Mark's suggested frame stack API makes sense to me, but being able to get/set specific values through the full frame API seems like it would be useful even if the lower level API existed - if we don't get one of the proxy PEPs in shape to land in 3.11, trace functions written in C could still use this to avoid materialising the locals dict if they only needed to manipulate specific values.

Even after a fast locals proxy is defined, there would still be some saving in skipping creating the proxy object when only accessing known keys.

We'd need the name-to-index mapping on the code objects to implement this API efficiently, but that isn't a PEP level change in its own right (the proxy PEPs only mention it because they need it)