Isn't there a long rest clock, per se? Aren't certain events dependent upon or locked behind various thresholds that way?

Verisimilitude. First time it happens it took me out of flow. Now I notice when NPCs use it against me.

To answer your question, no I don't rest after every fight. That's missing the point. Maybe I didn't do a good job explaining in the post. I like nuking people. Was curious if others came across this mechanic and how they use it.

If this was criticism of the difficulty I'd say ideally every character would get locked in turn based when combat started. Stealth could also use a pass to make it a little more internally logical. I shouldn't be able to walk undetected in plate, in half light, at 45 degrees to someone's eyeballs. But I'm not criticizing.

Anyone far enough from combat doesn't get pulled in. Anyone in hiding as long as they aren't in sight lines won't get pulled into combat. If they are in sight they have to pass a stealth check to remain hidden. Anytime they move they'll have to pass a check as well to remain hidden. You can abuse this during the Cazador fight to keep Astarion from being sacrificed. Leave him at the door and start the fight with Cazador then bring Astarion down to the fight. Cazador won't sacrifice Astarion.

Works even better with invisibility. You can waltz right through the middle of an ongoing battle and assassinate that hard to reach mage in the back.

So here's my best understanding of the mechanics of the first turn of combat:

If you use an action to attack someone and it starts combat, everyone rolls initiative and takes turns in order. When your turn comes around, you'll be missing that action--basically, you to use your action before everyone else got a turn, but that counts as your action for the round.

If you engage turn-based mode out of combat and your actions initiate combat, it works the same way. I this case, you might also have used some movement and/or your bonus action.

There are some abilities that grant all your actions, bonus actions, and movement back when you roll initiative (the Assassin gets this, I believe). So if you spec'd Astarion as an assassin, he'll "break" the above rule and have all his resources available, even if he did a massive sneak attack to start combat.

Even in real time, if you do something like jump, you'll notice your bonus action icon goes gray for a few seconds. If combat starts in that window, you'll have already used that bonus action for that round.

Hope that helps clarify!

When a non-tracked character enters the battle they roll initiative and get slotted in. So Astarion usually end up at the start. Then my paladin gets out at the back after the alpha strike. That part makes sense to me.

Otherwise, agreed turn based mode should be everywhere. Not just localized to the battle or a little tu n based bubble.

Like, I started my assault on the goblin camp with a fireball and then everyone outside of range piled on. The whole camp should've been locked in.