SESSION_CONTEXT() brings two major innovations. Firstly, it replaces a 128-byte scalar payload with a key-value structure that can accommodate 256kB of data. You can really go to town filling this thing up.
The second change is less glamorous, but possibly more significant: it is possible to set an entry to read-only, meaning that it can safely be used for the kind of contextual payload you don’t want tampered with. This makes me happy, not because I currently have a great need for it, but because it neatly ties in with things I have been thinking about a lot lately.
Read on for more.