{"abstract":"Home unexpectedly jumps to the first grid row.","category":"Keyboard accessibility","checks":11,"contract":"Arrow keys move one cell and clamp without wrapping; Home/End target row edges; Control additionally targets the first/last row.","evaluation_group":"xi-grid-navigation","failed_approach":"Never updating the row makes Control-Home fail.","family":"xi-grid-navigation-home-modifier","id":"FA-8371","implementations":{"attempt":{"sha256":"dc8f7c4c3001b37fa58ebf39f8cb6c24a1ce53b7d01fb2d497a5af96cdde3857","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows, columns, row, column, key, ctrl):\n    if key == 'Left': column = max(0, column-1)\n    elif key == 'Right': column = min(columns-1, column+1)\n    elif key == 'Up': row = max(0, row-1)\n    elif key == 'Down': row = min(rows-1, row+1)\n    elif key == 'Home': column = 0; row = row\n    elif key == 'End': column = columns-1; row = rows-1 if ctrl else row\n    return (row, column)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('left boundary', solve(3, 5, 1, 0, 'Left', False), (1, 0))\ncheck('left step', solve(3, 5, 1, 3, 'Left', False), (1, 2))\ncheck('right boundary', solve(3, 5, 1, 4, 'Right', False), (1, 4))\ncheck('right step', solve(3, 5, 1, 3, 'Right', False), (1, 4))\ncheck('up', solve(3, 5, 1, 3, 'Up', False), (0, 3))\ncheck('home', solve(3, 5, 1, 3, 'Home', False), (1, 0))\ncheck('ctrl home', solve(3, 5, 1, 3, 'Home', True), (0, 0))\ncheck('end', solve(3, 5, 1, 3, 'End', False), (1, 4))\ncheck('ctrl end', solve(3, 5, 1, 3, 'End', True), (2, 4))\ncheck('parameterized grid shape', solve(N+2,N+3,N,N,'Right',False), (N,N+1))\nfor repetition in range(N):\n    check('repeat ctrl end', solve(3, 5, 1, 3, 'End', True), (2, 4))\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":"e5d40e21a3f9f750495f95b34784bd1bdfe12b8087df479b98a76f4bd0c72126","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows, columns, row, column, key, ctrl):\n    if key == 'Left': column = max(0, column-1)\n    elif key == 'Right': column = min(columns-1, column+1)\n    elif key == 'Up': row = max(0, row-1)\n    elif key == 'Down': row = min(rows-1, row+1)\n    elif key == 'Home': column = 0; row = 0\n    elif key == 'End': column = columns-1; row = rows-1 if ctrl else row\n    return (row, column)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('left boundary', solve(3, 5, 1, 0, 'Left', False), (1, 0))\ncheck('left step', solve(3, 5, 1, 3, 'Left', False), (1, 2))\ncheck('right boundary', solve(3, 5, 1, 4, 'Right', False), (1, 4))\ncheck('right step', solve(3, 5, 1, 3, 'Right', False), (1, 4))\ncheck('up', solve(3, 5, 1, 3, 'Up', False), (0, 3))\ncheck('home', solve(3, 5, 1, 3, 'Home', False), (1, 0))\ncheck('ctrl home', solve(3, 5, 1, 3, 'Home', True), (0, 0))\ncheck('end', solve(3, 5, 1, 3, 'End', False), (1, 4))\ncheck('ctrl end', solve(3, 5, 1, 3, 'End', True), (2, 4))\ncheck('parameterized grid shape', solve(N+2,N+3,N,N,'Right',False), (N,N+1))\nfor repetition in range(N):\n    check('repeat ctrl end', solve(3, 5, 1, 3, 'End', True), (2, 4))\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":"08124ba6b65cc3f2bd3bca53c5632ac0f44721143cf2998bf0c58251541957cb","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows, columns, row, column, key, ctrl):\n    if key == 'Left': column = max(0, column-1)\n    elif key == 'Right': column = min(columns-1, column+1)\n    elif key == 'Up': row = max(0, row-1)\n    elif key == 'Down': row = min(rows-1, row+1)\n    elif key == 'Home': column = 0; row = 0 if ctrl else row\n    elif key == 'End': column = columns-1; row = rows-1 if ctrl else row\n    return (row, column)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('left boundary', solve(3, 5, 1, 0, 'Left', False), (1, 0))\ncheck('left step', solve(3, 5, 1, 3, 'Left', False), (1, 2))\ncheck('right boundary', solve(3, 5, 1, 4, 'Right', False), (1, 4))\ncheck('right step', solve(3, 5, 1, 3, 'Right', False), (1, 4))\ncheck('up', solve(3, 5, 1, 3, 'Up', False), (0, 3))\ncheck('home', solve(3, 5, 1, 3, 'Home', False), (1, 0))\ncheck('ctrl home', solve(3, 5, 1, 3, 'Home', True), (0, 0))\ncheck('end', solve(3, 5, 1, 3, 'End', False), (1, 4))\ncheck('ctrl end', solve(3, 5, 1, 3, 'End', True), (2, 4))\ncheck('parameterized grid shape', solve(N+2,N+3,N,N,'Right',False), (N,N+1))\nfor repetition in range(N):\n    check('repeat ctrl end', solve(3, 5, 1, 3, 'End', True), (2, 4))\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-grid-navigation-home-modifier","generated_at":"2026-09-29T14:38:20.783083+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic model of grid-cell keyboard movement; this isolates one interface invariant without requiring a browser.","repair":"Implement the home modifier operation as `row = 0 if ctrl else row`.","root_cause":"The home modifier operation uses `row = 0` where the contract requires `row = 0 if ctrl else row`.","sha256":"eb89220f709c5676d1d61716c9ea2a0bcf83c4c191750d648e8cc0d9807b64c2","title":"Grid-cell keyboard movement: Home unexpectedly jumps to the first grid row · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":40.743,"exit_code":1,"observations":[{"actual":[1,0],"check":"left boundary","expected":[1,0],"passed":true},{"actual":[1,2],"check":"left step","expected":[1,2],"passed":true},{"actual":[1,4],"check":"right boundary","expected":[1,4],"passed":true},{"actual":[1,4],"check":"right step","expected":[1,4],"passed":true},{"actual":[0,3],"check":"up","expected":[0,3],"passed":true},{"actual":[1,0],"check":"home","expected":[1,0],"passed":true},{"actual":[1,0],"check":"ctrl home","expected":[0,0],"passed":false},{"actual":[1,4],"check":"end","expected":[1,4],"passed":true},{"actual":[2,4],"check":"ctrl end","expected":[2,4],"passed":true},{"actual":[1,2],"check":"parameterized grid shape","expected":[1,2],"passed":true},{"actual":[2,4],"check":"repeat ctrl end","expected":[2,4],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"left boundary\", \"actual\": [1, 0], \"expected\": [1, 0], \"passed\": true}, {\"check\": \"left step\", \"actual\": [1, 2], \"expected\": [1, 2], \"passed\": true}, {\"check\": \"right boundary\", \"actual\": [1, 4], \"expected\": [1, 4], \"passed\": true}, {\"check\": \"right step\", \"actual\": [1, 4], \"expected\": [1, 4], \"passed\": true}, {\"check\": \"up\", \"actual\": [0, 3], \"expected\": [0, 3], \"passed\": true}, {\"check\": \"home\", \"actual\": [1, 0], \"expected\": [1, 0], \"passed\": true}, {\"check\": \"ctrl home\", \"actual\": [1, 0], \"expected\": [0, 0], \"passed\": false}, {\"check\": \"end\", \"actual\": [1, 4], \"expected\": [1, 4], \"passed\": true}, {\"check\": \"ctrl end\", \"actual\": [2, 4], \"expected\": [2, 4], \"passed\": true}, {\"check\": \"parameterized grid shape\", \"actual\": [1, 2], \"expected\": [1, 2], \"passed\": true}, {\"check\": \"repeat ctrl end\", \"actual\": [2, 4], \"expected\": [2, 4], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":36.387,"exit_code":1,"observations":[{"actual":[1,0],"check":"left boundary","expected":[1,0],"passed":true},{"actual":[1,2],"check":"left step","expected":[1,2],"passed":true},{"actual":[1,4],"check":"right boundary","expected":[1,4],"passed":true},{"actual":[1,4],"check":"right step","expected":[1,4],"passed":true},{"actual":[0,3],"check":"up","expected":[0,3],"passed":true},{"actual":[0,0],"check":"home","expected":[1,0],"passed":false},{"actual":[0,0],"check":"ctrl home","expected":[0,0],"passed":true},{"actual":[1,4],"check":"end","expected":[1,4],"passed":true},{"actual":[2,4],"check":"ctrl end","expected":[2,4],"passed":true},{"actual":[1,2],"check":"parameterized grid shape","expected":[1,2],"passed":true},{"actual":[2,4],"check":"repeat ctrl end","expected":[2,4],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"left boundary\", \"actual\": [1, 0], \"expected\": [1, 0], \"passed\": true}, {\"check\": \"left step\", \"actual\": [1, 2], \"expected\": [1, 2], \"passed\": true}, {\"check\": \"right boundary\", \"actual\": [1, 4], \"expected\": [1, 4], \"passed\": true}, {\"check\": \"right step\", \"actual\": [1, 4], \"expected\": [1, 4], \"passed\": true}, {\"check\": \"up\", \"actual\": [0, 3], \"expected\": [0, 3], \"passed\": true}, {\"check\": \"home\", \"actual\": [0, 0], \"expected\": [1, 0], \"passed\": false}, {\"check\": \"ctrl home\", \"actual\": [0, 0], \"expected\": [0, 0], \"passed\": true}, {\"check\": \"end\", \"actual\": [1, 4], \"expected\": [1, 4], \"passed\": true}, {\"check\": \"ctrl end\", \"actual\": [2, 4], \"expected\": [2, 4], \"passed\": true}, {\"check\": \"parameterized grid shape\", \"actual\": [1, 2], \"expected\": [1, 2], \"passed\": true}, {\"check\": \"repeat ctrl end\", \"actual\": [2, 4], \"expected\": [2, 4], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":38.034,"exit_code":0,"observations":[{"actual":[1,0],"check":"left boundary","expected":[1,0],"passed":true},{"actual":[1,2],"check":"left step","expected":[1,2],"passed":true},{"actual":[1,4],"check":"right boundary","expected":[1,4],"passed":true},{"actual":[1,4],"check":"right step","expected":[1,4],"passed":true},{"actual":[0,3],"check":"up","expected":[0,3],"passed":true},{"actual":[1,0],"check":"home","expected":[1,0],"passed":true},{"actual":[0,0],"check":"ctrl home","expected":[0,0],"passed":true},{"actual":[1,4],"check":"end","expected":[1,4],"passed":true},{"actual":[2,4],"check":"ctrl end","expected":[2,4],"passed":true},{"actual":[1,2],"check":"parameterized grid shape","expected":[1,2],"passed":true},{"actual":[2,4],"check":"repeat ctrl end","expected":[2,4],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"left boundary\", \"actual\": [1, 0], \"expected\": [1, 0], \"passed\": true}, {\"check\": \"left step\", \"actual\": [1, 2], \"expected\": [1, 2], \"passed\": true}, {\"check\": \"right boundary\", \"actual\": [1, 4], \"expected\": [1, 4], \"passed\": true}, {\"check\": \"right step\", \"actual\": [1, 4], \"expected\": [1, 4], \"passed\": true}, {\"check\": \"up\", \"actual\": [0, 3], \"expected\": [0, 3], \"passed\": true}, {\"check\": \"home\", \"actual\": [1, 0], \"expected\": [1, 0], \"passed\": true}, {\"check\": \"ctrl home\", \"actual\": [0, 0], \"expected\": [0, 0], \"passed\": true}, {\"check\": \"end\", \"actual\": [1, 4], \"expected\": [1, 4], \"passed\": true}, {\"check\": \"ctrl end\", \"actual\": [2, 4], \"expected\": [2, 4], \"passed\": true}, {\"check\": \"parameterized grid shape\", \"actual\": [1, 2], \"expected\": [1, 2], \"passed\": true}, {\"check\": \"repeat ctrl end\", \"actual\": [2, 4], \"expected\": [2, 4], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}