Some time ago I asked LLM to create my SDD harness. Then there were several iterations to have it work as I wanted. And it works. Spec (in my case it is behavioral contract) is the only source for any change in a code. There are also design (architecture description, depends on spec) and plan for implementation (depends on spec and design). Then I asked LLM to compare my harness with SpecKit. It concluded: no need to migrate to SpecKit. So, I stayed.