In section 24.9.1, your Glossary: Promises section, you say in part this:
"Resolving a promise P with a thenable T means that P can't be resolved anymore and will now follow T's state, including its fulfillment or rejection value [emphasis mine]"
I believe the bolded section is intended to convey the fact that a thenable resolved with a thenable value will be recursively unwrapped until a non-thenable fulfillment is found, and passed on to the chained promise? Would it be worth spelling that out a bit more? Just a friendly suggestion; if I hadn't already read Kyle's book I may not have fully grasped the implications of that passage.