False,tab=2)], None, 1), 1)\ncheck('reverse', solve([dict(visible=True,disabled=False,tab=0)]*3, 1, -1), 0)\ncheck('forward', solve([dict(visible=True,disabled=False,tab=0)]*3, 1, 1), 2)\ncheck('empty', solve([], None, 1), None)\ncheck('parameterized focus sequence', solve([dict(visible=True, disabled=False, tab=0)]*(N+2), N, 1), N+1)\nfor repetition in range(N):\n    check('repeat empty', solve([], None, 1), None)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":" 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.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"xi-tab-stop-hidden","generated_at":"2026-09-29T14:38:15.869837+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic model of sequential keyboard focus; this isolates one interface invariant without requiring a browser.","root_cause":"The hidden operation uses `` where the contract requires `item['visible'] and`.","sha256":"12a67657d41b848ff52d2534553e0064598dd8e1087a49e2e0adb9ab3348570b","title":"Sequential keyboard focus: Hidden controls enter the focus sequence · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":41.92,"exit_code":1,"observations":[{"actual":0,"check":"hidden","expected":1,"passed":false},{"actual":null,"check":"disabled","expected":1,"passed":false},{"actual":null,"check":"negative","expected":1,"passed":false},{"actual":null,"check":"priority","expected":1,"passed":false},{"actual":null,"check":"reverse","expected":0,"passed":false},{"actual":null,"check":"forward","expected":2,"passed":false},{"actual":null,"check":"empty","expected":null,"passed":true},{"actual":null,"check":"parameterized focus sequence","expected":2,"passed":false},{"actual":null,"check":"repeat empty","expected":null,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"hidden\", \"actual\": 0, \"expected\": 1, \"passed\": false}, {\"check\": \"disabled\", \"actual\": null, \"expected\": 1, \"passed\": false}, {\"check\": \"negative\", \"actual\": null, \"expected\": 1, \"passed\": false}, {\"check\": \"priority\", \"actual\": null, \"expected\": 1, \"passed\": false}, {\"check\": \"reverse\", \"actual\": null, \"expected\": 0, \"passed\": false}, {\"check\": \"forward\", \"actual\": null, \"expected\": 2, \"passed\": false}, {\"check\": \"empty\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"parameterized focus sequence\", \"actual\": null, \"expected\": 2, \"passed\": false}, {\"check\": \"repeat empty\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":40.253,"exit_code":1,"observations":[{"actual":0,"check":"hidden","expected":1,"passed":false},{"actual":1,"check":"disabled","expected":1,"passed":true},{"actual":1,"check":"negative","expected":1,"passed":true},{"actual":1,"check":"priority","expected":1,"passed":true},{"actual":0,"check":"reverse","expected":0,"passed":true},{"actual":2,"check":"forward","expected":2,"passed":true},{"actual":null,"check":"empty","expected":null,"passed":true},{"actual":2,"check":"parameterized focus sequence","expected":2,"passed":true},{"actual":null,"check":"repeat empty","expected":null,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"hidden\", \"actual\": 0, \"expected\": 1, \"passed\": false}, {\"check\": \"disabled\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"negative\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"priority\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"reverse\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"forward\", \"actual\": 2, \"expected\": 2, \"passed\": true}, {\"check\": \"empty\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"parameterized focus sequence\", \"actual\": 2, \"expected\": 2, \"passed\": true}, {\"check\": \"repeat empty\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}