{"abstract":"The replica bootstrap operation is admitted even though a replica interprets log records with an unsupported schema.","category":"Replication","checks":9,"contract":"Return a Boolean admission decision for promote a bootstrapped replica. The record r must satisfy all of: r['snapshot_ready'] is True; r['wal_bridge'][0] <= r['wal_bridge'][1]+1; r['replay_floor'][0] >= r['replay_floor'][1]; r['schema_compatible'][0] in r['schema_compatible'][1]; r['cluster_identity'][0] == r['cluster_identity'][1]. Extra tracing fields are ignored; validation does not mutate the record.","evaluation_group":"xd-replica-bootstrap","failed_approach":"Adding the schema compatible check repairs the reported defect, but replacing the adjacent cluster identity check loses that independent invariant.","family":"xd-replica-bootstrap-schema_compatible","id":"FA-566","implementations":{"attempt":{"sha256":"a5bca44cc0fa277102757a71ef711f59e6a14bb362fb3e23d113eef53d820614","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(r):\n    return (r['snapshot_ready'] is True) and (r['wal_bridge'][0] <= r['wal_bridge'][1]+1) and (r['replay_floor'][0] >= r['replay_floor'][1]) and (r['schema_compatible'][0] in r['schema_compatible'][1])\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr = {'snapshot_ready': True, 'wal_bridge': [11, 10], 'replay_floor': [20, 20], 'schema_compatible': [3, [2, 3]], 'cluster_identity': ['east', 'east']}\ncheck('valid operation', solve(r), True)\ncheck('A replica serves before loading its baseline snapshot', solve(dict(r, **{'snapshot_ready': False})), False)\ncheck('The retained log starts after the snapshot successor', solve(dict(r, **{'wal_bridge': [12, 10]})), False)\ncheck('Promotion occurs before replay reaches the required watermark', solve(dict(r, **{'replay_floor': [19, 20]})), False)\ncheck('A replica interprets log records with an unsupported schema', solve(dict(r, **{'schema_compatible': [4, [2, 3]]})), False)\ncheck('A snapshot from another cluster is installed', solve(dict(r, **{'cluster_identity': ['west', 'east']})), False)\ncheck('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)\ncheck('repeat validation is pure', solve(r), True)\ninvalid = {'snapshot_ready': False, 'wal_bridge': [12, 10], 'replay_floor': [19, 20], 'schema_compatible': [4, [2, 3]], 'cluster_identity': ['west', 'east']}\nkeys = list(invalid)\npair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}\ncheck('two independent violations in variant', solve(dict(r, **pair)), False)\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":"25353b4335f733cd3f510b2fd93a4d3dc40b34b2d2e29c57139657b9cb474944","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(r):\n    return (r['snapshot_ready'] is True) and (r['wal_bridge'][0] <= r['wal_bridge'][1]+1) and (r['replay_floor'][0] >= r['replay_floor'][1]) and (r['cluster_identity'][0] == r['cluster_identity'][1])\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr = {'snapshot_ready': True, 'wal_bridge': [11, 10], 'replay_floor': [20, 20], 'schema_compatible': [3, [2, 3]], 'cluster_identity': ['east', 'east']}\ncheck('valid operation', solve(r), True)\ncheck('A replica serves before loading its baseline snapshot', solve(dict(r, **{'snapshot_ready': False})), False)\ncheck('The retained log starts after the snapshot successor', solve(dict(r, **{'wal_bridge': [12, 10]})), False)\ncheck('Promotion occurs before replay reaches the required watermark', solve(dict(r, **{'replay_floor': [19, 20]})), False)\ncheck('A replica interprets log records with an unsupported schema', solve(dict(r, **{'schema_compatible': [4, [2, 3]]})), False)\ncheck('A snapshot from another cluster is installed', solve(dict(r, **{'cluster_identity': ['west', 'east']})), False)\ncheck('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)\ncheck('repeat validation is pure', solve(r), True)\ninvalid = {'snapshot_ready': False, 'wal_bridge': [12, 10], 'replay_floor': [19, 20], 'schema_compatible': [4, [2, 3]], 'cluster_identity': ['west', 'east']}\nkeys = list(invalid)\npair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}\ncheck('two independent violations in variant', solve(dict(r, **pair)), False)\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":"f50e1762ced7132aae48370c870710e99da7f1d9bd2ed40f6ef19cc2d1a465cf","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(r):\n    return (r['snapshot_ready'] is True) and (r['wal_bridge'][0] <= r['wal_bridge'][1]+1) and (r['replay_floor'][0] >= r['replay_floor'][1]) and (r['schema_compatible'][0] in r['schema_compatible'][1]) and (r['cluster_identity'][0] == r['cluster_identity'][1])\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nr = {'snapshot_ready': True, 'wal_bridge': [11, 10], 'replay_floor': [20, 20], 'schema_compatible': [3, [2, 3]], 'cluster_identity': ['east', 'east']}\ncheck('valid operation', solve(r), True)\ncheck('A replica serves before loading its baseline snapshot', solve(dict(r, **{'snapshot_ready': False})), False)\ncheck('The retained log starts after the snapshot successor', solve(dict(r, **{'wal_bridge': [12, 10]})), False)\ncheck('Promotion occurs before replay reaches the required watermark', solve(dict(r, **{'replay_floor': [19, 20]})), False)\ncheck('A replica interprets log records with an unsupported schema', solve(dict(r, **{'schema_compatible': [4, [2, 3]]})), False)\ncheck('A snapshot from another cluster is installed', solve(dict(r, **{'cluster_identity': ['west', 'east']})), False)\ncheck('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)\ncheck('repeat validation is pure', solve(r), True)\ninvalid = {'snapshot_ready': False, 'wal_bridge': [12, 10], 'replay_floor': [19, 20], 'schema_compatible': [4, [2, 3]], 'cluster_identity': ['west', 'east']}\nkeys = list(invalid)\npair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}\ncheck('two independent violations in variant', solve(dict(r, **pair)), False)\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":"xd-replica-bootstrap-schema_compatible","generated_at":"2026-09-29T14:36:54.237703+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic local contract for replication. Each negative fixture violates exactly one invariant. No transport timing, persistence, cryptographic verification, or full protocol implementation is claimed.","repair":"Require r['schema_compatible'][0] in r['schema_compatible'][1] together with every other stated precondition before accepting the operation.","root_cause":"The admission path omits the schema compatible invariant while validating the other operation preconditions.","sha256":"2e3296ecafdd0f2de909315ff96421db49adf07eefc294fcd62db593c82b7fe8","title":"Promote a bootstrapped replica: A replica interprets log records with an unsupported schema · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":31.499,"exit_code":1,"observations":[{"actual":true,"check":"valid operation","expected":true,"passed":true},{"actual":false,"check":"A replica serves before loading its baseline snapshot","expected":false,"passed":true},{"actual":false,"check":"The retained log starts after the snapshot successor","expected":false,"passed":true},{"actual":false,"check":"Promotion occurs before replay reaches the required watermark","expected":false,"passed":true},{"actual":false,"check":"A replica interprets log records with an unsupported schema","expected":false,"passed":true},{"actual":true,"check":"A snapshot from another cluster is installed","expected":false,"passed":false},{"actual":true,"check":"unrelated tracing metadata","expected":true,"passed":true},{"actual":true,"check":"repeat validation is pure","expected":true,"passed":true},{"actual":false,"check":"two independent violations in variant","expected":false,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"valid operation\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"A replica serves before loading its baseline snapshot\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"The retained log starts after the snapshot successor\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"Promotion occurs before replay reaches the required watermark\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A replica interprets log records with an unsupported schema\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A snapshot from another cluster is installed\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"unrelated tracing metadata\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"repeat validation is pure\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"two independent violations in variant\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":33.533,"exit_code":1,"observations":[{"actual":true,"check":"valid operation","expected":true,"passed":true},{"actual":false,"check":"A replica serves before loading its baseline snapshot","expected":false,"passed":true},{"actual":false,"check":"The retained log starts after the snapshot successor","expected":false,"passed":true},{"actual":false,"check":"Promotion occurs before replay reaches the required watermark","expected":false,"passed":true},{"actual":true,"check":"A replica interprets log records with an unsupported schema","expected":false,"passed":false},{"actual":false,"check":"A snapshot from another cluster is installed","expected":false,"passed":true},{"actual":true,"check":"unrelated tracing metadata","expected":true,"passed":true},{"actual":true,"check":"repeat validation is pure","expected":true,"passed":true},{"actual":false,"check":"two independent violations in variant","expected":false,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"valid operation\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"A replica serves before loading its baseline snapshot\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"The retained log starts after the snapshot successor\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"Promotion occurs before replay reaches the required watermark\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A replica interprets log records with an unsupported schema\", \"actual\": true, \"expected\": false, \"passed\": false}, {\"check\": \"A snapshot from another cluster is installed\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"unrelated tracing metadata\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"repeat validation is pure\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"two independent violations in variant\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":29.844,"exit_code":0,"observations":[{"actual":true,"check":"valid operation","expected":true,"passed":true},{"actual":false,"check":"A replica serves before loading its baseline snapshot","expected":false,"passed":true},{"actual":false,"check":"The retained log starts after the snapshot successor","expected":false,"passed":true},{"actual":false,"check":"Promotion occurs before replay reaches the required watermark","expected":false,"passed":true},{"actual":false,"check":"A replica interprets log records with an unsupported schema","expected":false,"passed":true},{"actual":false,"check":"A snapshot from another cluster is installed","expected":false,"passed":true},{"actual":true,"check":"unrelated tracing metadata","expected":true,"passed":true},{"actual":true,"check":"repeat validation is pure","expected":true,"passed":true},{"actual":false,"check":"two independent violations in variant","expected":false,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"valid operation\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"A replica serves before loading its baseline snapshot\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"The retained log starts after the snapshot successor\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"Promotion occurs before replay reaches the required watermark\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A replica interprets log records with an unsupported schema\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"A snapshot from another cluster is installed\", \"actual\": false, \"expected\": false, \"passed\": true}, {\"check\": \"unrelated tracing metadata\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"repeat validation is pure\", \"actual\": true, \"expected\": true, \"passed\": true}, {\"check\": \"two independent violations in variant\", \"actual\": false, \"expected\": false, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}