Block experience and explosions

Attach a BlockPart to the blocks that own the behavior.

exp_drop(level, event) answers Some(points) to replace the vanilla experience sample, before enchantments. None leaves the answer to another attached part and then vanilla. The query receives the dimension, state, position, optional block entity, breaker entity handle and tool. The level host reads without writing; level.block_entity_data(entity) reads the supplied entity's saved data without identity metadata and refuses stale handles. Answers are clamped to 0 through 32,767. Player breaks supply the part's answer to the global break_block event's exp_to_drop, after Silk Touch suppresses the starting amount (except for spawners). An explicit global override is applied as given. block_drops sees the resulting amount afterwards. Level and mob breaks use the shared resource-drop path. A canceled player break or a break that does not harvest produces no award.

on_block_exploded(host, event) runs before the engine removes each destroyed block. The server host permits writes. event.block_entity is a live handle, and entity.data(host) can read it while the block remains. The event borrows the same ExplosionStart description as the global start event: dimension, center, radius, fire, interaction, damage type, source and owner.

The engine still writes air after the callback, including when the callback replaced the block. Vanilla's separate wasExploded behavior follows removal. Air, spared blocks, canceled explosions and explosions that keep blocks produce no callback. Explosions retain their existing zero initial XP behavior.

Both methods route through prepared per-block subscriptions. Unsubscribed blocks build no callback context. Callback panics follow the existing native hook unwinding behavior; the engine does not apply a returned XP answer after a panic.