{"abstract":"Retransmitted replica updates contribute more than once.","category":"Distributed training aggregation","checks":7,"contract":"Rows [step,worker,value], target step; last row for each worker at that step wins, then values sum.","contract_signature":"rows, step","evaluation_group":"w3-dta-replica-deduplicate","failed_approach":"Deduplicating by worker alone suppresses legitimate contributions from another step.","family":"w3-distributed-training-aggregation-replica-deduplicate","id":"FA-99296","implementations":{"attempt":{"sha256":"3d4c8373d7b0346a8e44a37001b04f5d60bb73cbb7563bb16e7d16184396cae9","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows, step):\n    d={}\n    for s,w,v in rows: d[w]=(s,v)\n    return sum(v for s,v in d.values() if s==step)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr=[[N,'a',N],[N,'a',3*N],[N,'b',2*N]]\ncheck('retry replaces',solve(r,N),5*N)\ncheck('empty',solve([],N),0)\ncheck('other step',solve([[N+1,'a',9*N]],N),0)\ncheck('same worker different steps',solve([[N-1,'a',100],[N,'a',N]],N),N)\ncheck('singleton',solve([[N,'a',4]] ,N),4)\ncheck('last zero retry',solve([[N,'a',N],[N,'a',0]],N),0)\ncheck('stale retry after current',solve([[N,'a',N],[N-1,'a',50*N]],N),N)\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":"96421dcb384a4b6a2006a2087ca3041949d39e58e57d4abf69a8dba857d88ea5","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(rows, step):\n    return sum(v for s,w,v in rows if s==step)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr=[[N,'a',N],[N,'a',3*N],[N,'b',2*N]]\ncheck('retry replaces',solve(r,N),5*N)\ncheck('empty',solve([],N),0)\ncheck('other step',solve([[N+1,'a',9*N]],N),0)\ncheck('same worker different steps',solve([[N-1,'a',100],[N,'a',N]],N),N)\ncheck('singleton',solve([[N,'a',4]] ,N),4)\ncheck('last zero retry',solve([[N,'a',N],[N,'a',0]],N),0)\ncheck('stale retry after current',solve([[N,'a',N],[N-1,'a',50*N]],N),N)\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-replica-deduplicate","generated_at":"2026-09-30T16:48:22.633137+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":"Collective retries can deliver the same worker and step more than once.","sha256":"70ae321b5225d806940a88be4a583791b3083751906fd7575db60886bb0e921d","title":"Retransmitted replica updates contribute more than once · 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":28.484,"exit_code":1,"observations":[{"actual":5,"check":"retry replaces","expected":5,"passed":true},{"actual":0,"check":"empty","expected":0,"passed":true},{"actual":0,"check":"other step","expected":0,"passed":true},{"actual":1,"check":"same worker different steps","expected":1,"passed":true},{"actual":4,"check":"singleton","expected":4,"passed":true},{"actual":0,"check":"last zero retry","expected":0,"passed":true},{"actual":0,"check":"stale retry after current","expected":1,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"retry replaces\", \"actual\": 5, \"expected\": 5, \"passed\": true}, {\"check\": \"empty\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"other step\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"same worker different steps\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"singleton\", \"actual\": 4, \"expected\": 4, \"passed\": true}, {\"check\": \"last zero retry\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"stale retry after current\", \"actual\": 0, \"expected\": 1, \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":28.168,"exit_code":1,"observations":[{"actual":6,"check":"retry replaces","expected":5,"passed":false},{"actual":0,"check":"empty","expected":0,"passed":true},{"actual":0,"check":"other step","expected":0,"passed":true},{"actual":1,"check":"same worker different steps","expected":1,"passed":true},{"actual":4,"check":"singleton","expected":4,"passed":true},{"actual":1,"check":"last zero retry","expected":0,"passed":false},{"actual":1,"check":"stale retry after current","expected":1,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"retry replaces\", \"actual\": 6, \"expected\": 5, \"passed\": false}, {\"check\": \"empty\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"other step\", \"actual\": 0, \"expected\": 0, \"passed\": true}, {\"check\": \"same worker different steps\", \"actual\": 1, \"expected\": 1, \"passed\": true}, {\"check\": \"singleton\", \"actual\": 4, \"expected\": 4, \"passed\": true}, {\"check\": \"last zero retry\", \"actual\": 1, \"expected\": 0, \"passed\": false}, {\"check\": \"stale retry after current\", \"actual\": 1, \"expected\": 1, \"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."}}