feat(transport): route notifications/resources/updated to subscribed clients

src/core/constants.ts

@@ -134,3 +134,7 @@ export const announcementMethods: AnnouncementMethods = {
 
 export const INITIALIZE_METHOD = 'initialize';
 export const NOTIFICATIONS_INITIALIZED_METHOD = 'notifications/initialized';
+export const NOTIFICATIONS_RESOURCES_UPDATED_METHOD =
+  'notifications/resources/updated';
+export const RESOURCES_SUBSCRIBE_METHOD = 'resources/subscribe';
+export const RESOURCES_UNSUBSCRIBE_METHOD = 'resources/unsubscribe';

src/transport/nostr-server-transport.ts

@@ -25,6 +25,9 @@ import {
   GIFT_WRAP_KIND,
   NOSTR_TAGS,
   NOTIFICATIONS_INITIALIZED_METHOD,
+  NOTIFICATIONS_RESOURCES_UPDATED_METHOD,
+  RESOURCES_SUBSCRIBE_METHOD,
+  RESOURCES_UNSUBSCRIBE_METHOD,
   decryptMessage,
   DEFAULT_LRU_SIZE,
 } from '../core/index.js';
@@ -182,6 +185,12 @@ export class NostrServerTransport
   /** Receives inbound oversized-transfer frames from clients (client→server requests). */
   private readonly oversizedReceiver: OversizedTransferReceiver;
 
+  /**
+   * Tracks which clients have subscribed to which resource URIs.
+   * Maps resource URI → set of subscribed client public keys.
+   */
+  private readonly resourceSubscriptions = new Map<string, Set<string>>();
+
   // Oversized-transfer sender settings (for server→client responses)
   private readonly oversizedEnabled: boolean;
   private readonly oversizedThreshold: number;
@@ -213,6 +222,7 @@ export class NostrServerTransport
         // Clean up all correlation data for evicted session
         const removedCount =
           this.correlationStore.removeRoutesForClient(clientPubkey);
+        this.removeResourceSubscriptionsForClient(clientPubkey);
         this.logger.info(
           `Evicted session for ${clientPubkey} (removed ${removedCount} routes)`,
         );
@@ -379,13 +389,51 @@ export class NostrServerTransport
       this.correlationStore.clear();
       this.seenEventIds.clear();
       this.oversizedReceiver.clear();
+      this.resourceSubscriptions.clear();
       this.onclose?.();
     } catch (error) {
       this.onerror?.(error instanceof Error ? error : new Error(String(error)));
       this.logAndRethrowError('Error closing NostrServerTransport', error);
     }
   }
 
+  /**
+   * Records a client's subscription to a resource URI.
+   */
+  private addResourceSubscription(uri: string, clientPubkey: string): void {
+    let subscribers = this.resourceSubscriptions.get(uri);
+    if (!subscribers) {
+      subscribers = new Set();
+      this.resourceSubscriptions.set(uri, subscribers);
+    }
+    subscribers.add(clientPubkey);
+  }
+
+  /**
+   * Removes a client's subscription to a resource URI.
+   */
+  private removeResourceSubscription(uri: string, clientPubkey: string): void {
+    const subscribers = this.resourceSubscriptions.get(uri);
+    if (subscribers) {
+      subscribers.delete(clientPubkey);
+      if (subscribers.size === 0) {
+        this.resourceSubscriptions.delete(uri);
+      }
+    }
+  }
+
+  /**
+   * Removes all resource subscriptions for a given client (used on session eviction).
+   */
+  private removeResourceSubscriptionsForClient(clientPubkey: string): void {
+    for (const [uri, subscribers] of this.resourceSubscriptions) {
+      subscribers.delete(clientPubkey);
+      if (subscribers.size === 0) {
+        this.resourceSubscriptions.delete(uri);
+      }
+    }
+  }
+
   /**
    * Sends JSON-RPC messages over the Nostr transport.
    * @param message The JSON-RPC message to send.
@@ -556,6 +604,15 @@ export class NostrServerTransport
       progressToken ? String(progressToken) : undefined,
       wrapKind,
     );
+
+    const uri = request.params?.uri;
+    if (typeof uri === 'string') {
+      if (request.method === RESOURCES_SUBSCRIBE_METHOD) {
+        this.addResourceSubscription(uri, clientPubkey);
+      } else if (request.method === RESOURCES_UNSUBSCRIBE_METHOD) {
+        this.removeResourceSubscription(uri, clientPubkey);
+      }
+    }
   }
 
   /**
@@ -681,13 +738,13 @@ export class NostrServerTransport
     notification: JSONRPCMessage,
   ): Promise<void> {
     try {
-      // Special handling for progress notifications
-      // TODO: Add handling for `notifications/resources/updated`, as they need to be associated with an id
-      if (
-        isJSONRPCNotification(notification) &&
+      if (!isJSONRPCNotification(notification)) {
+        // Broadcast path below handles non-notification edge cases.
+      } else if (
         notification.method === 'notifications/progress' &&
         notification.params?.progressToken
       ) {
+        // Targeted routing for progress notifications
         const token = String(notification.params.progressToken);
 
         // Use O(1) lookup for progress token routing
@@ -710,6 +767,35 @@ export class NostrServerTransport
         this.logger.error('Progress token not found', { token });
         this.onerror?.(error);
         return;
+      } else if (
+        notification.method === NOTIFICATIONS_RESOURCES_UPDATED_METHOD
+      ) {
+        const uri = notification.params?.uri;
+        if (typeof uri === 'string') {
+          const subscribers = this.resourceSubscriptions.get(uri);
+          if (subscribers && subscribers.size > 0) {
+            for (const clientPubkey of subscribers) {
+              const session = this.sessionStore.getSession(clientPubkey);
+              if (session?.isInitialized) {
+                this.taskQueue.add(async () => {
+                  try {
+                    await this.sendNotification(clientPubkey, notification);
+                  } catch (error) {
+                    this.logger.error('Error sending resource update', {
+                      error:
+                        error instanceof Error
+                          ? error.message
+                          : String(error),
+                      clientPubkey,
+                      uri,
+                    });
+                  }
+                });
+              }
+            }
+          }
+          return;
+        }
       }
 
       // Use TaskQueue for outbound notification broadcasting to prevent event loop blocking