Add Subgraphs

[webfiltered]

[API] Subgraph System

This PR introduces a comprehensive subgraph system to litegraph.js, enabling modular graph composition through encapsulated subgraphs.

Core Features

Subgraph Implementation

The new subgraph system allows nodes to be converted into reusable subgraph components:

// Convert selected nodes to subgraph
const subgraphNode = graph.convertNodesToSubgraph(selectedNodes)

// Access the subgraph
const subgraph = subgraphNode.subgraph
subgraph.addInput("data", "number")
subgraph.addOutput("result", "string")

Subgraph I/O Nodes

Special nodes handle subgraph inputs and outputs with hoverable UI:

• SubgraphInputNode: Receives data from parent graph
• SubgraphOutputNode: Sends data to parent graph
• Support for linking from nodes directly to I/O nodes
• Empty slot interactions for dynamic slot management

Execution System

Rewritten & upstreamed execution logic to handle subgraphs:

• ExecutableNodeDTO for cleaner execution flow
• Bypass functionality
• Recursion prevention for nested subgraphs

UI additions

• Subgraph I/O nodes
• Context menu integration for subgraph operations
• Cursor changes when hovering over interactive elements
• Variadic slot support (basic implementation)

Usage

Creating Subgraphs

// Method 1: Convert existing nodes
const nodes = [node1, node2, node3]
const subgraphNode = graph.convertNodesToSubgraph(nodes)

// Method 2: Create empty subgraph
const subgraphNode = LiteGraph.createNode("graph/subgraph")
const subgraph = subgraphNode.subgraph

// Add I/O
subgraph.addInput("value", "number")
subgraph.addOutput("result", "boolean")

Nesting Subgraphs

// Subgraphs can contain other subgraphs
const outerSubgraph = outerNode.subgraph
const innerNode = LiteGraph.createNode("graph/subgraph")
outerSubgraph.add(innerNode)

// Recursion prevention built-in
// Attempting circular references throws RecursionError

Notes

• Subgraph nodes preserve their internal state across graph serialization
• I/O nodes support dynamic slot management with empty virtual slots
• New event: dropped-on-io-node via LinkConnector
• Compatible with existing serialization format (with version checks)

[Tekaiguy]

I don't see how to convert subgraphs back to regular nodes. Unlike the old group nodes feature, subgraphs seem to be created destructively. Is that a planned feature still to come?