fix(reactions): the reactions row no longer flickers or loses its spacing (#305)

Two bugs in the one-row "+N" collapse:
- measure() used the border box, which grows by 4 px while collapsed
  (margin -2 / padding 2), so a row within 4 px of fitting flipped
  collapsed↔expanded every frame (flicker, layout shifts, ~11 % of a core
  per looping message). It now measures the content box.
- The collapsed style used the `margin` shorthand, which overrode the
  timeline's marginTop and, when removed, cleared it; the row then stuck
  to the message text. Longhand margins keep marginTop (minus 2 px).

Verified headless (12 reactions, viewport sweep 1300–1400 px): before,
90 style flips in 1.5 s at 1344 px and margin-top 0px after a cycle;
now 0 flips at every width and margin-top stays 8px.

Fixes #305

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

e2e/security-nudge.spec.ts

@@ -29,32 +29,6 @@ async function settled(page: Page) {
   await page.waitForTimeout(2000);
 }
 
-/** [Gitea #307] Serve a Kuma status page for `localhost` with one posted announcement. */
-async function mockAnnouncement(page: Page) {
-  await page.route(/\/config\.json(\?.*)?$/, async (route) => {
-    const res = await route.fetch();
-    const cfg = await res.json();
-    cfg.statusPages = { localhost: { url: 'https://isitup.lotusguild.org', slug: 'matrix' } };
-    await route.fulfill({ response: res, json: cfg });
-  });
-  await page.route(/isitup\.lotusguild\.org\/api\/status-page\//, async (route) => {
-    const cors = { 'access-control-allow-origin': '*' };
-    if (route.request().url().includes('/heartbeat/')) {
-      await route.fulfill({ headers: cors, json: { heartbeatList: {}, uptimeList: {} } });
-      return;
-    }
-    await route.fulfill({
-      headers: cors,
-      json: {
-        config: { slug: 'matrix' },
-        incidents: [{ id: 7, title: 'Community call on Friday', content: '', style: 'info' }],
-        maintenanceList: [],
-        publicGroupList: [],
-      },
-    });
-  });
-}
-
 test.describe('security nudge (#110, #123)', () => {
   let user: TestUser;
 
@@ -86,22 +60,6 @@ test.describe('security nudge (#110, #123)', () => {
     await expect(page.getByText('Device Verification').first()).toBeVisible();
   });
 
-  test('a dismissed announcement no longer hides the nudge (#307)', async ({ page }) => {
-    test.setTimeout(200_000);
-    await mockAnnouncement(page);
-    await loginUI(page, user);
-    await pastGrace(page);
-    await settled(page);
-    // The announcement wins the one strip slot until it's dismissed.
-    const announcement = page.getByRole('status').filter({ hasText: 'Community call on Friday' });
-    await expect(announcement).toBeVisible();
-    await expect(strip(page)).toHaveCount(0);
-    await announcement.getByRole('button', { name: 'Dismiss' }).click();
-    await page.reload();
-    await settled(page);
-    await expect(strip(page)).toContainText("Your encryption keys aren't backed up");
-  });
-
   test('"Not now" snoozes it across a reload', async ({ page }) => {
     test.setTimeout(200_000);
     await loginUI(page, user);

src/app/features/room/message/Reactions.tsx

@@ -69,8 +69,15 @@ export const Reactions = as<'div', ReactionsProps>(
     const measure = useCallback(() => {
       const container = containerRef.current;
       if (!container) return;
-      const rowWidth = container.getBoundingClientRect().width;
-      const gap = parseFloat(getComputedStyle(container).columnGap) || 8;
+      // [Gitea #305] The width the chips actually get (content box). The border
+      // box grows by 4 px while collapsed (margin -2 / padding 2), and measuring
+      // it made a row within 4 px of fitting flip collapsed↔expanded every frame.
+      const cs = getComputedStyle(container);
+      const rowWidth =
+        container.clientWidth -
+        (parseFloat(cs.paddingLeft) || 0) -
+        (parseFloat(cs.paddingRight) || 0);
+      const gap = parseFloat(cs.columnGap) || 8;
       const chips = keys ? keys.split('\u0000').map((k) => chipRefs.current.get(k)) : [];
       const widths = chips.map((el) => el?.getBoundingClientRect().width ?? 0);
       const moreWidth = moreRef.current?.getBoundingClientRect().width ?? 48;
@@ -110,8 +117,21 @@ export const Reactions = as<'div', ReactionsProps>(
         style={{
           ...props.style,
           ...(collapsed && rowHeight
-            ? // 2px breathing room so row-1 focus outlines are not clipped.
-              { maxHeight: rowHeight + 4, overflow: 'hidden', padding: 2, margin: -2 }
+            ? // 2px breathing room so row-1 focus outlines are not clipped. Longhand
+              // margins so the timeline's marginTop survives (Gitea #305: the
+              // `margin` shorthand overrode it and, once removed, cleared it).
+              {
+                maxHeight: rowHeight + 4,
+                overflow: 'hidden',
+                padding: 2,
+                marginLeft: -2,
+                marginRight: -2,
+                marginBottom: -2,
+                marginTop:
+                  props.style?.marginTop !== undefined
+                    ? `calc(${typeof props.style.marginTop === 'number' ? `${props.style.marginTop}px` : props.style.marginTop} - 2px)`
+                    : -2,
+              }
             : {}),
         }}
         ref={(el) => {

src/app/features/security-nudge/SecurityBanner.tsx

@@ -14,7 +14,7 @@ import { useKeyBackupInfo, useKeyBackupStatusChange } from '../../hooks/useKeyBa
 import { useAlive } from '../../hooks/useAlive';
 import { useSyncState } from '../../hooks/useSyncState';
 import { settingsRequestAtom } from '../../state/settingsRequest';
-import { serverStatusAtom, statusDismissedAtom } from '../../state/serverStatus';
+import { serverStatusAtom } from '../../state/serverStatus';
 import { pickBanner } from '../../utils/kumaStatus';
 import {
   dismissNudge,
@@ -66,7 +66,6 @@ function SecurityBannerFor({ crypto }: { crypto: CryptoApi }) {
   const backupInfo = useKeyBackupInfo(crypto);
   const backupActive = useBackupActive(crypto);
   const { status: serverStatus, syncLost } = useAtomValue(serverStatusAtom);
-  const statusDismissed = useAtomValue(statusDismissedAtom);
   const requestSettings = useSetAtom(settingsRequestAtom);
   // Not urgent: wait until sync has settled (two SYNCING in a row), so it
   // never stacks under the "Connecting…" strip at startup.
@@ -92,11 +91,7 @@ function SecurityBannerFor({ crypto }: { crypto: CryptoApi }) {
   });
 
   // One strip at a time: outages, maintenance and a lost connection win.
-  // [Gitea #307] Pass what the user dismissed: a dismissed announcement isn't
-  // on screen and must not keep the nudge hidden for as long as it's posted.
-  const otherStrip =
-    syncLost ||
-    !!pickBanner(serverStatus, { syncLost, where: 'client', dismissed: new Set(statusDismissed) });
+  const otherStrip = syncLost || !!pickBanner(serverStatus, { syncLost, where: 'client' });
   if (!settled || !deviceId || !kind || otherStrip || !shouldShowNudge(kind, record, Date.now()))
     return null;
 

src/app/features/server-status/ServerStatusBanner.tsx

@@ -1,5 +1,5 @@
 import React, { useCallback, useEffect, useMemo, useState } from 'react';
-import { useAtom, useAtomValue, useSetAtom } from 'jotai';
+import { useAtomValue, useSetAtom } from 'jotai';
 import { MatrixClient, SyncState } from 'matrix-js-sdk';
 import { Box, Button, config, Icon, IconButton, Icons, IconSrc, Line, Text } from 'folds';
 import { ContainerColor } from '../../styles/ContainerColor.css';
@@ -7,9 +7,21 @@ import { useClientConfig } from '../../hooks/useClientConfig';
 import { useSyncState } from '../../hooks/useSyncState';
 import { useServerStatus } from '../../hooks/useServerStatus';
 import { ScreenSize, useScreenSizeContext } from '../../hooks/useScreenSize';
-import { serverStatusAtom, statusDismissedAtom } from '../../state/serverStatus';
+import { serverStatusAtom } from '../../state/serverStatus';
 import { pickBanner, resolveStatusPage, StatusBanner } from '../../utils/kumaStatus';
 
+const DISMISS_KEY = 'lotus-status-banner-dismissed';
+const DISMISS_MAX = 50;
+
+const readDismissed = (): string[] => {
+  try {
+    const v = JSON.parse(localStorage.getItem(DISMISS_KEY) ?? '[]');
+    return Array.isArray(v) ? v.filter((k): k is string => typeof k === 'string') : [];
+  } catch {
+    return [];
+  }
+};
+
 const bannerIcon = (b: StripContent): IconSrc => {
   if (b.kind === 'maintenance') return Icons.Setting;
   if (b.tone === 'Primary') return Icons.Info;
@@ -161,14 +173,22 @@ export function ServerStatusFeature({ mx }: { mx: MatrixClient }) {
 /** The logged-in app's status strip. */
 export function ServerStatusBanner() {
   const { status, syncLost } = useAtomValue(serverStatusAtom);
-  const [dismissed, dismissKey] = useAtom(statusDismissedAtom);
+  const [dismissed, setDismissed] = useState(readDismissed);
   const banner = pickBanner(status, {
     syncLost,
     where: 'client',
     dismissed: new Set(dismissed),
   });
   if (!banner) return null;
-  const dismiss = () => dismissKey(banner.key);
+  const dismiss = () => {
+    const next = [...dismissed.filter((k) => k !== banner.key), banner.key].slice(-DISMISS_MAX);
+    try {
+      localStorage.setItem(DISMISS_KEY, JSON.stringify(next));
+    } catch {
+      // storage unavailable — dismissed for this session only
+    }
+    setDismissed(next);
+  };
   return <StatusStrip banner={banner} onDismiss={dismiss} />;
 }
 

src/app/state/serverStatus.ts

@@ -16,35 +16,3 @@ export const serverStatusAtom = atom<{
   syncLost: false,
   lostAt: null,
 });
-
-const DISMISS_KEY = 'lotus-status-banner-dismissed';
-const DISMISS_MAX = 50;
-
-const readDismissed = (): string[] => {
-  try {
-    const v = JSON.parse(localStorage.getItem(DISMISS_KEY) ?? '[]');
-    return Array.isArray(v) ? v.filter((k): k is string => typeof k === 'string') : [];
-  } catch {
-    return [];
-  }
-};
-
-const baseDismissedAtom = atom<string[]>(readDismissed());
-
-/**
- * [Gitea #307] Status strips the user dismissed (by banner key), shared so
- * the security nudge knows a dismissed announcement isn't on screen.
- * Persisted to localStorage; session-only if storage is unavailable.
- */
-export const statusDismissedAtom = atom(
-  (get) => get(baseDismissedAtom),
-  (get, set, key: string) => {
-    const next = [...get(baseDismissedAtom).filter((k) => k !== key), key].slice(-DISMISS_MAX);
-    try {
-      localStorage.setItem(DISMISS_KEY, JSON.stringify(next));
-    } catch {
-      // storage unavailable — dismissed for this session only
-    }
-    set(baseDismissedAtom, next);
-  },
-);