> Suppose I write a server-based application that I wish to release under the AGPL and expose publicly. What concrete steps do I need to take in order to satisfy clause 13? 

As the author of the application, I can incorporate any or NO mechanism that would trigger the requirements of the [AGPL section 13][1]. So there are no specific steps I need to take. I am the author.

The point here is that the onus is on a user that would modify and redistribute or perform publicly my application. My application may not contain any such built-in mechanism to download the corresponding sources yet if a user modifies my code, then they would have to meet the requirements of section 13 nonetheless.

So I can include nothing or anything. If I include something I could include anything I like:

 - a valid link to a public git repository on an "About" page
 - the link may appear on every page of the application
 - it can be a direct download
 - it can be a link to a Github project or similar

Or I can include nothing at all. I am the author and I can do as I please.

If I include some or any of the above, a user:

 - may not remove any of these,
 - if they modify my code, they may need to update the mechanism (such as update the link, or the code that creates a tarball or else) such that this points to **the current code with their modifications** rather than to my original unmodified code.


See also this excellent related [answer][2] from [@apsillers][3] who contacted the FSF on a similar topic (this is small excerpt):

> So, if you use an unmodified AGPL application that doesn't have download-source functionality, you are not required to add one or otherwise offer the source to users. If you do modify the software, of course, you are required to add a mechanism to allow users to download your modified source.


  [1]: https://www.gnu.org/licenses/agpl-3.0.en.html#section13
  [2]: http://opensource.stackexchange.com/a/791/947
  [3]: http://opensource.stackexchange.com/users/50/apsillers