{"abstract":"Invalidating an empty-header variant also removes the absent-header variant.","category":"Caching","checks":4,"contract":"Entries are [variant-ID,normalized request-header mapping]. Remove entries matching every selected header in both presence and exact string value; preserve all other variants and their order. Empty selected names match every variant.","contract_signature":"entries, names, request","evaluation_group":"xc-vary-missing-variant-invalidation","failed_approach":"Comparing only truthiness additionally conflates all nonempty values.","family":"xc-vary-missing-variant-invalidation","id":"FA-10481","implementations":{"attempt":{"sha256":"4846a9d8d062b6e0c7361a3165e6cc2aad127dec0f2ed64f9c740eb53a331be4","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entries, names, request):\n    return [x for x in entries if not all(bool(x[1].get(k))==bool(request.get(k)) for k in names)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*([['missing', {}], ['empty', {'x': ''}]], ['x'], {'x': ''})), [['missing', {}]])\ncheck('fixture 2', solve(*([['one', {'x': 'one'}], ['two', {'x': 'two'}]], ['x'], {'x': 'one'})), [['two', {'x': 'two'}]])\ncheck('fixture 3', solve(*([['missing', {}], ['empty', {'x': ''}]], ['x'], {})), [['empty', {'x': ''}]])\ncheck('fixture 4', solve(*([], ['x'], {})), [])\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":"db18fdd83c596314e93c96d6bfbbd188b66b4233d3234bf13d629035169478af","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(entries, names, request):\n    return [x for x in entries if not all(x[1].get(k,'')==request.get(k,'') for k in names)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve(*([['missing', {}], ['empty', {'x': ''}]], ['x'], {'x': ''})), [['missing', {}]])\ncheck('fixture 2', solve(*([['one', {'x': 'one'}], ['two', {'x': 'two'}]], ['x'], {'x': 'one'})), [['two', {'x': 'two'}]])\ncheck('fixture 3', solve(*([['missing', {}], ['empty', {'x': ''}]], ['x'], {})), [['empty', {'x': ''}]])\ncheck('fixture 4', solve(*([], ['x'], {})), [])\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-vary-missing-variant-invalidation","generated_at":"2026-09-29T14:38:39.314626+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":"Variant invalidation defaults missing header values to empty strings and conflates two identities.","sha256":"a32539a1df54fafbf0e1b2c6fdaff612eeee9c50ec03fc695646f8f124004706","title":"Invalidating an empty-header variant also removes the absent-header variant · 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":41.846,"exit_code":1,"observations":[{"actual":[],"check":"fixture 1","expected":[["missing",{}]],"passed":false},{"actual":[],"check":"fixture 2","expected":[["two",{"x":"two"}]],"passed":false},{"actual":[],"check":"fixture 3","expected":[["empty",{"x":""}]],"passed":false},{"actual":[],"check":"fixture 4","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [], \"expected\": [[\"missing\", {}]], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [], \"expected\": [[\"two\", {\"x\": \"two\"}]], \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": [], \"expected\": [[\"empty\", {\"x\": \"\"}]], \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":42.134,"exit_code":1,"observations":[{"actual":[],"check":"fixture 1","expected":[["missing",{}]],"passed":false},{"actual":[["two",{"x":"two"}]],"check":"fixture 2","expected":[["two",{"x":"two"}]],"passed":true},{"actual":[],"check":"fixture 3","expected":[["empty",{"x":""}]],"passed":false},{"actual":[],"check":"fixture 4","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [], \"expected\": [[\"missing\", {}]], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [[\"two\", {\"x\": \"two\"}]], \"expected\": [[\"two\", {\"x\": \"two\"}]], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [], \"expected\": [[\"empty\", {\"x\": \"\"}]], \"passed\": false}, {\"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."}}