feat: Add support for MCP Resources (#13178)

Co-authored-by: Jack Wotherspoon <jackwoth@google.com>

packages/core/src/resources/resource-registry.ts

@@ -0,0 +1,72 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import type { Resource } from '@modelcontextprotocol/sdk/types.js';
+
+const resourceKey = (serverName: string, uri: string): string =>
+  `${serverName}::${uri}`;
+
+export interface MCPResource extends Resource {
+  serverName: string;
+  discoveredAt: number;
+}
+export type DiscoveredMCPResource = MCPResource;
+
+/**
+ * Tracks resources discovered from MCP servers so other
+ * components can query or include them in conversations.
+ */
+export class ResourceRegistry {
+  private resources: Map<string, MCPResource> = new Map();
+
+  /**
+   * Replace the resources for a specific server.
+   */
+  setResourcesForServer(serverName: string, resources: Resource[]): void {
+    this.removeResourcesByServer(serverName);
+    const discoveredAt = Date.now();
+    for (const resource of resources) {
+      if (!resource.uri) {
+        continue;
+      }
+      this.resources.set(resourceKey(serverName, resource.uri), {
+        serverName,
+        discoveredAt,
+        ...resource,
+      });
+    }
+  }
+
+  getAllResources(): MCPResource[] {
+    return Array.from(this.resources.values());
+  }
+
+  /**
+   * Find a resource by its identifier.
+   * Format: serverName:uri (e.g., "myserver:file:///data.txt")
+   */
+  findResourceByUri(identifier: string): MCPResource | undefined {
+    const colonIndex = identifier.indexOf(':');
+    if (colonIndex <= 0) {
+      return undefined;
+    }
+    const serverName = identifier.substring(0, colonIndex);
+    const uri = identifier.substring(colonIndex + 1);
+    return this.resources.get(resourceKey(serverName, uri));
+  }
+
+  removeResourcesByServer(serverName: string): void {
+    for (const key of Array.from(this.resources.keys())) {
+      if (key.startsWith(`${serverName}::`)) {
+        this.resources.delete(key);
+      }
+    }
+  }
+
+  clear(): void {
+    this.resources.clear();
+  }
+}