Add ensureLoaded helper for subscriptions and align error UX

js/channelProfile.js

@@ -3448,7 +3448,7 @@ export async function initChannelProfileView() {
   // 3) Load subscription state when logged in, but always render the toggle UI
   if (app?.pubkey) {
     subscriptionsTask = subscriptions
-      .loadSubscriptions(app.pubkey)
+      .ensureLoaded(app.pubkey)
       .catch((error) => {
         userLogger.error("Failed to load subscriptions for channel view:", error);
       })
@@ -3833,6 +3833,14 @@ function renderSubscribeButton(channelHex) {
         renderSubscribeButton(channelHex);
       } catch (err) {
         userLogger.error("Failed to update subscription:", err);
+        const permissionErrorCodes = new Set([
+          "extension-permission-denied",
+          "nip04-missing",
+        ]);
+        const message = permissionErrorCodes.has(err?.code)
+          ? "Your Nostr extension must support NIP-04 to manage private lists."
+          : "Failed to update your subscriptions. Please try again.";
+        currentApp?.showError?.(message);
       }
     });
   }

js/subscriptions.js

@@ -132,6 +132,7 @@ class SubscriptionsManager {
     this.subscribedPubkeys = new Set();
     this.subsEventId = null;
     this.loaded = false;
+    this.loadingPromise = null;
     this.subscriptionListView = null;
     this.lastRunOptions = null;
     this.lastResult = null;
@@ -297,6 +298,35 @@ class SubscriptionsManager {
     }
   }
 
+  async ensureLoaded(actorHex) {
+    if (this.loaded) {
+      return;
+    }
+
+    const normalizedActor = normalizeHexPubkey(actorHex) || actorHex;
+    if (!normalizedActor) {
+      return;
+    }
+
+    if (this.loadingPromise) {
+      try {
+        await this.loadingPromise;
+      } catch (error) {
+        throw error;
+      }
+      return;
+    }
+
+    const loader = this.loadSubscriptions(normalizedActor);
+    this.loadingPromise = loader;
+
+    try {
+      await loader;
+    } finally {
+      this.loadingPromise = null;
+    }
+  }
+
   isSubscribed(channelHex) {
     const normalized = normalizeHexPubkey(channelHex);
     if (!normalized) {
@@ -409,6 +439,7 @@ class SubscriptionsManager {
     if (!userPubkey) {
       throw new Error("No user pubkey => cannot addChannel.");
     }
+    await this.ensureLoaded(userPubkey);
     if (!normalizedChannel) {
       devLogger.warn("Attempted to subscribe to invalid pubkey", channelHex);
       return;
@@ -432,6 +463,7 @@ class SubscriptionsManager {
     if (!userPubkey) {
       throw new Error("No user pubkey => cannot removeChannel.");
     }
+    await this.ensureLoaded(userPubkey);
     if (!normalizedChannel) {
       devLogger.warn("Attempted to remove invalid pubkey from subscriptions", channelHex);
       return;
@@ -627,15 +659,13 @@ class SubscriptionsManager {
       return null;
     }
 
-    if (!this.loaded) {
-      try {
-        await this.loadSubscriptions(userPubkey);
-      } catch (error) {
-        userLogger.error(
-          "[SubscriptionsManager] Failed to load subscriptions while rendering feed:",
-          error,
-        );
-      }
+    try {
+      await this.ensureLoaded(userPubkey);
+    } catch (error) {
+      userLogger.error(
+        "[SubscriptionsManager] Failed to load subscriptions while rendering feed:",
+        error,
+      );
     }
 
     const channelHexes = this.getSubscribedAuthors();

tests/subscriptions-manager.test.mjs

@@ -540,6 +540,28 @@ test(
   },
 );
 
+test("ensureLoaded memoizes concurrent loads", async () => {
+  const SubscriptionsManager = subscriptions.constructor;
+  const manager = new SubscriptionsManager();
+
+  let loadCount = 0;
+  manager.loadSubscriptions = async () => {
+    loadCount += 1;
+    await new Promise((resolve) => setTimeout(resolve, 0));
+    manager.loaded = true;
+  };
+
+  const actorHex = "f".repeat(64);
+
+  await Promise.all([
+    manager.ensureLoaded(actorHex),
+    manager.ensureLoaded(actorHex),
+  ]);
+
+  assert.equal(loadCount, 1, "loadSubscriptions should only run once");
+  assert.equal(manager.loaded, true, "manager should be marked as loaded");
+});
+
 test(
   "publishSubscriptionList succeeds with direct signer without requesting extension permissions",
   async () => {