{"abstract":"Right-arrow on an expanded parent focuses its last child.","category":"Tree accessibility","checks":8,"contract":"Right expands then enters the first child; Left collapses only the current branch or focuses its parent; roots retain focus; collapse-all clears every expansion.","evaluation_group":"xi-tree-navigation","failed_approach":"Keeping focus on the parent prevents descending.","family":"xi-tree-navigation-enter-child","id":"FA-8386","implementations":{"attempt":{"sha256":"277676f442897ee21b03a98f0afce6b45e150238f6764f5ae43f29c27618d357","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(node, expanded, parents, children, key):\n    expanded = set(expanded)\n    kids = children.get(node, [])\n    if key == 'Right' and kids:\n        if node not in expanded: expanded.add(node)\n        else: node = node\n    elif key == 'Left':\n        if node in expanded: expanded.remove(node)\n        else: node = parents.get(node, node)\n    elif key == 'CollapseAll': expanded.clear()\n    return (node, sorted(expanded))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('expand', solve('a', ['z'], {}, {'a':['b','c']}, 'Right'), ('a', ['a', 'z']))\ncheck('descend', solve('a', ['a'], {}, {'a':['b','c']}, 'Right'), ('b', ['a']))\ncheck('collapse', solve('a', ['a','z'], {}, {'a':['b']}, 'Left'), ('a', ['z']))\ncheck('parent', solve('b', [], {'b':'a'}, {}, 'Left'), ('a', []))\ncheck('root', solve('a', [], {}, {}, 'Left'), ('a', []))\ncheck('all', solve('a', ['a','z'], {}, {}, 'CollapseAll'), ('a', []))\ncheck('parameterized child count', solve('a', [], {}, {'a':list(range(N))}, 'Right'), ('a',['a']))\nfor repetition in range(N):\n    check('repeat all', solve('a', ['a','z'], {}, {}, 'CollapseAll'), ('a', []))\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":"de7ea0a2f1e28f9157d9c7228f1705fa7ca0d9c60f71ee1f30400a4114a1cae8","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(node, expanded, parents, children, key):\n    expanded = set(expanded)\n    kids = children.get(node, [])\n    if key == 'Right' and kids:\n        if node not in expanded: expanded.add(node)\n        else: node = kids[-1]\n    elif key == 'Left':\n        if node in expanded: expanded.remove(node)\n        else: node = parents.get(node, node)\n    elif key == 'CollapseAll': expanded.clear()\n    return (node, sorted(expanded))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('expand', solve('a', ['z'], {}, {'a':['b','c']}, 'Right'), ('a', ['a', 'z']))\ncheck('descend', solve('a', ['a'], {}, {'a':['b','c']}, 'Right'), ('b', ['a']))\ncheck('collapse', solve('a', ['a','z'], {}, {'a':['b']}, 'Left'), ('a', ['z']))\ncheck('parent', solve('b', [], {'b':'a'}, {}, 'Left'), ('a', []))\ncheck('root', solve('a', [], {}, {}, 'Left'), ('a', []))\ncheck('all', solve('a', ['a','z'], {}, {}, 'CollapseAll'), ('a', []))\ncheck('parameterized child count', solve('a', [], {}, {'a':list(range(N))}, 'Right'), ('a',['a']))\nfor repetition in range(N):\n    check('repeat all', solve('a', ['a','z'], {}, {}, 'CollapseAll'), ('a', []))\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"},"fixed":{"sha256":"d8cc0e4d8b47f71a93b2eb97d9a27e6666808598de5a935b5c45db1e6e515900","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(node, expanded, parents, children, key):\n    expanded = set(expanded)\n    kids = children.get(node, [])\n    if key == 'Right' and kids:\n        if node not in expanded: expanded.add(node)\n        else: node = kids[0]\n    elif key == 'Left':\n        if node in expanded: expanded.remove(node)\n        else: node = parents.get(node, node)\n    elif key == 'CollapseAll': expanded.clear()\n    return (node, sorted(expanded))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('expand', solve('a', ['z'], {}, {'a':['b','c']}, 'Right'), ('a', ['a', 'z']))\ncheck('descend', solve('a', ['a'], {}, {'a':['b','c']}, 'Right'), ('b', ['a']))\ncheck('collapse', solve('a', ['a','z'], {}, {'a':['b']}, 'Left'), ('a', ['z']))\ncheck('parent', solve('b', [], {'b':'a'}, {}, 'Left'), ('a', []))\ncheck('root', solve('a', [], {}, {}, 'Left'), ('a', []))\ncheck('all', solve('a', ['a','z'], {}, {}, 'CollapseAll'), ('a', []))\ncheck('parameterized child count', solve('a', [], {}, {'a':list(range(N))}, 'Right'), ('a',['a']))\nfor repetition in range(N):\n    check('repeat all', solve('a', ['a','z'], {}, {}, 'CollapseAll'), ('a', []))\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-tree-navigation-enter-child","generated_at":"2026-09-29T14:38:20.858710+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic model of tree keyboard expansion; this isolates one interface invariant without requiring a browser.","repair":"Implement the enter child operation as `node = kids[0]`.","root_cause":"The enter child operation uses `node = kids[-1]` where the contract requires `node = kids[0]`.","sha256":"9b95adf83f8a5aa49aa2d924e12deb16b4ad4e502b1fc8d40314ef40169609b6","title":"Tree keyboard expansion: Right-arrow on an expanded parent focuses its last child · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":36.256,"exit_code":1,"observations":[{"actual":["a",["a","z"]],"check":"expand","expected":["a",["a","z"]],"passed":true},{"actual":["a",["a"]],"check":"descend","expected":["b",["a"]],"passed":false},{"actual":["a",["z"]],"check":"collapse","expected":["a",["z"]],"passed":true},{"actual":["a",[]],"check":"parent","expected":["a",[]],"passed":true},{"actual":["a",[]],"check":"root","expected":["a",[]],"passed":true},{"actual":["a",[]],"check":"all","expected":["a",[]],"passed":true},{"actual":["a",["a"]],"check":"parameterized child count","expected":["a",["a"]],"passed":true},{"actual":["a",[]],"check":"repeat all","expected":["a",[]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"expand\", \"actual\": [\"a\", [\"a\", \"z\"]], \"expected\": [\"a\", [\"a\", \"z\"]], \"passed\": true}, {\"check\": \"descend\", \"actual\": [\"a\", [\"a\"]], \"expected\": [\"b\", [\"a\"]], \"passed\": false}, {\"check\": \"collapse\", \"actual\": [\"a\", [\"z\"]], \"expected\": [\"a\", [\"z\"]], \"passed\": true}, {\"check\": \"parent\", \"actual\": [\"a\", []], \"expected\": [\"a\", []], \"passed\": true}, {\"check\": \"root\", \"actual\": [\"a\", []], \"expected\": [\"a\", []], \"passed\": true}, {\"check\": \"all\", \"actual\": [\"a\", []], \"expected\": [\"a\", []], \"passed\": true}, {\"check\": \"parameterized child count\", \"actual\": [\"a\", [\"a\"]], \"expected\": [\"a\", [\"a\"]], \"passed\": true}, {\"check\": \"repeat all\", \"actual\": [\"a\", []], \"expected\": [\"a\", []], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":36.629,"exit_code":1,"observations":[{"actual":["a",["a","z"]],"check":"expand","expected":["a",["a","z"]],"passed":true},{"actual":["c",["a"]],"check":"descend","expected":["b",["a"]],"passed":false},{"actual":["a",["z"]],"check":"collapse","expected":["a",["z"]],"passed":true},{"actual":["a",[]],"check":"parent","expected":["a",[]],"passed":true},{"actual":["a",[]],"check":"root","expected":["a",[]],"passed":true},{"actual":["a",[]],"check":"all","expected":["a",[]],"passed":true},{"actual":["a",["a"]],"check":"parameterized child count","expected":["a",["a"]],"passed":true},{"actual":["a",[]],"check":"repeat all","expected":["a",[]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"expand\", \"actual\": [\"a\", [\"a\", \"z\"]], \"expected\": [\"a\", [\"a\", \"z\"]], \"passed\": true}, {\"check\": \"descend\", \"actual\": [\"c\", [\"a\"]], \"expected\": [\"b\", [\"a\"]], \"passed\": false}, {\"check\": \"collapse\", \"actual\": [\"a\", [\"z\"]], \"expected\": [\"a\", [\"z\"]], \"passed\": true}, {\"check\": \"parent\", \"actual\": [\"a\", []], \"expected\": [\"a\", []], \"passed\": true}, {\"check\": \"root\", \"actual\": [\"a\", []], \"expected\": [\"a\", []], \"passed\": true}, {\"check\": \"all\", \"actual\": [\"a\", []], \"expected\": [\"a\", []], \"passed\": true}, {\"check\": \"parameterized child count\", \"actual\": [\"a\", [\"a\"]], \"expected\": [\"a\", [\"a\"]], \"passed\": true}, {\"check\": \"repeat all\", \"actual\": [\"a\", []], \"expected\": [\"a\", []], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":36.785,"exit_code":0,"observations":[{"actual":["a",["a","z"]],"check":"expand","expected":["a",["a","z"]],"passed":true},{"actual":["b",["a"]],"check":"descend","expected":["b",["a"]],"passed":true},{"actual":["a",["z"]],"check":"collapse","expected":["a",["z"]],"passed":true},{"actual":["a",[]],"check":"parent","expected":["a",[]],"passed":true},{"actual":["a",[]],"check":"root","expected":["a",[]],"passed":true},{"actual":["a",[]],"check":"all","expected":["a",[]],"passed":true},{"actual":["a",["a"]],"check":"parameterized child count","expected":["a",["a"]],"passed":true},{"actual":["a",[]],"check":"repeat all","expected":["a",[]],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"expand\", \"actual\": [\"a\", [\"a\", \"z\"]], \"expected\": [\"a\", [\"a\", \"z\"]], \"passed\": true}, {\"check\": \"descend\", \"actual\": [\"b\", [\"a\"]], \"expected\": [\"b\", [\"a\"]], \"passed\": true}, {\"check\": \"collapse\", \"actual\": [\"a\", [\"z\"]], \"expected\": [\"a\", [\"z\"]], \"passed\": true}, {\"check\": \"parent\", \"actual\": [\"a\", []], \"expected\": [\"a\", []], \"passed\": true}, {\"check\": \"root\", \"actual\": [\"a\", []], \"expected\": [\"a\", []], \"passed\": true}, {\"check\": \"all\", \"actual\": [\"a\", []], \"expected\": [\"a\", []], \"passed\": true}, {\"check\": \"parameterized child count\", \"actual\": [\"a\", [\"a\"]], \"expected\": [\"a\", [\"a\"]], \"passed\": true}, {\"check\": \"repeat all\", \"actual\": [\"a\", []], \"expected\": [\"a\", []], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}