# 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.