Mixed inputs and merged builders
This script is an implementation-oriented test case rather than a template for production data. It demonstrates two ways of adding metadata—extracting it from paths and supplying a pandas DataFrame—then merges the resulting builders.
It also includes a BED-to-bigBed conversion path, but replaces the actual converter with a mock so the demonstration can run without UCSC tools. Do not use the generated dummy files as a browser-ready hub.
For a real build, use valid bigWig/bigBed data or enable normal conversion with a matching chromosome-sizes file. BAM files must have a same-named .bai index beside them.