{"abstract":"Appending replaces earlier list elements.","category":"Configuration","checks":8,"contract":"Starting from defaults, process assignment, append, unset, enable, and disable operations in sequence. Append creates a new list or extends an existing list. Unknown operations are ignored.","contract_signature":"defaults, operations","evaluation_group":"xt-cli-configuration","failed_approach":"The attempted repair substitutes list(dict.fromkeys(list(result.get(key, [])) + [value])). Fixture 3 still yields {'a': [1, 2]} instead of {'a': [1, 2, 2]}.","family":"xt-cli-configuration-append-command","id":"FA-9711","implementations":{"attempt":{"sha256":"27b806de1e391fcae0454a7614f4af2c3ab939de8ff4ad0f0a0d0fdba57e82e0","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(defaults, operations):\n    result = dict(defaults)\n    for op, key, value in operations:\n        if op == 'set': result[key] = value\n        elif op == 'append': result[key] = list(dict.fromkeys(list(result.get(key, [])) + [value]))\n        elif op == 'unset': result.pop(key, None)\n        elif op == 'enable': result[key] = True\n        elif op == 'disable': result[key] = False\n    return result\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve({}, []), {})\ncheck('fixture 2', solve({'a': 1}, [('set', 'a', 0)]), {'a': 0})\ncheck('fixture 3', solve({'a': [1]}, [('append', 'a', 2), ('append', 'a', 2)]), {'a': [1, 2, 2]})\ncheck('fixture 4', solve({'a': 1}, [('unset', 'a', None)]), {})\ncheck('fixture 5', solve({}, [('unset', 'a', None)]), {})\ncheck('fixture 6', solve({}, [('enable', 'a', None)]), {'a': True})\ncheck('fixture 7', solve({'a': True}, [('disable', 'a', None)]), {'a': False})\ncheck('fixture 8', solve({'a': 1}, [('unknown', 'a', 2)]), {'a': 1})\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":"08bafc3bfd29bf10a147bab212b005fd2812818ff0a92aba62376360524bc034","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(defaults, operations):\n    result = dict(defaults)\n    for op, key, value in operations:\n        if op == 'set': result[key] = value\n        elif op == 'append': result[key] = [value]\n        elif op == 'unset': result.pop(key, None)\n        elif op == 'enable': result[key] = True\n        elif op == 'disable': result[key] = False\n    return result\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve({}, []), {})\ncheck('fixture 2', solve({'a': 1}, [('set', 'a', 0)]), {'a': 0})\ncheck('fixture 3', solve({'a': [1]}, [('append', 'a', 2), ('append', 'a', 2)]), {'a': [1, 2, 2]})\ncheck('fixture 4', solve({'a': 1}, [('unset', 'a', None)]), {})\ncheck('fixture 5', solve({}, [('unset', 'a', None)]), {})\ncheck('fixture 6', solve({}, [('enable', 'a', None)]), {'a': True})\ncheck('fixture 7', solve({'a': True}, [('disable', 'a', None)]), {'a': False})\ncheck('fixture 8', solve({'a': 1}, [('unknown', 'a', 2)]), {'a': 1})\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":"xt-cli-configuration-append-command","generated_at":"2026-09-29T14:38:32.525189+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"An offline model of command option assignment, suitable for testing build and release tooling without external services.","root_cause":"The implementation substitutes [value] for list(result.get(key, [])) + [value], so appending replaces earlier list elements.","sha256":"6f817906935c9bcee12222832adc5eb40dcd51643c2c60494f8e09fe323fc853","title":"Command option assignment: Appending replaces earlier list elements · 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":37.768,"exit_code":1,"observations":[{"actual":{},"check":"fixture 1","expected":{},"passed":true},{"actual":{"a":0},"check":"fixture 2","expected":{"a":0},"passed":true},{"actual":{"a":[1,2]},"check":"fixture 3","expected":{"a":[1,2,2]},"passed":false},{"actual":{},"check":"fixture 4","expected":{},"passed":true},{"actual":{},"check":"fixture 5","expected":{},"passed":true},{"actual":{"a":true},"check":"fixture 6","expected":{"a":true},"passed":true},{"actual":{"a":false},"check":"fixture 7","expected":{"a":false},"passed":true},{"actual":{"a":1},"check":"fixture 8","expected":{"a":1},"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": {}, \"expected\": {}, \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": {\"a\": 0}, \"expected\": {\"a\": 0}, \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": {\"a\": [1, 2]}, \"expected\": {\"a\": [1, 2, 2]}, \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": {}, \"expected\": {}, \"passed\": true}, {\"check\": \"fixture 5\", \"actual\": {}, \"expected\": {}, \"passed\": true}, {\"check\": \"fixture 6\", \"actual\": {\"a\": true}, \"expected\": {\"a\": true}, \"passed\": true}, {\"check\": \"fixture 7\", \"actual\": {\"a\": false}, \"expected\": {\"a\": false}, \"passed\": true}, {\"check\": \"fixture 8\", \"actual\": {\"a\": 1}, \"expected\": {\"a\": 1}, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.873,"exit_code":1,"observations":[{"actual":{},"check":"fixture 1","expected":{},"passed":true},{"actual":{"a":0},"check":"fixture 2","expected":{"a":0},"passed":true},{"actual":{"a":[2]},"check":"fixture 3","expected":{"a":[1,2,2]},"passed":false},{"actual":{},"check":"fixture 4","expected":{},"passed":true},{"actual":{},"check":"fixture 5","expected":{},"passed":true},{"actual":{"a":true},"check":"fixture 6","expected":{"a":true},"passed":true},{"actual":{"a":false},"check":"fixture 7","expected":{"a":false},"passed":true},{"actual":{"a":1},"check":"fixture 8","expected":{"a":1},"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": {}, \"expected\": {}, \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": {\"a\": 0}, \"expected\": {\"a\": 0}, \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": {\"a\": [2]}, \"expected\": {\"a\": [1, 2, 2]}, \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": {}, \"expected\": {}, \"passed\": true}, {\"check\": \"fixture 5\", \"actual\": {}, \"expected\": {}, \"passed\": true}, {\"check\": \"fixture 6\", \"actual\": {\"a\": true}, \"expected\": {\"a\": true}, \"passed\": true}, {\"check\": \"fixture 7\", \"actual\": {\"a\": false}, \"expected\": {\"a\": false}, \"passed\": true}, {\"check\": \"fixture 8\", \"actual\": {\"a\": 1}, \"expected\": {\"a\": 1}, \"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."}}