The decision-layer architecture also raises an interesting observability problem. If Jev sits between the agent and the tools, its value shouldn't be measured only by how much LLM cost it removes. You'd also want to know how often its decisions actually changed the downstream routing, how often the fallback path was triggered, and whether those decisions reduced unnecessary tool calls without increasing recovery work. That makes the decision layer measurable as an operational component rather than just a cheaper classifier. Over time, those signals could also reveal where the typed decision boundary is too narrow or where the agent is still sending cases that don't belong there.