@ochenmiller so looks to me like openaps isn't causing an oscillation, it's just being conservative about when to high-temp when BG is high but falling.
generally I haven't optimized the algorithm for being turned on when BG is super high with insufficient IOB. it sort of assumes that either you will have done a correction bolus when you turn it on, or the loop has been running for hours, and high-temping the whole way up.
the one tweak we should probably make is some sort of incorporation of just how far above target eventualBG is. right now it assumes that the IOB and BGI will start out appropriate for bringing BG back within range, so BG dropping faster than that is grounds to cancel the high-temp and see how it plays out.
but if you never got enough IOB in the first place, that assumption no longer holds, and it's more appropriate to maintain the high-temp until eventualBG gets closer to target