Considering that not even Linux has this quite down pat, this might not come anytime in the near future. Perhaps a good alternative would be saving global state (instead of per-app state) at shutdown and restoring it on next boot? Haiku boots and powers off so fast that it feels like suspend/resume on other desktop OSes already. For example, closing a laptop lid would save the global state and shutdown; opening the lid and pressing the power button after would boot the system and resume where it left off. This is basically a cheap form of hibernation, but (hopefully) without the complications of adding proper hibernation per se (see Linux, BSD attempts).
overall system resilliency
Haiku is in beta status right now, so that can still be improved upon in the future. For its type of software in beta, it is (admittedly) very stable compared to most others out there. To quote Bryan Lunduke:
“This kind of stability is what most other OSes would call release quality”
Note: That may not be the exact phrase, but he did say something to that effect in his latest video about Haiku.
automatic power management
Shouldn’t be too hard to have Haiku go into power saving mode automatically when the battery is at a certain percentage; is this accurate, Haiku devs?
Yeah, this is a big one that needs to be addressed. Would it be possible to get a compat layer for GPU drivers working (similar to wireless drivers)? Even FreeBSD uses one to get Linux drivers working; could that be adopted for Haiku or would it be better to make one specifically for Haiku and using the FreeBSD one as reference only? I feel like the former would become a case of layer-ception (yo dawg I heard you like layers, so we put layer on top of a layer on top of another layer ).
As for the login/session manager, it may be better to postpone making one until multi-user support is present in Haiku. Last I checked, it was planned to come after R1 (Looking Glass). Is this still the current plan?