diff --git a/apps/chat-worker/src/durable-objects/ChatRoom.ts b/apps/chat-worker/src/durable-objects/ChatRoom.ts
new file mode 100644
index 0000000..8c1982c
--- /dev/null
+++ b/apps/chat-worker/src/durable-objects/ChatRoom.ts
@@ -0,0 +1,155 @@
+import { DurableObject } from "cloudflare:workers";
+import type { Env, ClientMessage, ServerMessage } from "../lib/types";
+import { PostgREST } from "../lib/supabase";
+
+export class ChatRoom extends DurableObject<Env> {
+  private postgrest: PostgREST | null = null;
+
+  private getPostgREST(): PostgREST {
+    if (!this.postgrest) {
+      this.postgrest = new PostgREST(this.env.SUPABASE_URL, this.env.SUPABASE_SERVICE_ROLE_KEY);
+    }
+    return this.postgrest;
+  }
+
+  async handleWebSocket(request: Request, userId: string, channelId: string): Promise<Response> {
+    const pair = new WebSocketPair();
+    const [client, server] = [pair[0], pair[1]];
+
+    const stored = await this.ctx.storage.get<string>("channelId");
+    if (!stored) {
+      await this.ctx.storage.put("channelId", channelId);
+    }
+
+    this.ctx.acceptWebSocket(server, [userId]);
+
+    this.broadcast({
+      type: "presence.update",
+      userId,
+      status: "online",
+    }, server);
+
+    return new Response(null, { status: 101, webSocket: client });
+  }
+
+  async webSocketMessage(ws: WebSocket, raw: string | ArrayBuffer): Promise<void> {
+    const tags = this.ctx.getTags(ws);
+    const userId = tags[0];
+    if (!userId) {
+      ws.close(4001, "Missing user identity");
+      return;
+    }
+
+    let msg: ClientMessage;
+    try {
+      msg = JSON.parse(typeof raw === "string" ? raw : new TextDecoder().decode(raw));
+    } catch {
+      this.sendTo(ws, { type: "error", code: "PARSE_ERROR", message: "Invalid JSON" });
+      return;
+    }
+
+    switch (msg.type) {
+      case "message.send":
+        await this.handleSendMessage(ws, userId, msg.text, msg.clientId);
+        break;
+      case "typing.start":
+        this.broadcast({ type: "typing", userId, isTyping: true }, ws);
+        break;
+      case "typing.stop":
+        this.broadcast({ type: "typing", userId, isTyping: false }, ws);
+        break;
+      case "presence.ping":
+        break;
+    }
+  }
+
+  async webSocketClose(ws: WebSocket, code: number, reason: string, wasClean: boolean): Promise<void> {
+    const tags = this.ctx.getTags(ws);
+    const userId = tags[0];
+    if (userId) {
+      const remaining = this.ctx.getWebSockets(userId);
+      if (remaining.length === 0) {
+        this.broadcast({ type: "presence.update", userId, status: "offline" });
+      }
+    }
+  }
+
+  async webSocketError(ws: WebSocket, error: unknown): Promise<void> {
+    console.error("WebSocket error:", error);
+    ws.close(1011, "Internal error");
+  }
+
+  private async handleSendMessage(ws: WebSocket, userId: string, text: string, clientId: string): Promise<void> {
+    if (!text || text.trim().length === 0) {
+      this.sendTo(ws, { type: "error", code: "EMPTY_MESSAGE", message: "Message text is required" });
+      return;
+    }
+
+    const id = crypto.randomUUID();
+    const createdAt = new Date().toISOString();
+    const channelId = await this.getChannelId();
+
+    const serverMsg: ServerMessage = {
+      type: "message.new",
+      id,
+      userId,
+      text: text.trim(),
+      createdAt,
+      clientId,
+    };
+
+    this.broadcast(serverMsg);
+    this.ctx.waitUntil(this.persistMessage(channelId, id, userId, text.trim(), createdAt));
+  }
+
+  private async persistMessage(channelId: string, id: string, userId: string, text: string, createdAt: string): Promise<void> {
+    const db = this.getPostgREST();
+    const maxRetries = 3;
+
+    for (let attempt = 0; attempt < maxRetries; attempt++) {
+      try {
+        await db.insert("messages", {
+          id,
+          channel_id: channelId,
+          user_id: userId,
+          text,
+          created_at: createdAt,
+        });
+        return;
+      } catch (error) {
+        console.error(`Message persist attempt ${attempt + 1} failed:`, error);
+        if (attempt < maxRetries - 1) {
+          await new Promise((r) => setTimeout(r, 100 * (attempt + 1)));
+        }
+      }
+    }
+    console.error(`Failed to persist message ${id} after ${maxRetries} attempts`);
+  }
+
+  private async getChannelId(): Promise<string> {
+    const channelId = await this.ctx.storage.get<string>("channelId");
+    if (!channelId) throw new Error("channelId not stored in DO");
+    return channelId;
+  }
+
+  private sendTo(ws: WebSocket, msg: ServerMessage): void {
+    try {
+      ws.send(JSON.stringify(msg));
+    } catch {
+      // Connection already closed
+    }
+  }
+
+  private broadcast(msg: ServerMessage, exclude?: WebSocket): void {
+    const payload = JSON.stringify(msg);
+    for (const ws of this.ctx.getWebSockets()) {
+      if (ws !== exclude) {
+        try {
+          ws.send(payload);
+        } catch {
+          // Connection already closed
+        }
+      }
+    }
+  }
+}