Nodes¶

A node is one step in the pipeline graph. There are six kinds:

Node	Constructor	Role
Input	`add_input_node(**values)`	Holds user-supplied file paths and scalar parameters. Runs no tool.
Tool	`add_node(name)`	Wraps one registry tool; runs once per execution.
Gather	`add_gather_node(name, split_key=...)`	Runs a one-input tool once per item of an upstream collection, then gathers.
Decision	`add_decision_node(score_fn, conditions, modifier_tool)`	Re-runs an upstream until a scored condition holds (bounded feedback loop).
Output	`set_output_node(node)`	Marks the node whose result `execute()` returns.
Subgraph	`SubGraph()`	A one-in / one-out pipeline usable as a single node.