Overview Shipped
Every separation in this pipeline costs a dispatch. Each one is here because the cheaper arrangement was tried, or is standard, and fails in a specific way.
The obvious design is one strong model, one big prompt, the whole diff. It is cheaper, simpler, and it is what most tools do. The arguments below are why this pipeline does not — each one names the specific failure the extra structure is buying its way out of.
What the extra structure costs
Illustrative for a default-scope run on a mid-sized diff, not a measured benchmark. The shape is the point: the dispatch count is roughly forty times the naive design, and the sections below are the argument for why that is worth paying.