diff --git a/.github/workflows/docker.yml b/.github/workflows/docker.yml
index d709d3a508a..0d1c51a7cd8 100644
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -66,7 +66,13 @@ jobs:
         name: Test
         working-directory: etherpad
         run: |
-          docker run --rm -d -p 9001:9001 --name test ${{ env.TEST_TAG }}
+          # ADMIN_PASSWORD provisions settings.json.docker's admin user so
+          # the adminSettings_7819 container spec can authenticate against
+          # /admin and the /settings socket. pad.js doesn't touch /admin
+          # so the existing API specs are unaffected.
+          docker run --rm -d -p 9001:9001 \
+            -e ADMIN_PASSWORD=changeme1 \
+            --name test ${{ env.TEST_TAG }}
           ./bin/installDeps.sh
           docker logs -f test &
           while true; do
@@ -79,6 +85,34 @@ jobs:
             esac
           done
           (cd src && pnpm run test-container)
+          # Regression for #7819. adminSettings_7819.ts saves a marker via
+          # the admin /settings socket and intentionally leaves it on
+          # disk. We assert here that the save actually hit the file
+          # (mocha only sees the next `load` reply — this catches a
+          # scenario where the load is served from cache and the file
+          # never actually changed).
+          docker exec test grep -q persist-marker-7819 /opt/etherpad-lite/settings.json || {
+            echo "[#7819] socket-driven save did NOT reach /opt/etherpad-lite/settings.json on disk"
+            docker exec test cat /opt/etherpad-lite/settings.json | head -50
+            exit 1
+          }
+          # Now prove the on-disk file survives an in-place container
+          # restart. This is the scenario a docker-compose user with
+          # `restart: always` hits on every host reboot.
+          docker restart test >/dev/null
+          for i in $(seq 1 60); do
+            status=$(docker container inspect -f '{{.State.Health.Status}}' test 2>/dev/null) || { docker logs test; exit 1; }
+            case ${status} in
+              healthy) break;;
+              starting) sleep 2;;
+              *) docker logs test; exit 1;;
+            esac
+          done
+          docker exec test grep -q persist-marker-7819 /opt/etherpad-lite/settings.json || {
+            echo "[#7819 REGRESSION] settings.json was reset on docker restart — ep_oauth block vanished"
+            docker logs test
+            exit 1
+          }
           docker rm -f test
           git clean -dxf .
       -
diff --git a/src/package.json b/src/package.json
index 126ac0e54b8..fa2cf5ad44d 100644
--- a/src/package.json
+++ b/src/package.json
@@ -151,7 +151,7 @@
     "lint": "eslint .",
     "test": "cross-env NODE_ENV=production mocha --import=tsx --require ./tests/backend/diagnostics.ts --timeout 120000 --extension ts --recursive tests/backend/specs ../node_modules/ep_*/static/tests/backend/specs",
     "test-utils": "cross-env NODE_ENV=production mocha --import=tsx --timeout 5000 --recursive tests/backend/specs/*utils.ts",
-    "test-container": "mocha --import=tsx --timeout 5000 tests/container/specs/api",
+    "test-container": "mocha --import=tsx --timeout 30000 --extension ts,js tests/container/specs/api",
     "dev": "cross-env NODE_ENV=development  node --require tsx/cjs node/server.ts",
     "prod": "cross-env NODE_ENV=production node --require tsx/cjs node/server.ts",
     "ts-check": "tsc --noEmit",
diff --git a/src/tests/container/specs/api/adminSettings_7819.ts b/src/tests/container/specs/api/adminSettings_7819.ts
new file mode 100644
index 00000000000..5c58e7551e0
--- /dev/null
+++ b/src/tests/container/specs/api/adminSettings_7819.ts
@@ -0,0 +1,157 @@
+'use strict';
+
+// Regression coverage for https://github.com/ether/etherpad/issues/7819.
+// Drives the admin /settings socket against the running Docker container
+// (test-container target) to prove the save flow actually writes a new
+// top-level plugin block and the next `load` reads it back.
+//
+// Requires the container to be started with `-e ADMIN_PASSWORD=changeme1`
+// so settings.json.docker provisions the admin user used here. Run via
+// `pnpm run test-container` from the docker.yml workflow.
+
+import {strict as assert} from 'assert';
+import setCookieParser from 'set-cookie-parser';
+
+const supertest = require('supertest');
+const io = require('socket.io-client');
+
+const BASE_URL = 'http://localhost:9001';
+const ADMIN_USER = 'admin';
+const ADMIN_PASSWORD = 'changeme1';
+const MARKER = 'persist-marker-7819';
+
+// /admin-auth/ is the path webaccess.ts always treats as requireAdmin,
+// regardless of settings.requireAuthentication. The container runs with
+// REQUIRE_AUTHENTICATION=false (default), so GET /admin/ would NOT issue
+// a Basic challenge and we'd never get a session cookie. POSTing to
+// /admin-auth/ does.
+const adminCookieHeader = async (): Promise<string> => {
+  const res: any = await supertest(BASE_URL)
+      .post('/admin-auth/')
+      .auth(ADMIN_USER, ADMIN_PASSWORD);
+  if (res.status !== 200) {
+    throw new Error(
+        `/admin-auth/ POST returned ${res.status} (expected 200) — ` +
+        'is the container started with ADMIN_PASSWORD=changeme1? ' +
+        `Body: ${String(res.text).slice(0, 200)}`);
+  }
+  const cookies = setCookieParser.parse(res, {map: true}) as Record<string, any>;
+  if (Object.keys(cookies).length === 0) {
+    throw new Error('/admin-auth/ returned 200 but set no cookies — session middleware not wired?');
+  }
+  return Object.entries(cookies)
+      .map(([name, cookie]) => `${name}=${encodeURIComponent(cookie.value)}`)
+      .join('; ');
+};
+
+const settingsSocket = async (cookieHdr: string) => {
+  const socket = io(`${BASE_URL}/settings`, {
+    forceNew: true,
+    query: {cookie: cookieHdr},
+    transports: ['websocket'],
+  });
+  await new Promise<void>((res, rej) => {
+    const onErr = (err: any) => { socket.off('connect', onConn); rej(err); };
+    const onConn = () => { socket.off('connect_error', onErr); res(); };
+    socket.once('connect', onConn);
+    socket.once('connect_error', onErr);
+  });
+  return socket;
+};
+
+const load = (socket: any): Promise<{results: string; resolved?: any; flags?: any}> =>
+    new Promise((res, rej) => {
+      // No reply == handler never registered, which means our session
+      // wasn't admin. Surface that fast rather than burning the mocha
+      // timeout — the adminsettings.ts connection handler silently
+      // returns without binding any listeners when is_admin is false.
+      const t = setTimeout(
+          () => rej(new Error(
+              'load: no `settings` reply within 8s — likely not authenticated as admin')),
+          8000);
+      socket.once('settings', (s: any) => { clearTimeout(t); res(s); });
+      socket.emit('load', null);
+    });
+
+const save = (socket: any, payload: string): Promise<{status: string; detail?: any}> =>
+    new Promise((res, rej) => {
+      const t = setTimeout(
+          () => rej(new Error('saveSettings: no saveprogress within 8s')), 8000);
+      socket.once('saveprogress', (status: string, detail: any) => {
+        clearTimeout(t);
+        res({status, detail});
+      });
+      socket.emit('saveSettings', payload);
+    });
+
+describe('admin /settings socket (Docker container) — #7819', function () {
+  this.timeout(20000);
+  let socket: any;
+
+  before(async function () {
+    const cookieHdr = await adminCookieHeader();
+    socket = await settingsSocket(cookieHdr);
+    // Sanity: load works as admin. We don't keep the result — the file
+    // we're about to save replaces settings.json entirely.
+    const reply = await load(socket);
+    assert.equal(typeof reply.results, 'string',
+        'settings.results must be a string — container started without ADMIN_PASSWORD?');
+  });
+
+  after(function () {
+    if (socket) socket.disconnect();
+    // INTENTIONAL: do NOT restore baseline. docker.yml greps for MARKER
+    // via `docker exec` after this suite, then runs `docker restart`,
+    // then greps again — that whole chain proves the on-disk file
+    // survives container restart, which is the actual #7819 ask. The
+    // container is `docker rm -f`'d at the end of the workflow step, so
+    // leftover state doesn't poison anything.
+  });
+
+  it('save → load round-trip preserves a top-level plugin block', async function () {
+    // Hand-built minimal-but-viable settings document. Three reasons we
+    // don't splice into the original:
+    //   1. settings.json.docker uses jsonc `/* */` and `//` comments and
+    //      keeps a trailing-comma-before-comment-before-close pattern
+    //      that's annoying to patch correctly from the test side.
+    //   2. The backend `saveSettings` handler writes bytes verbatim with
+    //      zero validation — so what we save IS what should come back.
+    //      Whether the payload is "realistic" is orthogonal to whether
+    //      the file persists.
+    //   3. After this save the container will be `docker restart`ed by
+    //      the workflow. Minimal-but-viable means Etherpad starts back
+    //      up: `port` is required by the HTTP server, `users.admin`
+    //      keeps admin auth working post-restart, dbType=dirty keeps DB
+    //      init happy.
+    const augmented = JSON.stringify({
+      title: 'Etherpad',
+      ip: '0.0.0.0',
+      port: 9001,
+      dbType: 'dirty',
+      dbSettings: {filename: 'var/dirty.db'},
+      showSettingsInAdminPage: true,
+      enableAdminUITests: true,
+      users: {admin: {password: ADMIN_PASSWORD, is_admin: true}},
+      ep_oauth: {
+        clientID: MARKER,
+        clientSecret: 'x',
+        callbackURL: 'http://x/cb',
+      },
+    }, null, 2);
+
+    const ack = await save(socket, augmented);
+    assert.equal(ack.status, 'saved',
+        `saveSettings did not ack 'saved' — got ${JSON.stringify(ack)}`);
+
+    // Re-load over the same socket. adminsettings.ts re-reads
+    // settings.settingsFilename on every `load`, so this reflects the
+    // actual file on disk — not a client-side echo.
+    const reply = await load(socket);
+    assert.equal(reply.results, augmented,
+        'load.results must equal the bytes we just saved');
+    assert.ok(reply.results.includes('"ep_oauth"'),
+        'ep_oauth block missing from next load — file on disk does not match payload');
+    assert.ok(reply.results.includes(MARKER),
+        `marker '${MARKER}' missing from next load`);
+  });
+});