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

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/hooks/useCallRejoin.ts

@@ -17,8 +17,6 @@ import {
   CALL_SESSION_HEARTBEAT_MS,
   clearCallSession,
   decideRejoin,
-  othersInCall,
-  rejoinToastBody,
   readCallSession,
   writeCallSession,
 } from '../utils/callRejoin';
@@ -114,27 +112,6 @@ export function useCallRejoin(embed: CallEmbed | undefined, joined: boolean): vo
       };
       dismissToast(TOAST_ID);
       clearCallSession();
-      // [Gitea #302] A DM call the other person has since left is over;
-      // starting it again would ring them, so just say so.
-      const dm = l.directs.has(room.roomId);
-      if (
-        dm &&
-        !othersInCall(
-          session.memberships.map((m) => m.userId ?? ''),
-          mx.getUserId() ?? '',
-        )
-      ) {
-        // Own id: clicking a toast removes it by id after its onClick runs.
-        setToast({
-          id: `${TOAST_ID}-ended`,
-          iconSrc: Icons.Phone,
-          displayName: 'Call ended',
-          body: `${room.name ?? 'They'} already left the call.`,
-          roomName: room.name ?? '',
-          roomId: room.roomId,
-        });
-        return;
-      }
       try {
         (l.directs.has(room.roomId) ? l.startDmCall : l.startRoomCall)(room, pref);
       } catch {
@@ -156,7 +133,6 @@ export function useCallRejoin(embed: CallEmbed | undefined, joined: boolean): vo
           .filter((m) => m.userId === mx.getUserId())
           .map((m) => m.deviceId),
         memberCount: memberships.length,
-        dm: latest.current.directs.has(room.roomId),
       });
       // The RTC session fills in a moment after sync; keep waiting while it is
       // empty unless this is the final (timed-out) look.
@@ -176,7 +152,7 @@ export function useCallRejoin(embed: CallEmbed | undefined, joined: boolean): vo
         id: TOAST_ID,
         iconSrc: Icons.Phone,
         displayName: 'Rejoin voice?',
-        body: rejoinToastBody(room.name, latest.current.directs.has(room.roomId)),
+        body: `You were in the call in ${room.name ?? 'a room'} before the restart. Tap to rejoin.`,
         roomName: room.name ?? '',
         roomId: room.roomId,
         sticky: true,

src/app/utils/callRejoin.test.ts

@@ -1,12 +1,6 @@
 import { describe, it } from 'node:test';
 import assert from 'node:assert/strict';
-import {
-  CALL_REJOIN_MAX_AGE_MS,
-  decideRejoin,
-  othersInCall,
-  rejoinToastBody,
-  RejoinContext,
-} from './callRejoin';
+import { CALL_REJOIN_MAX_AGE_MS, decideRejoin, RejoinContext } from './callRejoin';
 
 const base: RejoinContext = {
   record: {
@@ -60,21 +54,3 @@ describe('decideRejoin', () => {
     });
   });
 });
-
-it('decideRejoin: DM calls are never auto-rejoined, only offered (#302)', () => {
-  assert.deepEqual(decideRejoin({ ...base, mode: 'auto', dm: true }), {
-    action: 'ask',
-    roomId: '!r',
-  });
-  assert.deepEqual(decideRejoin({ ...base, mode: 'auto' }), { action: 'auto', roomId: '!r' });
-});
-
-it('rejoinToastBody and othersInCall (#302)', () => {
-  assert.equal(
-    rejoinToastBody('Bob Builder', true),
-    'You were in a call with Bob Builder before the restart. Tap to rejoin.',
-  );
-  assert.match(rejoinToastBody('Voice Lounge', false), /in the call in Voice Lounge/);
-  assert.equal(othersInCall(['@me:x'], '@me:x'), false);
-  assert.equal(othersInCall(['@me:x', '@bob:x'], '@me:x'), true);
-});

src/app/utils/callRejoin.ts

@@ -67,8 +67,6 @@ export type RejoinContext = {
   ownMemberDevices: string[];
   /** Number of call memberships in the room, ours included. */
   memberCount: number;
-  /** A DM call: rejoining one may ring the other person. */
-  dm?: boolean;
 };
 
 export type RejoinDecision = { action: 'none' } | { action: 'ask' | 'auto'; roomId: string };
@@ -85,18 +83,5 @@ export function decideRejoin(ctx: RejoinContext): RejoinDecision {
   // Nobody there any more (our own stale membership doesn't count).
   const others = ctx.memberCount - ctx.ownMemberDevices.length;
   if (others <= 0) return { action: 'none' };
-  // [Gitea #302] Never rejoin a DM call on our own: if the other person has
-  // just left, starting it again would ring them. Ask instead.
-  if (ctx.dm && mode === 'auto') return { action: 'ask', roomId: record.roomId };
   return { action: mode, roomId: record.roomId };
 }
-
-/** Pure: whether anyone but us is still in the call (by call membership). */
-export const othersInCall = (memberUserIds: string[], myUserId: string): boolean =>
-  memberUserIds.some((u) => u !== myUserId);
-
-/** The rejoin toast's text; DMs name the person rather than "the call in <room>". */
-export const rejoinToastBody = (roomName: string | undefined, dm: boolean): string =>
-  dm
-    ? `You were in a call with ${roomName ?? 'them'} before the restart. Tap to rejoin.`
-    : `You were in the call in ${roomName ?? 'a room'} before the restart. Tap to rejoin.`;