diff --git a/specification/draft/apps.mdx b/specification/draft/apps.mdx index 070c7f62..5d017734 100644 --- a/specification/draft/apps.mdx +++ b/specification/draft/apps.mdx @@ -57,6 +57,16 @@ interface UIResource { name: string; // Human-readable identifier description?: string; // Description of the UI resource mimeType: string; // SHOULD be 'text/vnd.mcp.ui+html' in MVP + _meta?: UIResourceMeta // Resource Metadata +} + +interface UiResourceMeta { + csp?: { + connectDomains?: string[], + resourceDomains?: string[], + }, + domain?: string, + prefersBorder?: boolean, } ``` @@ -71,12 +81,14 @@ The resource content is returned via `resources/read`: text?: string; // HTML content as string blob?: string; // OR base64-encoded HTML _meta?: { - "ui/csp"?: { - connect_domains?: string[]; // Origins for fetch/XHR/WebSocket - resource_domains?: string[]; // Origins for images, scripts, styles + "ui"?: { + "csp"?: { + connect_domains?: string[]; // Origins for fetch/XHR/WebSocket + resource_domains?: string[]; // Origins for images, scripts, etc + }; + "domain"?: string; + "prefersBorder"?: boolean; }; - "ui/domain"?: string; - "ui/prefersBorder"?: boolean; }; }]; } @@ -91,7 +103,7 @@ The resource content is returned via `resources/read`: #### Metadata Fields: -**`ui/csp` - Content Security Policy configuration** +**`ui.csp` - Content Security Policy configuration** Servers declare which external origins their UI needs to access. Hosts use this to enforce appropriate CSP headers. @@ -106,14 +118,14 @@ Servers declare which external origins their UI needs to access. Hosts use this - Wildcard subdomains supported: `https://*.example.com` - Maps to CSP `img-src`, `script-src`, `style-src`, `font-src` directives -**`ui/domain` - Dedicated origin for widget** +**`ui.domain` - Dedicated origin for widget** Optional domain for the widget's sandbox origin. Useful when widgets need dedicated origins for API key allowlists or cross-origin isolation. - Example: `"https://weather-widget.example.com"` - If omitted, Host uses default sandbox origin -**`ui/prefersBorder` - Visual boundary preference** +**`ui.prefersBorder` - Visual boundary preference** Boolean indicating the UI prefers a visible border. Useful for widgets that might blend with host background. @@ -123,7 +135,7 @@ Boolean indicating the UI prefers a visible border. Useful for widgets that migh #### Host Behavior: - **CSP Enforcement:** Host MUST construct CSP headers based on declared domains -- **Restrictive Default:** If `ui/csp` is omitted, Host MUST use: +- **Restrictive Default:** If `ui.csp` is omitted, Host MUST use: ``` default-src 'none'; @@ -154,11 +166,13 @@ Example: "mimeType": "text/vnd.mcp.ui+html", "text": "...", "_meta": { - "ui/csp": { - "connect_domains": ["https://api.openweathermap.org"], - "resource_domains": ["https://cdn.jsdelivr.net"] - }, - "ui/prefersBorder": true + "ui" : { + "csp": { + "connect_domains": ["https://api.openweathermap.org"], + "resource_domains": ["https://cdn.jsdelivr.net"] + }, + "prefersBorder": true + } } }] } @@ -282,7 +296,7 @@ If the Host is a web page, it MUST wrap the Guest UI and communicate with it thr 3. The Sandbox MUST send a `ui/sandbox-ready` notification to the host when it’s ready to process an `ui/sandbox-resource-ready` notification. 4. Once the Sandbox is ready, the Host MUST send the raw HTML resource to load in a `ui/sandbox-resource-ready` notification. 5. The Sandbox MUST load the raw HTML of the Guest UI with CSP settings that: - - Enforce the domains declared in `ui/csp` metadata + - Enforce the domains declared in `ui.csp` metadata - Prevent nested iframes (`frame-src 'none'`) - Block dangerous features (`object-src 'none'`, `base-uri 'self'`) - Apply restrictive defaults if no CSP metadata is provided