diff --git a/extensions/openai/realtime-transcription-provider.test.ts b/extensions/openai/realtime-transcription-provider.test.ts
index 5fb6829df3a..6ee64399cd1 100644
--- a/extensions/openai/realtime-transcription-provider.test.ts
+++ b/extensions/openai/realtime-transcription-provider.test.ts
@@ -1,7 +1,88 @@
-import { describe, expect, it } from "vitest";
+import { beforeEach, describe, expect, it, vi } from "vitest";
 import { buildOpenAIRealtimeTranscriptionProvider } from "./realtime-transcription-provider.js";
 
+const { FakeWebSocket } = vi.hoisted(() => {
+  type Listener = (...args: unknown[]) => void;
+
+  class MockWebSocket {
+    static readonly OPEN = 1;
+    static readonly CLOSED = 3;
+    static instances: MockWebSocket[] = [];
+
+    readonly listeners = new Map<string, Listener[]>();
+    readyState = 0;
+    sent: string[] = [];
+    closed = false;
+
+    constructor() {
+      MockWebSocket.instances.push(this);
+    }
+
+    on(event: string, listener: Listener): this {
+      const listeners = this.listeners.get(event) ?? [];
+      listeners.push(listener);
+      this.listeners.set(event, listeners);
+      return this;
+    }
+
+    emit(event: string, ...args: unknown[]): void {
+      for (const listener of this.listeners.get(event) ?? []) {
+        listener(...args);
+      }
+    }
+
+    send(payload: string): void {
+      this.sent.push(payload);
+    }
+
+    close(code?: number, reason?: string): void {
+      this.closed = true;
+      this.readyState = MockWebSocket.CLOSED;
+      this.emit("close", code ?? 1000, Buffer.from(reason ?? ""));
+    }
+  }
+
+  return { FakeWebSocket: MockWebSocket };
+});
+
+vi.mock("ws", () => ({
+  default: FakeWebSocket,
+}));
+
+type FakeWebSocketInstance = InstanceType<typeof FakeWebSocket>;
+type SentRealtimeEvent = {
+  type: string;
+  audio?: string;
+  session?: {
+    type?: string;
+    audio?: {
+      input?: {
+        format?: { type?: string };
+        transcription?: {
+          model?: string;
+          language?: string;
+          prompt?: string;
+        };
+        turn_detection?: {
+          type?: string;
+          threshold?: number;
+          prefix_padding_ms?: number;
+          silence_duration_ms?: number;
+        };
+      };
+    };
+  };
+};
+
+function parseSent(socket: FakeWebSocketInstance): SentRealtimeEvent[] {
+  return socket.sent.map((payload) => JSON.parse(payload) as SentRealtimeEvent);
+}
+
 describe("buildOpenAIRealtimeTranscriptionProvider", () => {
+  beforeEach(() => {
+    FakeWebSocket.instances = [];
+  });
+
   it("normalizes OpenAI config defaults", () => {
     const provider = buildOpenAIRealtimeTranscriptionProvider();
     const resolved = provider.resolveConfig?.({
@@ -70,4 +151,88 @@ describe("buildOpenAIRealtimeTranscriptionProvider", () => {
     const provider = buildOpenAIRealtimeTranscriptionProvider();
     expect(provider.aliases).toContain("openai-realtime");
   });
+
+  it("waits for the OpenAI session update before draining audio", async () => {
+    const provider = buildOpenAIRealtimeTranscriptionProvider();
+    const session = provider.createSession({
+      providerConfig: {
+        apiKey: "sk-test", // pragma: allowlist secret
+        language: "en",
+        model: "gpt-4o-transcribe",
+        prompt: "expect OpenClaw product names",
+        silenceDurationMs: 900,
+        vadThreshold: 0.45,
+      },
+    });
+
+    const connecting = session.connect();
+    const socket = FakeWebSocket.instances[0];
+    if (!socket) {
+      throw new Error("expected session to create a websocket");
+    }
+
+    socket.readyState = FakeWebSocket.OPEN;
+    socket.emit("open");
+    session.sendAudio(Buffer.from("before-ready"));
+
+    expect(session.isConnected()).toBe(false);
+    expect(parseSent(socket)).toEqual([
+      {
+        type: "transcription_session.update",
+        session: {
+          type: "transcription",
+          audio: {
+            input: {
+              format: { type: "audio/pcmu" },
+              transcription: {
+                model: "gpt-4o-transcribe",
+                language: "en",
+                prompt: "expect OpenClaw product names",
+              },
+              turn_detection: {
+                type: "server_vad",
+                threshold: 0.45,
+                prefix_padding_ms: 300,
+                silence_duration_ms: 900,
+              },
+            },
+          },
+        },
+      },
+    ]);
+
+    socket.emit("message", Buffer.from(JSON.stringify({ type: "session.updated" })));
+    await connecting;
+
+    expect(session.isConnected()).toBe(true);
+    expect(parseSent(socket)).toEqual([
+      {
+        type: "transcription_session.update",
+        session: {
+          type: "transcription",
+          audio: {
+            input: {
+              format: { type: "audio/pcmu" },
+              transcription: {
+                model: "gpt-4o-transcribe",
+                language: "en",
+                prompt: "expect OpenClaw product names",
+              },
+              turn_detection: {
+                type: "server_vad",
+                threshold: 0.45,
+                prefix_padding_ms: 300,
+                silence_duration_ms: 900,
+              },
+            },
+          },
+        },
+      },
+      {
+        type: "input_audio_buffer.append",
+        audio: Buffer.from("before-ready").toString("base64"),
+      },
+    ]);
+    session.close();
+  });
 });
diff --git a/extensions/openai/realtime-transcription-provider.ts b/extensions/openai/realtime-transcription-provider.ts
index 38b2993024b..852148f80b3 100644
--- a/extensions/openai/realtime-transcription-provider.ts
+++ b/extensions/openai/realtime-transcription-provider.ts
@@ -72,8 +72,16 @@ function createOpenAIRealtimeTranscriptionSession(
 ): RealtimeTranscriptionSession {
   let pendingTranscript = "";
 
-  const handleEvent = (event: RealtimeEvent) => {
+  const handleEvent = (
+    event: RealtimeEvent,
+    transport: RealtimeTranscriptionWebSocketTransport,
+  ) => {
     switch (event.type) {
+      case "session.updated":
+      case "transcription_session.updated":
+        transport.markReady();
+        return;
+
       case "conversation.item.input_audio_transcription.delta":
         if (event.delta) {
           pendingTranscript += event.delta;
@@ -95,7 +103,11 @@ function createOpenAIRealtimeTranscriptionSession(
 
       case "error": {
         const detail = readRealtimeErrorDetail(event.error);
-        config.onError?.(new Error(detail));
+        const error = new Error(detail);
+        config.onError?.(error);
+        if (!transport.isReady()) {
+          transport.failConnect(error);
+        }
         return;
       }
 
@@ -121,7 +133,6 @@ function createOpenAIRealtimeTranscriptionSession(
       Authorization: `Bearer ${config.apiKey}`,
       "OpenAI-Beta": "realtime=v1",
     },
-    readyOnOpen: true,
     connectTimeoutMs: OPENAI_REALTIME_TRANSCRIPTION_CONNECT_TIMEOUT_MS,
     maxReconnectAttempts: OPENAI_REALTIME_TRANSCRIPTION_MAX_RECONNECT_ATTEMPTS,
     reconnectDelayMs: OPENAI_REALTIME_TRANSCRIPTION_RECONNECT_DELAY_MS,
@@ -137,17 +148,24 @@ function createOpenAIRealtimeTranscriptionSession(
       transport.sendJson({
         type: "transcription_session.update",
         session: {
-          input_audio_format: "g711_ulaw",
-          input_audio_transcription: {
-            model: config.model,
-            ...(config.language ? { language: config.language } : {}),
-            ...(config.prompt ? { prompt: config.prompt } : {}),
-          },
-          turn_detection: {
-            type: "server_vad",
-            threshold: config.vadThreshold,
-            prefix_padding_ms: 300,
-            silence_duration_ms: config.silenceDurationMs,
+          type: "transcription",
+          audio: {
+            input: {
+              format: {
+                type: "audio/pcmu",
+              },
+              transcription: {
+                model: config.model,
+                ...(config.language ? { language: config.language } : {}),
+                ...(config.prompt ? { prompt: config.prompt } : {}),
+              },
+              turn_detection: {
+                type: "server_vad",
+                threshold: config.vadThreshold,
+                prefix_padding_ms: 300,
+                silence_duration_ms: config.silenceDurationMs,
+              },
+            },
           },
         },
       });