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Overview

Session resumption allows you to continue voice conversations from where they left off, even after page refreshes or application restarts. This provides a seamless user experience for ongoing conversations.

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How It Works

To resume a session, pass the resume_session query parameter when requesting an ephemeral key from your backend.

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Backend Implementation

Update your /token endpoint to handle session resumption: 
app.post("/token", async (req, res) => {
  const { resume_session } = req.query; // resume_session is the ID of the session to resume
  
  let url = "https://api.outspeed.com/v1/realtime/sessions";
  if (resume_session) {
    url += `?resume_session=${resume_session}`;
  }

  const response = await fetch(url, {
    method: "POST",
    headers: {
      Authorization: `Bearer ${process.env.OUTSPEED_API_KEY}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify(req.body),
  });

  const data = await response.json();
  res.json(data);
});

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Frontend Usage

Request an ephemeral key with the session ID to resume: 
const getEphemeralKeyFromServer = async (config: SessionConfig, sessionId?: string) => {
  let url = `${SERVER_URL}/token`;
  if (sessionId) {
    url += `?resume_session=${sessionId}`;
  }

  const tokenResponse = await fetch(url, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify(config),
  });

  const data = await tokenResponse.json();
  return data.client_secret.value;
};

// Resume existing session
const ephemeralKey = await getEphemeralKeyFromServer(sessionConfig, "session_123");
await conversation.startSession(ephemeralKey);

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Context Restoration

When a session is resumed, the context is restored and you’ll receive a context.restored event: 
conversation.on("context.restored", (event) => {
  console.log("Context restored with items:", event.items);
  // Handle restored conversation items
  event.items.forEach(item => {
    console.log(`${item.role}: ${item.content}`);
  });
});

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Use Cases

  • Page refreshes: Continue conversations after accidental refreshes
  • Application restarts: Resume conversations across app sessions
  • Multi-device: Continue conversations on different devices