Addressbook/contacts - Recurring tagging

[Dashboard feature, though possibly API as well?]

When creating collaborative posts with frequent partners it can be a little repetitive and tiring to constantly look up the partner’s social media per-site and copy/paste their usernames per-platform, especially when that is the only real variable between the per-platform posts.

It would be really nice if there was an “Address book” or “contacts” feature where we can:
1 - Create a entry for the frequent individual or entity
2 - Populate their socials once into this entry
3 - When drafting a post, the ability to type “@” and LATE showing a list of contacts as we type, and during actual posting LATE providing the correct username per-platform

- Error handling: If the contact has no entered handle for a selected platform, I’m thinking it uses the plaintext name of the contact, with a warning letting us know it is falling back to the contact’s plain name or something of this nature?

This feature would be very beneficial for any recurring work with partners. For one-offs the current feature set of editing the post per-platform works perfectly fine of course!