refactor: add stronger types and optimize message sorting

- Add discriminated union types for ProtocolIdentifier (GroupIdentifier,
  LiveActivityIdentifier, DMIdentifier, NIP05Identifier, ChannelIdentifier)
- Optimize message sorting using reverse() instead of full sort (O(n) vs O(n log n))
- Add type narrowing in adapter resolveConversation methods
- Remove unused Observable import from ChatViewer

src/components/ChatViewer.tsx

@@ -1,6 +1,6 @@
 import { useMemo, useState, memo, useCallback, useRef, useEffect } from "react";
 import { use$ } from "applesauce-react/hooks";
-import { from, catchError, of, map, Observable } from "rxjs";
+import { from, catchError, of, map } from "rxjs";
 import { Virtuoso, VirtuosoHandle } from "react-virtuoso";
 import { Loader2, Reply, Zap, AlertTriangle, RefreshCw } from "lucide-react";
 import { getZapRequest } from "applesauce-common/helpers/zap";

src/lib/chat/adapters/nip-29-adapter.ts

@@ -101,6 +101,12 @@ export class Nip29Adapter extends ChatProtocolAdapter {
   async resolveConversation(
     identifier: ProtocolIdentifier,
   ): Promise<Conversation> {
+    // This adapter only handles group identifiers
+    if (identifier.type !== "group") {
+      throw new Error(
+        `NIP-29 adapter cannot handle identifier type: ${identifier.type}`,
+      );
+    }
     const groupId = identifier.value;
     const relayUrl = identifier.relays?.[0];
 
@@ -367,7 +373,10 @@ export class Nip29Adapter extends ChatProtocolAdapter {
         });
 
         console.log(`[NIP-29] Timeline has ${messages.length} events`);
-        return messages.sort((a, b) => a.timestamp - b.timestamp);
+        // EventStore timeline returns events sorted by created_at desc,
+        // we need ascending order for chat. Since it's already sorted,
+        // just reverse instead of full sort (O(n) vs O(n log n))
+        return messages.reverse();
       }),
     );
   }
@@ -413,7 +422,9 @@ export class Nip29Adapter extends ChatProtocolAdapter {
       return this.eventToMessage(event, conversation.id);
     });
 
-    return messages.sort((a, b) => a.timestamp - b.timestamp);
+    // loadMoreMessages returns events in desc order from relay,
+    // reverse for ascending chronological order
+    return messages.reverse();
   }
 
   /**

src/lib/chat/adapters/nip-53-adapter.ts

@@ -84,11 +84,13 @@ export class Nip53Adapter extends ChatProtocolAdapter {
   async resolveConversation(
     identifier: ProtocolIdentifier,
   ): Promise<Conversation> {
-    const { pubkey, identifier: dTag } = identifier.value as {
-      kind: number;
-      pubkey: string;
-      identifier: string;
-    };
+    // This adapter only handles live-activity identifiers
+    if (identifier.type !== "live-activity") {
+      throw new Error(
+        `NIP-53 adapter cannot handle identifier type: ${identifier.type}`,
+      );
+    }
+    const { pubkey, identifier: dTag } = identifier.value;
     const relayHints = identifier.relays || [];
 
     const activePubkey = accountManager.active$.value?.pubkey;
@@ -311,7 +313,10 @@ export class Nip53Adapter extends ChatProtocolAdapter {
           .filter((msg): msg is Message => msg !== null);
 
         console.log(`[NIP-53] Timeline has ${messages.length} events`);
-        return messages.sort((a, b) => a.timestamp - b.timestamp);
+        // EventStore timeline returns events sorted by created_at desc,
+        // we need ascending order for chat. Since it's already sorted,
+        // just reverse instead of full sort (O(n) vs O(n log n))
+        return messages.reverse();
       }),
     );
   }
@@ -380,7 +385,9 @@ export class Nip53Adapter extends ChatProtocolAdapter {
       })
       .filter((msg): msg is Message => msg !== null);
 
-    return messages.sort((a, b) => a.timestamp - b.timestamp);
+    // loadMoreMessages returns events in desc order from relay,
+    // reverse for ascending chronological order
+    return messages.reverse();
   }
 
   /**

src/lib/chat/adapters/nip-c7-adapter.ts

@@ -93,8 +93,15 @@ export class NipC7Adapter extends ChatProtocolAdapter {
         throw new Error(`Failed to resolve NIP-05: ${identifier.value}`);
       }
       pubkey = resolved;
-    } else {
+    } else if (
+      identifier.type === "chat-partner" ||
+      identifier.type === "dm-recipient"
+    ) {
       pubkey = identifier.value;
+    } else {
+      throw new Error(
+        `NIP-C7 adapter cannot handle identifier type: ${identifier.type}`,
+      );
     }
 
     const activePubkey = accountManager.active$.value?.pubkey;

src/types/chat.ts

@@ -120,14 +120,74 @@ export interface Message {
 }
 
 /**
- * Protocol-specific identifier
+ * NIP-29 group identifier
+ */
+export interface GroupIdentifier {
+  type: "group";
+  /** Group ID (e.g., "bitcoin-dev") */
+  value: string;
+  /** Relay URL where the group is hosted (required for NIP-29) */
+  relays: string[];
+}
+
+/**
+ * NIP-53 live activity identifier
+ */
+export interface LiveActivityIdentifier {
+  type: "live-activity";
+  /** Address pointer for the live activity */
+  value: {
+    kind: 30311;
+    pubkey: string;
+    identifier: string;
+  };
+  /** Relay hints from naddr encoding */
+  relays?: string[];
+}
+
+/**
+ * NIP-C7/NIP-17 direct message identifier (resolved pubkey)
+ */
+export interface DMIdentifier {
+  type: "dm-recipient" | "chat-partner";
+  /** Recipient pubkey (hex) */
+  value: string;
+  /** Relay hints */
+  relays?: string[];
+}
+
+/**
+ * NIP-C7 NIP-05 identifier (needs resolution)
+ */
+export interface NIP05Identifier {
+  type: "chat-partner-nip05";
+  /** NIP-05 address to resolve */
+  value: string;
+  /** Relay hints */
+  relays?: string[];
+}
+
+/**
+ * NIP-28 channel identifier (future)
+ */
+export interface ChannelIdentifier {
+  type: "channel";
+  /** Channel creation event ID or address */
+  value: string;
+  /** Relay hints */
+  relays?: string[];
+}
+
+/**
+ * Protocol-specific identifier - discriminated union
  * Returned by adapter parseIdentifier()
  */
-export interface ProtocolIdentifier {
-  type: string; // e.g., 'dm-recipient', 'channel-event', 'group-id'
-  value: any; // Protocol-specific value
-  relays?: string[]; // Relay hints from bech32 encoding
-}
+export type ProtocolIdentifier =
+  | GroupIdentifier
+  | LiveActivityIdentifier
+  | DMIdentifier
+  | NIP05Identifier
+  | ChannelIdentifier;
 
 /**
  * Chat command parsing result