Animations
Jenny Mod ships a custom animation system on top of the vanilla biped rig. Different companions have their own styles, and some animations only unlock once relationship progression reaches a certain point.
Animation types
Walking and running use proper knee bend, so Jenny does not slide across the ground the way a plain villager does. Combat animations include arm swings and a blocking pose. Idle animations cover looking around, fixing hair, waving or sitting down while waiting.
Dialogue animations shift the face to match the current mood: smiling, frowning or reacting to a specific gift item.
Per-character styles
Jenny, Ellie and Bia each have their own animation styles rather than sharing a single set. Some higher-affection animations only unlock once the relationship value climbs into later tiers.
Triggers and Creative commands
Animations trigger from held items (diamonds, emeralds, flowers) or from relationship milestones. In Creative, players can force a specific animation with text commands.
Sharing GIFs
Community GIFs are usually captured with OBS Studio or Medal.tv and then converted through sites like Ezgif or Giphy. That workflow is what most of the "Jenny Mod animation" clips online are made with.