Once a spec becomes sufficiently large and detailed and complicated, it becomes very difficult to ensure it is internally consistent. That's why I start every project with a METASPEC.md so that Claude can break up the task of writing SPEC.md into manageable steps.

Everyone knows a philosophy comes before a spec. Claude has to write your applications philosophy first, then you write your spec. But a philosophy is crap without a values statement, so Claude has to actually write that first.