Comment by storystarling

I built a similar gateway for my own stack and thought it would be a quick project, but the complexity is hidden in the details. A basic proxy is simple enough, but getting accurate token counts for streaming responses turned out to be a huge pain since every provider handles chunks differently. You also end up spending a lot of time writing adapters to unify the schemas so your application logic stays clean. If you care about precise billing or logging, it is definitely not a two day build.