Fix chat zap preview display logic (#106)

* fix: hide zap reply previews for missing or non-chat events

Only show reply previews for zaps when:
1. The replied-to event exists in the event store
2. The replied-to event is a chat kind (9, 9321, or 1311)

This prevents showing loading states or reply previews for
zaps replying to events we don't have or non-chat events.

* refactor: extract CHAT_KINDS constant and include zap receipts

- Create CHAT_KINDS constant in types/chat.ts with all chat event kinds
- Include kind 9735 (zap receipts) as a chat kind
- Update ChatViewer to use the new constant for validation
- Improves maintainability and makes it easier to update chat kinds

Chat kinds now include:
- 9: NIP-29 group chat messages
- 9321: NIP-61 nutzaps
- 1311: NIP-53 live chat messages
- 9735: NIP-57 zap receipts

---------

Co-authored-by: Claude <noreply@anthropic.com>

src/components/ChatViewer.tsx

@@ -23,6 +23,7 @@ import type {
   Conversation,
   LiveActivityMetadata,
 } from "@/types/chat";
+import { CHAT_KINDS } from "@/types/chat";
 // import { NipC7Adapter } from "@/lib/chat/adapters/nip-c7-adapter";  // Coming soon
 import { Nip29Adapter } from "@/lib/chat/adapters/nip-29-adapter";
 import { Nip53Adapter } from "@/lib/chat/adapters/nip-53-adapter";
@@ -269,6 +270,20 @@ const MessageItem = memo(function MessageItem({
       zapRequest?.tags.find((t) => t[0] === "e")?.[1] ||
       undefined;
 
+    // Check if the replied-to event exists and is a chat kind
+    const replyEvent = use$(
+      () => (zapReplyTo ? eventStore.event(zapReplyTo) : undefined),
+      [zapReplyTo],
+    );
+
+    // Only show reply preview if:
+    // 1. The event exists in our store
+    // 2. The event is a chat kind (includes messages, nutzaps, live chat, and zap receipts)
+    const shouldShowReplyPreview =
+      zapReplyTo &&
+      replyEvent &&
+      (CHAT_KINDS as readonly number[]).includes(replyEvent.kind);
+
     return (
       <div className="pl-2 my-1">
         <div
@@ -300,7 +315,7 @@ const MessageItem = memo(function MessageItem({
                 <Timestamp timestamp={message.timestamp} />
               </span>
             </div>
-            {zapReplyTo && (
+            {shouldShowReplyPreview && (
               <ReplyPreview
                 replyToId={zapReplyTo}
                 adapter={adapter}

src/types/chat.ts

@@ -1,5 +1,16 @@
 import type { NostrEvent } from "./nostr";
 
+/**
+ * Event kinds that are considered chat messages across all protocols
+ * Used for filtering and validating chat-related events
+ */
+export const CHAT_KINDS = [
+  9, // NIP-29: Group chat messages
+  9321, // NIP-61: Nutzaps (ecash zaps in groups/live chats)
+  1311, // NIP-53: Live chat messages
+  9735, // NIP-57: Zap receipts (part of chat context)
+] as const;
+
 /**
  * Chat protocol identifier
  */