[dreadpirates]

We hit this exact problem and built NORNR (nornr.com) around it. Instead of trying to forecast costs upfront, we enforce them at runtime. Every agent action that involves spend has to request a mandate first. Policy decides approved, queued, or blocked based on budget, rate, context, whatever you define. Every decision gets a signed receipt so you have a full audit trail. It doesn't replace your cost estimates but it puts a hard ceiling on what agents can actually spend. Free tier if you want to try it.