{"abstract":"Retry generation violates retry transition semantics","category":"HTTP retries","checks":12,"contract":"begin resets generation and final result. launch creates next active generation; response(generation,status,payload) accepts only current active attempt. A 2xx result completes immediately, retryable statuses 429/503 leave logical request pending with a retry token, other statuses terminally fail. retry consumes token to launch next attempt. cancel wins if no final result. Once final, every later event except begin is ignored. Return result and number of attempts launched.","evaluation_group":"s3-http_retries-retry-result-arbitration","failed_approach":"The attempted repair changes the faulty site to token=False; generation+=2 but still violates a regression oracle.","family":"s3-http_retries-retry-result-arbitration-retry-generation","id":"FA-30666","implementations":{"attempt":{"sha256":"66c4130d76aa56ed559ae9d34e52b9803bcc39331ad1b8c9ca4f2808bea8860c","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events):\n    generation=0; active=False; token=False; result=None\n    for e in events:\n        if e[0]=='begin': generation=0; active=False; token=False; result=None; continue\n        if result is not None: continue\n        if e[0]=='launch':\n            if active or generation!=0: continue\n            generation+=1; active=True\n        elif e[0]=='response':\n            if not active or e[1]!=generation: continue\n            active=False\n            if 200<=e[2]<300: result=['success',e[3]]\n            elif e[2] in (429,503): token=True\n            else: result=['failure',e[2]]\n        elif e[0]=='retry':\n            if not token or active: continue\n            token=False; generation+=2; active=True\n        elif e[0]=='cancel':\n            result=['cancelled',None]; active=False; token=False\n    return [result,generation]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([]), [None,0])\ncheck('1', solve([('begin',),('launch',),('response',1,200,N),('cancel',),('launch',)]), [['success',N],1])\ncheck('2', solve([('begin',),('launch',),('response',1,503,0),('launch',),('retry',),('response',1,200,0),('response',3,200,0),('response',2,204,N)]), [['success',N],2])\ncheck('3', solve([('launch',),('response',1,429,0),('response',1,200,N),('retry',),('response',2,400,N),('cancel',)]), [['failure',400],2])\ncheck('4', solve([('launch',),('cancel',),('response',1,200,N),('retry',)]), [['cancelled',None],1])\ncheck('5', solve([('retry',),('launch',),('response',1,300,N)]), [['failure',300],1])\ncheck('6', solve([('launch',),('response',1,199,N)]), [['failure',199],1])\ncheck('7', solve([('launch',),('response',1,500,N)]), [['failure',500],1])\ncheck('8', solve([('launch',),('response',1,200,0),('begin',),('launch',),('response',1,201,N)]), [['success',N],1])\ncheck('9', solve([('launch',),('response',1,503,N),('launch',)]), [None,1])\ncheck('10', solve([('launch',),('launch',)]), [None,1])\ncheck('11', solve([('retry',)]), [None,0])\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":"b6c4f1edfe1db80c6c31f7c7faa909974ffc7e558253a4614845f51f56730c1c","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events):\n    generation=0; active=False; token=False; result=None\n    for e in events:\n        if e[0]=='begin': generation=0; active=False; token=False; result=None; continue\n        if result is not None: continue\n        if e[0]=='launch':\n            if active or generation!=0: continue\n            generation+=1; active=True\n        elif e[0]=='response':\n            if not active or e[1]!=generation: continue\n            active=False\n            if 200<=e[2]<300: result=['success',e[3]]\n            elif e[2] in (429,503): token=True\n            else: result=['failure',e[2]]\n        elif e[0]=='retry':\n            if not token or active: continue\n            token=False; generation=1; active=True\n        elif e[0]=='cancel':\n            result=['cancelled',None]; active=False; token=False\n    return [result,generation]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([]), [None,0])\ncheck('1', solve([('begin',),('launch',),('response',1,200,N),('cancel',),('launch',)]), [['success',N],1])\ncheck('2', solve([('begin',),('launch',),('response',1,503,0),('launch',),('retry',),('response',1,200,0),('response',3,200,0),('response',2,204,N)]), [['success',N],2])\ncheck('3', solve([('launch',),('response',1,429,0),('response',1,200,N),('retry',),('response',2,400,N),('cancel',)]), [['failure',400],2])\ncheck('4', solve([('launch',),('cancel',),('response',1,200,N),('retry',)]), [['cancelled',None],1])\ncheck('5', solve([('retry',),('launch',),('response',1,300,N)]), [['failure',300],1])\ncheck('6', solve([('launch',),('response',1,199,N)]), [['failure',199],1])\ncheck('7', solve([('launch',),('response',1,500,N)]), [['failure',500],1])\ncheck('8', solve([('launch',),('response',1,200,0),('begin',),('launch',),('response',1,201,N)]), [['success',N],1])\ncheck('9', solve([('launch',),('response',1,503,N),('launch',)]), [None,1])\ncheck('10', solve([('launch',),('launch',)]), [None,1])\ncheck('11', solve([('retry',)]), [None,0])\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"},"fixed":{"sha256":"86ade7e878686193203b8b1bb9f1ed9316522aa24991ef6790fc52798a3aa5be","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events):\n    generation=0; active=False; token=False; result=None\n    for e in events:\n        if e[0]=='begin': generation=0; active=False; token=False; result=None; continue\n        if result is not None: continue\n        if e[0]=='launch':\n            if active or generation!=0: continue\n            generation+=1; active=True\n        elif e[0]=='response':\n            if not active or e[1]!=generation: continue\n            active=False\n            if 200<=e[2]<300: result=['success',e[3]]\n            elif e[2] in (429,503): token=True\n            else: result=['failure',e[2]]\n        elif e[0]=='retry':\n            if not token or active: continue\n            token=False; generation+=1; active=True\n        elif e[0]=='cancel':\n            result=['cancelled',None]; active=False; token=False\n    return [result,generation]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([]), [None,0])\ncheck('1', solve([('begin',),('launch',),('response',1,200,N),('cancel',),('launch',)]), [['success',N],1])\ncheck('2', solve([('begin',),('launch',),('response',1,503,0),('launch',),('retry',),('response',1,200,0),('response',3,200,0),('response',2,204,N)]), [['success',N],2])\ncheck('3', solve([('launch',),('response',1,429,0),('response',1,200,N),('retry',),('response',2,400,N),('cancel',)]), [['failure',400],2])\ncheck('4', solve([('launch',),('cancel',),('response',1,200,N),('retry',)]), [['cancelled',None],1])\ncheck('5', solve([('retry',),('launch',),('response',1,300,N)]), [['failure',300],1])\ncheck('6', solve([('launch',),('response',1,199,N)]), [['failure',199],1])\ncheck('7', solve([('launch',),('response',1,500,N)]), [['failure',500],1])\ncheck('8', solve([('launch',),('response',1,200,0),('begin',),('launch',),('response',1,201,N)]), [['success',N],1])\ncheck('9', solve([('launch',),('response',1,503,N),('launch',)]), [None,1])\ncheck('10', solve([('launch',),('launch',)]), [None,1])\ncheck('11', solve([('retry',)]), [None,0])\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-retry-result-arbitration-retry-generation","generated_at":"2026-09-29T14:41:54.954093+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Offline deterministic model of HTTP request retries.","repair":"Restore the specified transition token=False; generation+=1.","root_cause":"Retry generation violates retry transition semantics","sha256":"e5e93da1b9d5085e50570a12ed2ced4d5fe353b00170dce3d0f01874d94e82c3","title":"Exactly one logical request completion: Retry generation violates retry transition semantics · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":39.822,"exit_code":1,"observations":[{"actual":[null,0],"check":"0","expected":[null,0],"passed":true},{"actual":[["success",1],1],"check":"1","expected":[["success",1],1],"passed":true},{"actual":[["success",0],3],"check":"2","expected":[["success",1],2],"passed":false},{"actual":[["cancelled",null],3],"check":"3","expected":[["failure",400],2],"passed":false},{"actual":[["cancelled",null],1],"check":"4","expected":[["cancelled",null],1],"passed":true},{"actual":[["failure",300],1],"check":"5","expected":[["failure",300],1],"passed":true},{"actual":[["failure",199],1],"check":"6","expected":[["failure",199],1],"passed":true},{"actual":[["failure",500],1],"check":"7","expected":[["failure",500],1],"passed":true},{"actual":[["success",1],1],"check":"8","expected":[["success",1],1],"passed":true},{"actual":[null,1],"check":"9","expected":[null,1],"passed":true},{"actual":[null,1],"check":"10","expected":[null,1],"passed":true},{"actual":[null,0],"check":"11","expected":[null,0],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [null, 0], \"expected\": [null, 0], \"passed\": true}, {\"check\": \"1\", \"actual\": [[\"success\", 1], 1], \"expected\": [[\"success\", 1], 1], \"passed\": true}, {\"check\": \"2\", \"actual\": [[\"success\", 0], 3], \"expected\": [[\"success\", 1], 2], \"passed\": false}, {\"check\": \"3\", \"actual\": [[\"cancelled\", null], 3], \"expected\": [[\"failure\", 400], 2], \"passed\": false}, {\"check\": \"4\", \"actual\": [[\"cancelled\", null], 1], \"expected\": [[\"cancelled\", null], 1], \"passed\": true}, {\"check\": \"5\", \"actual\": [[\"failure\", 300], 1], \"expected\": [[\"failure\", 300], 1], \"passed\": true}, {\"check\": \"6\", \"actual\": [[\"failure\", 199], 1], \"expected\": [[\"failure\", 199], 1], \"passed\": true}, {\"check\": \"7\", \"actual\": [[\"failure\", 500], 1], \"expected\": [[\"failure\", 500], 1], \"passed\": true}, {\"check\": \"8\", \"actual\": [[\"success\", 1], 1], \"expected\": [[\"success\", 1], 1], \"passed\": true}, {\"check\": \"9\", \"actual\": [null, 1], \"expected\": [null, 1], \"passed\": true}, {\"check\": \"10\", \"actual\": [null, 1], \"expected\": [null, 1], \"passed\": true}, {\"check\": \"11\", \"actual\": [null, 0], \"expected\": [null, 0], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":40.487,"exit_code":1,"observations":[{"actual":[null,0],"check":"0","expected":[null,0],"passed":true},{"actual":[["success",1],1],"check":"1","expected":[["success",1],1],"passed":true},{"actual":[["success",0],1],"check":"2","expected":[["success",1],2],"passed":false},{"actual":[["cancelled",null],1],"check":"3","expected":[["failure",400],2],"passed":false},{"actual":[["cancelled",null],1],"check":"4","expected":[["cancelled",null],1],"passed":true},{"actual":[["failure",300],1],"check":"5","expected":[["failure",300],1],"passed":true},{"actual":[["failure",199],1],"check":"6","expected":[["failure",199],1],"passed":true},{"actual":[["failure",500],1],"check":"7","expected":[["failure",500],1],"passed":true},{"actual":[["success",1],1],"check":"8","expected":[["success",1],1],"passed":true},{"actual":[null,1],"check":"9","expected":[null,1],"passed":true},{"actual":[null,1],"check":"10","expected":[null,1],"passed":true},{"actual":[null,0],"check":"11","expected":[null,0],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [null, 0], \"expected\": [null, 0], \"passed\": true}, {\"check\": \"1\", \"actual\": [[\"success\", 1], 1], \"expected\": [[\"success\", 1], 1], \"passed\": true}, {\"check\": \"2\", \"actual\": [[\"success\", 0], 1], \"expected\": [[\"success\", 1], 2], \"passed\": false}, {\"check\": \"3\", \"actual\": [[\"cancelled\", null], 1], \"expected\": [[\"failure\", 400], 2], \"passed\": false}, {\"check\": \"4\", \"actual\": [[\"cancelled\", null], 1], \"expected\": [[\"cancelled\", null], 1], \"passed\": true}, {\"check\": \"5\", \"actual\": [[\"failure\", 300], 1], \"expected\": [[\"failure\", 300], 1], \"passed\": true}, {\"check\": \"6\", \"actual\": [[\"failure\", 199], 1], \"expected\": [[\"failure\", 199], 1], \"passed\": true}, {\"check\": \"7\", \"actual\": [[\"failure\", 500], 1], \"expected\": [[\"failure\", 500], 1], \"passed\": true}, {\"check\": \"8\", \"actual\": [[\"success\", 1], 1], \"expected\": [[\"success\", 1], 1], \"passed\": true}, {\"check\": \"9\", \"actual\": [null, 1], \"expected\": [null, 1], \"passed\": true}, {\"check\": \"10\", \"actual\": [null, 1], \"expected\": [null, 1], \"passed\": true}, {\"check\": \"11\", \"actual\": [null, 0], \"expected\": [null, 0], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":39.228,"exit_code":0,"observations":[{"actual":[null,0],"check":"0","expected":[null,0],"passed":true},{"actual":[["success",1],1],"check":"1","expected":[["success",1],1],"passed":true},{"actual":[["success",1],2],"check":"2","expected":[["success",1],2],"passed":true},{"actual":[["failure",400],2],"check":"3","expected":[["failure",400],2],"passed":true},{"actual":[["cancelled",null],1],"check":"4","expected":[["cancelled",null],1],"passed":true},{"actual":[["failure",300],1],"check":"5","expected":[["failure",300],1],"passed":true},{"actual":[["failure",199],1],"check":"6","expected":[["failure",199],1],"passed":true},{"actual":[["failure",500],1],"check":"7","expected":[["failure",500],1],"passed":true},{"actual":[["success",1],1],"check":"8","expected":[["success",1],1],"passed":true},{"actual":[null,1],"check":"9","expected":[null,1],"passed":true},{"actual":[null,1],"check":"10","expected":[null,1],"passed":true},{"actual":[null,0],"check":"11","expected":[null,0],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [null, 0], \"expected\": [null, 0], \"passed\": true}, {\"check\": \"1\", \"actual\": [[\"success\", 1], 1], \"expected\": [[\"success\", 1], 1], \"passed\": true}, {\"check\": \"2\", \"actual\": [[\"success\", 1], 2], \"expected\": [[\"success\", 1], 2], \"passed\": true}, {\"check\": \"3\", \"actual\": [[\"failure\", 400], 2], \"expected\": [[\"failure\", 400], 2], \"passed\": true}, {\"check\": \"4\", \"actual\": [[\"cancelled\", null], 1], \"expected\": [[\"cancelled\", null], 1], \"passed\": true}, {\"check\": \"5\", \"actual\": [[\"failure\", 300], 1], \"expected\": [[\"failure\", 300], 1], \"passed\": true}, {\"check\": \"6\", \"actual\": [[\"failure\", 199], 1], \"expected\": [[\"failure\", 199], 1], \"passed\": true}, {\"check\": \"7\", \"actual\": [[\"failure\", 500], 1], \"expected\": [[\"failure\", 500], 1], \"passed\": true}, {\"check\": \"8\", \"actual\": [[\"success\", 1], 1], \"expected\": [[\"success\", 1], 1], \"passed\": true}, {\"check\": \"9\", \"actual\": [null, 1], \"expected\": [null, 1], \"passed\": true}, {\"check\": \"10\", \"actual\": [null, 1], \"expected\": [null, 1], \"passed\": true}, {\"check\": \"11\", \"actual\": [null, 0], \"expected\": [null, 0], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}