+--------+
| |
| User |
| |
+---+----+
|
|
+---v-----+
| |
| Device |
+---------+ |<----------------+
| | | |
| | | |
| +--+--^---+ |
| | | |
| | | establish_session |
|qr_engagement | | |
| | | | new_request
| | | |
+-v--------------v--+-------------------+---+
| Reader |
| |
| +--------------------+ handle_response |
| | +---------------+ |
| | SessionManager | | |
| | |<--------------+ |
| +--------------------+ |
| |
+-------------------------------------------+