{"abstract":"Last-page navigation stops one page early.","category":"Client navigation","checks":10,"contract":"Empty pagination uses page zero with disabled controls; nonempty page clamps to 1..pages; actions move by one or to endpoints; availability reflects resulting page.","contract_signature":"page, pages, action","evaluation_group":"xi-pagination-controls","failed_approach":"Routing to page one implements First instead.","family":"xi-pagination-controls-last","id":"FA-8616","implementations":{"attempt":{"sha256":"95c6b9178a4b14d7756c663e230203992f52f68179c76299cd1ed993be13c21c","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(page, pages, action):\n    if pages == 0: return (0, False, False)\n    page = max(1, min(page, pages))\n    if action == 'first': page = 1\n    elif action == 'last': page = 1\n    elif action == 'next': page = min(pages, page+1)\n    elif action == 'previous': page = max(1, page-1)\n    return (page, page > 1, page < pages)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('empty', solve(1, 0, \"none\"), (0, False, False))\ncheck('shrink', solve(8, 3, \"none\"), (3, True, False))\ncheck('zero', solve(0, 3, \"none\"), (1, False, True))\ncheck('last', solve(1, 5, \"last\"), (5, True, False))\ncheck('next end', solve(5, 5, \"next\"), (5, True, False))\ncheck('next step', solve(1, 5, \"next\"), (2, True, True))\ncheck('previous start', solve(1, 5, \"previous\"), (1, False, True))\ncheck('previous step', solve(4, 5, \"previous\"), (3, True, True))\ncheck('parameterized page count', solve(N,N+1,'next'), (N+1,True,False))\nfor repetition in range(N):\n    check('repeat previous step', solve(4, 5, \"previous\"), (3, True, True))\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":"4eef5ce9ff3401398886c78915baccbae97f63a73a6d267d726d0ba2aa089ecb","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(page, pages, action):\n    if pages == 0: return (0, False, False)\n    page = max(1, min(page, pages))\n    if action == 'first': page = 1\n    elif action == 'last': page = pages-1\n    elif action == 'next': page = min(pages, page+1)\n    elif action == 'previous': page = max(1, page-1)\n    return (page, page > 1, page < pages)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('empty', solve(1, 0, \"none\"), (0, False, False))\ncheck('shrink', solve(8, 3, \"none\"), (3, True, False))\ncheck('zero', solve(0, 3, \"none\"), (1, False, True))\ncheck('last', solve(1, 5, \"last\"), (5, True, False))\ncheck('next end', solve(5, 5, \"next\"), (5, True, False))\ncheck('next step', solve(1, 5, \"next\"), (2, True, True))\ncheck('previous start', solve(1, 5, \"previous\"), (1, False, True))\ncheck('previous step', solve(4, 5, \"previous\"), (3, True, True))\ncheck('parameterized page count', solve(N,N+1,'next'), (N+1,True,False))\nfor repetition in range(N):\n    check('repeat previous step', solve(4, 5, \"previous\"), (3, True, True))\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-pagination-controls-last","generated_at":"2026-09-29T14:38:23.090978+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic model of pagination button state; this isolates one interface invariant without requiring a browser.","root_cause":"The last operation uses `elif action == 'last': page = pages-1` where the contract requires `elif action == 'last': page = pages`.","sha256":"30d971c0ee8e64d0afcd852e3b0437bf02d525ef1df18e6ec60430b137bf27dd","title":"Pagination button state: Last-page navigation stops one page early · 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":39.241,"exit_code":1,"observations":[{"actual":[0,false,false],"check":"empty","expected":[0,false,false],"passed":true},{"actual":[3,true,false],"check":"shrink","expected":[3,true,false],"passed":true},{"actual":[1,false,true],"check":"zero","expected":[1,false,true],"passed":true},{"actual":[1,false,true],"check":"last","expected":[5,true,false],"passed":false},{"actual":[5,true,false],"check":"next end","expected":[5,true,false],"passed":true},{"actual":[2,true,true],"check":"next step","expected":[2,true,true],"passed":true},{"actual":[1,false,true],"check":"previous start","expected":[1,false,true],"passed":true},{"actual":[3,true,true],"check":"previous step","expected":[3,true,true],"passed":true},{"actual":[2,true,false],"check":"parameterized page count","expected":[2,true,false],"passed":true},{"actual":[3,true,true],"check":"repeat previous step","expected":[3,true,true],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"empty\", \"actual\": [0, false, false], \"expected\": [0, false, false], \"passed\": true}, {\"check\": \"shrink\", \"actual\": [3, true, false], \"expected\": [3, true, false], \"passed\": true}, {\"check\": \"zero\", \"actual\": [1, false, true], \"expected\": [1, false, true], \"passed\": true}, {\"check\": \"last\", \"actual\": [1, false, true], \"expected\": [5, true, false], \"passed\": false}, {\"check\": \"next end\", \"actual\": [5, true, false], \"expected\": [5, true, false], \"passed\": true}, {\"check\": \"next step\", \"actual\": [2, true, true], \"expected\": [2, true, true], \"passed\": true}, {\"check\": \"previous start\", \"actual\": [1, false, true], \"expected\": [1, false, true], \"passed\": true}, {\"check\": \"previous step\", \"actual\": [3, true, true], \"expected\": [3, true, true], \"passed\": true}, {\"check\": \"parameterized page count\", \"actual\": [2, true, false], \"expected\": [2, true, false], \"passed\": true}, {\"check\": \"repeat previous step\", \"actual\": [3, true, true], \"expected\": [3, true, true], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":37.046,"exit_code":1,"observations":[{"actual":[0,false,false],"check":"empty","expected":[0,false,false],"passed":true},{"actual":[3,true,false],"check":"shrink","expected":[3,true,false],"passed":true},{"actual":[1,false,true],"check":"zero","expected":[1,false,true],"passed":true},{"actual":[4,true,true],"check":"last","expected":[5,true,false],"passed":false},{"actual":[5,true,false],"check":"next end","expected":[5,true,false],"passed":true},{"actual":[2,true,true],"check":"next step","expected":[2,true,true],"passed":true},{"actual":[1,false,true],"check":"previous start","expected":[1,false,true],"passed":true},{"actual":[3,true,true],"check":"previous step","expected":[3,true,true],"passed":true},{"actual":[2,true,false],"check":"parameterized page count","expected":[2,true,false],"passed":true},{"actual":[3,true,true],"check":"repeat previous step","expected":[3,true,true],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"empty\", \"actual\": [0, false, false], \"expected\": [0, false, false], \"passed\": true}, {\"check\": \"shrink\", \"actual\": [3, true, false], \"expected\": [3, true, false], \"passed\": true}, {\"check\": \"zero\", \"actual\": [1, false, true], \"expected\": [1, false, true], \"passed\": true}, {\"check\": \"last\", \"actual\": [4, true, true], \"expected\": [5, true, false], \"passed\": false}, {\"check\": \"next end\", \"actual\": [5, true, false], \"expected\": [5, true, false], \"passed\": true}, {\"check\": \"next step\", \"actual\": [2, true, true], \"expected\": [2, true, true], \"passed\": true}, {\"check\": \"previous start\", \"actual\": [1, false, true], \"expected\": [1, false, true], \"passed\": true}, {\"check\": \"previous step\", \"actual\": [3, true, true], \"expected\": [3, true, true], \"passed\": true}, {\"check\": \"parameterized page count\", \"actual\": [2, true, false], \"expected\": [2, true, false], \"passed\": true}, {\"check\": \"repeat previous step\", \"actual\": [3, true, true], \"expected\": [3, true, true], \"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."}}