fix: pad-wide view settings apply to the creator's own view (#7900)

The pad creator is never "enforced upon themselves" (isPadSettingsEnforcedForMe
is false whenever canEditPadSettings is true), so getEffectivePadOptions always
merges their personal view overrides (cookies) on top of the pad-wide options.

As a result, a creator who had at some point toggled e.g. their personal "Read
content from right to left" carried a stale rtlIsTrue=false cookie that silently
masked the pad-wide value they later set — toggling the pad-wide control (and
then enforcing it) appeared to do nothing on the creator's own screen.

Fix: when the creator changes a pad-wide view option, sync their personal pref
to the chosen value so their own view adopts the pad-wide setting immediately.
This deliberately does NOT change the precedence model — the creator can still
override the setting afterwards via the "My view" controls, so the existing
behaviour where a creator keeps personal overrides while enforcing settings for
other users (pad_settings.spec.ts) is preserved.

Adds a frontend test reproducing the stale-personal-cookie scenario.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: JohnMcLear

src/static/js/pad.ts

@@ -876,6 +876,14 @@ const pad = {
           options,
           changedBy: pad.myUserInfo.name || 'unnamed',
         });
+    // The pad creator is never "enforced upon themselves", so their personal
+    // view overrides (cookies) are always merged on top of the pad-wide value
+    // in getEffectivePadOptions. A stale personal pref would therefore mask the
+    // pad-wide value they just set, making the control appear to do nothing
+    // (#7900). Sync the creator's personal pref to the value they chose so
+    // their own view adopts it immediately. They can still override it
+    // afterwards via the "My view" controls.
+    pad.setMyViewOption(key, value);
   },
   changeViewOption: (key, value) => {
     const effectiveOptions = pad.getEffectivePadOptions();

src/tests/frontend-new/specs/rtl_pad_wide_enforce.spec.ts

@@ -0,0 +1,61 @@
+import {expect, test} from "@playwright/test";
+import {goToNewPad} from "../helper/padHelper";
+import {showSettings} from "../helper/settingsHelper";
+
+// Regression test for ether/etherpad#7900.
+//
+// The pad creator is never "enforced upon themselves" (they can always edit
+// pad settings), so their personal view overrides (cookies) are always merged
+// on top of the pad-wide options in getEffectivePadOptions. A creator who had
+// at some point toggled their personal "Read content from right to left"
+// carried a stale rtlIsTrue=false cookie that silently masked the pad-wide RTL
+// value they later set — the pad content stayed LTR and the pad-wide control
+// appeared to "do nothing".
+//
+// Fix: changePadViewOption syncs the creator's personal pref to the value they
+// chose, so their own view adopts the pad-wide setting immediately (while still
+// allowing them to override it afterwards via the "My view" controls).
+test.beforeEach(async ({page, browser}) => {
+  const context = await browser.newContext();
+  await context.clearCookies();
+  await goToNewPad(page);
+});
+
+test.describe('RTL pad-wide + enforce', function () {
+  test('pad-wide RTL applies to the creator even with a stale personal setting', {tag: '@feature:rtl-toggle'}, async function ({page}) {
+    const innerBody = page
+      .frameLocator('iframe[name="ace_outer"]')
+      .frameLocator('iframe[name="ace_inner"]')
+      .locator('#innerdocbody');
+    const computedDir = () => innerBody.evaluate((el) =>
+        el.ownerDocument.defaultView!.getComputedStyle(el).direction);
+
+    await showSettings(page);
+
+    // The checkboxes are visually replaced by styled labels, so drive the UI
+    // the way a user does — by clicking the labels.
+    // The creator first toggles their PERSONAL RTL on, then off. This writes a
+    // personal cookie pref rtlIsTrue=false that used to mask the pad-wide value.
+    await page.locator('label[for="options-rtlcheck"]').click();
+    await expect(page.locator('#options-rtlcheck')).toBeChecked();
+    await expect.poll(computedDir).toBe('rtl');
+    await page.locator('label[for="options-rtlcheck"]').click();
+    await expect(page.locator('#options-rtlcheck')).not.toBeChecked();
+    await expect.poll(computedDir).toBe('ltr');
+
+    // Pad-wide settings are visible because the new pad's first user is its
+    // creator (canEditPadSettings). Setting pad-wide RTL must now flip the
+    // creator's own content despite the stale personal cookie...
+    await page.locator('label[for="padsettings-options-rtlcheck"]').click();
+    await expect(page.locator('#padsettings-options-rtlcheck')).toBeChecked();
+    await expect.poll(computedDir).toBe('rtl');
+    await expect(innerBody).toHaveClass(/\brtl\b/);
+    // ...and the personal control reflects the synced value.
+    await expect(page.locator('#options-rtlcheck')).toBeChecked();
+
+    // Enforcing for other users keeps the creator's content RTL.
+    await page.locator('label[for="padsettings-enforcecheck"]').click();
+    await expect(page.locator('#padsettings-enforcecheck')).toBeChecked();
+    await expect.poll(computedDir).toBe('rtl');
+  });
+});