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Classroom_Desktop/docs/browser.md
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ekklesiaandClaude Opus 5 a1a218b29f fix: draw classroom icons at the display's real pixel density
Icons went soft under UI_SCALE while the clock text beside them stayed
sharp, which is visible on a 24" monitor even if it hides on a TV.

new_from_file_at_scale rasterises an SVG at its *logical* size. The
artwork is vector, but by the time sway scaled the session it was
already a fixed raster, and the compositor enlarged that. Text never had
the problem because GTK draws it at the real density.

GTK 3 has no fractional scaling, so sway advertises the ceiling integer
scale and scales the finished buffer down. Measured under sway: scale
factor 1 at output scale 1.0, and 2 at 1.25, 1.5 and 2.0. So each icon
is now rasterised at size x scale_factor physical pixels and handed to
GTK as a cairo surface carrying that device scale. The icon lands at the
real density; its logical size, and the whole dock layout, is unchanged.

Icons redraw on notify::scale-factor as well as at realize, since the
scale factor is not known until a widget is on a display and changes if
UI_SCALE is changed under a running session.

Browser, DVD, LIVE and all six DVD control icons go through it, in a
shared module so the dock and the DVD session cannot diverge. The
throbber is drawn rather than loaded and had the same flaw, so it draws
on a device-scaled surface too rather than being the one soft thing left
in a sharp dock.

The artwork is untouched. Verified by rendering the dock under sway at
1.0, 1.25, 1.5 and 2.0 against the previous build: apparent icon size is
identical at every scale (28, 35, 42, 56 px), 1.0 is unchanged
pixel-for-pixel, and peak edge contrast on the Chrome icon goes from 60
to 99 at 1.25, 49 to 83 at 1.5, and 37 to 82 at 2.0 out of 255. The DVD
control bar was checked the same way.

Also records that Wonder Ink session-only cookies are confirmed working
on the endpoint, which settles the question 0.1.34 shipped as unverified
and tells us the session is in cookies rather than localStorage.

Co-Authored-By: Claude Opus 5 <[email protected]>
2026-09-06 14:19:38 -05:00

4.6 KiB

The classroom browser

A classroom computer is a shared appliance, not somebody's laptop. There is one local Chrome profile, owned by the room. Teachers sign into websites; nobody signs into Chrome.

Policies

All of these are in /etc/opt/chrome/policies/managed/ekklesia-classroom.json, and every name was checked against the strings of the installed Chrome 152 binary with deliberately invalid names as a control.

Policy Value Why
BrowserSignin 0 Chrome never asks who is using it
SyncDisabled true Explicit, though BrowserSignin: 0 implies it
SigninInterceptionEnabled false No "this account is managed" bubble
BrowserAddPersonEnabled false No new Chrome profiles
BrowserGuestModeEnabled false Removes the Guest entry point from the profile menu
ProfilePickerOnStartupAvailability 1 No profile picker at startup
PasswordManagerEnabled false No offers to save passwords
PasswordLeakDetectionEnabled false No leak warnings
BackgroundModeEnabled false Closing the last window really ends the session
CookiesSessionOnlyForUrls ["[*.]wonderink.org"] Wonder Ink should not outlive a teacher
DefaultBrowserSettingEnabled false No default-browser prompt
PromotionalTabsEnabled false No welcome tabs
MetricsReportingEnabled false —
ShowHomeButton true One obvious way back
HomepageLocation Wonder Ink —
HomepageIsNewTabPage false —

BrowserGuestModeEnabled: false is the answer to "other profile switching entry points". Guest mode is the one that survives BrowserAddPersonEnabled: false, and disabling it is the supported mechanism — no UI hacks. Guest mode is not used as the browsing model: the room needs one persistent profile so the church YouTube login survives.

None of this touches website logins. Wonder Ink, Google and YouTube sign-ins are ordinary site sessions and are unaffected by BrowserSignin: 0, which governs signing in to the browser.

What the policies do not remove

The avatar button stays in the toolbar. Verified by screenshotting Chrome with these policies applied and comparing against Chrome without them: the button is in the same place either way.

What changes is what is behind it. Sign-in, adding a profile and Guest mode are all disabled by policy, so the menu has nothing left that creates or switches a profile. Chrome 152 has no policy that removes the button itself — ProfileSwitcherEnabled and similar names do not exist, checked against the binary — and hiding it would mean the UI hacks this is meant to avoid.

Worth a look at the endpoint: open that menu once and confirm it offers nothing actionable.

Wonder Ink between teachers — CONFIRMED WORKING

Teacher A signs in, uses the room, Chrome closes, teacher B opens Chrome and Wonder Ink is signed out, while YouTube stays signed into the church account.

CookiesSessionOnlyForUrls with [*.]wonderink.org does it. That pattern covers app.wonderink.org and every other subdomain.

Confirmed on the physical endpoint, which is the only place it could be: it needs a real Wonder Ink login. It could not be established here, and three attempts to prove the mechanism against a local test site were inconclusive because the positive control never worked — so this was shipped as unverified and the endpoint settled it.

Two consequences worth keeping in mind.

Wonder Ink's session is therefore in cookies, not in localStorage. That matters because there is no per-site Chrome policy that clears localStorage on exit: ClearBrowsingDataOnExitList and BrowsingDataLifetime both exist in Chrome 152 but are global, and blanket clearing would take YouTube with it. Had it gone the other way, this would have needed a classroom-owned cleanup instead.

If Wonder Ink login is "Sign in with Google"

app.wonderink.org loads Google Identity Services (accounts.google.com/gsi/client), so Google sign-in is at least offered.

If teachers sign into Wonder Ink through Google, clearing wonderink.org will sign them out of Wonder Ink — but the Google session at accounts.google.com is deliberately kept, because that is what keeps YouTube Premium signed in. The next teacher could then be one click from re-entering the previous teacher's Wonder Ink account.

These two requirements genuinely conflict, and which one applies depends on how teachers actually sign in. Worth knowing before Sunday. If teachers use Wonder Ink email-and-password accounts, there is no conflict at all.