Skill Rails Upgrade

This handles the tedious parts of Rails upgrades by checking your current version against the latest release, pulling the official upgrade guide and railsdiff changes, then giving you a concrete assessment of what you're dealing with. It checks JavaScript dependencies too, which is nice since those often get overlooked. The best part is it specifically warns you not to blindly run rails app:update and instead walks through selective file merging so you don't clobber your customizations. Use it when you're planning an upgrade and want to know if you're looking at an afternoon or a week of work. It won't do the upgrade for you, but it does the research legwork and gives you an honest complexity rating.