Guardian, not optimizer — watches client ad spend and pauses campaigns the moment a budget cap is hit.
An agency's worst phone call is the one where a client's ad account has spent past the number everyone agreed on. Platform budget controls are per-campaign and easy to drift; the agency carries the overspend commercially even though the money left through someone else's dashboard. The exposure is real, and nothing in the standard toolset actually stops it.
PaceGuard reads every connected account against one plan and answers three questions: what was spent, what the plan said by now, and where the hard cap sits. When spend crosses the cap it pauses campaigns — and that is the only write it ever makes. It deliberately never touches bids, budgets or creative, because a tool trusted to stop spending has to be a tool nobody suspects of quietly changing performance. Narrow scope is the product.