What makes a decision hold up afterwards

A decision is worth something only if it still means the same thing in three years, when the people who made it have moved on and somebody is asking why a contract was certified at that price.

What the platform does about that

• **The record is added to, never rewritten.** A case accumulates versions; an assessment that is superseded stays on the file beside the one that replaced it. There is no edit that removes what was previously true.
• **The evidence is frozen and hashed at the decision.** What the decision rested on is fixed at that moment and a hash of it is recorded, so the file can be shown later to be the same file.
• **A case is judged under the rules in force when its clock started.** Thresholds and targets are configuration with effective dates. Changing one never reopens a decided case.
• **Every action is attributed.** Who did what, when, against which case — including the automatic ones, which are attributed to the job that took them.
• **Certificate numbers are allocated without gaps,** inside the same transaction as the decision. A missing number would be unexplainable, and unexplainable is the one thing a register cannot be.

What a certificate proves, and what it does not

It records that the Office assessed this contract, at this scope, up to this value ceiling, on this date, and reached this outcome. Anyone holding the number can confirm that much without an account. It does not authorise the award, and it does not stop one: the procurement system decides what to do with it. The Office supplies an assessment; acting on it is somebody else's authority, and pretending otherwise would misrepresent what this system is.