25w16a: Movement issues in lead-connected entities (iron golems, wolves, foxes, and happy ghasts)

When two or more entities are connected with leads (such as iron golems, wolves, foxes, or happy ghasts), their movement behavior becomes severely affected under certain connection configurations, especially when loops are formed.

Bug Reproduction (Iron Golems):

1. Connect one iron golem to another using a lead.

2. Then connect the second golem back to the first (creating a bidirectional connection).

3. Result: Both golems stop moving normally. They only move extremely slowly (less than 1 block per minute), although walking particles still appear.

4. If only a one-way connection is made (first golem to second), movement works as expected.

Combat Behavior:

• Hitting one or both golems in Survival mode causes them to try to follow the player, but they barely move.

• Attack animations and damage are unaffected. Only movement is impacted

Reproduction with Multiple Golems:

• Connecting three golems in a closed loop (1↔2, 2↔3, 3↔1) causes movement issues for all.

• However, connecting them in a straight line (1→2→3 without reconnecting the third to the first) does not cause problems.

Fox Behavior Observation:

• Foxes are less affected and can move more naturally if targeting the same enemy.

• The issue becomes more noticeable when each fox chases a different target—the lead mechanics interfere more clearly with their AI.

Similar Behavior in Wolves:

• The same problem occurs when two wolves are connected bidirectionally.

• When targeting a distant enemy, they fail to move properly.

• While their attacks still work (they leap at nearby targets), it's difficult for them to track and reach faraway ones when tethered.

Special Case: Happy Ghasts in Loops:

• Connecting three happy ghasts in a loop (1↔2, 2↔3, 3↔1) works as expected.

• But when connecting more than three (e.g., 1↔2↔3↔4↔1), one lead drops as an item, and the loop breaks.

• they haven't movements problems

Suggested Improvement:

A conditional cooperation mechanic could help:

• If the tethered mobs have different targets at different positions, the closest one (similar to selector @n) could be chosen as a shared target.

• If there's only one target, all tethered mobs should coordinate and pursue it together without interfering with each other's movement logic.

I hope this report helps improve the behavior of lead-connected entities. I'm happy to help with further testing if needed!

Thanks for your hard work — Minecraft keeps getting better!