A markdown card for Home Assistant's Lovelace UI, which shows the YAML for all your current lights, ready to be copied and pasted directly into your config to create a new scene.
This template uses a Markdown card to display a textarea with the current state of all my lights, in YAML form. All I have to do is copy this, paste it into scenes.yaml, add a scene name and unique id and restart HomeAssistant and the current state of my lights is added as an available scene, without futzing around manually in the tedious built-in scene editor.
It's been so long since I set this up, I forget if the markdown card is standard or if I had to install something to make it available, so in the spirit of HomeAssistant's own forums I say to anyone interested in using this: figure it out yourself.
Have fun!