This is an official Funtoo development effort to re-implement and crafting a robust yet simplified autogen for the two main Linux kernel packages that Funtoo supports:

1. sys-kernel/debian-sources
2. sys-kernel/debian-sources-lts

The key here is to use a methodology that deterministically derives new kernel versions from Debian upstream in a way that is robust and has a low probability of breaking the auto-generation process of core-kit (as these are some of the most critical packages) yet is simple to debug.

As noted by drobbins in FL-10732:

This would be a good time to re-implement the debian-sources autogen to be simpler. It became complicated due to having to query multiple debian repositories (debian has a very horrible organization for this) and then make decisions about what ebuilds to generate and mask. So it became really hard to maintain.