What's The Story?
When you install CodeKit 3, it automatically finds and uses your old 2.x license. Every feature that was part of CodeKit 2 will remain unlocked, forever, for free. The Registration Window will look like this:
Try The 3.0 Stuff
You'll get a 10-day trial of all the new 3.0 features. After that, just the new 3.0 stuff will lock. If you like the new stuff, you can upgrade to a 3.0 license at a large discount. Otherwise, just keep using the app as-is; it's still way better and faster than CodeKit 2!
Upgrading Your License
Visit the Purchase Page and click the link for upgraders in the Pricing section. Enter your old license to verify eligibility and the prices will automatically adjust.
If you purchased CodeKit 2 within 90 days of the 3.0 launch, your upgrade will be free.
The first time you run CodeKit 3, your preferences from version 2.x are automatically migrated. All New Project Defaults and App Preferences come across.
Projects Don't Move Automatically
CodeKit 3 will not automatically move all your projects to the new app. This lets you migrate a few at a time, if needed, or continue using CodeKit 2 for certain projects until you're ready to migrate.
Project Settings Are Kept
When you add a 2.x Project on CodeKit 3, every setting is migrated automatically. Some settings no longer apply in 3.0, so those are dropped. Other settings have changed formats, so they'll be updated.
Note: CodeKit 3 forces all Sass files to compile with Libsass, unless your project uses Compass. If you use import globbing, you will need to switch your Sass files back to the old Ruby compiler.
New Config File
After adding a project to CodeKit 3, you'll see a new file named config.codekit3 in the project's folder. The old, 2.x file ("config.codekit") is left in place just in case. You can safely delete the 2.x config file after you add your project to CodeKit 3.