fix: show display names when pasting npub/nprofile in editors

Previously, pasting npub/nprofile strings would only check the EventStore's
in-memory cache for profiles. If a profile was cached in IndexedDB but not
yet loaded into the EventStore, it would show a hex preview instead.

This adds a ProfileCache service that:
- Loads profiles from IndexedDB on startup for instant access
- Subscribes to EventStore for new profiles as they arrive
- Provides synchronous lookups for the paste handler

Also uses consistent fallback format (XXXX:YYYY) when no profile is found.

src/components/editor/extensions/nostr-paste-handler.ts

@@ -1,37 +1,21 @@
 import { Extension } from "@tiptap/core";
 import { Plugin, PluginKey, TextSelection } from "@tiptap/pm/state";
 import { nip19 } from "nostr-tools";
-import eventStore from "@/services/event-store";
-import { getProfileContent } from "applesauce-core/helpers";
+import profileCache from "@/services/profile-cache";
 import { getDisplayName } from "@/lib/nostr-utils";
 
 /**
  * Helper to get display name for a pubkey (synchronous lookup from cache)
  */
 function getDisplayNameForPubkey(pubkey: string): string {
-  try {
-    // Try to get profile from event store (check if it's a BehaviorSubject with .value)
-    const profile$ = eventStore.replaceable(0, pubkey) as any;
-    if (profile$ && profile$.value) {
-      const profileEvent = profile$.value;
-      if (profileEvent) {
-        const content = getProfileContent(profileEvent);
-        if (content) {
-          // Use the Grimoire helper which handles fallbacks
-          return getDisplayName(pubkey, content);
-        }
-      }
-    }
-  } catch (err) {
-    // Ignore errors, fall through to default
-    console.debug(
-      "[NostrPasteHandler] Could not get profile for",
-      pubkey.slice(0, 8),
-      err,
-    );
+  // Check profile cache first (includes Dexie + EventStore profiles)
+  const cachedProfile = profileCache.get(pubkey);
+  if (cachedProfile) {
+    return getDisplayName(pubkey, cachedProfile);
   }
-  // Fallback to short pubkey
-  return pubkey.slice(0, 8);
+
+  // Fallback to placeholder format
+  return getDisplayName(pubkey, undefined);
 }
 
 /**

src/services/profile-cache.ts

@@ -0,0 +1,93 @@
+import type { NostrEvent } from "nostr-tools";
+import {
+  getProfileContent,
+  type ProfileContent,
+} from "applesauce-core/helpers";
+import eventStore from "./event-store";
+import db from "./db";
+
+/**
+ * Simple singleton profile cache for synchronous display name lookups.
+ * Used by paste handlers and other places that need instant profile access.
+ */
+class ProfileCache {
+  private profiles = new Map<string, ProfileContent>();
+  private initialized = false;
+
+  /**
+   * Initialize the cache by:
+   * 1. Loading profiles from Dexie (IndexedDB)
+   * 2. Subscribing to EventStore for new kind 0 events
+   */
+  async init(): Promise<void> {
+    if (this.initialized) return;
+    this.initialized = true;
+
+    // Load from Dexie first (persisted profiles)
+    try {
+      const cachedProfiles = await db.profiles.toArray();
+      for (const profile of cachedProfiles) {
+        const { pubkey, created_at: _created_at, ...content } = profile;
+        this.profiles.set(pubkey, content as ProfileContent);
+      }
+      console.debug(
+        `[ProfileCache] Loaded ${cachedProfiles.length} profiles from IndexedDB`,
+      );
+    } catch (err) {
+      console.warn("[ProfileCache] Failed to load from IndexedDB:", err);
+    }
+
+    // Subscribe to EventStore for new kind 0 events
+    eventStore.timeline([{ kinds: [0] }]).subscribe({
+      next: (events) => {
+        for (const event of events) {
+          this.addFromEvent(event);
+        }
+      },
+      error: (err) => {
+        console.warn("[ProfileCache] EventStore subscription error:", err);
+      },
+    });
+  }
+
+  /**
+   * Add a profile from a kind 0 event
+   */
+  addFromEvent(event: NostrEvent): void {
+    if (event.kind !== 0) return;
+
+    const content = getProfileContent(event);
+    if (content) {
+      this.profiles.set(event.pubkey, content);
+    }
+  }
+
+  /**
+   * Get profile content for a pubkey (synchronous)
+   */
+  get(pubkey: string): ProfileContent | undefined {
+    return this.profiles.get(pubkey);
+  }
+
+  /**
+   * Check if a profile is cached
+   */
+  has(pubkey: string): boolean {
+    return this.profiles.has(pubkey);
+  }
+
+  /**
+   * Get the number of cached profiles
+   */
+  get size(): number {
+    return this.profiles.size;
+  }
+}
+
+// Singleton instance
+const profileCache = new ProfileCache();
+
+// Auto-initialize on module load
+profileCache.init();
+
+export default profileCache;