"Systems drift because no one owns the accumulated risk.
In a migration that looks reversible until the data moves, the conversation keeps returning to what you do not know. The practical question is what you will do anyway.
A team can handle bad news. What it cannot handle is ambiguity that keeps reopening the same argument. Clarity removes noise faster than reassurance does. Write it for the person who inherits it later, because they will not have today’s context or today’s goodwill. A standard you cannot apply in one pass is not a standard; it is a preference disguised as governance.
Draft the future critique now: how this fails and what justification you will be tempted to use, then name one guardrail. That is how you keep pressure from rewriting the decision. Write it so execution is obvious.