The kernel memory killer's "Memory Shortage Avoided" notice carried a
Configure button that ran kcmshell6 and opened KDE's whole Notifications
settings under the teacher's account. Reproduced in the lab.
Plasma draws that button without consulting the Kiosk policy, but
kcmshell6 and System Settings do: every settings module Debian 13's
Plasma 6.3 installs (90) is now refused in the classroom's immutable
kdeglobals, so the same click shows only "disabled by the system
administrator". The clock's Configure Digital Clock goes with
plasma/allow_configure_when_locked=false; Configure Audio Devices
disappears on its own; the disabled window's Help button opened KDE Help
Center, which the package now conflicts with (plasma-desktop only
recommends it).
The maintenance terminal runs outside the classroom's configuration and
still opens every module, verified. converged-check fails if any module
on a machine is ever left unrestricted: 126 passed in the lab.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
These are shared computers in rooms full of people, and in a stock Plasma
desktop "use the network" and "read the network's password" are much
closer together than they look.
Measured on Debian 13 with NetworkManager 1.52 and Plasma 6.3:
* org.freedesktop.NetworkManager.settings.modify.own ships as "yes" for
an active session — no prompt, no administrator. It covers any
connection whose connection.permissions names that user, and a Wi-Fi
network added from the desktop is created exactly that way. So a
password a teacher types in is readable by the next person to sit
down.
* the applet offers "Show Network's QR Code" on every saved wireless
connection, and the QR code contains the pre-shared key.
* that action, and the "Configure…" beside it, are contextual actions in
ConnectionItem.qml and do NOT consult
authorizeControlModule("kcm_networkmanagement"). The Kiosk key gates
the toolbar button only. Hiding buttons was never going to be the
answer.
Every one of those paths ends at NetworkManager's GetSecrets, so that is
where this is answered. A polkit rule refuses settings.modify.own,
settings.modify.system, both wifi.share actions and the machine-wide
settings, for the classroom user by name.
Deliberately NOT refused: network-control, wifi.scan and the
enable/disable actions. None returns a secret, and they are what
connecting and seeing a network are made of. Automatic reconnection does
not go through polkit at all — NetworkManager does it as root — so nothing
here can stop the room coming back on the network after a reboot, which is
the property that matters most on a Sunday.
An administrator's account and root are untouched, and the override route
is the same one the sleep rule has.
classroom-wifi is the other half, and it is a requirement rather than a
convenience: it provisions the church Wi-Fi as a SYSTEM connection, with
no connection.permissions, psk-flags=0 and a 0600 root:root file. A
connection the machine owns is one nobody in the room can read. Verified
against real NetworkManager in the lab — the classroom account gets
"Permission denied" on the file, "--" from nmcli and "Insufficient
privileges" from GetSecrets, while autoconnect stays on.
There is deliberately no teacher-facing join dialog. Anything that lets
the room add a connection lets the room own it, and an owned connection is
a readable one; docs/networking.md says so rather than leaving it to be
rediscovered.
The rule is plain JavaScript, so the test evaluates it with polkit's
objects stubbed and asserts both halves: which actions come back NO, and
which are left alone. What it cannot test is the last mile — polkit
resolves a subject through logind and a container has no graphical seat
session, so every check there is denied for reasons unrelated to this
rule. That one is a physical check, and it is written down as one.
Co-Authored-By: Claude Opus 5 <[email protected]>
Parent Call told rooms they had never been set up. Nothing about the
rooms was wrong. Read from the church broker: …/coordinator and
…/pending are retained and …/mode is absent, and the coordinator's own
source says why — it publishes the retained mode only in answer to an
operator writing to …/mode/set, and nobody ever has. Every classroom
waited a second and a half for a message that will never exist.
A missing mode is now read as the coordinator's own default rather than
as an unconfigured room: the room offers the call and lets the sanctuary
end answer, because that is the end that knows. A mode that really is
off still refuses, in the coordinator's words, and a broker that is
missing or unreachable still says which of those it is. Proved against a
rig broker made to match the church's exactly, with a call landing on
the sanctuary mock.
The card is anchored to the bottom-left corner instead of centred, by
layer shell, which is what the disc player's cover has used under KWin
for months. Anchoring rather than positioning is what makes it right at
1080p and at 4K without a coordinate anywhere. It falls back to the
centred card if the library is missing.
Notifications are sized for a room. Every Plasma measurement is a grid
unit and a grid unit is the height of the general font, so the font is
the lever — 15 point instead of Breeze's 10, which takes the card from
about 350x110 to about 410x145 at 100% and doubles again at 200%. Text,
icon, padding and buttons move together. The chime stays off. No shell
package: that path cost the panel and is not coming back.
And the product name is gone from everything a teacher sees. The
notification card is from Classroom, the disc player's from DVD.
Co-Authored-By: Claude Opus 5 <[email protected]>
Little Waders took the Plasma build and reported what a container
cannot. A disc player on a machine with no optical drive, a clock nobody
at the back of the room could read, a browser at half the size of the
panel around it, and Parent Call with no broker to call.
The broker is the same for every classroom, so it is a default now and
not something to fill in room by room. classroom-migrate brings an
existing room to the same place without touching its name, its username
or its password, and Parent Call distinguishes a broker it cannot reach
from one that was never set up: those send somebody to look at
completely different things.
The disc player's detection was right and ran too late — alongside the
session rather than before it, and the panel is built from the layout the
moment a session starts. It runs before the display manager now, and
again from udev when a drive is plugged in.
UI_SCALE had a ceiling of 1.5, which cannot express a 4K television; a
clock pinned at 15 points, which is the same size at every scale; and a
browser that was never told the number at all. All three are fixed and
the room doubles together at 200%.
This also brings 0.1.47's work into the repository, where it had only
ever existed in a build directory under /tmp: the hidden display dialog,
its authenticated writer, the polkit action, and the church's own
wallpaper. One piece of it is deliberately left out. The custom volume
display needed a shell package of our own, and with one selected
plasmashell builds no panel at all — measured twice, with that build's
own files, on a classroom that deletes its panel configuration at every
login by design.
The lab connected to the real church broker the moment the package
defaulted to it. Nothing was left behind, which was checked, but the
guard that should have stopped it had never worked: it used iptables,
which the lab image does not have, and probed with /dev/tcp under dash,
where that always fails. Both reported success.
Co-Authored-By: Claude Opus 5 <[email protected]>
A real room upgraded to 0.1.45 and came up as stock Debian Plasma with
the old Waybar across the top, mako still catching notifications, and a
lock screen on an account that has no password.
The cause was one line, and it was in the lab: the harness handed the
session under test XDG_CONFIG_DIRS by hand, so every result it had ever
produced was a result about a machine somebody had already configured.
On a machine SDDM starts the session through PAM, PAM does not read
/etc/environment.d, and Debian's own plasma-workspace env.sh then set the
variable from scratch — so the classroom's settings directory was not in
the cascade at all. No layout, no lock policy, no Kiosk restrictions.
The settings now arrive the way Plasma delivers them, through a file in
/etc/xdg/plasma-workspace/env. Around that: the look and feel is
immutable on its own key so a stale profile cannot answer for it; the
palette is composed into the package, because naming a colour scheme does
not produce one and the dark bar had been coming from a technician's
hand; the desktop reset converges another desktop's appearance state and
keeps the room's own; and classroom-migrate stops, deactivates and masks
the old shell, including the D-Bus activation that brought mako back
while the panel was down — found only by killing the panel on a migrated
machine.
device.conf loses COMPOSITOR and comes off the hyprland channel, which
would otherwise have handed the room the experiment back.
The lab stops flattering the package: it restarts the machine, lets SDDM
actually autologin, and asks a fresh install and a machine upgraded from
the Hyprland package the same sixty questions. Both answer identically,
twice, and the panel still comes back from eight SIGKILLs.
Co-Authored-By: Claude Opus 5 <[email protected]>
Two layers for the button, because one is not enough: while a session is
running PowerDevil holds logind's handle-power-key inhibitor and acts on
the button itself, so a logind drop-in alone would be overruled. logind
covers the machine before the session starts, after it ends, and if
PowerDevil is not running. Verified: after the drop-in is installed and
logind reloaded, it reports ignore for the power, suspend, hibernate and
lid keys, and the running session was not disturbed by the reload.
Holding the button still cuts the power. That is firmware, below any
operating system, and it is deliberately left alone as the only recovery
a person standing at a wedged machine has.
The maintenance terminal is Meta+Ctrl+Alt+Shift+K, declared in the
package rather than seeded into a teacher's configuration, where an
update could not reach it. KGlobalAccel read it and registered the
component; invoking it opened a working shell.
It needed a wrapper. The classroom's Kiosk policy sets shell_access=false
and Konsole honours it — measured: with the classroom configuration in
its cascade Konsole starts and says "Program to run not set." The
restriction is worth keeping everywhere else, so it is lifted for this
one process by leaving the classroom's configuration directory out of
its cascade. It grants no privilege: the classroom user has no sudo
rule, and that restriction was always a barrier in the interface rather
than a privilege boundary.
Konsole's own entry is shadowed and hidden from /usr/local/share, so
nothing is patched and Konsole's package stays maintainable. Nothing is
pinned to the panel; a task button appears only while a terminal is
open, and closing it returns the bar to three launchers.
Co-Authored-By: Claude Opus 5 <[email protected]>
The coordinator already existed on the control computer and its contract
is frozen, so this is the classroom half of a contract that was read from
its README and source rather than guessed: four fields out, the status
topic subscribed before anything is published, and every word the teacher
reads taken from the coordinator's own message field.
It is a separate process, not a Plasma applet. A broker library, a
network timeout and a text entry have no business inside the only way a
teacher has of getting anywhere; if this dies the bar is untouched.
The panel mark is Breeze's call-outgoing. The old one was a bell, sitting
two inches from Plasma's notification bell in the same bar and meaning
something entirely different.
Two things it will not do: claim a call was displayed, and let a teacher
type the room. The machine already knows which room it is.
Sixty tests cover the contract without a broker. The live path was proven
against the real coordinator running in the lab, on a loopback broker,
with ProPresenter mocked and the church's networks rejected from inside
the container first.
Co-Authored-By: Claude Opus 5 <[email protected]>
The room that prompted this had a television on HDMI with working PCM
audio and nothing in the analog jack, and WirePlumber chose analog. A
teacher who corrected it by hand then had to restart the browser before
any sound came out.
The policy is a pure function so it can be tested against that room
rather than against a machine: an unavailable port is not a candidate,
an analog port merely existing is not evidence of a cable, and an
explicit AUDIO_OUTPUT overrides the lot. Twelve cases, the real room
among them.
The daemon follows PipeWire's own event stream rather than polling, and
moves streams that are already playing, which is the part that stops a
teacher having to close and reopen the browser.
Co-Authored-By: Claude Opus 5 <[email protected]>
The whole appliance UI is now configuration for a desktop Debian already
ships: a Plasma 6.3 session with a colour scheme, a look and feel package
that builds the bar, window rules, and KDE's own Kiosk restrictions.
Two things were measured rather than assumed, and both changed a decision.
Plasma restarts a crashed panel three times a minute and then gives up,
which is the failure a classroom has already had. Four lines of systemd
drop-in make it unconditional; the panel then survived eight SIGKILLs a
second apart, back each time in 2.4s.
Plasma draws a minimised task and a background task identically, so the
five states the room needs cannot all be shown. Rather than write a task
manager, the classroom removes minimise: clicking a launcher always means
show me this.
Co-Authored-By: Claude Opus 5 <[email protected]>
