Enum NodeContent 

pub(super) enum NodeContent {
    Sequence(Vec<AnimNode>),
    Stack(Vec<AnimNode>),
    Leaf(Box<dyn EvalDyn>),
    Static(Vec<DynItem>),
    Audio(Box<AudioTrack>),
}

What a runtime node IS — the closed vocabulary of the tree.

Each variant earns its seat by having non-desugarable evaluation semantics (a combinator expressible as pure window placement belongs in IntoAnimNode::into_anim_node, not here):

• NodeContent::Sequence — exclusive selection: the LAST child containing the content time evaluates (children placed with .at() may overlap);
• NodeContent::Stack — overlay: EVERY child containing the content time evaluates and the outputs sum;
• NodeContent::Leaf — the open world: any user Eval implementation, the only type-erased box in the tree;
• NodeContent::Static — a captured output batch replayed over a window;
• NodeContent::Audio — a sound leaf, consumed by the seal-time bake.

Variants

Sequence(Vec<AnimNode>)

Exclusive succession: the LAST child containing the content time evaluates.

Stack(Vec<AnimNode>)

Overlay: EVERY child containing the content time evaluates.

Leaf(Box<dyn EvalDyn>)

A typed evaluator (Eval implementation) — no children.

Static(Vec<DynItem>)

A captured, type-erased static output batch.

Audio(Box<AudioTrack>)

An audio leaf: its track resolves through the seal-time bake.

Boxed: a track is the fattest payload in the tree, and sibling scanning (window checks over many nodes) is cache-bound — nodes stay slim, the track pays one indirection only when audible.

Implementations

impl NodeContent

fn info_kind(&self) -> AnimationInfoKind