The budget guard

Every path in Kno that can call a provider goes through the same four steps: estimate, authorize, invoke, settle, in integer micro-dollars end to end.

Caps bind before the call

Kno prices each case from its own dated price table, so the cap is known before the call rather than discovered at settlement. Two consequences:

• A run above its estimate asks for consent, [y] / [n] / [c] change the cap, or proceeds with --yes.
• A cap whose cost cannot be estimated is refused up front. Kno would rather not run than run unguarded.

Interruption is boring on purpose

Work checkpoints as each case completes, in one transaction with its result. --resume skips finished work and reconstructs prior spend from disk. An interrupted run cannot pay twice, and a budget-stopped run is a configuration outcome (exit code 2), not a failure (1).

Why the pricing table rots on purpose

Prices change. Kno ships a dated pricing table and a weekly drift detector: if the table is more than 90 days old, the weekly pricing check fails and a pricing-drift issue is filed. A budget guard with stale prices is theater.