They... don't? I've not had enemies leave combat after patch 9. Combat ending after the first attack was only possible Patch 8 and earlier. Now, enemies stand around and do fuck all when they can't detect you. (Also sneak attack damage is 2d6 and 3d6 unless at really early level...)
Please, give me your enemies who leave combat and heal...
They don’t leave combat, but (some?) NPCs have the ability to heal back up to 100% when out of combat and sometimes, when enemies are out of normal range (I think), even if you attack them the game doesn’t register that they’re in combat and they’ll use that logic to heal.
Eg, in my last playthrough I shot the far web bridge out from under the spider queen matriarch, she plummeted, lost half her HP, then promptly healed herself back to full health. In this case, combat wasn’t triggered.
Other times, as you say, enemies won’t see you and enter combat, but they don’t heal themselves.
