Summary: This document specifies the use of HPKE with COSE, supporting both integrated content encryption and encryption of content-encryption keys for multiple recipients. The description is clear and easy to understand. 

There are some minor issues/questions: 
- In Section 3.1 (Overview), page 4, the second paragraph following the bullet list states:
In both cases, the new COSE header parameter "ek" MUST be present. It contains the encapsulated KEM shared secret. The value of this parameter MUST be the "enc" value output by the HPKE Seal() Single-Shot operation, as defined in Section 6.1 of [I-D.ietf-hpke-hpke]. 

Question: is the COSE header parameter "ek" contains the encapsulated KEM shared secret? why the value has to be "enc"? 

- Sections 3.2 and 3.3.4:  The specification permits externally supplied HPKE "info" and "recipient_extra_info", which are not transmitted in the COSE message. 
Question: are both sender and recipient must use identical context values and encodings?

Best Regards, 
Linda Dunbar