function trustZonesFigure(host) { ensureStyles(); var shell = document.createElement('div'); shell.className = 'mf-shell'; shell.innerHTML = [ '
Trust Zones in an MCP Exchange host and client trusted, server and upstream untrusted, the model reads only labeled content
', '
', '', '', 'trusted zone', 'untrusted zone', '', '', 'trust boundary', '', 'host', 'the user\'s app', '', 'client', 'one per server', '', 'model', 'sees labeled data', '', 'server', 'third party', '', 'upstream systems', 'once removed', '', '', '', '', '', '', 'trust filter', '', '', '', '', '', '
', '
The host and the client it owns sit with the model inside one trust domain. A request crosses the dashed boundary to reach the server; whatever the server returns crosses back through the trust filter, marked untrusted, before the model reads it. The server may reach further upstream systems that the client never observes directly.
' ].join(''); host.appendChild(shell); } // register as: mcpa-22-trust-zones