{"abstract":"Empty deque borrow unnecessarily pins backing storage.","category":"Bounded deques","checks":7,"contract":"Borrow a valid logical subrange from a bounded ring as at most two physical spans. Reject negative or out-of-live-range requests. Borrow captures the current epoch and pins storage only for nonempty ranges.","evaluation_group":"s3-bounded-deques-range-borrow","failed_approach":"The partial repair still applies the incorrect transition to an admitted boundary or multi-element case.","family":"s3-bounded-deques-range-borrow-empty-pin","id":"FA-46636","implementations":{"attempt":{"sha256":"ba628565028b641f23b2832224ba007076cda8456f03cd808bc40318480aaf05","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    cap,head,size,start,count,epoch=x\n    if start<0 or count<0 or start+count>size:return [False,[],epoch,0,False]\n    origin=(head+start)%cap\n    first=min(count,cap-origin)\n    spans=[[origin,first]] if first else []\n    if count>first:spans.append([0,count-first])\n    captured=epoch\n    pin=count>0 or start>0\n    return [True,spans,captured,count,pin]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([8,6,5,1,3,N]), {1: [True, [[7, 1], [0, 2]], 1, 3, True], 2: [True, [[7, 1], [0, 2]], 2, 3, True], 3: [True, [[7, 1], [0, 2]], 3, 3, True], 4: [True, [[7, 1], [0, 2]], 4, 3, True], 5: [True, [[7, 1], [0, 2]], 5, 3, True]}[N])\ncheck('1', solve([8,2,4,1,2,N]), {1: [True, [[3, 2]], 1, 2, True], 2: [True, [[3, 2]], 2, 2, True], 3: [True, [[3, 2]], 3, 2, True], 4: [True, [[3, 2]], 4, 2, True], 5: [True, [[3, 2]], 5, 2, True]}[N])\ncheck('2', solve([7,5,4,0,4,N]), {1: [True, [[5, 2], [0, 2]], 1, 4, True], 2: [True, [[5, 2], [0, 2]], 2, 4, True], 3: [True, [[5, 2], [0, 2]], 3, 4, True], 4: [True, [[5, 2], [0, 2]], 4, 4, True], 5: [True, [[5, 2], [0, 2]], 5, 4, True]}[N])\ncheck('3', solve([8,3,2,2,0,N]), {1: [True, [], 1, 0, False], 2: [True, [], 2, 0, False], 3: [True, [], 3, 0, False], 4: [True, [], 4, 0, False], 5: [True, [], 5, 0, False]}[N])\ncheck('4', solve([8,3,2,1,2,N]), {1: [False, [], 1, 0, False], 2: [False, [], 2, 0, False], 3: [False, [], 3, 0, False], 4: [False, [], 4, 0, False], 5: [False, [], 5, 0, False]}[N])\ncheck('5', solve([6,2,3,-1,2,N]), {1: [False, [], 1, 0, False], 2: [False, [], 2, 0, False], 3: [False, [], 3, 0, False], 4: [False, [], 4, 0, False], 5: [False, [], 5, 0, False]}[N])\ncheck('6', solve([7,1,5,3,-1,N]), {1: [False, [], 1, 0, False], 2: [False, [], 2, 0, False], 3: [False, [], 3, 0, False], 4: [False, [], 4, 0, False], 5: [False, [], 5, 0, False]}[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":"5acb6f319a6d6fe7cc0609c658532018abcfe6db83958150a5592eb4e20849d0","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    cap,head,size,start,count,epoch=x\n    if start<0 or count<0 or start+count>size:return [False,[],epoch,0,False]\n    origin=(head+start)%cap\n    first=min(count,cap-origin)\n    spans=[[origin,first]] if first else []\n    if count>first:spans.append([0,count-first])\n    captured=epoch\n    pin=True\n    return [True,spans,captured,count,pin]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([8,6,5,1,3,N]), {1: [True, [[7, 1], [0, 2]], 1, 3, True], 2: [True, [[7, 1], [0, 2]], 2, 3, True], 3: [True, [[7, 1], [0, 2]], 3, 3, True], 4: [True, [[7, 1], [0, 2]], 4, 3, True], 5: [True, [[7, 1], [0, 2]], 5, 3, True]}[N])\ncheck('1', solve([8,2,4,1,2,N]), {1: [True, [[3, 2]], 1, 2, True], 2: [True, [[3, 2]], 2, 2, True], 3: [True, [[3, 2]], 3, 2, True], 4: [True, [[3, 2]], 4, 2, True], 5: [True, [[3, 2]], 5, 2, True]}[N])\ncheck('2', solve([7,5,4,0,4,N]), {1: [True, [[5, 2], [0, 2]], 1, 4, True], 2: [True, [[5, 2], [0, 2]], 2, 4, True], 3: [True, [[5, 2], [0, 2]], 3, 4, True], 4: [True, [[5, 2], [0, 2]], 4, 4, True], 5: [True, [[5, 2], [0, 2]], 5, 4, True]}[N])\ncheck('3', solve([8,3,2,2,0,N]), {1: [True, [], 1, 0, False], 2: [True, [], 2, 0, False], 3: [True, [], 3, 0, False], 4: [True, [], 4, 0, False], 5: [True, [], 5, 0, False]}[N])\ncheck('4', solve([8,3,2,1,2,N]), {1: [False, [], 1, 0, False], 2: [False, [], 2, 0, False], 3: [False, [], 3, 0, False], 4: [False, [], 4, 0, False], 5: [False, [], 5, 0, False]}[N])\ncheck('5', solve([6,2,3,-1,2,N]), {1: [False, [], 1, 0, False], 2: [False, [], 2, 0, False], 3: [False, [], 3, 0, False], 4: [False, [], 4, 0, False], 5: [False, [], 5, 0, False]}[N])\ncheck('6', solve([7,1,5,3,-1,N]), {1: [False, [], 1, 0, False], 2: [False, [], 2, 0, False], 3: [False, [], 3, 0, False], 4: [False, [], 4, 0, False], 5: [False, [], 5, 0, False]}[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":"2851c069034c3cd8ddb5cb61b343f334ab5207d9976d03a0d84ae21cb23960e7","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    cap,head,size,start,count,epoch=x\n    if start<0 or count<0 or start+count>size:return [False,[],epoch,0,False]\n    origin=(head+start)%cap\n    first=min(count,cap-origin)\n    spans=[[origin,first]] if first else []\n    if count>first:spans.append([0,count-first])\n    captured=epoch\n    pin=count>0\n    return [True,spans,captured,count,pin]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([8,6,5,1,3,N]), {1: [True, [[7, 1], [0, 2]], 1, 3, True], 2: [True, [[7, 1], [0, 2]], 2, 3, True], 3: [True, [[7, 1], [0, 2]], 3, 3, True], 4: [True, [[7, 1], [0, 2]], 4, 3, True], 5: [True, [[7, 1], [0, 2]], 5, 3, True]}[N])\ncheck('1', solve([8,2,4,1,2,N]), {1: [True, [[3, 2]], 1, 2, True], 2: [True, [[3, 2]], 2, 2, True], 3: [True, [[3, 2]], 3, 2, True], 4: [True, [[3, 2]], 4, 2, True], 5: [True, [[3, 2]], 5, 2, True]}[N])\ncheck('2', solve([7,5,4,0,4,N]), {1: [True, [[5, 2], [0, 2]], 1, 4, True], 2: [True, [[5, 2], [0, 2]], 2, 4, True], 3: [True, [[5, 2], [0, 2]], 3, 4, True], 4: [True, [[5, 2], [0, 2]], 4, 4, True], 5: [True, [[5, 2], [0, 2]], 5, 4, True]}[N])\ncheck('3', solve([8,3,2,2,0,N]), {1: [True, [], 1, 0, False], 2: [True, [], 2, 0, False], 3: [True, [], 3, 0, False], 4: [True, [], 4, 0, False], 5: [True, [], 5, 0, False]}[N])\ncheck('4', solve([8,3,2,1,2,N]), {1: [False, [], 1, 0, False], 2: [False, [], 2, 0, False], 3: [False, [], 3, 0, False], 4: [False, [], 4, 0, False], 5: [False, [], 5, 0, False]}[N])\ncheck('5', solve([6,2,3,-1,2,N]), {1: [False, [], 1, 0, False], 2: [False, [], 2, 0, False], 3: [False, [], 3, 0, False], 4: [False, [], 4, 0, False], 5: [False, [], 5, 0, False]}[N])\ncheck('6', solve([7,1,5,3,-1,N]), {1: [False, [], 1, 0, False], 2: [False, [], 2, 0, False], 3: [False, [], 3, 0, False], 4: [False, [], 4, 0, False], 5: [False, [], 5, 0, False]}[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":"Offline finite deterministic model; no claim of production implementation or concurrent memory-model conformance. 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":"s3-bounded-deques-range-borrow-empty-pin","generated_at":"2026-09-29T14:44:33.900444+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Controlled bounded deque implementation model with explicit storage and lifecycle observations.","repair":"Restore the documented empty pin invariant in range-borrow.","root_cause":"Empty deque borrow unnecessarily pins backing storage.","sha256":"b458f031a1582707d7b00ea7eb583a51f17746ba46c1dbde039288df2005c21b","title":"Empty deque borrow unnecessarily pins backing storage · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":42.3,"exit_code":1,"observations":[{"actual":[true,[[7,1],[0,2]],1,3,true],"check":"0","expected":[true,[[7,1],[0,2]],1,3,true],"passed":true},{"actual":[true,[[3,2]],1,2,true],"check":"1","expected":[true,[[3,2]],1,2,true],"passed":true},{"actual":[true,[[5,2],[0,2]],1,4,true],"check":"2","expected":[true,[[5,2],[0,2]],1,4,true],"passed":true},{"actual":[true,[],1,0,true],"check":"3","expected":[true,[],1,0,false],"passed":false},{"actual":[false,[],1,0,false],"check":"4","expected":[false,[],1,0,false],"passed":true},{"actual":[false,[],1,0,false],"check":"5","expected":[false,[],1,0,false],"passed":true},{"actual":[false,[],1,0,false],"check":"6","expected":[false,[],1,0,false],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [true, [[7, 1], [0, 2]], 1, 3, true], \"expected\": [true, [[7, 1], [0, 2]], 1, 3, true], \"passed\": true}, {\"check\": \"1\", \"actual\": [true, [[3, 2]], 1, 2, true], \"expected\": [true, [[3, 2]], 1, 2, true], \"passed\": true}, {\"check\": \"2\", \"actual\": [true, [[5, 2], [0, 2]], 1, 4, true], \"expected\": [true, [[5, 2], [0, 2]], 1, 4, true], \"passed\": true}, {\"check\": \"3\", \"actual\": [true, [], 1, 0, true], \"expected\": [true, [], 1, 0, false], \"passed\": false}, {\"check\": \"4\", \"actual\": [false, [], 1, 0, false], \"expected\": [false, [], 1, 0, false], \"passed\": true}, {\"check\": \"5\", \"actual\": [false, [], 1, 0, false], \"expected\": [false, [], 1, 0, false], \"passed\": true}, {\"check\": \"6\", \"actual\": [false, [], 1, 0, false], \"expected\": [false, [], 1, 0, false], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":44.314,"exit_code":1,"observations":[{"actual":[true,[[7,1],[0,2]],1,3,true],"check":"0","expected":[true,[[7,1],[0,2]],1,3,true],"passed":true},{"actual":[true,[[3,2]],1,2,true],"check":"1","expected":[true,[[3,2]],1,2,true],"passed":true},{"actual":[true,[[5,2],[0,2]],1,4,true],"check":"2","expected":[true,[[5,2],[0,2]],1,4,true],"passed":true},{"actual":[true,[],1,0,true],"check":"3","expected":[true,[],1,0,false],"passed":false},{"actual":[false,[],1,0,false],"check":"4","expected":[false,[],1,0,false],"passed":true},{"actual":[false,[],1,0,false],"check":"5","expected":[false,[],1,0,false],"passed":true},{"actual":[false,[],1,0,false],"check":"6","expected":[false,[],1,0,false],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [true, [[7, 1], [0, 2]], 1, 3, true], \"expected\": [true, [[7, 1], [0, 2]], 1, 3, true], \"passed\": true}, {\"check\": \"1\", \"actual\": [true, [[3, 2]], 1, 2, true], \"expected\": [true, [[3, 2]], 1, 2, true], \"passed\": true}, {\"check\": \"2\", \"actual\": [true, [[5, 2], [0, 2]], 1, 4, true], \"expected\": [true, [[5, 2], [0, 2]], 1, 4, true], \"passed\": true}, {\"check\": \"3\", \"actual\": [true, [], 1, 0, true], \"expected\": [true, [], 1, 0, false], \"passed\": false}, {\"check\": \"4\", \"actual\": [false, [], 1, 0, false], \"expected\": [false, [], 1, 0, false], \"passed\": true}, {\"check\": \"5\", \"actual\": [false, [], 1, 0, false], \"expected\": [false, [], 1, 0, false], \"passed\": true}, {\"check\": \"6\", \"actual\": [false, [], 1, 0, false], \"expected\": [false, [], 1, 0, false], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":38.58,"exit_code":0,"observations":[{"actual":[true,[[7,1],[0,2]],1,3,true],"check":"0","expected":[true,[[7,1],[0,2]],1,3,true],"passed":true},{"actual":[true,[[3,2]],1,2,true],"check":"1","expected":[true,[[3,2]],1,2,true],"passed":true},{"actual":[true,[[5,2],[0,2]],1,4,true],"check":"2","expected":[true,[[5,2],[0,2]],1,4,true],"passed":true},{"actual":[true,[],1,0,false],"check":"3","expected":[true,[],1,0,false],"passed":true},{"actual":[false,[],1,0,false],"check":"4","expected":[false,[],1,0,false],"passed":true},{"actual":[false,[],1,0,false],"check":"5","expected":[false,[],1,0,false],"passed":true},{"actual":[false,[],1,0,false],"check":"6","expected":[false,[],1,0,false],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [true, [[7, 1], [0, 2]], 1, 3, true], \"expected\": [true, [[7, 1], [0, 2]], 1, 3, true], \"passed\": true}, {\"check\": \"1\", \"actual\": [true, [[3, 2]], 1, 2, true], \"expected\": [true, [[3, 2]], 1, 2, true], \"passed\": true}, {\"check\": \"2\", \"actual\": [true, [[5, 2], [0, 2]], 1, 4, true], \"expected\": [true, [[5, 2], [0, 2]], 1, 4, true], \"passed\": true}, {\"check\": \"3\", \"actual\": [true, [], 1, 0, false], \"expected\": [true, [], 1, 0, false], \"passed\": true}, {\"check\": \"4\", \"actual\": [false, [], 1, 0, false], \"expected\": [false, [], 1, 0, false], \"passed\": true}, {\"check\": \"5\", \"actual\": [false, [], 1, 0, false], \"expected\": [false, [], 1, 0, false], \"passed\": true}, {\"check\": \"6\", \"actual\": [false, [], 1, 0, false], \"expected\": [false, [], 1, 0, false], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}