docs: a desktop the layout never saw, and the television check only a room can do

What Tiny Pebbles showed, what the lab measured (a new activity gives the same bare desktop; a file path as the fallback is ignored; live D-Bus is refused by the lockdown), the two parts of the fix, and the check with a real television switched on after a reboot — the one thing the lab cannot do, because KWin will not start with no screen. Co-Authored-By: Claude Opus 5.5 <[email protected]>
2026-09-29 18:06:08 -05:00
parent a9700536bf
commit aaa3f8d063
2 changed files with 96 additions and 0 deletions
@@ -11,6 +11,39 @@ before promoting to stable with `./update_stable.sh`.
 - [ ] Dock appears, centred
 - [ ] Clock appears, bottom right

+### The television switched on after a night-time reboot
+
+This is how Tiny Pebbles lost its wallpaper after the 0.2.2 upgrade, and
+the lab cannot do it: KWin will not start a session with no screen, and
+the lab cannot plug one in. The lab proves the same code path through a
+new activity (`tools/lab/wallpaper-check`); only a real television
+proves that switching it on takes that path. See
+[ui-scale.md](ui-scale.md#a-desktop-the-layout-never-saw-0266). Do it once, on a
+desktop whose television is switched off at the set, not the remote:
+
+1. [ ] Television **off** at the set. `sudo reboot`, and wait five minutes.
+2. [ ] Television **on**. The classroom's landscape is on the screen,
+       **not** Plasma's purple wallpaper. The panel is the room's own.
+3. [ ] From the maintenance terminal (Meta+Ctrl+Alt+Shift+K),
+       `classroom-desktop-wallpaper --check`. Note what it says. If it
+       names a desktop that "had no wallpaper configured", the television
+       really did arrive after the shell, and the screen in step 2 is the
+       fix working
+4. [ ] `systemctl --user restart plasma-plasmashell.service`: the panel
+       blinks and comes back, open windows stay, the wallpaper is unchanged
+5. [ ] `classroom-desktop-wallpaper --check` now says "the classroom
+       wallpaper already"
+6. [ ] Reboot with the television on: the same picture and the same panel
+
+Tiny Pebbles can confirm the cause **before** it takes the release, because
+the update reboots it and a login rebuilds the file. If its panel was built
+with no screen, the panel is `[Containments][1]` next to the desktop's 10:
+
+```
+grep -A6 '^\[Containments\]\[[0-9]*\]$' \
+    ~/.config/plasma-org.kde.plasma.desktop-appletsrc | grep -E '^\[|^plugin='
+```
+
 ## Provisioning

 - [ ] `journalctl -u ekklesia-classroom-provision` shows a clean run