The AGPL is based on the GPL, not the LGPL. It does not contain any linking exceptions, and any work using AGPL code (linked or otherwise, modified or not) must also be AGPL licensed and distributed.
Using separate processes can circumvent the (A)GPL, but this is murky ground. If your end application depends on the external process, such that it wouldn't function properly without it, then it would be considered a derived work of the AGPL software.
In most cases where people use separate GPL applications in closed source programs, they provide the GPL work as an optional extension, or an alternative back-end to some other piece of code etc.
The (A)GPL work cannot be distributed alongside the final application even as a separate app (eg, putting them into the same archive or repository), although it's fine to provide instructions on where to find the GPL work and how to use it with your app.
https://softwareengineering.stackexchange.com/questions/107883/agpl-what-you-can-do-and-what-you-cant