Mobs Lose Core AI When Acting as Mounts

When most hostile or neutral mobs are used as mounts,they lose fundamental AI behaviors. This includes the complete suppression of attack capabilities (melee and ranged) and, in some cases, the disruption of their natural movement patterns.

Exceptions: A small subset of mobs retains full functionality when ridden: Piglins, Piglin Brutes, Hoglins, Zoglins, Wardens, Creakings and Breezes.

Description:

General Phenomenon:

For the vast majority of mobs(Zombies, Skeletons,Spiders,Drowned,Ravagers), being ridden completely disables their attack AI.They become passive carriers, even when provoked.

Special Case:

1. Illusioner: It retains its spellcasting AI (can cast Blindness) but loses its bow attack AI entirely.

2. Evoker: Functions correctly because its attacks (summoning fangs/vexes) are implemented as spellcasting AI,which appears exempt from the "ridden" state suppression.

3. Witch: It retains "drink potion" behavior but loses "throw potion" attack behavior.

4. Ghast: It retains its "shoot fireball" attack AI,but its flight movement AI is disabled, causing it to hover statically.

5. Wither: When ridden, its behavior fragments:
   · It retains mobility.
   · Its two side heads retain their Wither skull attack AI.
   · Its central primary head loses attack capability.

6. Ravager: It retains normal attack AI when ridden by Illagers and Witches, but not by Vexes. However, when ridden by Pillagers or Witches, their movement AI is still affected, as these riders tend to maintain distance from their targets, overriding the Ravager's natural charging behavior.

Steps to reproduce the issue:

1. Use the following command to summon a Skeleton riding on top of another Skeleton (both holding bows):

   /summon minecraft:skeleton ~ ~ ~ {Passengers:[{id:"skeleton",equipment:{mainhand:{id:"bow"}}}],equipment:{mainhand:{id:"bow"}}}

2. Observe the behavior of both Skeletons.

3. The top Skeleton will attack normally using its bow, while the bottom Skeleton will only move around with its arms down, and will not perform any attacks.

4. Kill the top Skeleton (the rider).

Observe that the bottom Skeleton (now no longer being ridden) immediately regains its normal attack behavior.

Expected result:

The bottom Skeleton,acting as a mount, should retain its full combat AI. Even while carrying a rider, it should still be able to draw its bow and shoot at hostile targets.

Actual result:

The bottom Skeleton's attack AI is completely suppressed.It behaves as a passive vehicle, only capable of movement with a default "arms down" animation, and will not engage in combat under any circumstances.

Possible Cause Speculation:

This issue is likely determined by the attack AI system used by the mobs. Mobs utilizing the newer attack AI (such as Piglins and Breezes) are completely unaffected by this bug. In contrast, mobs with the legacy attack AI are affected to varying degrees, most notably Spiders, which, when serving as mounts for Skeletons, completely lose their attack capabilities and become purely a means of transportation.

Scope of Impact:

This behavior clearly contradicts the intended design of the game, especially following the "Mounts of Mayhem" update,which introduced and expanded upon mounted combat as a combat mechanic. While the impact on vanilla "rider" mobs may be limited (as their mounts are often passive), it severely hinders monster design in custom PVE maps, as map creators are unable to design challenging or creative encounters using aggressive creatures as functional mounts.