{"abstract":"A second payload with the same version but newer per-flag versions is discarded.","category":"Feature flag rollout bucketing","checks":8,"contract":"Payloads are {version, flags: {key: {value, version, deleted?}}}. An incoming payload with a lower payload version than local is ignored entirely. Otherwise each incoming flag replaces the local entry only when the key is new or its flag version is strictly higher; deleted tombstones follow the same rule. Return sorted [key, value] pairs for merged flags that are not deleted.","contract_signature":"local, incoming","evaluation_group":"w2-feature-flag-rollout-bucketing-bootstrap-merge","failed_approach":"Comparing the highest flag version with the payload version mixes two unrelated counters.","family":"w2-feature-flag-rollout-bucketing-bootstrap-merge-stale-payload","id":"FA-74261","implementations":{"attempt":{"sha256":"70692a1792e38b24f12b26c92206f0f7e50f28a66126fc42507fde2de657e451","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(local, incoming):\n    merged = dict(local['flags'])\n    if max([f['version'] for f in incoming['flags'].values()] or [0]) >= local['version']:\n        for k, f in incoming['flags'].items():\n            cur = merged.get(k)\n            if cur is None or f['version'] > cur['version']:\n                merged[k] = f\n    return sorted([k, f['value']] for k, f in merged.items() if not f.get('deleted'))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('equal flag version keeps the local value',\n   [{'version': 1, 'flags': {'a': {'value': 'local', 'version': 2}}},\n    {'version': 2, 'flags': {'a': {'value': 'remote', 'version': 2}}}],\n   [['a', 'local']]),\n  ('newer tombstone deletes the flag',\n   [{'version': 1, 'flags': {'a': {'value': True, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': None, 'version': 2, 'deleted': True}}}],\n   []),\n  ('older tombstone is ignored',\n   [{'version': 1, 'flags': {'a': {'value': True, 'version': 3}}},\n    {'version': 2, 'flags': {'a': {'value': None, 'version': 1, 'deleted': True}}}],\n   [['a', True]]),\n  ('equal payload version still merges',\n   [{'version': 2, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 2}}}],\n   [['a', 2]]),\n  ('stale payload is ignored',\n   [{'version': 3, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 5}}}],\n   [['a', 1]]),\n  ('new flag with version zero is adopted',\n   [{'version': 1, 'flags': {}}, {'version': 1, 'flags': {'b': {'value': 'on', 'version': 0}}}],\n   [['b', 'on']]),\n  ('output is sorted by key',\n   [{'version': 1, 'flags': {'c': {'value': 3, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': 1, 'version': 1}, 'b': {'value': 2, 'version': 1}}}],\n   [['a', 1], ['b', 2], ['c', 3]]),\n  ('payload pair sample 1',\n   [{'version': 3, 'flags': {'d': {'value': 'x', 'version': 1}, 'a': {'value': True, 'version': 0}}},\n    {'version': 1,\n     'flags': {'d': {'value': False, 'version': 1}, 'a': {'value': 2, 'version': 2, 'deleted': True}}}],\n   [['a', True], ['d', 'x']])],\n [('newer tombstone deletes the flag',\n   [{'version': 1, 'flags': {'a': {'value': True, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': None, 'version': 2, 'deleted': True}}}],\n   []),\n  ('older tombstone is ignored',\n   [{'version': 1, 'flags': {'a': {'value': True, 'version': 3}}},\n    {'version': 2, 'flags': {'a': {'value': None, 'version': 1, 'deleted': True}}}],\n   [['a', True]]),\n  ('equal payload version still merges',\n   [{'version': 2, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 2}}}],\n   [['a', 2]]),\n  ('stale payload is ignored',\n   [{'version': 3, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 5}}}],\n   [['a', 1]]),\n  ('new flag with version zero is adopted',\n   [{'version': 1, 'flags': {}}, {'version': 1, 'flags': {'b': {'value': 'on', 'version': 0}}}],\n   [['b', 'on']]),\n  ('output is sorted by key',\n   [{'version': 1, 'flags': {'c': {'value': 3, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': 1, 'version': 1}, 'b': {'value': 2, 'version': 1}}}],\n   [['a', 1], ['b', 2], ['c', 3]]),\n  ('payload pair sample 15',\n   [{'version': 1,\n     'flags': {'a': {'value': True, 'version': 0},\n               'c': {'value': True, 'version': 1},\n               'd': {'value': 2, 'version': 3}}},\n    {'version': 1,\n     'flags': {'d': {'value': 'x', 'version': 3},\n               'a': {'value': False, 'version': 2},\n               'b': {'value': True, 'version': 2}}}],\n   [['a', False], ['b', True], ['c', True], ['d', 2]]),\n  ('payload pair sample 38',\n   [{'version': 2, 'flags': {'b': {'value': 'x', 'version': 2}}},\n    {'version': 2,\n     'flags': {'a': {'value': True, 'version': 0},\n               'c': {'value': True, 'version': 0},\n               'b': {'value': True, 'version': 0}}}],\n   [['a', True], ['b', 'x'], ['c', True]])],\n [('older tombstone is ignored',\n   [{'version': 1, 'flags': {'a': {'value': True, 'version': 3}}},\n    {'version': 2, 'flags': {'a': {'value': None, 'version': 1, 'deleted': True}}}],\n   [['a', True]]),\n  ('equal payload version still merges',\n   [{'version': 2, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 2}}}],\n   [['a', 2]]),\n  ('stale payload is ignored',\n   [{'version': 3, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 5}}}],\n   [['a', 1]]),\n  ('new flag with version zero is adopted',\n   [{'version': 1, 'flags': {}}, {'version': 1, 'flags': {'b': {'value': 'on', 'version': 0}}}],\n   [['b', 'on']]),\n  ('output is sorted by key',\n   [{'version': 1, 'flags': {'c': {'value': 3, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': 1, 'version': 1}, 'b': {'value': 2, 'version': 1}}}],\n   [['a', 1], ['b', 2], ['c', 3]]),\n  ('payload pair sample 11',\n   [{'version': 2,\n     'flags': {'d': {'value': 2, 'version': 2, 'deleted': True},\n               'b': {'value': 'x', 'version': 2},\n               'a': {'value': False, 'version': 1}}},\n    {'version': 3,\n     'flags': {'d': {'value': 2, 'version': 2},\n               'a': {'value': 2, 'version': 2},\n               'b': {'value': False, 'version': 0}}}],\n   [['a', 2], ['b', 'x']]),\n  ('payload pair sample 23',\n   [{'version': 2,\n     'flags': {'a': {'value': False, 'version': 1},\n               'b': {'value': True, 'version': 0},\n               'd': {'value': 2, 'version': 0}}},\n    {'version': 1, 'flags': {'d': {'value': False, 'version': 2}, 'a': {'value': 'x', 'version': 3}}}],\n   [['a', False], ['b', True], ['d', 2]]),\n  ('payload pair sample 38',\n   [{'version': 2, 'flags': {'b': {'value': 'x', 'version': 2}}},\n    {'version': 2,\n     'flags': {'a': {'value': True, 'version': 0},\n               'c': {'value': True, 'version': 0},\n               'b': {'value': True, 'version': 0}}}],\n   [['a', True], ['b', 'x'], ['c', True]])],\n [('equal flag version keeps the local value',\n   [{'version': 1, 'flags': {'a': {'value': 'local', 'version': 2}}},\n    {'version': 2, 'flags': {'a': {'value': 'remote', 'version': 2}}}],\n   [['a', 'local']]),\n  ('equal payload version still merges',\n   [{'version': 2, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 2}}}],\n   [['a', 2]]),\n  ('stale payload is ignored',\n   [{'version': 3, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 5}}}],\n   [['a', 1]]),\n  ('new flag with version zero is adopted',\n   [{'version': 1, 'flags': {}}, {'version': 1, 'flags': {'b': {'value': 'on', 'version': 0}}}],\n   [['b', 'on']]),\n  ('output is sorted by key',\n   [{'version': 1, 'flags': {'c': {'value': 3, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': 1, 'version': 1}, 'b': {'value': 2, 'version': 1}}}],\n   [['a', 1], ['b', 2], ['c', 3]]),\n  ('payload pair sample 16', [{'version': 2, 'flags': {}}, {'version': 3, 'flags': {}}], []),\n  ('payload pair sample 17',\n   [{'version': 2, 'flags': {}}, {'version': 3, 'flags': {'d': {'value': 2, 'version': 2, 'deleted': True}}}],\n   []),\n  ('payload pair sample 51',\n   [{'version': 3,\n     'flags': {'b': {'value': True, 'version': 1, 'deleted': True}, 'a': {'value': True, 'version': 0}}},\n    {'version': 3, 'flags': {'a': {'value': False, 'version': 2}, 'c': {'value': False, 'version': 0}}}],\n   [['a', False], ['c', False]])],\n [('equal flag version keeps the local value',\n   [{'version': 1, 'flags': {'a': {'value': 'local', 'version': 2}}},\n    {'version': 2, 'flags': {'a': {'value': 'remote', 'version': 2}}}],\n   [['a', 'local']]),\n  ('newer tombstone deletes the flag',\n   [{'version': 1, 'flags': {'a': {'value': True, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': None, 'version': 2, 'deleted': True}}}],\n   []),\n  ('stale payload is ignored',\n   [{'version': 3, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 5}}}],\n   [['a', 1]]),\n  ('new flag with version zero is adopted',\n   [{'version': 1, 'flags': {}}, {'version': 1, 'flags': {'b': {'value': 'on', 'version': 0}}}],\n   [['b', 'on']]),\n  ('output is sorted by key',\n   [{'version': 1, 'flags': {'c': {'value': 3, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': 1, 'version': 1}, 'b': {'value': 2, 'version': 1}}}],\n   [['a', 1], ['b', 2], ['c', 3]]),\n  ('payload pair sample 20',\n   [{'version': 2, 'flags': {'b': {'value': 2, 'version': 3}, 'd': {'value': 2, 'version': 2}}},\n    {'version': 2,\n     'flags': {'a': {'value': False, 'version': 0},\n               'b': {'value': False, 'version': 2},\n               'd': {'value': 2, 'version': 2}}}],\n   [['a', False], ['b', 2], ['d', 2]]),\n  ('payload pair sample 21',\n   [{'version': 2,\n     'flags': {'a': {'value': False, 'version': 2, 'deleted': True},\n               'b': {'value': False, 'version': 1, 'deleted': True}}},\n    {'version': 1,\n     'flags': {'d': {'value': True, 'version': 0},\n               'c': {'value': False, 'version': 3},\n               'b': {'value': True, 'version': 3}}}],\n   []),\n  ('payload pair sample 35',\n   [{'version': 2, 'flags': {'c': {'value': 2, 'version': 1}}},\n    {'version': 1, 'flags': {'b': {'value': 'x', 'version': 3}, 'c': {'value': False, 'version': 1}}}],\n   [['c', 2]])]]\nfor label, args, expected in fixtures[N - 1]:\n    check(label, solve(*args), expected)\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":"75dbe6c968ea4641684121108f262c89dee2bc079a8c03ef4b8d881dccb6af06","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(local, incoming):\n    merged = dict(local['flags'])\n    if incoming['version'] > local['version']:\n        for k, f in incoming['flags'].items():\n            cur = merged.get(k)\n            if cur is None or f['version'] > cur['version']:\n                merged[k] = f\n    return sorted([k, f['value']] for k, f in merged.items() if not f.get('deleted'))\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('equal flag version keeps the local value',\n   [{'version': 1, 'flags': {'a': {'value': 'local', 'version': 2}}},\n    {'version': 2, 'flags': {'a': {'value': 'remote', 'version': 2}}}],\n   [['a', 'local']]),\n  ('newer tombstone deletes the flag',\n   [{'version': 1, 'flags': {'a': {'value': True, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': None, 'version': 2, 'deleted': True}}}],\n   []),\n  ('older tombstone is ignored',\n   [{'version': 1, 'flags': {'a': {'value': True, 'version': 3}}},\n    {'version': 2, 'flags': {'a': {'value': None, 'version': 1, 'deleted': True}}}],\n   [['a', True]]),\n  ('equal payload version still merges',\n   [{'version': 2, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 2}}}],\n   [['a', 2]]),\n  ('stale payload is ignored',\n   [{'version': 3, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 5}}}],\n   [['a', 1]]),\n  ('new flag with version zero is adopted',\n   [{'version': 1, 'flags': {}}, {'version': 1, 'flags': {'b': {'value': 'on', 'version': 0}}}],\n   [['b', 'on']]),\n  ('output is sorted by key',\n   [{'version': 1, 'flags': {'c': {'value': 3, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': 1, 'version': 1}, 'b': {'value': 2, 'version': 1}}}],\n   [['a', 1], ['b', 2], ['c', 3]]),\n  ('payload pair sample 1',\n   [{'version': 3, 'flags': {'d': {'value': 'x', 'version': 1}, 'a': {'value': True, 'version': 0}}},\n    {'version': 1,\n     'flags': {'d': {'value': False, 'version': 1}, 'a': {'value': 2, 'version': 2, 'deleted': True}}}],\n   [['a', True], ['d', 'x']])],\n [('newer tombstone deletes the flag',\n   [{'version': 1, 'flags': {'a': {'value': True, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': None, 'version': 2, 'deleted': True}}}],\n   []),\n  ('older tombstone is ignored',\n   [{'version': 1, 'flags': {'a': {'value': True, 'version': 3}}},\n    {'version': 2, 'flags': {'a': {'value': None, 'version': 1, 'deleted': True}}}],\n   [['a', True]]),\n  ('equal payload version still merges',\n   [{'version': 2, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 2}}}],\n   [['a', 2]]),\n  ('stale payload is ignored',\n   [{'version': 3, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 5}}}],\n   [['a', 1]]),\n  ('new flag with version zero is adopted',\n   [{'version': 1, 'flags': {}}, {'version': 1, 'flags': {'b': {'value': 'on', 'version': 0}}}],\n   [['b', 'on']]),\n  ('output is sorted by key',\n   [{'version': 1, 'flags': {'c': {'value': 3, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': 1, 'version': 1}, 'b': {'value': 2, 'version': 1}}}],\n   [['a', 1], ['b', 2], ['c', 3]]),\n  ('payload pair sample 15',\n   [{'version': 1,\n     'flags': {'a': {'value': True, 'version': 0},\n               'c': {'value': True, 'version': 1},\n               'd': {'value': 2, 'version': 3}}},\n    {'version': 1,\n     'flags': {'d': {'value': 'x', 'version': 3},\n               'a': {'value': False, 'version': 2},\n               'b': {'value': True, 'version': 2}}}],\n   [['a', False], ['b', True], ['c', True], ['d', 2]]),\n  ('payload pair sample 38',\n   [{'version': 2, 'flags': {'b': {'value': 'x', 'version': 2}}},\n    {'version': 2,\n     'flags': {'a': {'value': True, 'version': 0},\n               'c': {'value': True, 'version': 0},\n               'b': {'value': True, 'version': 0}}}],\n   [['a', True], ['b', 'x'], ['c', True]])],\n [('older tombstone is ignored',\n   [{'version': 1, 'flags': {'a': {'value': True, 'version': 3}}},\n    {'version': 2, 'flags': {'a': {'value': None, 'version': 1, 'deleted': True}}}],\n   [['a', True]]),\n  ('equal payload version still merges',\n   [{'version': 2, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 2}}}],\n   [['a', 2]]),\n  ('stale payload is ignored',\n   [{'version': 3, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 5}}}],\n   [['a', 1]]),\n  ('new flag with version zero is adopted',\n   [{'version': 1, 'flags': {}}, {'version': 1, 'flags': {'b': {'value': 'on', 'version': 0}}}],\n   [['b', 'on']]),\n  ('output is sorted by key',\n   [{'version': 1, 'flags': {'c': {'value': 3, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': 1, 'version': 1}, 'b': {'value': 2, 'version': 1}}}],\n   [['a', 1], ['b', 2], ['c', 3]]),\n  ('payload pair sample 11',\n   [{'version': 2,\n     'flags': {'d': {'value': 2, 'version': 2, 'deleted': True},\n               'b': {'value': 'x', 'version': 2},\n               'a': {'value': False, 'version': 1}}},\n    {'version': 3,\n     'flags': {'d': {'value': 2, 'version': 2},\n               'a': {'value': 2, 'version': 2},\n               'b': {'value': False, 'version': 0}}}],\n   [['a', 2], ['b', 'x']]),\n  ('payload pair sample 23',\n   [{'version': 2,\n     'flags': {'a': {'value': False, 'version': 1},\n               'b': {'value': True, 'version': 0},\n               'd': {'value': 2, 'version': 0}}},\n    {'version': 1, 'flags': {'d': {'value': False, 'version': 2}, 'a': {'value': 'x', 'version': 3}}}],\n   [['a', False], ['b', True], ['d', 2]]),\n  ('payload pair sample 38',\n   [{'version': 2, 'flags': {'b': {'value': 'x', 'version': 2}}},\n    {'version': 2,\n     'flags': {'a': {'value': True, 'version': 0},\n               'c': {'value': True, 'version': 0},\n               'b': {'value': True, 'version': 0}}}],\n   [['a', True], ['b', 'x'], ['c', True]])],\n [('equal flag version keeps the local value',\n   [{'version': 1, 'flags': {'a': {'value': 'local', 'version': 2}}},\n    {'version': 2, 'flags': {'a': {'value': 'remote', 'version': 2}}}],\n   [['a', 'local']]),\n  ('equal payload version still merges',\n   [{'version': 2, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 2}}}],\n   [['a', 2]]),\n  ('stale payload is ignored',\n   [{'version': 3, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 5}}}],\n   [['a', 1]]),\n  ('new flag with version zero is adopted',\n   [{'version': 1, 'flags': {}}, {'version': 1, 'flags': {'b': {'value': 'on', 'version': 0}}}],\n   [['b', 'on']]),\n  ('output is sorted by key',\n   [{'version': 1, 'flags': {'c': {'value': 3, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': 1, 'version': 1}, 'b': {'value': 2, 'version': 1}}}],\n   [['a', 1], ['b', 2], ['c', 3]]),\n  ('payload pair sample 16', [{'version': 2, 'flags': {}}, {'version': 3, 'flags': {}}], []),\n  ('payload pair sample 17',\n   [{'version': 2, 'flags': {}}, {'version': 3, 'flags': {'d': {'value': 2, 'version': 2, 'deleted': True}}}],\n   []),\n  ('payload pair sample 51',\n   [{'version': 3,\n     'flags': {'b': {'value': True, 'version': 1, 'deleted': True}, 'a': {'value': True, 'version': 0}}},\n    {'version': 3, 'flags': {'a': {'value': False, 'version': 2}, 'c': {'value': False, 'version': 0}}}],\n   [['a', False], ['c', False]])],\n [('equal flag version keeps the local value',\n   [{'version': 1, 'flags': {'a': {'value': 'local', 'version': 2}}},\n    {'version': 2, 'flags': {'a': {'value': 'remote', 'version': 2}}}],\n   [['a', 'local']]),\n  ('newer tombstone deletes the flag',\n   [{'version': 1, 'flags': {'a': {'value': True, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': None, 'version': 2, 'deleted': True}}}],\n   []),\n  ('stale payload is ignored',\n   [{'version': 3, 'flags': {'a': {'value': 1, 'version': 1}}},\n    {'version': 2, 'flags': {'a': {'value': 2, 'version': 5}}}],\n   [['a', 1]]),\n  ('new flag with version zero is adopted',\n   [{'version': 1, 'flags': {}}, {'version': 1, 'flags': {'b': {'value': 'on', 'version': 0}}}],\n   [['b', 'on']]),\n  ('output is sorted by key',\n   [{'version': 1, 'flags': {'c': {'value': 3, 'version': 1}}},\n    {'version': 1, 'flags': {'a': {'value': 1, 'version': 1}, 'b': {'value': 2, 'version': 1}}}],\n   [['a', 1], ['b', 2], ['c', 3]]),\n  ('payload pair sample 20',\n   [{'version': 2, 'flags': {'b': {'value': 2, 'version': 3}, 'd': {'value': 2, 'version': 2}}},\n    {'version': 2,\n     'flags': {'a': {'value': False, 'version': 0},\n               'b': {'value': False, 'version': 2},\n               'd': {'value': 2, 'version': 2}}}],\n   [['a', False], ['b', 2], ['d', 2]]),\n  ('payload pair sample 21',\n   [{'version': 2,\n     'flags': {'a': {'value': False, 'version': 2, 'deleted': True},\n               'b': {'value': False, 'version': 1, 'deleted': True}}},\n    {'version': 1,\n     'flags': {'d': {'value': True, 'version': 0},\n               'c': {'value': False, 'version': 3},\n               'b': {'value': True, 'version': 3}}}],\n   []),\n  ('payload pair sample 35',\n   [{'version': 2, 'flags': {'c': {'value': 2, 'version': 1}}},\n    {'version': 1, 'flags': {'b': {'value': 'x', 'version': 3}, 'c': {'value': False, 'version': 1}}}],\n   [['c', 2]])]]\nfor label, args, expected in fixtures[N - 1]:\n    check(label, solve(*args), expected)\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":"A deterministic toy flag-evaluation model with a stipulated contract; it does not reproduce any vendor SDK byte for byte. 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":"w2-feature-flag-rollout-bucketing-bootstrap-merge-stale-payload","generated_at":"2026-09-29T14:48:55.104188+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Clients bootstrap from HTML-embedded flags and then stream updates; stale data must not win.","root_cause":"The stale check requires incoming version > local version.","sha256":"40c574adc025cb75beb50dbb016e0842cea8c195c1dfe3c3f801c5d2139d4885","title":"Bootstrapped flag payload merge: An equal payload version is treated as stale · 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":40.144,"exit_code":1,"observations":[{"actual":[["a","local"]],"check":"equal flag version keeps the local value","expected":[["a","local"]],"passed":true},{"actual":[],"check":"newer tombstone deletes the flag","expected":[],"passed":true},{"actual":[["a",true]],"check":"older tombstone is ignored","expected":[["a",true]],"passed":true},{"actual":[["a",2]],"check":"equal payload version still merges","expected":[["a",2]],"passed":true},{"actual":[["a",2]],"check":"stale payload is ignored","expected":[["a",1]],"passed":false},{"actual":[],"check":"new flag with version zero is adopted","expected":[["b","on"]],"passed":false},{"actual":[["a",1],["b",2],["c",3]],"check":"output is sorted by key","expected":[["a",1],["b",2],["c",3]],"passed":true},{"actual":[["a",true],["d","x"]],"check":"payload pair sample 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