feat(frontend): split members sidebar into channel + guild sections

When a channel is selected the Members panel shows 'In channel — N'
(that channel's members) above 'Guild — N' (all guild members).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/pages/ChatPage.tsx

@@ -40,6 +40,7 @@ export default function ChatPage() {
   const { session, logout, ensureFreshToken, refreshGuilds, updateName } = useAuth()
   const [selectedGuildId, setSelectedGuildId] = useState('')
   const [selectedChannelId, setSelectedChannelId] = useState('')
+  const [channelMemberIds, setChannelMemberIds] = useState<string[]>([])
   const [channels, setChannels] = useState<GuildChannel[]>([])
   const [guildDbId, setGuildDbId] = useState('')
   const [members, setMembers] = useState<MemberItem[]>([])
@@ -134,6 +135,20 @@ export default function ChatPage() {
     }
   }
 
+  async function loadChannelMembers() {
+    if (!guild || !guildToken || !selectedChannelId) {
+      setChannelMemberIds([])
+      return
+    }
+    try {
+      const res = await guildApi().get(`/channels/${selectedChannelId}/members`)
+      const list = Array.isArray(res.data) ? (res.data as Array<{ userId: string }>) : []
+      setChannelMemberIds(list.map((x) => x.userId))
+    } catch {
+      setChannelMemberIds([])
+    }
+  }
+
   async function pullMessages() {
     if (!selectedChannelId || !guild || !guildToken) return
     setLoading(true)
@@ -242,6 +257,7 @@ export default function ChatPage() {
       await guildApi().post(`/channels/${c.id}/join`)
       await loadChannels()
       await loadMembers()
+      await loadChannelMembers()
     } catch {
       setError('Failed to join channel')
     }
@@ -257,6 +273,7 @@ export default function ChatPage() {
       }
       await loadChannels()
       await loadMembers()
+      await loadChannelMembers()
     } catch {
       setError('Failed to leave channel')
     }
@@ -290,6 +307,7 @@ export default function ChatPage() {
 
   useEffect(() => {
     void pullMessages()
+    void loadChannelMembers()
   }, [selectedChannelId])
 
   useEffect(() => {
@@ -318,6 +336,23 @@ export default function ChatPage() {
   const authorLabel = (uid?: string) =>
     uid ? (uid === session?.user.id ? session?.user.name || 'You' : nameById.get(uid) || uid.slice(0, 8)) : 'unknown'
 
+  const guildById = new Map(members.map((m) => [m.userId, m]))
+  const channelMembers = channelMemberIds.map(
+    (id) => guildById.get(id) ?? { userId: id, email: '', name: '', status: 'active' },
+  )
+  const renderMember = (m: { userId: string; name?: string; email?: string }) => {
+    const label = m.name || m.email || m.userId.slice(0, 8)
+    return (
+      <div key={m.userId} className="member-row">
+        <div className="avatar dot">{initials(label)}</div>
+        <div style={{ minWidth: 0 }}>
+          <span className="nm">{label}</span>
+          {m.userId === session?.user.id ? <span className="you">you</span> : null}
+        </div>
+      </div>
+    )
+  }
+
   return (
     <div className="dc-shell">
       <nav className="dc-rail">
@@ -479,18 +514,25 @@ export default function ChatPage() {
 
       {showMembers ? (
         <aside className="dc-members">
-          <div className="dc-section-label">
-            <span>Members — {members.length}</span>
-          </div>
-          {members.map((m) => (
-            <div key={m.userId} className="member-row">
-              <div className="avatar dot">{initials(m.name || m.email)}</div>
-              <div style={{ minWidth: 0 }}>
-                <span className="nm">{m.name || m.email}</span>
-                {m.userId === session?.user.id ? <span className="you">you</span> : null}
+          {currentChannel ? (
+            <>
+              <div className="dc-section-label">
+                <span>In channel — {channelMembers.length}</span>
               </div>
-            </div>
-          ))}
+              {channelMembers.map(renderMember)}
+              <div className="dc-section-label" style={{ marginTop: 14 }}>
+                <span>Guild — {members.length}</span>
+              </div>
+              {members.map(renderMember)}
+            </>
+          ) : (
+            <>
+              <div className="dc-section-label">
+                <span>Members — {members.length}</span>
+              </div>
+              {members.map(renderMember)}
+            </>
+          )}
         </aside>
       ) : null}