{"abstract":"Left-arrow on a collapsed child does not move to its parent.","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.","contract_signature":"node, expanded, parents, children, key","evaluation_group":"xi-tree-navigation","failed_approach":"A missing parent must keep root focus rather than return None.","family":"xi-tree-navigation-parent-left","id":"FA-8396","implementations":{"attempt":{"sha256":"5810454dfe630f63d0a7acad536a36648fbd2460f506ce0fa19b8378740e5406","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)\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":"77d6eb5d0281c609bf8e54202955ebfefadaec29ff7f6fa9e8abaea931094cfc","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 = 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-parent-left","generated_at":"2026-09-29T14:38:21.061370+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.","root_cause":"The parent left operation uses `node` where the contract requires `parents.get(node, node)`.","sha256":"dfb8611e3b73c5fd7b769ec661d5990145cd5cd63d305c01a7e18f633ef34ce8","title":"Tree keyboard expansion: Left-arrow on a collapsed child does not move to its parent · 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":37.516,"exit_code":1,"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":[null,[]],"check":"root","expected":["a",[]],"passed":false},{"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\": [\"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\": [null, []], \"expected\": [\"a\", []], \"passed\": false}, {\"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":35.524,"exit_code":1,"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":["b",[]],"check":"parent","expected":["a",[]],"passed":false},{"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\": [\"b\", [\"a\"]], \"expected\": [\"b\", [\"a\"]], \"passed\": true}, {\"check\": \"collapse\", \"actual\": [\"a\", [\"z\"]], \"expected\": [\"a\", [\"z\"]], \"passed\": true}, {\"check\": \"parent\", \"actual\": [\"b\", []], \"expected\": [\"a\", []], \"passed\": false}, {\"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"}},"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."}}