Electron ships Chromium's renderer without the browser-side web-app
install machinery, so beforeinstallprompt never fires and every site's
own "Install our app" chip (coin-spectrum.com's, for one) stays hidden
in Theseus. The browser side now exists:
- webapps.js reads a page's <link rel="manifest">, accepts it when it
names an app with a standalone-style display mode and a start_url on
the page's origin, and records the descriptor on the tab.
- The address bar shows an install chip for such pages (filled once the
app is installed: click then opens or removes it); the page context
menu carries the same entry.
- Pages get a synthetic beforeinstallprompt whose prompt() routes to the
Theseus install dialog and resolves userChoice like Chrome, and an
appinstalled event afterwards, so sites' own chips appear and work.
- Installing stores the app under <userData>/webapps/, wraps the
manifest icon into an .ico, writes a Start Menu (optionally desktop)
shortcut that launches Theseus with --app=<start_url>, and opens the
app in a chromeless window with its own taskbar identity. The window
shares the session, BCNR resolution, fingerprint and add-on bridges
with tabs; popups and "open in Theseus" go to the browser window,
Alt+arrows / F5 / Ctrl+R cover navigation without a toolbar.
- Theseus takes the single-instance lock so a shortcut launch lands in
the running browser (second-instance) instead of a second profile
owner; launched cold, --app= opens only the app window and a later
plain launch brings the browser window back.
