Details are where intentions encounter reality.

You can hold a clear picture of what you want, and that picture stays intact until it has to be built. The moment it meets materials, budgets, other people, and time, it starts negotiating, and every detail is one of those negotiations. What you actually intended only becomes knowable through how you settle them.

When a plan feels obviously right, push it down one level and specify what happens in a particular case. That is where you discover whether the idea holds. Do that early with the two or three details that seem most boring, because those are usually where the plan is really being decided.