diff --git a/src/components/GroupListViewer.tsx b/src/components/GroupListViewer.tsx
new file mode 100644
index 0000000..6dfd755
--- /dev/null
+++ b/src/components/GroupListViewer.tsx
@@ -0,0 +1,430 @@
+import { useState, useMemo, memo, useCallback } from "react";
+import { use$ } from "applesauce-react/hooks";
+import { map } from "rxjs/operators";
+import { Loader2 } from "lucide-react";
+import eventStore from "@/services/event-store";
+import pool from "@/services/relay-pool";
+import accountManager from "@/services/accounts";
+import { ChatViewer } from "./ChatViewer";
+import { getTagValue } from "applesauce-core/helpers";
+import type { NostrEvent } from "@/types/nostr";
+import type { ProtocolIdentifier } from "@/types/chat";
+import { cn } from "@/lib/utils";
+import Timestamp from "./Timestamp";
+import { useEffect } from "react";
+import { UserName } from "./nostr/UserName";
+import { RichText } from "./nostr/RichText";
+
+interface GroupInfo {
+  groupId: string;
+  relayUrl: string;
+  metadata?: NostrEvent;
+  lastMessage?: NostrEvent;
+}
+
+/**
+ * Format relay URL for display
+ */
+function formatRelayForDisplay(url: string): string {
+  return url.replace(/^wss?:\/\//, "").replace(/\/$/, "");
+}
+
+/**
+ * GroupListItem - Single group in the list
+ */
+const GroupListItem = memo(function GroupListItem({
+  group,
+  isSelected,
+  onClick,
+}: {
+  group: GroupInfo;
+  isSelected: boolean;
+  onClick: () => void;
+}) {
+  // Extract group name from metadata
+  const isUnmanagedGroup = group.groupId === "_";
+  let groupName: string;
+  if (isUnmanagedGroup) {
+    groupName = formatRelayForDisplay(group.relayUrl);
+  } else if (group.metadata && group.metadata.kind === 39000) {
+    groupName = getTagValue(group.metadata, "name") || group.groupId;
+  } else {
+    groupName = group.groupId;
+  }
+
+  // Get last message author and content
+  const lastMessageAuthor = group.lastMessage?.pubkey;
+  const lastMessageContent = group.lastMessage?.content;
+
+  return (
+    <div
+      className={cn(
+        "flex flex-col gap-0 px-2 py-0.5 cursor-crosshair hover:bg-muted/50 transition-colors border-b",
+        isSelected && "bg-muted/70",
+      )}
+      onClick={onClick}
+    >
+      <div className="flex items-center justify-between gap-2">
+        <span className="text-sm font-medium truncate">{groupName}</span>
+        {group.lastMessage && (
+          <span className="text-xs text-muted-foreground flex-shrink-0">
+            <Timestamp timestamp={group.lastMessage.created_at} />
+          </span>
+        )}
+      </div>
+      {/* Last message preview - hide images and event embeds */}
+      {lastMessageAuthor && lastMessageContent && (
+        <div className="text-xs text-muted-foreground truncate line-clamp-1">
+          <UserName
+            pubkey={lastMessageAuthor}
+            className="text-xs font-medium"
+          />
+          :{" "}
+          <span className="inline truncate">
+            <RichText
+              event={group.lastMessage}
+              className="inline"
+              options={{
+                showImages: false,
+                showEventEmbeds: false,
+              }}
+            />
+          </span>
+        </div>
+      )}
+    </div>
+  );
+});
+
+/**
+ * MemoizedChatViewer - Memoized chat viewer to prevent unnecessary re-renders
+ */
+const MemoizedChatViewer = memo(
+  function MemoizedChatViewer({
+    groupId,
+    relayUrl,
+  }: {
+    groupId: string;
+    relayUrl: string;
+  }) {
+    return (
+      <ChatViewer
+        protocol="nip-29"
+        identifier={
+          {
+            type: "group",
+            value: groupId,
+            relays: [relayUrl],
+          } as ProtocolIdentifier
+        }
+      />
+    );
+  },
+  // Custom comparison: only re-render if group actually changed
+  (prev, next) =>
+    prev.groupId === next.groupId && prev.relayUrl === next.relayUrl,
+);
+
+/**
+ * GroupListViewer - Multi-room chat interface
+ *
+ * Left panel: List of groups from user's kind 10009, sorted by recency
+ * Right panel: Chat view for selected group
+ */
+export function GroupListViewer() {
+  const activeAccount = use$(accountManager.active$);
+  const activePubkey = activeAccount?.pubkey;
+
+  // State for selected group
+  const [selectedGroup, setSelectedGroup] = useState<{
+    groupId: string;
+    relayUrl: string;
+  } | null>(null);
+
+  // State for sidebar width
+  const [sidebarWidth, setSidebarWidth] = useState(280);
+  const [isResizing, setIsResizing] = useState(false);
+
+  // Handle resize with proper cleanup
+  const handleMouseDown = useCallback(
+    (e: React.MouseEvent) => {
+      e.preventDefault();
+      setIsResizing(true);
+
+      const startX = e.clientX;
+      const startWidth = sidebarWidth;
+
+      const handleMouseMove = (moveEvent: MouseEvent) => {
+        const deltaX = moveEvent.clientX - startX;
+        const newWidth = startWidth + deltaX;
+        // Clamp between 200px and 500px
+        setSidebarWidth(Math.max(200, Math.min(500, newWidth)));
+      };
+
+      const handleMouseUp = () => {
+        setIsResizing(false);
+        document.removeEventListener("mousemove", handleMouseMove);
+        document.removeEventListener("mouseup", handleMouseUp);
+      };
+
+      document.addEventListener("mousemove", handleMouseMove);
+      document.addEventListener("mouseup", handleMouseUp);
+
+      // Cleanup listeners on component unmount (stored in ref)
+      return () => {
+        document.removeEventListener("mousemove", handleMouseMove);
+        document.removeEventListener("mouseup", handleMouseUp);
+      };
+    },
+    [sidebarWidth],
+  );
+
+  // Cleanup resize event listeners on unmount
+  useEffect(() => {
+    return () => {
+      setIsResizing(false);
+    };
+  }, []);
+
+  // Load user's kind 10009 (group list) event
+  const groupListEvent = use$(
+    () =>
+      activePubkey ? eventStore.replaceable(10009, activePubkey) : undefined,
+    [activePubkey],
+  );
+
+  // Extract groups from the event with relay URL validation
+  const groups = useMemo(() => {
+    if (!groupListEvent) return [];
+
+    const extractedGroups: Array<{
+      groupId: string;
+      relayUrl: string;
+    }> = [];
+
+    for (const tag of groupListEvent.tags) {
+      if (tag[0] === "group" && tag[1] && tag[2]) {
+        // Validate relay URL before adding
+        const relayUrl = tag[2];
+        try {
+          const url = new URL(
+            relayUrl.startsWith("ws://") || relayUrl.startsWith("wss://")
+              ? relayUrl
+              : `wss://${relayUrl}`,
+          );
+          // Only accept ws:// or wss:// protocols
+          if (url.protocol === "ws:" || url.protocol === "wss:") {
+            extractedGroups.push({
+              groupId: tag[1],
+              relayUrl: url.toString(),
+            });
+          }
+        } catch {
+          // Invalid URL, skip this group
+          continue;
+        }
+      }
+    }
+
+    return extractedGroups;
+  }, [groupListEvent]);
+
+  // Subscribe to group metadata (kind 39000) for all groups
+  useEffect(() => {
+    if (groups.length === 0) return;
+
+    const groupIds = groups.map((g) => g.groupId).filter((id) => id !== "_");
+    const relayUrls = Array.from(new Set(groups.map((g) => g.relayUrl)));
+
+    if (groupIds.length === 0) return;
+
+    const subscription = pool
+      .subscription(relayUrls, [{ kinds: [39000], "#d": groupIds }], {
+        eventStore,
+      })
+      .subscribe();
+
+    return () => {
+      subscription.unsubscribe();
+    };
+  }, [groups]);
+
+  // Load metadata for all groups
+  const groupMetadataMap = use$(() => {
+    const groupIds = groups.map((g) => g.groupId).filter((id) => id !== "_");
+    if (groupIds.length === 0) return undefined;
+
+    return eventStore.timeline([{ kinds: [39000], "#d": groupIds }]).pipe(
+      map((events) => {
+        const metadataMap = new Map<string, NostrEvent>();
+        for (const evt of events) {
+          const dTag = evt.tags.find((t) => t[0] === "d");
+          if (dTag && dTag[1]) {
+            metadataMap.set(dTag[1], evt);
+          }
+        }
+        return metadataMap;
+      }),
+    );
+  }, [groups]);
+
+  // Subscribe to latest messages (kind 9) for all groups to get recency
+  // NOTE: Separate filters needed to ensure we get 1 message per group (not N total across all groups)
+  useEffect(() => {
+    if (groups.length === 0) return;
+
+    const relayUrls = Array.from(new Set(groups.map((g) => g.relayUrl)));
+    const groupIds = groups.map((g) => g.groupId);
+
+    // One filter per group to ensure limit:1 applies per group, not globally
+    const subscription = pool
+      .subscription(
+        relayUrls,
+        groupIds.map((groupId) => ({
+          kinds: [9],
+          "#h": [groupId],
+          limit: 1,
+        })),
+        { eventStore },
+      )
+      .subscribe();
+
+    return () => {
+      subscription.unsubscribe();
+    };
+  }, [groups]);
+
+  // Load latest messages and merge with group data
+  const groupsWithRecency = use$(() => {
+    if (groups.length === 0) return undefined;
+
+    const groupIds = groups.map((g) => g.groupId);
+
+    return eventStore
+      .timeline(
+        groupIds.map((groupId) => ({
+          kinds: [9],
+          "#h": [groupId],
+          limit: 1,
+        })),
+      )
+      .pipe(
+        map((events) => {
+          // Create a map of groupId -> latest message
+          const messageMap = new Map<string, NostrEvent>();
+          for (const evt of events) {
+            const hTag = evt.tags.find((t) => t[0] === "h");
+            if (hTag && hTag[1]) {
+              const existing = messageMap.get(hTag[1]);
+              if (!existing || evt.created_at > existing.created_at) {
+                messageMap.set(hTag[1], evt);
+              }
+            }
+          }
+
+          // Merge with groups
+          const groupsWithInfo: GroupInfo[] = groups.map((g) => ({
+            groupId: g.groupId,
+            relayUrl: g.relayUrl,
+            metadata: groupMetadataMap?.get(g.groupId),
+            lastMessage: messageMap.get(g.groupId),
+          }));
+
+          // Sort by recency (most recent first)
+          groupsWithInfo.sort((a, b) => {
+            const aTime = a.lastMessage?.created_at || 0;
+            const bTime = b.lastMessage?.created_at || 0;
+            return bTime - aTime;
+          });
+
+          return groupsWithInfo;
+        }),
+      );
+  }, [groups, groupMetadataMap]);
+
+  if (!activePubkey) {
+    return (
+      <div className="flex h-full items-center justify-center text-sm text-muted-foreground">
+        Sign in to view your groups
+      </div>
+    );
+  }
+
+  if (!groupListEvent) {
+    return (
+      <div className="flex h-full flex-col items-center justify-center gap-2 text-muted-foreground">
+        <Loader2 className="size-6 animate-spin" />
+        <span>Loading groups...</span>
+      </div>
+    );
+  }
+
+  if (!groups || groups.length === 0) {
+    return (
+      <div className="flex h-full items-center justify-center text-sm text-muted-foreground">
+        No groups configured. Add groups to your kind 10009 list.
+      </div>
+    );
+  }
+
+  if (!groupsWithRecency) {
+    return (
+      <div className="flex h-full flex-col items-center justify-center gap-2 text-muted-foreground">
+        <Loader2 className="size-6 animate-spin" />
+        <span>Loading group details...</span>
+      </div>
+    );
+  }
+
+  return (
+    <div className="flex h-full">
+      {/* Left sidebar: Group list */}
+      <aside
+        className="flex flex-col border-r bg-background"
+        style={{ width: sidebarWidth }}
+      >
+        <div className="flex-1 overflow-y-auto">
+          {groupsWithRecency.map((group) => (
+            <GroupListItem
+              key={`${group.relayUrl}'${group.groupId}`}
+              group={group}
+              isSelected={
+                selectedGroup?.groupId === group.groupId &&
+                selectedGroup?.relayUrl === group.relayUrl
+              }
+              onClick={() =>
+                setSelectedGroup({
+                  groupId: group.groupId,
+                  relayUrl: group.relayUrl,
+                })
+              }
+            />
+          ))}
+        </div>
+      </aside>
+
+      {/* Resize handle */}
+      <div
+        className={cn(
+          "w-1 bg-border hover:bg-primary/50 cursor-col-resize transition-colors",
+          isResizing && "bg-primary",
+        )}
+        onMouseDown={handleMouseDown}
+      />
+
+      {/* Right panel: Chat view */}
+      <div className="flex-1 min-w-0">
+        {selectedGroup ? (
+          <MemoizedChatViewer
+            groupId={selectedGroup.groupId}
+            relayUrl={selectedGroup.relayUrl}
+          />
+        ) : (
+          <div className="flex h-full items-center justify-center text-sm text-muted-foreground">
+            Select a group to view chat
+          </div>
+        )}
+      </div>
+    </div>
+  );
+}
diff --git a/src/components/WindowRenderer.tsx b/src/components/WindowRenderer.tsx
index 576d35e..a00275f 100644
--- a/src/components/WindowRenderer.tsx
+++ b/src/components/WindowRenderer.tsx
@@ -30,6 +30,9 @@ const ConnViewer = lazy(() => import("./ConnViewer"));
 const ChatViewer = lazy(() =>
   import("./ChatViewer").then((m) => ({ default: m.ChatViewer })),
 );
+const GroupListViewer = lazy(() =>
+  import("./GroupListViewer").then((m) => ({ default: m.GroupListViewer })),
+);
 const SpellsViewer = lazy(() =>
   import("./SpellsViewer").then((m) => ({ default: m.SpellsViewer })),
 );
@@ -173,13 +176,18 @@ export function WindowRenderer({ window, onClose }: WindowRendererProps) {
         content = <ConnViewer />;
         break;
       case "chat":
-        content = (
-          <ChatViewer
-            protocol={window.props.protocol}
-            identifier={window.props.identifier}
-            customTitle={window.customTitle}
-          />
-        );
+        // Check if this is a group list (kind 10009) - render multi-room interface
+        if (window.props.identifier?.type === "group-list") {
+          content = <GroupListViewer />;
+        } else {
+          content = (
+            <ChatViewer
+              protocol={window.props.protocol}
+              identifier={window.props.identifier}
+              customTitle={window.customTitle}
+            />
+          );
+        }
         break;
       case "spells":
         content = <SpellsViewer />;
diff --git a/src/lib/chat-parser.ts b/src/lib/chat-parser.ts
index 3e91358..8a0778f 100644
--- a/src/lib/chat-parser.ts
+++ b/src/lib/chat-parser.ts
@@ -1,7 +1,8 @@
-import type { ChatCommandResult } from "@/types/chat";
+import type { ChatCommandResult, GroupListIdentifier } from "@/types/chat";
 // import { NipC7Adapter } from "./chat/adapters/nip-c7-adapter";
 import { Nip29Adapter } from "./chat/adapters/nip-29-adapter";
 import { Nip53Adapter } from "./chat/adapters/nip-53-adapter";
+import { nip19 } from "nostr-tools";
 // Import other adapters as they're implemented
 // import { Nip17Adapter } from "./chat/adapters/nip-17-adapter";
 // import { Nip28Adapter } from "./chat/adapters/nip-28-adapter";
@@ -34,6 +35,31 @@ export function parseChatCommand(args: string[]): ChatCommandResult {
     identifier = `${args[0]}'${args[1]}`;
   }
 
+  // Check for kind 10009 (group list) naddr - open multi-room interface
+  if (identifier.startsWith("naddr1")) {
+    try {
+      const decoded = nip19.decode(identifier);
+      if (decoded.type === "naddr" && decoded.data.kind === 10009) {
+        const groupListIdentifier: GroupListIdentifier = {
+          type: "group-list",
+          value: {
+            kind: 10009,
+            pubkey: decoded.data.pubkey,
+            identifier: decoded.data.identifier,
+          },
+          relays: decoded.data.relays,
+        };
+        return {
+          protocol: "nip-29", // Use nip-29 as the protocol designation
+          identifier: groupListIdentifier,
+          adapter: null, // No adapter needed for group list view
+        };
+      }
+    } catch (e) {
+      // Not a valid naddr, continue to adapter parsing
+    }
+  }
+
   // Try each adapter in priority order
   const adapters = [
     // new Nip17Adapter(),  // Phase 2
@@ -68,6 +94,9 @@ Currently supported formats:
   - naddr1... (NIP-53 live activity chat, kind 30311)
     Example:
       chat naddr1... (live stream address)
+  - naddr1... (Multi-room group list, kind 10009)
+    Example:
+      chat naddr1... (group list address)
 
 More formats coming soon:
   - npub/nprofile/hex pubkey (NIP-C7/NIP-17 direct messages)
diff --git a/src/types/chat.ts b/src/types/chat.ts
index 6d77c7f..51b7b45 100644
--- a/src/types/chat.ts
+++ b/src/types/chat.ts
@@ -178,6 +178,22 @@ export interface ChannelIdentifier {
   relays?: string[];
 }
 
+/**
+ * Group list identifier (kind 10009)
+ * Used to open multi-room chat interface
+ */
+export interface GroupListIdentifier {
+  type: "group-list";
+  /** Address pointer for the group list (kind 10009) */
+  value: {
+    kind: 10009;
+    pubkey: string;
+    identifier: string;
+  };
+  /** Relay hints from naddr encoding */
+  relays?: string[];
+}
+
 /**
  * Protocol-specific identifier - discriminated union
  * Returned by adapter parseIdentifier()
@@ -187,7 +203,8 @@ export type ProtocolIdentifier =
   | LiveActivityIdentifier
   | DMIdentifier
   | NIP05Identifier
-  | ChannelIdentifier;
+  | ChannelIdentifier
+  | GroupListIdentifier;
 
 /**
  * Chat command parsing result
diff --git a/src/types/man.ts b/src/types/man.ts
index a31f4c8..a97b2bd 100644
--- a/src/types/man.ts
+++ b/src/types/man.ts
@@ -350,18 +350,19 @@ export const manPages: Record<string, ManPageEntry> = {
     section: "1",
     synopsis: "chat <identifier>",
     description:
-      "Join and participate in Nostr chat conversations. Supports NIP-29 relay-based groups and NIP-53 live activity chat. For NIP-29 groups, use format 'relay'group-id' where relay is the WebSocket URL (wss:// prefix optional). For NIP-53 live activities, pass the naddr of a kind 30311 live event to join its chat.",
+      "Join and participate in Nostr chat conversations. Supports NIP-29 relay-based groups, NIP-53 live activity chat, and multi-room group list interface. For NIP-29 groups, use format 'relay'group-id' where relay is the WebSocket URL (wss:// prefix optional). For NIP-53 live activities, pass the naddr of a kind 30311 live event. For multi-room interface, pass the naddr of a kind 10009 group list event.",
     options: [
       {
         flag: "<identifier>",
         description:
-          "NIP-29 group (relay'group-id) or NIP-53 live activity (naddr1...)",
+          "NIP-29 group (relay'group-id), NIP-53 live activity (naddr1... kind 30311), or group list (naddr1... kind 10009)",
       },
     ],
     examples: [
       "chat relay.example.com'bitcoin-dev        Join NIP-29 relay group",
       "chat wss://nos.lol'welcome                Join NIP-29 group with explicit protocol",
-      "chat naddr1...                            Join NIP-53 live activity chat",
+      "chat naddr1...30311...                    Join NIP-53 live activity chat",
+      "chat naddr1...10009...                    Open multi-room group list interface",
     ],
     seeAlso: ["profile", "open", "req", "live"],
     appId: "chat",