feat: add mcp app renderer (#6095)

Co-authored-by: Douwe Osinga <douwe@block.xyz>
Co-authored-by: Douwe Osinga <douwe@squareup.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

crates/goose/src/goose_apps/mod.rs

@@ -0,0 +1,9 @@
+//! goose Apps module
+//!
+//! This module contains types and utilities for working with goose Apps,
+//! which are UI resources that can be rendered in an MCP server or native
+//! goose apps, or something in between.
+
+pub mod resource;
+
+pub use resource::{CspMetadata, McpAppResource, ResourceMetadata, UiMetadata};

crates/goose/src/goose_apps/resource.rs

@@ -0,0 +1,112 @@
+use serde::{Deserialize, Serialize};
+use utoipa::ToSchema;
+
+/// Content Security Policy metadata for MCP Apps
+/// Specifies allowed domains for network connections and resource loading
+#[derive(Debug, Clone, Serialize, Deserialize, ToSchema, PartialEq, Eq)]
+#[serde(rename_all = "camelCase")]
+pub struct CspMetadata {
+    /// Domains allowed for connect-src (fetch, XHR, WebSocket)
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub connect_domains: Option<Vec<String>>,
+    /// Domains allowed for resource loading (scripts, styles, images, fonts, media)
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub resource_domains: Option<Vec<String>>,
+}
+
+/// UI-specific metadata for MCP resources
+#[derive(Debug, Clone, Serialize, Deserialize, ToSchema, PartialEq, Eq)]
+#[serde(rename_all = "camelCase")]
+pub struct UiMetadata {
+    /// Content Security Policy configuration
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub csp: Option<CspMetadata>,
+    /// Preferred domain for the app (used for CORS)
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub domain: Option<String>,
+    /// Whether the app prefers to have a border around it
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub prefers_border: Option<bool>,
+}
+
+/// Resource metadata containing UI configuration
+#[derive(Debug, Clone, Serialize, Deserialize, ToSchema, PartialEq, Eq)]
+#[serde(rename_all = "camelCase")]
+pub struct ResourceMetadata {
+    /// UI-specific configuration
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub ui: Option<UiMetadata>,
+}
+
+/// MCP App Resource
+/// Represents a UI resource that can be rendered in an MCP App
+#[derive(Debug, Clone, Serialize, Deserialize, ToSchema)]
+#[serde(rename_all = "camelCase")]
+pub struct McpAppResource {
+    /// URI of the resource (must use ui:// scheme)
+    pub uri: String,
+    /// Human-readable name of the resource
+    pub name: String,
+    /// Optional description of what this resource does
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub description: Option<String>,
+    /// MIME type (should be "text/html;profile=mcp-app" for MCP Apps)
+    pub mime_type: String,
+    /// Text content of the resource (HTML for MCP Apps)
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub text: Option<String>,
+    /// Base64-encoded binary content (alternative to text)
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub blob: Option<String>,
+    /// Resource metadata including UI configuration
+    #[serde(skip_serializing_if = "Option::is_none", rename = "_meta")]
+    pub meta: Option<ResourceMetadata>,
+}
+
+impl McpAppResource {
+    pub fn new_html(uri: String, name: String, html: String) -> Self {
+        Self {
+            uri,
+            name,
+            description: None,
+            mime_type: "text/html;profile=mcp-app".to_string(),
+            text: Some(html),
+            blob: None,
+            meta: None,
+        }
+    }
+
+    pub fn new_html_with_csp(uri: String, name: String, html: String, csp: CspMetadata) -> Self {
+        Self {
+            uri,
+            name,
+            description: None,
+            mime_type: "text/html;profile=mcp-app".to_string(),
+            text: Some(html),
+            blob: None,
+            meta: Some(ResourceMetadata {
+                ui: Some(UiMetadata {
+                    csp: Some(csp),
+                    domain: None,
+                    prefers_border: None,
+                }),
+            }),
+        }
+    }
+
+    pub fn with_description(mut self, description: String) -> Self {
+        self.description = Some(description);
+        self
+    }
+
+    pub fn with_ui_metadata(mut self, ui_metadata: UiMetadata) -> Self {
+        if let Some(meta) = &mut self.meta {
+            meta.ui = Some(ui_metadata);
+        } else {
+            self.meta = Some(ResourceMetadata {
+                ui: Some(ui_metadata),
+            });
+        }
+        self
+    }
+}

crates/goose/src/lib.rs

@@ -4,6 +4,7 @@ pub mod config;
 pub mod context_mgmt;
 pub mod conversation;
 pub mod execution;
+pub mod goose_apps;
 pub mod hints;
 pub mod logging;
 pub mod mcp_utils;