i've almost sorted all of this out. after some funny math and a smarter order to calculating contributing velocity vectors, i got the point where i could slip down steep slopes assuming i stopped on top of them. the first gif shows two not-steep surfaces, and then shows a third slope where i just kind of shove my way up it despite the game wanting me to slip.

fixing this is tough, but the second gif shows a lot more arrows proving that i got something kind of working. now the moment you're considered slipping, you can't move in any direction up the slope. however, it's still possible to jump into the air and then air-steer into the wall for a little additional movement up the wall, which looks kind of unnatural and feels more confusing than clever in practice.

i have a full travel day tomorrow, so prepare for a pretty small update upcoming. i think the movement is basically sufficient for me to now just go and fix the camera, or work on something else more interesting (attacking...?)