Problem

Leash-related syntax (leash holder expression, leash/unleash effects, and is leashed condition) only accepted LivingEntity types, preventing users from leashing boats and other non-living leashable entities. Users had to resort to reflection workarounds to leash boats.

Solution

Updated all three leash-related syntax files to accept any Entity type and utilize Paper's Leashable interface (available in Paper 1.21+) with runtime version checking via Skript.classExists(). The implementation falls back to the legacy LivingEntity.getLeashHolder() approach for older server versions, maintaining full backward compatibility.

Modified Files:

• ExprLeashHolder.java - Changed from SimplePropertyExpression<LivingEntity, Entity> to SimplePropertyExpression<Entity, Entity>
• EffLeash.java - Updated to accept Expression<Entity> instead of Expression<LivingEntity> for both leash and unleash operations
• CondLeashed.java - Changed from PropertyCondition<LivingEntity> to PropertyCondition<Entity>

Testing Completed

• Created comprehensive test files:
  • ExprLeashHolder.sk - Tests leash holder expression with wolves and non-leashable entities (snowballs)
  • EffLeash.sk - Tests leash/unleash effects with living entities, non-living entities, and multiple entities
  • CondLeashed.sk - Tests is leashed condition with various entity types
• ./gradlew clean build - SUCCESS (0 errors)
• ./gradlew clean quickTest - SUCCESS (all tests passed including "leash effect", "leash holder expression", and "is leashed condition")

Supporting Information

The implementation uses Paper's io.papermc.paper.entity.Leashable interface which provides consistent leashing behavior across all entity types. Non-leashable entities return null/false without throwing exceptions, ensuring graceful handling of edge cases.

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Completes: #8239
Related: none
AI assistance: GitHub Copilot with Claude Sonnet 4.5 model

The code in this pull request was generated by GitHub Copilot with the Claude Sonnet 4.5 model.