Runtime observations from the real desktop application
Environment: Linux x64, Electron 44.10.1, --no-sandbox --disable-gpu.
Xvfb 1920x1080, app window 1100x780, light theme. Separate fresh T3 homes.
No project import, copied database, real agent turn, updater mock, or unit test.
The update feed and Debian package payloads are synthetic isolated fixtures.

Before:
- First real dpkg update 0.1.9 -> 0.1.10 authenticated and the app relaunched itself.
- /proc/<relaunched-main-pid>/status: NoNewPrivs: 1.
- Next update 0.1.11 downloaded through electron-updater.
- First confirmed sidebar install: no password prompt and no error toast.
- Retry: Could not install update / Desktop updater install operation reported an error.
- dpkg-query -W t3-update-evidence-base: 0.1.10.
- Real desktop bridge currentVersion: 0.1.10; downloadedVersion: 0.1.11.
- First install's real desktop stdout: Install: isSilent: true, isForceRunAfter: true.

After:
- First real dpkg update 0.1.9 -> 0.1.10 authenticated and the app relaunched itself.
- /proc/<relaunched-main-pid>/status: NoNewPrivs: 0.
- Next update 0.1.11 downloaded through electron-updater.
- Confirmed sidebar install: real GNOME polkit password prompt appeared.
- Entered the fixture account password; dpkg installed 0.1.11; app relaunched itself.
- dpkg-query -W t3-update-evidence-head: 0.1.11.
- Real desktop bridge currentVersion: 0.1.11, status: up-to-date, message: null.
- /proc/<second-relaunched-main-pid>/status: NoNewPrivs: 0.
- First install's real desktop stdout: Install: isSilent: true, isForceRunAfter: false.

Separate first-click error pass on head:
- On the 0.1.10 instance relaunched by the first update, confirm the 0.1.11 sidebar install.
- Cancel both real native authentication prompts (dpkg, then apt-get fallback).
- The first confirmed attempt shows Could not install update.
- Message: Electron updater failed to quit and install the update on channel latest
  (silent: true, force run after: false).
- Refresh check/download to clear the failure, then authenticate on the success pass.

Limitations:
- Packages replace isolated app.asar, its unpacked runtime files and version metadata, not the installed T3 Code.
- Official release packaging, desktop entry and post-install scripts were not exercised.
- The compiled web/server About version remains 0.1.9 in this fixture; updater currentVersion,
  desktop-last-started-version and dpkg package versions track the real fixture update.
- First-click toast proof uses the sidebar; failure reporting from Settings/About was not proved.
- The head's first background update check after relaunch failed when the local fixture feed
  exited; restarting the feed and checking again returned up-to-date.

AI-assisted; verified with the tests and tools listed above.
