{"abstract":"ineligible responses become pair endpoints.","category":"Preference pair construction","checks":6,"contract":"Candidates are [id,score,eligible]. Select the highest and lowest scored eligible candidates; return [best_id,worst_id], or None with fewer than two eligible candidates.","contract_signature":"candidates","evaluation_group":"preference-eligibility-first","failed_approach":"Filtering only the chosen endpoint can leave a rejected endpoint that is forbidden.","family":"w3-preference-pair-construction-eligibility-first","id":"FA-100051","implementations":{"attempt":{"sha256":"7d9a75b0fede1a5b7f744ebaf9b1e018ce4dc5274fc29592b4d50e81cffdb2c7","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(candidates):\n    ok=[c for c in candidates if c[2]]\n    return [max(ok,key=lambda x:x[1])[0],min(candidates,key=lambda x:x[1])[0]] if len(ok)>1 else None\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\na='a'+str(N); b='b'+str(N); x='x'+str(N)\ncheck('excluded maximum',solve([[a,N,True],[x,N+3,False],[b,0,True]]),[a,b])\ncheck('excluded minimum',solve([[a,N,True],[x,-N,False],[b,0,True]]),[a,b])\ncheck('one eligible',solve([[a,N,True],[x,0,False]]),None)\ncheck('none eligible',solve([[a,N,False],[b,0,False]]),None)\ncheck('empty',solve([]),None)\ncheck('two eligible',solve([[a,2*N,True],[b,N,True]]),[a,b])\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":"8f1becb91e686f358aeca0cb11f0b83e4bee0eb5aacddf23d1a0500cd010bb96","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(candidates):\n    return [max(candidates,key=lambda x:x[1])[0],min(candidates,key=lambda x:x[1])[0]] if len(candidates)>1 else None\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\na='a'+str(N); b='b'+str(N); x='x'+str(N)\ncheck('excluded maximum',solve([[a,N,True],[x,N+3,False],[b,0,True]]),[a,b])\ncheck('excluded minimum',solve([[a,N,True],[x,-N,False],[b,0,True]]),[a,b])\ncheck('one eligible',solve([[a,N,True],[x,0,False]]),None)\ncheck('none eligible',solve([[a,N,False],[b,0,False]]),None)\ncheck('empty',solve([]),None)\ncheck('two eligible',solve([[a,2*N,True],[b,N,True]]),[a,b])\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":"These are explicit toy record contracts; they do not claim compatibility with a trainer or improved model behavior. 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":"w3-preference-pair-construction-eligibility-first","generated_at":"2026-09-30T16:48:31.262650+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A small deterministic preference-data transform makes pair semantics inspectable without a training framework.","root_cause":"Preference is evaluated before candidate eligibility is applied.","sha256":"514a6985016bf1c69f5d05c3cf16a40839f82a8e990e2cf6388d4d09176cbbbf","title":"Preference pairs: ineligible responses become pair endpoints · case 01","variant":1,"variant_policy":"The fixture code references N, supplied as 1 through 5. Fixed boundary checks may repeat. These records share one mechanism and must remain together in evaluation splits.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":28.238,"exit_code":1,"observations":[{"actual":["a1","b1"],"check":"excluded maximum","expected":["a1","b1"],"passed":true},{"actual":["a1","x1"],"check":"excluded minimum","expected":["a1","b1"],"passed":false},{"actual":null,"check":"one eligible","expected":null,"passed":true},{"actual":null,"check":"none eligible","expected":null,"passed":true},{"actual":null,"check":"empty","expected":null,"passed":true},{"actual":["a1","b1"],"check":"two eligible","expected":["a1","b1"],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"excluded maximum\", \"actual\": [\"a1\", \"b1\"], \"expected\": [\"a1\", \"b1\"], \"passed\": true}, {\"check\": \"excluded minimum\", \"actual\": [\"a1\", \"x1\"], \"expected\": [\"a1\", \"b1\"], \"passed\": false}, {\"check\": \"one eligible\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"none eligible\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"empty\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"two eligible\", \"actual\": [\"a1\", \"b1\"], \"expected\": [\"a1\", \"b1\"], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":27.887,"exit_code":1,"observations":[{"actual":["x1","b1"],"check":"excluded maximum","expected":["a1","b1"],"passed":false},{"actual":["a1","x1"],"check":"excluded minimum","expected":["a1","b1"],"passed":false},{"actual":["a1","x1"],"check":"one eligible","expected":null,"passed":false},{"actual":["a1","b1"],"check":"none eligible","expected":null,"passed":false},{"actual":null,"check":"empty","expected":null,"passed":true},{"actual":["a1","b1"],"check":"two eligible","expected":["a1","b1"],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"excluded maximum\", \"actual\": [\"x1\", \"b1\"], \"expected\": [\"a1\", \"b1\"], \"passed\": false}, {\"check\": \"excluded minimum\", \"actual\": [\"a1\", \"x1\"], \"expected\": [\"a1\", \"b1\"], \"passed\": false}, {\"check\": \"one eligible\", \"actual\": [\"a1\", \"x1\"], \"expected\": null, \"passed\": false}, {\"check\": \"none eligible\", \"actual\": [\"a1\", \"b1\"], \"expected\": null, \"passed\": false}, {\"check\": \"empty\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"two eligible\", \"actual\": [\"a1\", \"b1\"], \"expected\": [\"a1\", \"b1\"], \"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."}}