Additional Information regarding Chat transition:
Google Chat conversations DO NOT migrate
Google Chat Spaces DO NOT migrate, and new Chat spaces will need to be created from your @ucsd.edu Google account
In order to allow cross-domain Chat spaces, please make sure that when you create the new Chat Space, you "allow people outside your organization to join"
To make it clearer for everyone on my team, I have been creating the new Space from my @ucsd.edu account, and then going back to the archive @eng account and renaming the old Chat Space to preface the name with RETIRED -. Then, I send a message in the RETIRED - Chat space that says "RETIRING THIS SPACE - PLEASE USE THE UCSD SPACE" (see example 1 below)
If you utilize Google Chat quite a bit - then you may want to go into your archive @eng account and set a custom Chat status to redirect people to your new Chat address (mine says "new account: email@example.com") and then set your status to Away or Do Not Disturb (see example 2 below). You also may want to ensure that your Chat Notifications are set to send you an email if you haven't read a message (see example 3 below).
IF you installed the Google Chat Desktop app, this is a Chrome Profile add-on specific to the Google account using that Chrome Profile.
To keep using the Chat Desktop app, please go to https://chat.google.com from your NEW @ucsd.edu Chrome Profile and install the app again
PLEASE DO NOT try to switch accounts from within the Chat app on your old Chrome Profile - this will cause confusion, not only to Google trying to determine what account is currently in use, but with which Profile you should use for either account
NOTE: You can export your Chat conversations using Google Takeout, however this exports to a .json file, and Google does not provide a way to import that file into your new account. The export is not user-friendly, so depending on your skill at processing text files at the command line, your ability to get valuable information from the Takeout may be limited.
I will say that Chat is meant to be ephemeral - but if there is information in a Chat conversation that you need to keep, you may want to go into your archive @eng account, open that Chat, and either screenshot the info, copy and paste somewhere else, or Google does provide a "Forward to Inbox" function, that will email a specific portion of the chat to you for your record-keeping.