What exactly does the server version mean?

[tredondo]

.on('server', version => console.log(version)) always shows 76, whether I connect to Gateway 972, or to TWB 979.

What does the server version field mean?

[nemozny]

I think it is API version.
I haven't seen a word about how this works, but from pilwon's comments somewhere in the code in here I've understood 76 is the last old (non-V100plus) version.
If you manage to get v100plus handshake working, you actually report to IB gateway a range of versions (i.e. v110..152) in your v100plus handshake, based on the functionality you implemented in your client (see constants.js).
So in order to get functionality 100+ working (with some exceptions I also saw in the code here), you have to have v100plus.

[tredondo]

A year later, I still get 76 with TWS 981.

I see a [lot of ifs based on the version in lib/incoming.js, deciding what fields to dequeue. Where are these versions listed? How can we find out at which version a given field has become available? Does that even matter, since most servers will be on the latest version anyway?

[nemozny]

There is 76, because nobody implemented the v100plus handshake. If you tell IB servers any higher version than 76, they will expect the handshake.
I've switched my IB client and language since the last comment, so don't look at me.