{"abstract":"Zero denial violates retry transition semantics","category":"HTTP retries","checks":9,"contract":"configure(capacity) resets a shared retry pool. reserve(request) consumes one token only for a new reservation; commit spends its token and removes the reservation, abort refunds exactly once, refill is capped. Repeated reserve is idempotent; unknown commit/abort does nothing. Return admissions and available token count.","contract_signature":"events","evaluation_group":"s3-http_retries-budget-reservations","failed_approach":"The attempted repair changes the faulty site to if available<=1: but still violates a regression oracle.","family":"s3-http_retries-budget-reservations-zero-denial","id":"FA-29891","implementations":{"attempt":{"sha256":"65134dc75f70e9cc39cd3723e1466e4894509cb33251613c3fcb325673d89b61","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events):\n    capacity=0; available=0; held=set(); out=[]\n    for e in events:\n        if e[0]=='configure':\n            capacity=e[1]; available=capacity; held.clear()\n        elif e[0]=='reserve':\n            if e[1] in held: out.append('held'); continue\n            if available<=1: out.append('denied'); continue\n            available-=1\n            held.add(e[1])\n            out.append('reserved')\n        elif e[0]=='commit':\n            if e[1] in held:\n                held.remove(e[1])\n        elif e[0]=='abort':\n            if e[1] in held:\n                held.remove(e[1])\n                available=min(capacity,available+1)\n        elif e[0]=='refill':\n            available=min(capacity-len(held),available+e[1])\n    return [out,available,sorted(held)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([('configure',3),('reserve','a'),('reserve','b'),('abort','a')]), [['reserved','reserved'],2,['b']])\ncheck('1', solve([('configure',3),('reserve','a'),('commit','a'),('reserve','a'),('commit','a'),('reserve','a'),('commit','a'),('refill',2)]), [['reserved','reserved','reserved'],2,[]])\ncheck('2', solve([]), [[],0,[]])\ncheck('3', solve([('configure',0),('reserve','a')]), [['denied'],0,[]])\ncheck('4', solve([('configure',2),('reserve','a'),('reserve','a'),('reserve','b'),('reserve','c')]), [['reserved','held','reserved','denied'],0,['a','b']])\ncheck('5', solve([('configure',3),('reserve','a'),('reserve','b'),('commit','a'),('abort','a'),('abort','b'),('abort','b')]), [['reserved','reserved'],2,[]])\ncheck('6', solve([('configure',N+3),('reserve','a'),('refill',N+10)]), [['reserved'],N+2,['a']])\ncheck('7', solve([('configure',4),('reserve','a'),('commit','a'),('reserve','b'),('commit','b'),('refill',1)]), [['reserved','reserved'],3,[]])\ncheck('8', solve([('configure',1),('reserve','a'),('configure',2),('reserve','a')]), [['reserved','reserved'],1,['a']])\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":"265c0b43e23ffe26c7a76ea34f00c76a4f0f4e30cb56e171be0e901806108303","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events):\n    capacity=0; available=0; held=set(); out=[]\n    for e in events:\n        if e[0]=='configure':\n            capacity=e[1]; available=capacity; held.clear()\n        elif e[0]=='reserve':\n            if e[1] in held: out.append('held'); continue\n            if available<0: out.append('denied'); continue\n            available-=1\n            held.add(e[1])\n            out.append('reserved')\n        elif e[0]=='commit':\n            if e[1] in held:\n                held.remove(e[1])\n        elif e[0]=='abort':\n            if e[1] in held:\n                held.remove(e[1])\n                available=min(capacity,available+1)\n        elif e[0]=='refill':\n            available=min(capacity-len(held),available+e[1])\n    return [out,available,sorted(held)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('0', solve([('configure',3),('reserve','a'),('reserve','b'),('abort','a')]), [['reserved','reserved'],2,['b']])\ncheck('1', solve([('configure',3),('reserve','a'),('commit','a'),('reserve','a'),('commit','a'),('reserve','a'),('commit','a'),('refill',2)]), [['reserved','reserved','reserved'],2,[]])\ncheck('2', solve([]), [[],0,[]])\ncheck('3', solve([('configure',0),('reserve','a')]), [['denied'],0,[]])\ncheck('4', solve([('configure',2),('reserve','a'),('reserve','a'),('reserve','b'),('reserve','c')]), [['reserved','held','reserved','denied'],0,['a','b']])\ncheck('5', solve([('configure',3),('reserve','a'),('reserve','b'),('commit','a'),('abort','a'),('abort','b'),('abort','b')]), [['reserved','reserved'],2,[]])\ncheck('6', solve([('configure',N+3),('reserve','a'),('refill',N+10)]), [['reserved'],N+2,['a']])\ncheck('7', solve([('configure',4),('reserve','a'),('commit','a'),('reserve','b'),('commit','b'),('refill',1)]), [['reserved','reserved'],3,[]])\ncheck('8', solve([('configure',1),('reserve','a'),('configure',2),('reserve','a')]), [['reserved','reserved'],1,['a']])\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-budget-reservations-zero-denial","generated_at":"2026-09-29T14:41:48.185976+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":"Zero denial violates retry transition semantics","sha256":"1d5b6832de4ec77df580db0bb35e23156887886cdeada77ddc88ac46e7db81f3","title":"Retry budget reservation lifecycle: Zero denial 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":42.232,"exit_code":1,"observations":[{"actual":[["reserved","reserved"],2,["b"]],"check":"0","expected":[["reserved","reserved"],2,["b"]],"passed":true},{"actual":[["reserved","reserved","denied"],3,[]],"check":"1","expected":[["reserved","reserved","reserved"],2,[]],"passed":false},{"actual":[[],0,[]],"check":"2","expected":[[],0,[]],"passed":true},{"actual":[["denied"],0,[]],"check":"3","expected":[["denied"],0,[]],"passed":true},{"actual":[["reserved","held","denied","denied"],1,["a"]],"check":"4","expected":[["reserved","held","reserved","denied"],0,["a","b"]],"passed":false},{"actual":[["reserved","reserved"],2,[]],"check":"5","expected":[["reserved","reserved"],2,[]],"passed":true},{"actual":[["reserved"],3,["a"]],"check":"6","expected":[["reserved"],3,["a"]],"passed":true},{"actual":[["reserved","reserved"],3,[]],"check":"7","expected":[["reserved","reserved"],3,[]],"passed":true},{"actual":[["denied","reserved"],1,["a"]],"check":"8","expected":[["reserved","reserved"],1,["a"]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [[\"reserved\", \"reserved\"], 2, [\"b\"]], \"expected\": [[\"reserved\", \"reserved\"], 2, [\"b\"]], \"passed\": true}, {\"check\": \"1\", \"actual\": [[\"reserved\", \"reserved\", \"denied\"], 3, []], \"expected\": [[\"reserved\", \"reserved\", \"reserved\"], 2, []], \"passed\": false}, {\"check\": \"2\", \"actual\": [[], 0, []], \"expected\": [[], 0, []], \"passed\": true}, {\"check\": \"3\", \"actual\": [[\"denied\"], 0, []], \"expected\": [[\"denied\"], 0, []], \"passed\": true}, {\"check\": \"4\", \"actual\": [[\"reserved\", \"held\", \"denied\", \"denied\"], 1, [\"a\"]], \"expected\": [[\"reserved\", \"held\", \"reserved\", \"denied\"], 0, [\"a\", \"b\"]], \"passed\": false}, {\"check\": \"5\", \"actual\": [[\"reserved\", \"reserved\"], 2, []], \"expected\": [[\"reserved\", \"reserved\"], 2, []], \"passed\": true}, {\"check\": \"6\", \"actual\": [[\"reserved\"], 3, [\"a\"]], \"expected\": [[\"reserved\"], 3, [\"a\"]], \"passed\": true}, {\"check\": \"7\", \"actual\": [[\"reserved\", \"reserved\"], 3, []], \"expected\": [[\"reserved\", \"reserved\"], 3, []], \"passed\": true}, {\"check\": \"8\", \"actual\": [[\"denied\", \"reserved\"], 1, [\"a\"]], \"expected\": [[\"reserved\", \"reserved\"], 1, [\"a\"]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":45.82,"exit_code":1,"observations":[{"actual":[["reserved","reserved"],2,["b"]],"check":"0","expected":[["reserved","reserved"],2,["b"]],"passed":true},{"actual":[["reserved","reserved","reserved"],2,[]],"check":"1","expected":[["reserved","reserved","reserved"],2,[]],"passed":true},{"actual":[[],0,[]],"check":"2","expected":[[],0,[]],"passed":true},{"actual":[["reserved"],-1,["a"]],"check":"3","expected":[["denied"],0,[]],"passed":false},{"actual":[["reserved","held","reserved","reserved"],-1,["a","b","c"]],"check":"4","expected":[["reserved","held","reserved","denied"],0,["a","b"]],"passed":false},{"actual":[["reserved","reserved"],2,[]],"check":"5","expected":[["reserved","reserved"],2,[]],"passed":true},{"actual":[["reserved"],3,["a"]],"check":"6","expected":[["reserved"],3,["a"]],"passed":true},{"actual":[["reserved","reserved"],3,[]],"check":"7","expected":[["reserved","reserved"],3,[]],"passed":true},{"actual":[["reserved","reserved"],1,["a"]],"check":"8","expected":[["reserved","reserved"],1,["a"]],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"0\", \"actual\": [[\"reserved\", \"reserved\"], 2, [\"b\"]], \"expected\": [[\"reserved\", \"reserved\"], 2, [\"b\"]], \"passed\": true}, {\"check\": \"1\", \"actual\": [[\"reserved\", \"reserved\", \"reserved\"], 2, []], \"expected\": [[\"reserved\", \"reserved\", \"reserved\"], 2, []], \"passed\": true}, {\"check\": \"2\", \"actual\": [[], 0, []], \"expected\": [[], 0, []], \"passed\": true}, {\"check\": \"3\", \"actual\": [[\"reserved\"], -1, [\"a\"]], \"expected\": [[\"denied\"], 0, []], \"passed\": false}, {\"check\": \"4\", \"actual\": [[\"reserved\", \"held\", \"reserved\", \"reserved\"], -1, [\"a\", \"b\", \"c\"]], \"expected\": [[\"reserved\", \"held\", \"reserved\", \"denied\"], 0, [\"a\", \"b\"]], \"passed\": false}, {\"check\": \"5\", \"actual\": [[\"reserved\", \"reserved\"], 2, []], \"expected\": [[\"reserved\", \"reserved\"], 2, []], \"passed\": true}, {\"check\": \"6\", \"actual\": [[\"reserved\"], 3, [\"a\"]], \"expected\": [[\"reserved\"], 3, [\"a\"]], \"passed\": true}, {\"check\": \"7\", \"actual\": [[\"reserved\", \"reserved\"], 3, []], \"expected\": [[\"reserved\", \"reserved\"], 3, []], \"passed\": true}, {\"check\": \"8\", \"actual\": [[\"reserved\", \"reserved\"], 1, [\"a\"]], \"expected\": [[\"reserved\", \"reserved\"], 1, [\"a\"]], \"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."}}