Derive Macro GraphState 

#[derive(GraphState)]
{
    // Attributes available to this derive:
    #[reducer]
}

Derive macro for generating graph state schemas with per-field reducers.

Attributes

• #[reducer(append)] — append arrays/values
• #[reducer(last_value)] — overwrite with latest (default)
• #[reducer(add)] — add numeric values
• #[reducer(merge)] — deep-merge JSON objects