fix(calls): sidebar voice-channel join respects the voice limit

channelFull was computed only in the prescreen; a second click on the
channel in the room nav joined a full channel. Extract
useVoiceChannelFull, use it in both places, and refuse with a
"Channel full (N/N)" toast.

Fixes #30

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/features/call/CallView.tsx

@@ -18,8 +18,7 @@ import { useMatrixClient } from '../../hooks/useMatrixClient';
 import { StateEvent } from '../../../types/matrix/room';
 import { useCallMembers, useCallSession } from '../../hooks/useCall';
 import { LotusDecorationPusher } from '../lotus/LotusDecorationPusher';
-import { useStateEvent } from '../../hooks/useStateEvent';
-import { VoiceLimitContent } from '../common-settings/general/RoomVoiceLimit';
+import { useVoiceChannelFull } from '../../hooks/useVoiceChannelFull';
 import { CallMemberRenderer } from './CallMemberCard';
 import * as css from './styles.css';
 import { CallControls } from './CallControls';
@@ -114,12 +113,9 @@ function CallPrescreen() {
   const callEmbed = useCallEmbed();
   const inOtherCall = callEmbed && callEmbed.roomId !== room.roomId;
 
-  // Voice channel user limit (io.lotus.voice_limit). 0 / absent means no limit.
-  const limitEvent = useStateEvent(room, StateEvent.LotusVoiceLimit);
-  const maxUsers = limitEvent?.getContent<VoiceLimitContent>().max_users ?? 0;
-  // A user already counted in the session is rejoining and should not be blocked.
-  const alreadyMember = callMembers.some((m) => m.sender === mx.getSafeUserId());
-  const channelFull = maxUsers > 0 && !alreadyMember && callMembers.length >= maxUsers;
+  // [Gitea #30] Voice channel user limit (io.lotus.voice_limit), shared with the
+  // room-nav join path via useVoiceChannelFull so both agree on "full".
+  const { channelFull, current: callMembersCount, max: maxUsers } = useVoiceChannelFull(room);
 
   const canJoin = hasPermission && livekitSupported && rtcSupported && !channelFull;
 
@@ -144,7 +140,7 @@ function CallPrescreen() {
           <Box className={css.PrescreenMessage} alignItems="Center">
             {!inOtherCall && !hasPermission && <NoPermissionMessage />}
             {!inOtherCall && hasPermission && channelFull && (
-              <ChannelFullMessage current={callMembers.length} max={maxUsers} />
+              <ChannelFullMessage current={callMembersCount} max={maxUsers} />
             )}
             {!inOtherCall && hasPermission && !channelFull && (
               <JoinMessage

src/app/features/room-nav/RoomNavItem.tsx

@@ -80,6 +80,7 @@ import {
 } from '../../hooks/useRoomMeta';
 import { useCallMembers, useCallSession } from '../../hooks/useCall';
 import { useCallEmbed, useCallStart } from '../../hooks/useCallEmbed';
+import { useVoiceChannelFull } from '../../hooks/useVoiceChannelFull';
 import { callChatAtom } from '../../state/callEmbed';
 import { createErrorToast, toastQueueAtom } from '../../state/toast';
 import { useCallPreferencesAtom } from '../../state/hooks/callPreferences';
@@ -691,8 +692,12 @@ function RoomNavItem_({
   const callMembers = useCallMembers(callSession);
   const startCall = useCallStart(direct);
   const callEmbed = useCallEmbed();
+  // [Gitea #30] Same voice-limit check the call prescreen uses, so the sidebar
+  // second-click join path can't bypass a full channel.
+  const { channelFull, current: voiceCurrent, max: voiceMax } = useVoiceChannelFull(room);
   const callPref = useAtomValue(useCallPreferencesAtom());
   const autoDiscoveryInfo = useAutoDiscoveryInfo();
+  const setToast = useSetAtom(toastQueueAtom);
 
   const handleStartCall: MouseEventHandler<HTMLAnchorElement> = (evt) => {
     const powerLevelsEvent = getStateEvent(room, StateEvent.RoomPowerLevels);
@@ -714,6 +719,22 @@ function RoomNavItem_({
     if (callEmbed) {
       return;
     }
+
+    // [Gitea #30] Refuse to start a call into a full voice channel — the
+    // prescreen already blocks this, but the sidebar second-click join path
+    // skipped the check entirely.
+    if (channelFull) {
+      evt.preventDefault();
+      setToast(
+        createErrorToast(
+          `Channel full (${voiceCurrent}/${voiceMax})`,
+          Icons.Warning,
+          'Cannot join',
+        ),
+      );
+      return;
+    }
+
     // Start call in second click
     if (selected) {
       evt.preventDefault();

src/app/hooks/useVoiceChannelFull.ts

@@ -0,0 +1,34 @@
+import { Room } from 'matrix-js-sdk';
+import { useMemo } from 'react';
+import { useStateEvent } from './useStateEvent';
+import { StateEvent } from '../../types/matrix/room';
+import { VoiceLimitContent } from '../features/common-settings/general/RoomVoiceLimit';
+import { useCallMembers, useCallSession } from './useCall';
+import { useMatrixClient } from './useMatrixClient';
+
+export type VoiceChannelFull = {
+  channelFull: boolean;
+  current: number;
+  max: number;
+};
+
+/**
+ * [Gitea #30] Voice channel user limit (`io.lotus.voice_limit`), shared between
+ * `CallPrescreen` and any other join path (e.g. the room-nav second-click join)
+ * so they agree on when a channel is full. 0/absent `max_users` means no limit.
+ */
+export const useVoiceChannelFull = (room: Room): VoiceChannelFull => {
+  const mx = useMatrixClient();
+  const callSession = useCallSession(room);
+  const callMembers = useCallMembers(callSession);
+
+  const limitEvent = useStateEvent(room, StateEvent.LotusVoiceLimit);
+
+  return useMemo(() => {
+    const maxUsers = limitEvent?.getContent<VoiceLimitContent>().max_users ?? 0;
+    // A user already counted in the session is rejoining and should not be blocked.
+    const alreadyMember = callMembers.some((m) => m.sender === mx.getSafeUserId());
+    const channelFull = maxUsers > 0 && !alreadyMember && callMembers.length >= maxUsers;
+    return { channelFull, current: callMembers.length, max: maxUsers };
+  }, [limitEvent, callMembers, mx]);
+};