UNION_PATHS = frozenset({('mcp', 'disabled_project_servers'), ('mcp', 'disabled_servers')})Paths whose lists accumulate instead of being replaced.
Deny lists must union across layers: replacing a managed deny list with a user one would be a fail-open.
Governs the two table merges — merge_managed_over_user and
config_manifest.resolve_scalar. It does not govern the two readers that union
name sets rather than TOML tables: model_config.load_mcp_server_trust_lists
and mcp_disabled.get_disabled_servers accumulate their own layers directly,
including the env tier this set knows nothing about. A third deny list therefore
needs an entry here and a decision in those two readers.