{"abstract":"A sampled command delay reads newly written input too early.","category":"Discrete control systems","checks":6,"contract":"A nonempty queue stores pending oldest-first delayed commands; return [output,new_queue] after one tick. Its length is the exact integer sample delay.","evaluation_group":"model-43d6e1927f077f02","failed_approach":"Shifting first shortens the delay by one sample.","family":"z-control_systems-transport-delay","id":"FA-11986","implementations":{"attempt":{"sha256":"025416d2fd7c1362849def56935516fc777a6bcc8d536d31cce6555dba77c09f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(queue, command):\n    updated=queue[1:]+[command]\n    return [updated[0],updated]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('single delay', solve([0], N), [0,[N]])\ncheck('two delay', solve([N,2*N], 3*N), [N,[2*N,3*N]])\ncheck('negative history', solve([-N,0], N), [-N,[0,N]])\ncheck('zero command', solve([N], 0), [N,[0]])\ncheck('constant stream', solve([N,N], N), [N,[N,N]])\ncheck('long queue', solve([N,0,-N], 2*N), [N,[0,-N,2*N]])\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":"0c125ef260958750dbf713b89dbb3c1f809b1fd5e94ed04522d013aa57c12704","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(queue, command):\n    return [command, queue[1:]+[command]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('single delay', solve([0], N), [0,[N]])\ncheck('two delay', solve([N,2*N], 3*N), [N,[2*N,3*N]])\ncheck('negative history', solve([-N,0], N), [-N,[0,N]])\ncheck('zero command', solve([N], 0), [N,[0]])\ncheck('constant stream', solve([N,N], N), [N,[N,N]])\ncheck('long queue', solve([N,0,-N], 2*N), [N,[0,-N,2*N]])\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":"9617650965f5938d1a2af7b6897df0fa2a1856a78161dc88c1687f841d6f80ae","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(queue, command):\n    return [queue[0],queue[1:]+[command]]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('single delay', solve([0], N), [0,[N]])\ncheck('two delay', solve([N,2*N], 3*N), [N,[2*N,3*N]])\ncheck('negative history', solve([-N,0], N), [-N,[0,N]])\ncheck('zero command', solve([N], 0), [N,[0]])\ncheck('constant stream', solve([N,N], N), [N,[N,N]])\ncheck('long queue', solve([N,0,-N], 2*N), [N,[0,-N,2*N]])\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":"Integer-valued controlled examples only; no physical plant, stability guarantee, timing jitter, or hardware behavior is modeled. 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":"z-control_systems-transport-delay","generated_at":"2026-09-29T14:38:52.824223+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"An offline discrete controller model isolates this state or arithmetic fault; it makes no physical plant or safety claim.","repair":"Read the oldest queue element before shifting in the current input.","root_cause":"The input is returned immediately instead of passing through the delay queue.","sha256":"69d3ee04014bf2d05a1925f402ab345c7f0c844619ae182158bc4ceb9e903cf3","title":"A sampled command delay reads newly written input too early · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":39.808,"exit_code":1,"observations":[{"actual":[1,[1]],"check":"single delay","expected":[0,[1]],"passed":false},{"actual":[2,[2,3]],"check":"two delay","expected":[1,[2,3]],"passed":false},{"actual":[0,[0,1]],"check":"negative history","expected":[-1,[0,1]],"passed":false},{"actual":[0,[0]],"check":"zero command","expected":[1,[0]],"passed":false},{"actual":[1,[1,1]],"check":"constant stream","expected":[1,[1,1]],"passed":true},{"actual":[0,[0,-1,2]],"check":"long queue","expected":[1,[0,-1,2]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"single delay\", \"actual\": [1, [1]], \"expected\": [0, [1]], \"passed\": false}, {\"check\": \"two delay\", \"actual\": [2, [2, 3]], \"expected\": [1, [2, 3]], \"passed\": false}, {\"check\": \"negative history\", \"actual\": [0, [0, 1]], \"expected\": [-1, [0, 1]], \"passed\": false}, {\"check\": \"zero command\", \"actual\": [0, [0]], \"expected\": [1, [0]], \"passed\": false}, {\"check\": \"constant stream\", \"actual\": [1, [1, 1]], \"expected\": [1, [1, 1]], \"passed\": true}, {\"check\": \"long queue\", \"actual\": [0, [0, -1, 2]], \"expected\": [1, [0, -1, 2]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":42.705,"exit_code":1,"observations":[{"actual":[1,[1]],"check":"single delay","expected":[0,[1]],"passed":false},{"actual":[3,[2,3]],"check":"two delay","expected":[1,[2,3]],"passed":false},{"actual":[1,[0,1]],"check":"negative history","expected":[-1,[0,1]],"passed":false},{"actual":[0,[0]],"check":"zero command","expected":[1,[0]],"passed":false},{"actual":[1,[1,1]],"check":"constant stream","expected":[1,[1,1]],"passed":true},{"actual":[2,[0,-1,2]],"check":"long queue","expected":[1,[0,-1,2]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"single delay\", \"actual\": [1, [1]], \"expected\": [0, [1]], \"passed\": false}, {\"check\": \"two delay\", \"actual\": [3, [2, 3]], \"expected\": [1, [2, 3]], \"passed\": false}, {\"check\": \"negative history\", \"actual\": [1, [0, 1]], \"expected\": [-1, [0, 1]], \"passed\": false}, {\"check\": \"zero command\", \"actual\": [0, [0]], \"expected\": [1, [0]], \"passed\": false}, {\"check\": \"constant stream\", \"actual\": [1, [1, 1]], \"expected\": [1, [1, 1]], \"passed\": true}, {\"check\": \"long queue\", \"actual\": [2, [0, -1, 2]], \"expected\": [1, [0, -1, 2]], \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":38.333,"exit_code":0,"observations":[{"actual":[0,[1]],"check":"single delay","expected":[0,[1]],"passed":true},{"actual":[1,[2,3]],"check":"two delay","expected":[1,[2,3]],"passed":true},{"actual":[-1,[0,1]],"check":"negative history","expected":[-1,[0,1]],"passed":true},{"actual":[1,[0]],"check":"zero command","expected":[1,[0]],"passed":true},{"actual":[1,[1,1]],"check":"constant stream","expected":[1,[1,1]],"passed":true},{"actual":[1,[0,-1,2]],"check":"long queue","expected":[1,[0,-1,2]],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"single delay\", \"actual\": [0, [1]], \"expected\": [0, [1]], \"passed\": true}, {\"check\": \"two delay\", \"actual\": [1, [2, 3]], \"expected\": [1, [2, 3]], \"passed\": true}, {\"check\": \"negative history\", \"actual\": [-1, [0, 1]], \"expected\": [-1, [0, 1]], \"passed\": true}, {\"check\": \"zero command\", \"actual\": [1, [0]], \"expected\": [1, [0]], \"passed\": true}, {\"check\": \"constant stream\", \"actual\": [1, [1, 1]], \"expected\": [1, [1, 1]], \"passed\": true}, {\"check\": \"long queue\", \"actual\": [1, [0, -1, 2]], \"expected\": [1, [0, -1, 2]], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}