Website mode for tabs

[sr258]

As far as I‘ve understood it, Teams offers links to a website mode of custom tabs in various places (e.g. in the mobile client if the app hasn‘t been been released for mobile usage by Microsoft). By default the URL of the website is the same as the one for the tab:

generator-teams/src/tab/templates/src/app/scripts/{tabName}/{tabReactComponentName}Config.tsx

Line 24 in 6d227ad

websiteUrl: host + "/<%=tabName%>/?name={loginHint}&tenant={tid}&group={groupId}&theme={theme}",

I‘d like users who open the URL in the browser to see the same content as they would when opening the tab inside Teams. I need SSO support in my tab / web app and have followed the tutorial on SSO (it works fine inside Teams). How do I authenticate users when the user doesn‘t open the page inside Teams but by simply navigating to the URL directly? I guess I simply have to do a „normal“ OAuth 2 login, but I haven‘t found the right documentation on how to do this. Do I need to register a second app at Azure AD for the web app or can I use the app registration I already have for the teams app? I didn‘t configure any OAuth endpoints, as they were not needed for the auth flow inside teams. What happens if I add them for the web app and the user authenticates inside teams?