Files, strategy, communication, your branding guidelines, and design foundations. Even the designs built from them. You own everything, your files will be ready for your in-house designer, or the print shop so every detail stays flexible when my work ends.
It can vary a lot depending on a lot of things including our communication frequency. I will always be up front about what to expect when quoting projects. Retainer partnerships are estimated separately.
I communicate primarily through Slack and Email. The fewer communication channels the easier for us both to manage revisions in a consistent manner. This leaves more time for designing.
Specific designs sometimes have a time and place. The files and assets built with them remain an important part of your brand that you can continue to build off of, and change with the times. This looks like creating a new seasonal campaign, built within the framework, using the files given. No more starting from scratch.