Edit in Word using Wopi and Office Online Server
<p>I am working on a project where we have implemented content management with word. 
We have some word files, that are being processed using OpenXML.
Users can open those files in two ways - download a copy or edit online. Online editing is implemented using Office Online Server and custom Wopi server, built based on <a href="https://github.com/marx-yu/WopiHost">this example</a>.</p>

<p>Editing online works fine, but Word Online has limited features compared to desktop Word.</p>

<p>I am trying to build a functionality similar to Sharepoint, where user has 2 options - Edit in Word, Edit in Browser:
<a href="https://i.stack.imgur.com/gJ6eJ.png"><img src="https://i.stack.imgur.com/gJ6eJ.png" alt="Sharepoint Word edit options"></a></p>

<p>In Office Online Server I don't have such options, I can only edit in browser:
<a href="https://i.stack.imgur.com/8MP5y.png"><img src="https://i.stack.imgur.com/8MP5y.png" alt="OOS Word edit options"></a></p>

<p>Even in edit mode Sharepoint provides a link for Edit in Word:
<a href="https://i.stack.imgur.com/n6JVW.png"><img src="https://i.stack.imgur.com/n6JVW.png" alt="Sharepoint in edit mode"></a></p>

<p>whereas Office Online Server does not have it:
<a href="https://i.stack.imgur.com/Em1k2.png"><img src="https://i.stack.imgur.com/Em1k2.png" alt="OOS in edit mode"></a></p>

<p>My question is how it is implemented in Sharepoint?
In other words, am I missing something in Wopi server to enable it or Microsoft has built this functionality into Sharepoint, without the need of Wopi and/or OWA?</p>

<p>Any ideas would be appreciated!</p>