{"abstract":"Unknown worker IDs inflate a replica average.","category":"Distributed training aggregation","checks":6,"contract":"Given configured workers and [worker,value] rows, last listed value per eligible worker contributes; return mean or None.","contract_signature":"workers, rows","evaluation_group":"w3-dta-worker-membership","failed_approach":"Filtering membership but counting retries still inflates the average.","family":"w3-distributed-training-aggregation-worker-membership","id":"FA-99336","implementations":{"attempt":{"sha256":"561439b62eec91b92833bfa1f294e364449d815d39fa6220c374e427d8e07663","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(workers, rows):\n    valid=[(w,v) for w,v in rows if w in workers]; return sum(v for w,v in valid)/len(valid) if valid else None\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('foreign ignored',solve(['a','b'],[['a',N],['x',100*N]]),N)\ncheck('retry latest',solve(['a','b'],[['a',N],['a',3*N],['b',2*N]]),2.5*N)\ncheck('empty workers',solve([], [['x',N]]),None)\ncheck('empty rows',solve(['a'],[]),None)\ncheck('single worker',solve(['a'],[['a',N]]),N)\ncheck('unknown-only',solve(['a'],[['x',N],['y',2*N]]),None)\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":"338a7cdcb42e0927430c8e786d533412e79c9210d2748afaf67fd29ce787840d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(workers, rows):\n    return sum(v for w,v in rows)/len(rows) if rows else None\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('foreign ignored',solve(['a','b'],[['a',N],['x',100*N]]),N)\ncheck('retry latest',solve(['a','b'],[['a',N],['a',3*N],['b',2*N]]),2.5*N)\ncheck('empty workers',solve([], [['x',N]]),None)\ncheck('empty rows',solve(['a'],[]),None)\ncheck('single worker',solve(['a'],[['a',N]]),N)\ncheck('unknown-only',solve(['a'],[['x',N],['y',2*N]]),None)\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":"Inputs are already materialized Python values from a fixed toy collective; no transport, failure recovery, optimizer state, or real model behavior is represented. 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-distributed-training-aggregation-worker-membership","generated_at":"2026-09-30T16:48:23.079151+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A toy distributed-training contract makes replica and shard contribution rules explicit without claiming framework compatibility or performance.","root_cause":"A stale or malformed sender must not participate in the configured collective.","sha256":"039f66b9d7b67f17e0560ab1cf36115c5e8153ac7aed430961d815c47e874507","title":"Unknown worker IDs inflate a replica average · 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":28.691,"exit_code":1,"observations":[{"actual":1.0,"check":"foreign ignored","expected":1,"passed":true},{"actual":2.0,"check":"retry latest","expected":2.5,"passed":false},{"actual":null,"check":"empty workers","expected":null,"passed":true},{"actual":null,"check":"empty rows","expected":null,"passed":true},{"actual":1.0,"check":"single worker","expected":1,"passed":true},{"actual":null,"check":"unknown-only","expected":null,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"foreign ignored\", \"actual\": 1.0, \"expected\": 1, \"passed\": true}, {\"check\": \"retry latest\", \"actual\": 2.0, \"expected\": 2.5, \"passed\": false}, {\"check\": \"empty workers\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"empty rows\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"single worker\", \"actual\": 1.0, \"expected\": 1, \"passed\": true}, {\"check\": \"unknown-only\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":25.662,"exit_code":1,"observations":[{"actual":50.5,"check":"foreign ignored","expected":1,"passed":false},{"actual":2.0,"check":"retry latest","expected":2.5,"passed":false},{"actual":1.0,"check":"empty workers","expected":null,"passed":false},{"actual":null,"check":"empty rows","expected":null,"passed":true},{"actual":1.0,"check":"single worker","expected":1,"passed":true},{"actual":1.5,"check":"unknown-only","expected":null,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"foreign ignored\", \"actual\": 50.5, \"expected\": 1, \"passed\": false}, {\"check\": \"retry latest\", \"actual\": 2.0, \"expected\": 2.5, \"passed\": false}, {\"check\": \"empty workers\", \"actual\": 1.0, \"expected\": null, \"passed\": false}, {\"check\": \"empty rows\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"single worker\", \"actual\": 1.0, \"expected\": 1, \"passed\": true}, {\"check\": \"unknown-only\", \"actual\": 1.5, \"expected\": null, \"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."}}