3.8.7 Changelog
Bunch of Jigsaw changes + improvements:

Added delay_generation action type.
Added random_chance structure condition type.
StructureModifiers now use 'actions' field instead of singular 'action'.
StructureTargetSelectors now return a list of PieceEntry's instead of an Optional.
Changed piece_in_horizontal_direction wildcard to 'yungsapi:all' to match other conditions.
Fixed piece search conditions erroneously passing if they had internal jigsaw pieces.
Fixed deadend pieces not properly updating stored piece counts when removing previous piece.
Fixed TransformAction not properly updating stored PieceEntry with the new piece's bounding box.
Fixed piece counts not being updated when deadend pool is used. Small optimizations & null checks to some conditions.

YUNG's API

[1.19.4] v3.10.1 (Forge)