fix(web): normalize channel and server IDs across channel store and auto-select default channel

web/src/components/ChannelList.tsx

@@ -117,9 +117,21 @@ export function ChannelList() {
   }, [fetchNotifSettings, fetchReadStates]);
 
   const channels = useMemo(() => {
-    return activeServerId ? channelsByServer[activeServerId] || [] : [];
+    return activeServerId ? channelsByServer[activeServerId.toLowerCase()] || [] : [];
   }, [activeServerId, channelsByServer]);
 
+  useEffect(() => {
+    if (channels.length > 0) {
+      const activeExists = activeChannelId && channels.some((c) => c.id === activeChannelId);
+      if (!activeExists) {
+        const defaultChannel = channels.find((c) => c.type === 'text') || channels[0];
+        if (defaultChannel) {
+          setActiveChannel(defaultChannel.id);
+        }
+      }
+    }
+  }, [channels, activeChannelId, setActiveChannel]);
+
   const activeServer = useMemo(() => {
     if (!activeServerId) return null;
     return servers.find((s) => s.id === activeServerId) || null;

web/src/components/ChatArea.tsx

@@ -332,8 +332,8 @@ export function ChatArea() {
   );
   const canBulkDelete = true;
 
-  const channels = activeServerId ? channelsByServer[activeServerId] || [] : [];
+  const channels = activeServerId ? channelsByServer[activeServerId.toLowerCase()] || [] : [];
-  const activeChannel = channels.find((c) => c.id === activeChannelId);
+  const activeChannel = channels.find((c) => c.id.toLowerCase() === activeChannelId);
   const members = activeServerId ? membersByServer[activeServerId] || [] : [];
   // Humans only for mentions / nickname lookup (bots live in member list separately).
   const humanMembers = useMemo(() => members.filter((m) => !m.is_bot), [members]);

web/src/stores/channel.ts

@@ -33,11 +33,18 @@ export const useChannelStore = create<ChannelState>((set) => ({
   error: null,
 
   fetchChannels: async (serverId) => {
+    const srvId = serverId.toLowerCase();
     set({ isLoading: true, error: null });
     try {
-      const channels = await api.get<Channel[]>(`/servers/${serverId}/channels`);
+      const channels = await api.get<Channel[]>(`/servers/${srvId}/channels`);
+      const list = Array.isArray(channels) ? channels : [];
+      const normalized = list.map((c) => ({
+        ...c,
+        id: c.id.toLowerCase(),
+        server_id: c.server_id.toLowerCase(),
+      }));
       set((state) => ({
-        channelsByServer: { ...state.channelsByServer, [serverId]: channels },
+        channelsByServer: { ...state.channelsByServer, [srvId]: normalized },
         isLoading: false,
       }));
     } catch (error) {
@@ -63,37 +70,52 @@ export const useChannelStore = create<ChannelState>((set) => ({
     }
   },
 
-  addChannel: (channel) =>
+  addChannel: (channel) => {
+    const norm = {
+      ...channel,
+      id: channel.id.toLowerCase(),
+      server_id: channel.server_id.toLowerCase(),
+    };
     set((state) => {
-      const list = state.channelsByServer[channel.server_id] || [];
+      const list = state.channelsByServer[norm.server_id] || [];
+      if (list.some((c) => c.id === norm.id)) return state;
       return {
         channelsByServer: {
           ...state.channelsByServer,
-          [channel.server_id]: [...list, channel],
+          [norm.server_id]: [...list, norm],
         },
       };
-    }),
+    });
+  },
 
-  updateChannel: (channel) =>
+  updateChannel: (channel) => {
+    const norm = {
+      ...channel,
+      id: channel.id.toLowerCase(),
+      server_id: channel.server_id.toLowerCase(),
+    };
     set((state) => {
-      const list = state.channelsByServer[channel.server_id] || [];
+      const list = state.channelsByServer[norm.server_id] || [];
       return {
         channelsByServer: {
           ...state.channelsByServer,
-          [channel.server_id]: list.map((c) => (c.id === channel.id ? channel : c)),
+          [norm.server_id]: list.map((c) => (c.id === norm.id ? norm : c)),
         },
       };
-    }),
+    });
+  },
 
-  removeChannel: (id) =>
+  removeChannel: (id) => {
+    const chId = id.toLowerCase();
     set((state) => {
       const next: Record<string, Channel[]> = {};
       for (const serverId of Object.keys(state.channelsByServer)) {
-        next[serverId] = state.channelsByServer[serverId].filter((c) => c.id !== id);
+        next[serverId] = state.channelsByServer[serverId].filter((c) => c.id !== chId);
       }
       return {
         channelsByServer: next,
-        activeChannelId: state.activeChannelId === id ? null : state.activeChannelId,
+        activeChannelId: state.activeChannelId === chId ? null : state.activeChannelId,
       };
-    }),
+    });
+  },
 }));