- HTTP & HTTPS canonical URLs (bug 5440)
- MediaWiki-ness so we know if we can format search URLs, API hits etc (bug 20603 etc)
- target database name for page existence checks (bug 11, bug 10237)
- target language (bug 4901)
Note though that if we have a decent local config database, the languages, canonical URLs, etc can be gotten out of the config DB for our sister sites as long as we have the target DB name. But if we want good MW integration for 'foreign' sites as well, we need to be able to store these separately.