OTP via WebSocket

message OTPRequest {
  bool reserved = 1; // reserved for future fields (e.g. scope)
}

message OTPResponse {
  string otp = 1;           // The OTP code
  uint64 expires_at_ms = 2; // Expiration timestamp in milliseconds (Unix)
  string error = 3;         // Non-empty if the request failed
}

// --- Request ---

otpReq := &entities.OTPRequest{}
data, err := proto.Marshal(otpReq)
if err != nil {
    return err
}

frame := protocol.NewHapticFrame(entities.FrameType_OTP_REQUEST, data)
if err := frame.WriteFrame(stream); err != nil {
    return err
}

// --- Response ---

respFrame, err := protocol.ReadNextFrame(stream)
if err != nil {
    return err
}

if respFrame.Type != entities.FrameType_OTP_RESPONSE {
    return fmt.Errorf("unexpected frame type: %v", respFrame.Type)
}

otpResp := &entities.OTPResponse{}
if err := proto.Unmarshal(respFrame.Data, otpResp); err != nil {
    return err
}

if otpResp.Error != "" {
    return fmt.Errorf("OTP generation failed: %s", otpResp.Error)
}

fmt.Printf("OTP: %s, expires at: %d ms\n", otpResp.Otp, otpResp.ExpiresAtMs)