Why the tenth case beats the first
Stop rebuilding the parts your team already knows.
Your product’s economics do not change per deal. The buyer’s baseline does. Serre separates the two: the claims, conditions and evidence your team has approved stay put, and each case supplies only what is specific to this buyer.
Source to case
A claim enters the library once, from a source you can open. Every later case that uses it points back to the same claim, the same conditions and the same evidence. When you correct the claim, later cases start from the corrected version, and the cases your buyers already received stay as they were.
Where every number came from
Each input is marked buyer-confirmed, estimate, or from the library, and carries the source it came from. Arithmetic is deterministic — the same inputs give the same result, and no prose generation touches the sum. Open any figure and read the derivation.
What the model tells you about itself
Serre flags unsupported, stale, and conflicting items. A person decides what to change. Reuse carries approved reasoning forward; it does not validate a claim.
The arithmetic discipline
Hours multiplied by a labor rate are a valuation of capacity, not a cash saving. Turning capacity into a financial effect needs a named capture action, an owner and a date.
Operational, budget and realized readings of one benefit are never added together. This is the reason a finance reviewer can read a Serre case without reaching for a red pen.
It is your model
Your team approves the drivers, claims, and evidence standard. Serre proposes and flags; a person decides what enters the library.