Module apps 

Typed server support for the stable MCP Apps extension (SEP-1865).

This module deliberately separates compile-time availability from runtime activation:

• enable the mcp-apps Cargo feature to compile these APIs;
• call McpRouter::with_mcp_apps or McpClientBuilder::with_mcp_apps to declare support on the wire;
• check RequestContext::supports_mcp_apps before applying extension-specific behavior.

UI resources built here use the required ui:// scheme and text/html;profile=mcp-app MIME type. External CSP sources are restricted to origins: credentials, paths, queries, fragments, and unsupported schemes are rejected.

See crate::guides::mcp_apps for the task-oriented setup, security boundary, CSP and permissions policy, and visibility guidance.

Structs

McpAppDomain

A validated host-dependent dedicated sandbox domain.

McpAppHtml

A minimally validated complete HTML5 document.

McpAppResourceBuilder

Builder for one predeclared raw-HTML MCP Apps resource.

McpAppUri

A validated MCP Apps resource identifier.

McpAppsCapabilitySettings

Capability settings advertised for MCP Apps.

McpUiPermissions

Browser permissions requested by an MCP App.

McpUiResourceCsp

Content Security Policy inputs declared by an MCP Apps resource.

McpUiResourceMeta

Rendering and security metadata for a UI resource.

McpUiToolMeta

MCP Apps metadata attached to a tool definition.

Enums

McpAppError

A validation or construction error from the typed MCP Apps API.

McpUiToolVisibility

Who may see or call a UI-linked tool.

Constants

MCP_APPS_EXTENSION_ID

Stable extension identifier reserved for MCP Apps.

MCP_APP_HTML_MIME_TYPE

The only content type defined by the stable MCP Apps MVP.

Functions

mcp_app_tool_result

Construct an Apps-friendly tool result with a useful text-only fallback.

mcp_apps_extension

Build the validated core extension declaration for MCP Apps.