{"abstract":"finished hypotheses are discarded at the next timestep.","category":"Beam search bookkeeping","checks":6,"contract":"Return prior finished rows followed by new completion rows, retaining all hypotheses.","contract_signature":"finished, newly_finished","evaluation_group":"model-b8efe79624d877b4","failed_approach":"Appending only the highest-scoring new completion can still discard a better earlier result.","family":"w3-beam-search-bookkeeping-finished-pool-retention","id":"FA-98471","implementations":{"attempt":{"sha256":"753c94ff81b6cca9d17c302747d065ee086b9f1e78211af05ba67c4f9cf9542a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(finished, newly_finished):\n    return list(finished)+sorted(newly_finished,key=lambda r:-r[1])[:1]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('preserve earlier completion',solve([['old',N]],[['new',N+1]]),[['old',N],['new',N+1]])\ncheck('no new completion',solve([['old',N]],[]),[['old',N]])\ncheck('empty pools',solve([],[]),[])\ncheck('two prior paths',solve([['a',1],['b',2]],[['c',3]]),[['a',1],['b',2],['c',3]])\ncheck('two new paths',solve([],[['c',3],['d',4]]),[['c',3],['d',4]])\ncheck('scores do not replace identity',solve([[str(N),N]],[[str(N+1),N+1]]),[[str(N),N],[str(N+1),N+1]])\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":"ade2ea79839aa2b4c56b66af5e8c481a2c0de1041d6121374cba09dcde906537","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(finished, newly_finished):\n    return list(newly_finished)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('preserve earlier completion',solve([['old',N]],[['new',N+1]]),[['old',N],['new',N+1]])\ncheck('no new completion',solve([['old',N]],[]),[['old',N]])\ncheck('empty pools',solve([],[]),[])\ncheck('two prior paths',solve([['a',1],['b',2]],[['c',3]]),[['a',1],['b',2],['c',3]])\ncheck('two new paths',solve([],[['c',3],['d',4]]),[['c',3],['d',4]])\ncheck('scores do not replace identity',solve([[str(N),N]],[[str(N+1),N+1]]),[[str(N),N],[str(N+1),N+1]])\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 is a finite toy beam-state contract and makes no claim about neural model quality or production decoding. 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-beam-search-bookkeeping-finished-pool-retention","generated_at":"2026-09-30T16:48:13.239141+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Beam decoders rely on consistent hypothesis state while expanding and ranking candidates.","root_cause":"The update replaces the finished pool with completions from only the latest step.","sha256":"f38fa42fb996f5ceda090aed6496e4c09de90225654ceed878d793dd54233e74","title":"Beam search: finished hypotheses are discarded at the next timestep · 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":28.52,"exit_code":1,"observations":[{"actual":[["old",1],["new",2]],"check":"preserve earlier completion","expected":[["old",1],["new",2]],"passed":true},{"actual":[["old",1]],"check":"no new completion","expected":[["old",1]],"passed":true},{"actual":[],"check":"empty pools","expected":[],"passed":true},{"actual":[["a",1],["b",2],["c",3]],"check":"two prior paths","expected":[["a",1],["b",2],["c",3]],"passed":true},{"actual":[["d",4]],"check":"two new paths","expected":[["c",3],["d",4]],"passed":false},{"actual":[["1",1],["2",2]],"check":"scores do not replace identity","expected":[["1",1],["2",2]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"preserve earlier completion\", \"actual\": [[\"old\", 1], [\"new\", 2]], \"expected\": [[\"old\", 1], [\"new\", 2]], \"passed\": true}, {\"check\": \"no new completion\", \"actual\": [[\"old\", 1]], \"expected\": [[\"old\", 1]], \"passed\": true}, {\"check\": \"empty pools\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"two prior paths\", \"actual\": [[\"a\", 1], [\"b\", 2], [\"c\", 3]], \"expected\": [[\"a\", 1], [\"b\", 2], [\"c\", 3]], \"passed\": true}, {\"check\": \"two new paths\", \"actual\": [[\"d\", 4]], \"expected\": [[\"c\", 3], [\"d\", 4]], \"passed\": false}, {\"check\": \"scores do not replace identity\", \"actual\": [[\"1\", 1], [\"2\", 2]], \"expected\": [[\"1\", 1], [\"2\", 2]], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":25.622,"exit_code":1,"observations":[{"actual":[["new",2]],"check":"preserve earlier completion","expected":[["old",1],["new",2]],"passed":false},{"actual":[],"check":"no new completion","expected":[["old",1]],"passed":false},{"actual":[],"check":"empty pools","expected":[],"passed":true},{"actual":[["c",3]],"check":"two prior paths","expected":[["a",1],["b",2],["c",3]],"passed":false},{"actual":[["c",3],["d",4]],"check":"two new paths","expected":[["c",3],["d",4]],"passed":true},{"actual":[["2",2]],"check":"scores do not replace identity","expected":[["1",1],["2",2]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"preserve earlier completion\", \"actual\": [[\"new\", 2]], \"expected\": [[\"old\", 1], [\"new\", 2]], \"passed\": false}, {\"check\": \"no new completion\", \"actual\": [], \"expected\": [[\"old\", 1]], \"passed\": false}, {\"check\": \"empty pools\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"two prior paths\", \"actual\": [[\"c\", 3]], \"expected\": [[\"a\", 1], [\"b\", 2], [\"c\", 3]], \"passed\": false}, {\"check\": \"two new paths\", \"actual\": [[\"c\", 3], [\"d\", 4]], \"expected\": [[\"c\", 3], [\"d\", 4]], \"passed\": true}, {\"check\": \"scores do not replace identity\", \"actual\": [[\"2\", 2]], \"expected\": [[\"1\", 1], [\"2\", 2]], \"passed\": false}], \"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."}}