A classroom computer is shared. There is one local Chrome profile owned
by the room, teachers sign into websites, and nobody signs into Chrome.
BrowserSignin=0 stops Chrome asking who is using it, with SyncDisabled
set explicitly alongside it so the intent is in the file rather than
implied. BrowserAddPersonEnabled=false stops new profiles and
ProfilePickerOnStartupAvailability=1 stops the picker.
BrowserGuestModeEnabled=false is the answer to the other profile
switching entry point. Guest is the one that survives disabling add
person, and turning it off is the supported mechanism rather than hiding
UI. Guest is not the browsing model: the room needs one persistent
profile so the church YouTube login survives.
CookiesSessionOnlyForUrls scoped to [*.]wonderink.org, which covers
app.wonderink.org and every other subdomain, so a teacher's Wonder Ink
session does not outlive them. BackgroundModeEnabled was already false,
which is what lets a session actually end.
Every policy name was checked against the strings of the installed
Chrome 152 binary, with deliberately invalid names as a control so the
check is known to discriminate.
Two things are recorded honestly in docs/browser.md rather than claimed.
The avatar button stays in the toolbar — screenshotted with and without
these policies, it is in the same place either way; what changes is that
nothing behind it can create or switch a profile, and no Chrome 152
policy removes the button. And whether session-only cookies actually
sign Wonder Ink out is unverified: it needs a real Wonder Ink login,
which this machine does not have, and three attempts to prove the
mechanism against a local site were inconclusive because the positive
control never worked. The endpoint procedure to settle it, including how
to tell a cookie session from a localStorage one, is written down.
Co-Authored-By: Claude Opus 5 <[email protected]>
Vimeo plays in the normal lesson view and stops immediately in Present
view, which rules the machine out: same video, same host, same codecs, a
click earlier. No packages were installed and nothing was changed.
Written as a decision procedure rather than a shrug. The first step is a
stock Chrome with no classroom policy and a clean profile, which settles
in one run whether this is Wonder Ink or something at our end. Two
candidates follow if it turns out to be ours, each with the diagnostic
that would confirm it, and the note that AutoplayAllowlist is recognised
by Chrome 152 but has deliberately not been applied — allowing autoplay
on a classroom machine should follow evidence rather than a guess.
Co-Authored-By: Claude Opus 5 <[email protected]>
Clicking Browser and watching nothing happen for several seconds is the
one place the classroom felt broken rather than quiet. The button now
becomes a throbber the instant it is pressed, and stays one until the
window actually appears in the sway tree.
Only a real launch spins. The dock asks sway whether Chrome is already
open first, so focusing or restoring an existing window stays immediate,
which is how it should feel. DVD is left alone: it has its own
full-screen loading surface and does not need two answers to one click.
A launch that never arrives gives up after thirty seconds, puts the icon
back and says so, so a broken start cannot spin all morning.
The throbber is drawn rather than a GtkSpinner: the stock one is capped
well below the size of the icon it replaces, so it read as a hesitation
rather than as work in progress. Pre-rendered frames swapped into the
same Gtk.Image keep the button an ordinary image with ordinary clicks,
and it falls back to GtkSpinner if cairo is ever missing.
The pointer also turns busy while it is over the dock. Wayland gives the
cursor to whichever client the pointer is over and sway offers no way to
set one globally, so this only holds on our own surface — which is
exactly where the pointer is at the moment a dock button is pressed.
Co-Authored-By: Claude Opus 5 <[email protected]>
Three things a volunteer should never have to see.
Sway was drawing its own title bar above Chrome's tab strip, which
already carries the window controls. Verified on a real session: Chrome
is an xdg_shell client with app_id "google-chrome" and sway was giving
it border "normal". A scoped rule removes the compositor decoration
only — Chrome keeps its tabs and address bar, stays a normal window, and
still maximises and minimises. A class rule covers an XWayland fallback.
Nothing else changes: the only other window in this classroom is VLC,
which is already borderless, so no broader rule is warranted.
"Restore pages? Chrome didn't shut down correctly" is suppressed with
--hide-crash-restore-bubble. Note the name. The switch this was going to
use, --disable-session-crashed-bubble, is not present in Chrome 152 at
all — checked against the strings of the installed binary — so it would
have silently done nothing.
That hides the prompt; the profile was still being marked as crashed,
which is the untidy half. Chrome's browser process shuts down cleanly on
SIGTERM, so a shutdown unit now gives it one and waits up to eight
seconds before the session is torn out from under it. Best effort by
construction: a shutdown that will not finish is far worse than a crash
flag.
Password prompts go off with the PasswordManagerEnabled policy, on the
path the classroom already manages. Existing profile and session data
are untouched, and website logins are unaffected: Wonder Ink and YouTube
stay signed in.
Co-Authored-By: Claude Opus 5 <[email protected]>
UI_SCALE only ever reached the surfaces we draw ourselves. Chrome stayed
tiny — its tabs, omnibox and menus are Chrome's own pixels, and Ctrl+
only scales page content, which is no use to a volunteer reading a
toolbar from across the room.
UI_SCALE is a property of the television, not of one program, so it now
sets sway's output scale, which every client is measured against.
classroom-scale runs first in the session and applies it. The display
mode is untouched: the panel stays at 1920x1080 and only the logical
coordinate space shrinks, which is what makes everything in it larger.
Our own surfaces stop scaling themselves. They are measured in the same
logical pixels sway is already scaling, so applying UI_SCALE again would
double it. SHELL_SCALE is that decision in one named place, and setting
it back to ui_scale(config) would restore per-surface scaling without
touching a template.
Measured at 1920x1080 with Chrome 152. Chrome's tab strip 40 -> 49 ->
59px against 1.0, 1.25, 1.5; sway's title bar 25 -> 31 -> 38px; the
classroom dock 74 -> 92 -> 110px. Everything scales once, together, and
1.0 is identical to no scaling at all.
Two tradeoffs, both measured rather than assumed. GTK 3 has no
fractional scaling, so at 1.5 it renders at 2x and sway scales down —
very slightly softer, invisible at classroom distance. XWayland is
softer too: terminal text at 1.5 showed about 50% more intermediate-tone
pixels than at 1.0. VLC is the only XWayland application here, and in
DVD mode none of its interface is on screen, only video from a 720x480
disc that is being upscaled regardless. Chrome is a native Wayland
client and stays sharp, which is what matters for reading.
Co-Authored-By: Claude Opus 5 <[email protected]>
The readiness condition was playback state alone, and on a real disc
VLC reports playing well before its window has taken the screen. The
cover came off onto VLC's ordinary tiled startup window — black, sized
to everything except the dock's reserved strip — and the disc menu only
arrived afterwards. Exactly the state the cover exists to hide.
Ask sway instead. VLC only takes the display when its window goes
fullscreen, and the tree says when that happens. The cover now comes off
when VLC reports playing or paused, its window is fullscreen, and 800ms
have passed for the menu to draw its first frames. The playback check
runs first because it is local and cheap; the tree is only walked once
VLC claims to be playing something.
The twenty second deadline is unchanged: a cover with nothing behind it
is still the one outcome DVD mode must never produce.
Co-Authored-By: Claude Opus 5 <[email protected]>
classroom-dvd-session needs to ask sway whether VLC has taken the
screen, which is the same tree walking classroom-window already does.
One copy, in a module both import; classroom-window loses a third of its
length.
The state machine is worth protecting through a move like that, so its
regression test comes with it: the exact swaymsg commands for launch,
focus, minimise, restore, Super+M, Super+Shift+M, the scratchpad rescue
and sway not running at all.
Co-Authored-By: Claude Opus 5 <[email protected]>
The loading surface was invisible. GtkWindow only renders its own CSS
background when the application is not painting the window itself, and
this window was created app-paintable with no draw handler and no child
— so it drew nothing at all. The black area during loading was never it:
it was VLC's own window, tiled by sway into the usable area, which
excludes the strip the dock reserves. That is why the dock and the
wallpaper stayed on screen underneath.
An earlier headless check missed this because that sway had no wallpaper
configured, so an invisible surface and a black one looked identical.
Rechecked with the real wallpaper and the real dock underneath.
The surface now paints, and carries a spinner and "Loading DVD..." on
the same translucent rounded card as the dock. It moves from the top
layer to the overlay layer, because the dock is a top-layer surface and
DVD mode has to cover it rather than depend on which surface sway
created first. Its exclusive zone of -1 keeps sway from moving it out of
the way of the dock's reserved strip.
It goes up before VLC is started rather than alongside it, so no part of
VLC's window is ever seen against the wallpaper, and comes down only
once VLC reports playback on screen. The deadline that takes it down
regardless is now twenty seconds, since an optical drive can be slow,
and a failure to start VLC at all ends the session instead of leaving a
cover with nothing behind it.
Co-Authored-By: Claude Opus 5 <[email protected]>
Pressing DVD now enters DVD mode rather than opening VLC. VLC is still
the backend, because its dvdnav module is what decodes disc menus and
nothing else on Debian does that reliably, but nothing a person can see
or press belongs to it any more.
classroom-dvd-session owns the whole thing. It puts a full-screen black
layer-shell surface up the moment the button is pressed, starts VLC
behind it, and drops it once playback is actually on screen — so the
harsh cut from wallpaper to VLC's black window is gone, and no partial
VLC window or reserved dock strip is ever visible. A deadline drops the
surface regardless, because DVD mode must never leave a black screen
with nothing behind it.
The controls are a classroom bar on the overlay layer, the one layer
sway draws above a fullscreen window. It slides up when the pointer
reaches the bottom of the screen and hides again shortly after it
leaves. It is drawn from the dock's own stylesheet at the room's UI
scale, so it is the same surface, the same radius and the same white
icons. While hidden it only accepts the pointer in a thin strip along
the bottom edge, so a click on a disc menu goes to the disc.
The bar reaches VLC through an HTTP interface on loopback behind a
password generated per session, sending hotkey *actions* by name. That
is what makes the next part possible.
All 108 hotkeys VLC 3.0.23 defines are unset, then Space, Esc and the
arrow keys plus Enter are bound. Crop, aspect ratio, subtitles, audio
tracks and deinterlacing are no longer reachable by pressing a key at
random, and the arrow keys no longer change VLC's volume — the
television owns volume, and CEC will own it properly later.
Esc quits instead of leaving fullscreen. There is nothing to leave, and
leaving it was what stranded people on a black VLC window. Close, Eject
and Esc all ask VLC to quit and escalate to SIGTERM then SIGKILL if it
does not; when VLC exits by any route, including a crash, the session
ends and the classroom desktop comes back.
Verified against VLC 3.0.23 on Trixie: every argument accepted, every
control action accepted over the control interface, a wrong password
refused, and quit exiting cleanly. The surfaces were rendered under a
headless sway and screenshotted to check the bar against the dock.
Co-Authored-By: Claude Opus 5 <[email protected]>
The DVD control bar has to look like the dock, which is best guaranteed
by drawing it from the same template with the same measurements rather
than by keeping two stylesheets in step by hand.
Co-Authored-By: Claude Opus 5 <[email protected]>
A fresh classroom needed two things installed by hand on every box:
Google Chrome, which is not in Debian, and the DVD codecs, which Debian
cannot ship. Both now happen on their own.
ekklesia-classroom-provision.service runs after every boot and does the
work that needs the network and the apt lock, neither of which a package
postinst can have. Each step returns immediately if it is already done,
so a provisioned machine costs nothing and a machine that was offline
the first time gets another go at the next boot. Nothing there is
allowed to fail the boot: a classroom with no DVD codecs is still a
working classroom, and it says so in the log rather than silently.
The postinst enables the service but deliberately does not start it.
Every OTA update reboots the moment the install finishes, and an apt run
killed by that reboot would leave dpkg half-configured.
Chrome comes from Google's own repository rather than a one-off .deb, so
it keeps getting security updates. Google's package migrates whatever we
write into a deb822 file of its own, so the repository is looked for
across every source file instead of only the one we would write;
otherwise a machine that had Chrome removed would end up with two copies
of the same repository.
The DVD codec helper previously assumed deb822 sources and did nothing
on a machine using a classic /etc/apt/sources.list, which is what the
hardware actually runs. It now handles both formats, and only ever adds
a missing component to an existing Debian entry — so it cannot produce a
duplicate repository or a duplicate component however many times it
runs, and third-party repositories like Chrome's are never touched. It
also answers libdvd-pkg's debconf questions, so nothing blocks on a
prompt in a service with no terminal.
Tested against fixture APT trees for classic sources.list, deb822
.sources, contrib already enabled, repeated runs, third-party
repositories and the awkward real lines: bracketed options, indentation,
trailing comments and flat repositories.
Co-Authored-By: Claude Opus 5 <[email protected]>
Stock VLC looks like a desktop media player, which is wrong for a room
where the TV is the whole interface. VLC stays the backend because its
dvdnav module is what provides the disc menus, and menus are the part
that matters on a commercial disc.
It is dressed down with documented VLC 3.x options, all verified against
the 3.0.23 build in Debian Trixie: minimal view, dark palette, no cone,
no tray, no now-playing popups, no resume prompt, no recent-disc
history, no title banner. sway draws no border on the window either, so
there is nothing above the video.
The auto-hiding fullscreen controller is deliberately kept: it is not
persistent chrome, and it is the only way a volunteer with a mouse can
pause or change chapter.
No skin is involved. Skins replace the interface wholesale and take the
keyboard and mouse handling that DVD menu navigation depends on with
them, as would --intf dummy.
Also drops --no-qt-updates-notif, which was not an option in Debian's
VLC at all. It made VLC exit before it started, so the DVD button could
never have launched a disc.
Co-Authored-By: Claude Opus 5 <[email protected]>
A 32" panel a few feet from the children and a 65" set across a hall
want the same design at different sizes. UI_SCALE in device.conf now
sets that, and nobody has to edit CSS or source to tune a room.
The stylesheet and the notification config become templates carrying
measurement tokens. classroom-dock resolves the stylesheet in memory at
startup; classroom-notifications resolves the notification config into
the session's runtime directory and execs mako on it, so the process is
still just mako and everything that looks for it by name still finds it.
Neither template is rewritten on disk, so an update cannot lose a room's
setting and a room cannot drift from the packaged design.
Dock height and the reserved strip, corner radii, padding, button size,
spacing, every icon, the clock and its inset, and the notification
geometry all follow the scale. Colours, translucency and the hairline
borders do not: those are the design, not the size.
At UI_SCALE=1.0 the rendered stylesheet is byte-identical to the one the
shell used before any of this existed, which is the property worth
keeping. Values outside 0.8 to 1.5 are clamped and anything that is not
a number falls back to 1.0, so a typo in device.conf cannot produce an
unusable classroom.
Device configuration moves into a shared module, since the dock and the
notification daemon now have to agree about what a setting means.
Co-Authored-By: Claude Opus 5 <[email protected]>
The classroom desktop belongs to the classroom user and mako sits on
that user's D-Bus session. An administrator over SSH is in a different
session where nothing owns org.freedesktop.Notifications, so notify-send
asked D-Bus to start a second mako, which had no display to open and
timed out with NoReply.
Find the running sway process for the classroom user and deliver into
its session instead. XDG_RUNTIME_DIR and the bus address are read from
that process, falling back to /run/user/<uid> and its bus socket when
the environment cannot be read — root has ptrace access on the endpoint,
but that is not somewhere to be brittle. The Wayland display is read the
same way, and failing that from the wayland-N.lock sway holds open, so
no socket name is ever assumed. notify-send only needs the bus, so a
display that cannot be resolved is not worth refusing to send over.
Refuses to send when mako is not already running, rather than letting
D-Bus start one, and says plainly what is wrong when there is no
session, no privileges, or no bus socket. --dry-run reports what it
resolved without sending.
Behaviour inside the session is unchanged, and the sample notifications
and styling are untouched.
The tests stand a real background process in for sway so /proc/<pid>/environ
is genuine rather than mocked, and cover both invocation paths plus the
fallbacks and every refusal. The build runs them.
Co-Authored-By: Claude Opus 5 <[email protected]>
Nothing puts windows there any more, but a window parked by an older
classroom build — the exact case this work exists to fix — would
otherwise be invisible to restore and stranded until the next reboot.
Counting the scratchpad as hidden means the Browser button and
Super+Shift+M both pull it back, tiled.
Co-Authored-By: Claude Opus 5 <[email protected]>
mako 1.10 only searches $XDG_CONFIG_HOME/mako/config and ~/.mako/config
— confirmed against the shipped binary, and mako(5) documents no system
path. The config installed to /etc/xdg/mako/config would have been read
by nothing and every notification would have come out stock.
Ship it alongside the rest of the package's config in
/etc/ekklesia-classroom/mako/ and name it on mako's command line, which
also keeps it dpkg-owned instead of writing into the user's home.
Start mako before the dock as well, so nothing can send a notification
early and have D-Bus activate an unstyled instance that then holds the
bus name for the rest of the session.
Co-Authored-By: Claude Opus 5 <[email protected]>
The checklist covers the bottom-shell regression explicitly, since that
is the part most likely to be broken by a later change, and records the
known limitation that Chrome's own minimize button does nothing under
sway.
Co-Authored-By: Claude Opus 5 <[email protected]>
DVD support stays optional per room: DVD_ENABLED decides whether the
button is built at all, and rooms without it poll nothing. Upgrades
append a commented DVD_ENABLED=false so the option is discoverable
without changing what those rooms already do.
The dock polls the drive with CDROM_DRIVE_STATUS, which is a status
query rather than a read, so it does not spin the disc up. A disc that
becomes ready announces itself once and brings the DVD logo up to full
strength; an empty or unplugged drive holds it back, the same gray
versus colour language the LIVE icon already uses. Nothing autoplays —
playback always needs a deliberate press.
Playback is VLC rather than mpv because mpv dropped DVD menu support,
and menus are the part that matters for a commercial disc. It goes
through classroom-window like everything else, so the player minimizes
and restores from the dock exactly as the browser does.
Pressing the button with no drive, no disc, or a disc still spinning up
gives a plain-language notification instead of failing silently.
Reading the drive needs group cdrom, which the postinst grants and the
OTA reboot activates. Commercial CSS discs additionally need libdvdcss,
which Debian cannot ship; classroom-dvd-css-setup bootstraps it from
contrib. That is deliberately not run from the postinst, which executes
while dpkg already holds the apt lock.
The optical helpers live in a shared module both the dock and
classroom-dvd import, and the dock imports it defensively: if it ever
goes missing the shell loses disc detection rather than failing to
start.
Co-Authored-By: Claude Opus 5 <[email protected]>
Chrome stays a full browser. The managed policy only removes the things
a volunteer should never be asked about — the first-run tour, the
default-browser prompt, sync and sign-in promos, the profile picker —
and pins the Home button to Wonder Ink so there is always one obvious
way back. Startup URL is a recommended policy rather than a managed one,
so a teacher can still change it. Nothing restricts where they browse,
and the profile is untouched, so YouTube and other logins survive
reboots and updates.
Notifications were still stock mako, which looked nothing like the rest
of the shell. Give them the dock's palette: the same dark slate, the
same hairline white border, rounded, white text, top right. Kept a
little more opaque than the dock so text stays readable over video, and
on the overlay layer so a parent-call alert can still reach someone
watching a fullscreen DVD.
mako was only ever reaching the session through D-Bus activation. Start
it from the sway config so it is running before anything needs it.
classroom-notify-test sends a sample so the styling can be checked
without waiting for a real event.
Co-Authored-By: Claude Opus 5 <[email protected]>
The scratchpad technically minimized Chrome, but sway hands scratchpad
windows back floating, so restoring gave a draggable window instead of
the maximized one the user put away. Park windows on a hidden workspace
as ordinary tiled containers instead, and move them back to the visible
workspace on restore.
classroom-window carries the whole state machine, so the dock buttons
and Super+M share one implementation:
not running -> launch
unfocused -> focus
focused -> minimize
minimized -> restore, tiled and maximized
Fullscreen is dropped on the way out, since a container parked while
still fullscreen keeps drawing over everything else. floating disable on
the way back also rescues windows left floating by the old scratchpad
path.
Super+Shift+M restores the newest minimized window, so nothing can get
stranded on the hidden workspace.
Co-Authored-By: Claude Opus 5 <[email protected]>
