Thunderbird

link.sh links config/thunderbird/userChrome.css, userContent.css and user.js into the default profile. It also writes nightdrive-icons.css, the Lucide icons with this machine's paths, and builds the unsigned folder-pane toggle add-on into the profile's extensions/. user.js sets extensions.autoDisableScopes=14, so the add-on is enabled without asking. Its button shows up from the second start.

Two things can't be linked and are set by hand in xulstore.json, with Thunderbird closed:

• Toolbar buttons: unifiedToolbar.state = {"mail":["ext-folderpane-toggle@jokela-night","spacer","get-messages","reply","reply-all","forward-inline","archive","junk","delete","spacer"]}
• Message header: in aboutMessage.xhtml → messageHeader.layout, turn on hideLabels, subjectLarge, showAvatar and showFullAddress.

A pitfall: if you change mail.addressDisplayFormat in user.js, also bump mail.displayname.version in prefs.js. Otherwise the cached "Name <address>" display stays as it was.