Thanks for working on this! I think this could be very helpful, one thing worth noting is the fuel is currently reset for before each call - I'm not sure if this will be an issue for your use case.

I have a branch with a slightly simplified implementation here: https://github.com/extism/extism/tree/consumed-fuel-direct - it avoids the extra field on Plugin by just calling store.get_fuel directly in the fuel_consumed - is there a benefit to storing the remaining fuel in the Plugin structure that I'm missing?

We actually want fuel to be reset for each call, the usecase for us is to see how much fuel is consumed by a call so that we can keep track of this.

I don't see a reason to store it if it's reset after every call. Calling it directly like in your branch is better I think.

Great, I will push up my changes to your branch and merge once CI passes!