Name of the pass currently running (e.g. 'landmass', 'moisture', 'rivers').
0-based index of the current pass.
Total number of passes in the pipeline.
Progress within the current pass, 0–1.
Estimated overall progress, 0–1, weighted by typical pass cost.
One progress event from a step-generator pipeline. Emitted at every suspension point — feed it straight into a loading bar.