{"abstract":"Explicit empty key violates retry transition semantics","category":"HTTP retries","checks":6,"contract":"begin(provided key or None,body) starts a logical operation and advances a local operation serial. Generated key is operation serial; explicit keys including zero remain exact. send(body) first sends only matching snapshotted body. uncertain authorizes a resend; reject is terminal; success is terminal. Retried sends reuse the initial key. Return sent key/body pairs or refusal reason.","contract_signature":"events","evaluation_group":"s3-http_retries-client-idempotency-key","failed_approach":"The attempted repair changes the faulty site to e[1]==0 but still violates a regression oracle.","family":"s3-http_retries-client-idempotency-key-explicit-empty-key","id":"FA-30736","implementations":{"attempt":{"sha256":"f3d565fc833b0ad597dcd9e333822e21356b11873ed31d03fdf2bc723a0d499a","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events):\n    serial=0; key=None; original=None; state='idle'; out=[]\n    for e in events:\n        if e[0]=='begin':\n            serial+=1\n            key=serial if e[1]==0 else e[1]\n            original=e[2]\n            state='ready'\n        elif e[0]=='send':\n            if state not in ('ready','uncertain'): out.append('blocked'); continue\n            if e[1]!=original: out.append('body-conflict'); continue\n            out.append([key,original])\n            state='sent'\n        elif e[0]=='uncertain':\n            if state=='sent': state='uncertain'\n        elif e[0]=='reject': state='rejected'\n        elif e[0]=='success':\n            if state=='sent': state='done'\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([]), [])\ncheck('1', solve([('begin',None,N),('send',N),('uncertain',),('send',N),('send',N),('success',),('uncertain',),('send',N)]), [[1,N],[1,N],'blocked','blocked'])\ncheck('2', solve([('begin',0,N),('send',N)]), [[0,N]])\ncheck('3', solve([('begin','customer-key',N),('send',N),('uncertain',),('send',N+1),('send',N)]), [['customer-key',N],'body-conflict',['customer-key',N]])\ncheck('4', solve([('begin',None,N),('send',N),('reject',),('uncertain',),('send',N),('begin',None,N+1),('send',N+1)]), [[1,N],'blocked',[2,N+1]])\ncheck('5', solve([('begin',None,N),('send',N+1),('send',N)]), ['body-conflict',[1,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":"03d504f7071306ab3a0f97b0128db36e07ec7efd37635eabbe91f2b20b2e8ecd","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events):\n    serial=0; key=None; original=None; state='idle'; out=[]\n    for e in events:\n        if e[0]=='begin':\n            serial+=1\n            key=serial if not e[1] else e[1]\n            original=e[2]\n            state='ready'\n        elif e[0]=='send':\n            if state not in ('ready','uncertain'): out.append('blocked'); continue\n            if e[1]!=original: out.append('body-conflict'); continue\n            out.append([key,original])\n            state='sent'\n        elif e[0]=='uncertain':\n            if state=='sent': state='uncertain'\n        elif e[0]=='reject': state='rejected'\n        elif e[0]=='success':\n            if state=='sent': state='done'\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([]), [])\ncheck('1', solve([('begin',None,N),('send',N),('uncertain',),('send',N),('send',N),('success',),('uncertain',),('send',N)]), [[1,N],[1,N],'blocked','blocked'])\ncheck('2', solve([('begin',0,N),('send',N)]), [[0,N]])\ncheck('3', solve([('begin','customer-key',N),('send',N),('uncertain',),('send',N+1),('send',N)]), [['customer-key',N],'body-conflict',['customer-key',N]])\ncheck('4', solve([('begin',None,N),('send',N),('reject',),('uncertain',),('send',N),('begin',None,N+1),('send',N+1)]), [[1,N],'blocked',[2,N+1]])\ncheck('5', solve([('begin',None,N),('send',N+1),('send',N)]), ['body-conflict',[1,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":"Stipulated bounded simulator, not a complete HTTP implementation or a standards conformance claim. 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":"s3-http_retries-client-idempotency-key-explicit-empty-key","generated_at":"2026-09-29T14:41:56.111686+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Offline deterministic model of HTTP request retries.","root_cause":"Explicit empty key violates retry transition semantics","sha256":"71abe7d4055cad08862c9f3a48af77a284af66f2034d7c826601d722df616519","title":"Stable client operation identity over retries: Explicit empty key violates retry transition semantics · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":40.797,"exit_code":1,"observations":[{"actual":[],"check":"0","expected":[],"passed":true},{"actual":[[null,1],[null,1],"blocked","blocked"],"check":"1","expected":[[1,1],[1,1],"blocked","blocked"],"passed":false},{"actual":[[1,1]],"check":"2","expected":[[0,1]],"passed":false},{"actual":[["customer-key",1],"body-conflict",["customer-key",1]],"check":"3","expected":[["customer-key",1],"body-conflict",["customer-key",1]],"passed":true},{"actual":[[null,1],"blocked",[null,2]],"check":"4","expected":[[1,1],"blocked",[2,2]],"passed":false},{"actual":["body-conflict",[null,1]],"check":"5","expected":["body-conflict",[1,1]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"1\", \"actual\": [[null, 1], [null, 1], \"blocked\", \"blocked\"], \"expected\": [[1, 1], [1, 1], \"blocked\", \"blocked\"], \"passed\": false}, {\"check\": \"2\", \"actual\": [[1, 1]], \"expected\": [[0, 1]], \"passed\": false}, {\"check\": \"3\", \"actual\": [[\"customer-key\", 1], \"body-conflict\", [\"customer-key\", 1]], \"expected\": [[\"customer-key\", 1], \"body-conflict\", [\"customer-key\", 1]], \"passed\": true}, {\"check\": \"4\", \"actual\": [[null, 1], \"blocked\", [null, 2]], \"expected\": [[1, 1], \"blocked\", [2, 2]], \"passed\": false}, {\"check\": \"5\", \"actual\": [\"body-conflict\", [null, 1]], \"expected\": [\"body-conflict\", [1, 1]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":41.484,"exit_code":1,"observations":[{"actual":[],"check":"0","expected":[],"passed":true},{"actual":[[1,1],[1,1],"blocked","blocked"],"check":"1","expected":[[1,1],[1,1],"blocked","blocked"],"passed":true},{"actual":[[1,1]],"check":"2","expected":[[0,1]],"passed":false},{"actual":[["customer-key",1],"body-conflict",["customer-key",1]],"check":"3","expected":[["customer-key",1],"body-conflict",["customer-key",1]],"passed":true},{"actual":[[1,1],"blocked",[2,2]],"check":"4","expected":[[1,1],"blocked",[2,2]],"passed":true},{"actual":["body-conflict",[1,1]],"check":"5","expected":["body-conflict",[1,1]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"1\", \"actual\": [[1, 1], [1, 1], \"blocked\", \"blocked\"], \"expected\": [[1, 1], [1, 1], \"blocked\", \"blocked\"], \"passed\": true}, {\"check\": \"2\", \"actual\": [[1, 1]], \"expected\": [[0, 1]], \"passed\": false}, {\"check\": \"3\", \"actual\": [[\"customer-key\", 1], \"body-conflict\", [\"customer-key\", 1]], \"expected\": [[\"customer-key\", 1], \"body-conflict\", [\"customer-key\", 1]], \"passed\": true}, {\"check\": \"4\", \"actual\": [[1, 1], \"blocked\", [2, 2]], \"expected\": [[1, 1], \"blocked\", [2, 2]], \"passed\": true}, {\"check\": \"5\", \"actual\": [\"body-conflict\", [1, 1]], \"expected\": [\"body-conflict\", [1, 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."}}