If I have a "work" container that has a bunch of docs and bug tabs, and I click a URL from an email or slack client to a new doc or bug, I would like it to open in the "work" container so I don't get sent to a login page.

I can't think of a way for this to always be right, but we could make a best guess on behalf of the user. Maybe whichever container has the most tabs from the same host, or whichever container the current selected tab belongs to, or something.

The external opening is handled in https://searchfox.org/mozilla-central/source/browser/components/BrowserContentHandler.jsm and ultimately makes it's way to getContentWindowOrOpenURI at https://searchfox.org/mozilla-central/source/browser/base/content/browser.js#6013.

Drum roll …

• Always In Container

(In reply to comment #1)

Context:

• Feature Request: Always Open links from Email Programm on PC / Email Website in selected container · Issue #1995 · mozilla/multi-account-containers
• Feature Request: Ask in which container to open a link or new tab · Issue #2001 · mozilla/multi-account-containers

– there's some overlap between the two.

Also, some overlap between Multi-Account Containers issue 1995 and this bug 1692124.

From https://github.com/mozilla/multi-account-containers/issues/2001#issuecomment-826337954:

Whilst Always In Container makes no attempt to guess, it can (at least) ask in which container to open a link or new tab.

A point of reference in GitHub:

• https://github.com/tiansh/always-in-container/issues/6

This isn't intended to land, but it shows a demo of opening the right URL based on
the userContextId of currently opened tabs with the same host.