{"abstract":"Failed background refresh leaves a permanent in-flight marker.","category":"Caching","checks":4,"contract":"Completion, successful or failed, removes only its own refresh key from the in-flight registry; output is a sorted unique key list.","contract_signature":"active, key, outcome","evaluation_group":"xc-refresh-singleflight-cleanup","failed_approach":"Clearing the whole registry lets unrelated active refreshes start duplicate work.","family":"xc-refresh-singleflight-cleanup","id":"FA-10501","implementations":{"attempt":{"sha256":"66621a6382100471a98bb42990c21a47f4e763406318012a1f806f95c601cd01","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(active, key, outcome):\n    return []\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*(['a', 'b'], 'a', 'error')), ['b'])\ncheck('fixture 2', solve(*(['a', 'b'], 'a', 'success')), ['b'])\ncheck('fixture 3', solve(*(['b'], 'a', 'error')), ['b'])\ncheck('fixture 4', solve(*([], 'a', 'success')), [])\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":"0729d4a28d80926e58a7397e4985cf6a33930943a76ce29dc1f0b4a0f960c262","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(active, key, outcome):\n    return sorted(set(active)-({key} if outcome=='success' else set()))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*(['a', 'b'], 'a', 'error')), ['b'])\ncheck('fixture 2', solve(*(['a', 'b'], 'a', 'success')), ['b'])\ncheck('fixture 3', solve(*(['b'], 'a', 'error')), ['b'])\ncheck('fixture 4', solve(*([], 'a', 'success')), [])\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":" 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":"xc-refresh-singleflight-cleanup","generated_at":"2026-09-29T14:38:39.610518+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic cache state transformation. Inputs are copied or treated as immutable; no remote storage, real clock, or concurrent interleaving is simulated.","root_cause":"Only successful completion releases the refresh ownership marker.","sha256":"6286006dc20d395e9faac0e36c06c86c80f45617a0e5339569c6f09f0145863a","title":"Failed background refresh leaves a permanent in-flight marker · 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":38.906,"exit_code":1,"observations":[{"actual":[],"check":"fixture 1","expected":["b"],"passed":false},{"actual":[],"check":"fixture 2","expected":["b"],"passed":false},{"actual":[],"check":"fixture 3","expected":["b"],"passed":false},{"actual":[],"check":"fixture 4","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [], \"expected\": [\"b\"], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [], \"expected\": [\"b\"], \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": [], \"expected\": [\"b\"], \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":41.817,"exit_code":1,"observations":[{"actual":["a","b"],"check":"fixture 1","expected":["b"],"passed":false},{"actual":["b"],"check":"fixture 2","expected":["b"],"passed":true},{"actual":["b"],"check":"fixture 3","expected":["b"],"passed":true},{"actual":[],"check":"fixture 4","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [\"a\", \"b\"], \"expected\": [\"b\"], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [\"b\"], \"expected\": [\"b\"], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [\"b\"], \"expected\": [\"b\"], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [], \"expected\": [], \"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."}}