What problem does it solve? Building Graph Neural Networks involves many error-prone details: correct edge_index formatting, choosing the right convolution layer, mini-batch sampling for large graphs, and handling heterogeneous node and edge types. This Skill provides working patterns and reference implementations for every stage of PyG development. ## Core Features & Use Cases - GNN Model Building: Ready-to-use patterns for GCN, GAT, GraphSAGE, GIN, and custom MessagePassing layers with the _i/_j indexing convention. - Task-Specific Training Loops: Complete code for node classification, graph classification with global pooling, and link prediction with negative sampling and GAE/VGAE autoencoders. - Scaling & Heterogeneous Graphs: NeighborLoader mini-batch training, DDP multi-GPU setup, to_hetero() conversion, HeteroConv, and HGTConv for multi-type graphs. - Use Case: You need to train a GraphSAGE model on a large citation network that does not fit in GPU memory. The Skill shows you how to configure NeighborLoader with num_neighbors matching your layer count and slice seed-node outputs correctly. ## Quick Start Ask the assistant to build a two-layer GCN for node classification on the Cora dataset using PyTorch Geometric.