Class Checkpoint

A reusable checkpointed wrapper over a JS-built subgraph.

fn(inputs) receives the input arrays (in order) and returns one or more output arrays. Applying the checkpoint builds the same forward graph, but marks it for recomputation: the enclosing backward recomputes fn rather than reading retained activations. Gradients flow to the explicit inputs AND to any outer-trace leaves captured by fn (e.g. swapped-in LoRA primals), exactly as if fn had been inlined.