how it works
what it is
sign-in & accounts
fort.uwp doesn't have its own accounts system - signing in just links the app to your existing fort.social account (fort.social runs Sharkey/Misskey). This page walks through exactly how that works, mostly based on Services\MisskeyAuthService.cs and Services\ProfileService.cs.
search
The search box at the top of the nav pane searches three things at once: the app's own nav/settings items, your fort.social profile (if you're signed in), and a bundled snapshot of the fort1nd.com sitemap. This page covers how that actually works, based on Services\SearchCatalog.cs, Services\SitemapService.cs, Models\SearchItem.cs, and the search handlers in Views\MainPage.Search.cs.
settings & customization
Settings isn't a separate page - it's an inline panel in MainPage, made of five collapsible rows: Appearance, Data Storage, Live Tile, Welcome Dialog, and About. Everything here is backed by ApplicationData.LocalSettings, so it's per-user, per-machine, and wiped if you uninstall the app. The code lives split across Views\MainPage.Appearance.cs and Views\MainPage.Settings.cs.