docs/plugins/prometheus-widgets.md covers: - where templates live and how to copy one in, duplicate, export and share; - a first template, walked through; - each block (states with its deadlines, values, times, table, info) with an example; - the format reference: keys, units, spans, limits, what the checker refuses; - the Fabled Archives template, block by block, with what it leaves out and why. Linked from the README, the plugin guide, the editor and template_format. tests/plugins/prometheus/test_widget_guide.py checks every YAML example in the guide against the checker, so the guide can't drift from the format. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>