v3.48.1

Fixed

• An update that quits and never installs no longer fails silently. The
  install waiter's detached PowerShell process could die before running a
  single line of its own script — event-log evidence on a real machine showed
  it starting the same second the app called app.quit() and never getting
  further, consistent with Windows Job Object cleanup catching a "detached"
  child that never requested breakaway. The waiter now writes a heartbeat as
  its first act, and the app waits (up to 3s) to see it before tearing
  anything down. A waiter that never signals costs nothing — no daemon
  shutdown, no quit, no install — instead of the app disappearing into an
  unexplainable hang. (#1057)

• A failed update now says what happened, where you can see it. The
  refused-install notice carries the installer's actual refusal reason and
  stays on screen instead of fading after five seconds; install errors on
  macOS that landed minutes after the click (staging and handoff deadlines)
  are no longer silently dropped; and after a failed install the "Install
  now" button comes back instead of leaving nowhere to retry from. When an
  update left the installation itself broken, the stale "try again" toast no
  longer contradicts the boot notice that says to reinstall — including on
  the first boot after the reinstall it asked for. (#1058)

• Clicking Install can no longer quit wmux into a silent no-op. On
  current Windows builds the helper process that runs the installer after
  wmux quits could die before executing a single line, leaving the old
  version in place with no error and no trace anywhere. The helper's launch
  is now verified before wmux commits to quitting — if it cannot be proven
  to run, the update is refused on the spot with the app still open — and a
  helper that dies partway through now leaves a note that wmux shows on the
  next start. (#1059)

What's Changed

• fix(updater): confirm the waiter actually started before quitting by @p-poppe in #1057
• fix(updater): surface install failures where the user can actually see them by @openwong2kim in #1058
• fix(updater): make the install waiter's launch provable, and survivable by @openwong2kim in #1059
• chore(release): 3.48.1 by @openwong2kim in #1061

Full Changelog: v3.48.0...v3.48.1