For UX, I believe most cards are operating if a manually coded stop has been added. Like before you draw a card per turn, there is a manual stop added if Sheoldred the Apocalypse is in play (opponent controlled, so you gain this stop regardless of holding full control). This stop is also regardless if you have an instant/flash or activated ability.

To clarify, this is a good thing.

However lets code this as a general rule (which can be augmented with special manual cases).

condition 1) If spell or ability targets you, your zones, your spells, your permanents then place an autostop
condition 2) If a player declares attackers and that damage would be calculated as lethal: place an autostop (so you can crew, change your devotion count, etc to have the opportunity to earn a blocker which isn’t obvious to the client)
condition 3) If you control a permanent that has conditional text (like it could gain flying or could become a creature), provide a stop so players have an opportunity to cast/activate and not skip past blockers.
condition 4) If you are auto passing and opponent as casting/activating on their own, continue to auto pass UNTIL condition1 or condition2 is true. We shortcut this in paper: ‘go do your thing. Just let me know if you are going to attack or target my stuff’.

What prompted this; see attached. It is hard to see all of the enchantments on Light Paws but I believe they had one instant of flying. I could have chumped if I lost 1 life via the land. Drawn removal for the flying. Then chumped for a few turns until assembling infinite life.