TL;DRA node with a science pack in it (for example, Advanced Electronics which unlocks Science Pack 3) should be a prerequisite for ALL nodes that use that science pack (for example, Advanced Oil Processing, which needs Science Pack 3 but does not have Advanced Electronics as a prerequisite).
What ?What it says on the tin, and the tl;dr. But as an example:
Advanced Electronics unlocks Science Pack 3, but that node is not a prerequisite for Advanced Oil Processing, which needs Science Pack 3.
I propose that AE should be a prereq. for AOP, and similarly for all similar tech nodes.
Note: It does not need to be a DIRECT prereq, just the prereq should be somewhere in the tree before the node. For example, Military 2 unlocks the Military Science Pack, but it is not a DIRECT prereq of Cluster Grenade. This is fine, because it IS a prereq of Military 3, which is a prereq of Military 4, which is a prereq of Cluste Grenade.
Why ?It's confusing to be able to queue research for something when you've not even unlocked the node that contains that science pack, and it's hard to find the science pack node in a vast swath of red nodes in that list on the left.
With my proposal, every green tech tree node will be guaranteed to be achievable, and for every red one you can tell instantly why it's not achievable and what you need to do to unlock and research it.