feat(admin): show each domain's most recent client IP

Adds lastClientIP to every domain row on the traffic page so operators
can see at a glance who last touched a domain. Under a client filter the
column shows the filter itself; otherwise it reports the client with the
most recent activity on the domain (approximation for source-filtered
views, since the per-client map has no source dimension).

internal/admin/stats.go

@@ -71,13 +71,16 @@ func (s Source) valid() bool {
 }
 
 // DomainStat aggregates traffic for a single domain. Conns counts both proxy
-// connections and DNS queries involving the domain.
+// connections and DNS queries involving the domain. LastClientIP is the most
+// recent client IP for the displayed view: the filtered client itself when a
+// client filter is active, otherwise the latest client across all sources.
 type DomainStat struct {
-	Domain    string    `json:"domain"`
-	Conns     uint64    `json:"conns"`
-	BytesUp   uint64    `json:"bytesUp"`
-	BytesDown uint64    `json:"bytesDown"`
-	LastSeen  time.Time `json:"lastSeen"`
+	Domain       string    `json:"domain"`
+	Conns        uint64    `json:"conns"`
+	BytesUp      uint64    `json:"bytesUp"`
+	BytesDown    uint64    `json:"bytesDown"`
+	LastSeen     time.Time `json:"lastSeen"`
+	LastClientIP string    `json:"lastClientIP"`
 }
 
 // TrafficSnapshot is an immutable point-in-time view of traffic stats.
@@ -400,6 +403,17 @@ func (s *Stats) Snapshot(sort DomainSort, source Source, client string) TrafficS
 			ds.BytesUp = dc.bytesUp
 			ds.BytesDown = dc.bytesDown
 			ds.LastSeen = dc.lastSeen
+			ds.LastClientIP = client
+		} else {
+			// Most recent client across all sources for the domain; the
+			// per-client map has no source dimension, so this is the best
+			// approximation for a source-filtered view.
+			var latest time.Time
+			for ip, c := range d.byClient {
+				if c.lastSeen.After(latest) {
+					latest, ds.LastClientIP = c.lastSeen, ip
+				}
+			}
 		}
 		snap.Domains = append(snap.Domains, ds)
 	}

internal/admin/stats_test.go

@@ -473,6 +473,33 @@ func TestStatsSnapshotClientFilter(t *testing.T) {
 	}
 }
 
+func TestStatsSnapshotLastClientIP(t *testing.T) {
+	s := newTestStats(t)
+	now := time.Now()
+
+	s.mu.Lock()
+	s.domains["a.example"] = &domainStat{
+		lastSeen: now,
+		byClient: map[string]*clientStat{
+			"192.168.1.10": {conns: 1, bytesUp: 100, bytesDown: 100, lastSeen: now.Add(-2 * time.Minute)},
+			"192.168.1.20": {conns: 1, bytesUp: 100, bytesDown: 100, lastSeen: now.Add(-1 * time.Minute)},
+		},
+	}
+	s.mu.Unlock()
+
+	// unfiltered: the client with the most recent activity wins
+	view := s.Snapshot(DomainSortBytes, SourceAll, "")
+	if len(view.Domains) != 1 || view.Domains[0].LastClientIP != "192.168.1.20" {
+		t.Fatalf("expected .20 as last client, got %+v", view.Domains)
+	}
+
+	// client-filtered: the filter itself is the last client of the view
+	filtered := s.Snapshot(DomainSortBytes, SourceAll, "192.168.1.10")
+	if len(filtered.Domains) != 1 || filtered.Domains[0].LastClientIP != "192.168.1.10" {
+		t.Fatalf("expected filter client as last client, got %+v", filtered.Domains)
+	}
+}
+
 func TestStatsSnapshotClientsAggregate(t *testing.T) {
 	s := newTestStats(t)
 	now := time.Now()

web/dist/index.html

@@ -5,7 +5,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <meta name="color-scheme" content="light" />
     <title>Sower Admin</title>
-    <script type="module" crossorigin src="/assets/index-CCzmNAbo.js"></script>
+    <script type="module" crossorigin src="/assets/index-5cU5DjAW.js"></script>
     <link rel="stylesheet" crossorigin href="/assets/index-C8oAZ1sn.css">
   </head>
   <body>

web/src/lib/api.ts

@@ -17,6 +17,7 @@ export interface DomainStat {
 	bytesUp: number;
 	bytesDown: number;
 	lastSeen: string;
+	lastClientIP: string;
 }
 
 export interface ClientStat {

web/src/views/Traffic.svelte

@@ -144,13 +144,14 @@
             <Table.TableHead class={headCell + ' text-right'}>Down</Table.TableHead>
             <Table.TableHead class={headCell + ' text-right'}>Total</Table.TableHead>
           {/if}
+          <Table.TableHead class={headCell}>Client</Table.TableHead>
           <Table.TableHead class={headCell + ' text-right'}>Last seen</Table.TableHead>
         </Table.TableRow>
       </Table.TableHeader>
       <Table.TableBody>
         {#if visibleDomains.length === 0}
           <Table.TableRow>
-            <Table.TableCell colspan={isDNSView ? 3 : 6} class="py-8 text-center text-sm text-muted-foreground">
+            <Table.TableCell colspan={isDNSView ? 4 : 7} class="py-8 text-center text-sm text-muted-foreground">
               没有匹配“{filter}”的域名。
             </Table.TableCell>
           </Table.TableRow>
@@ -166,6 +167,9 @@
                 {formatBytes(d.bytesUp + d.bytesDown)}
               </Table.TableCell>
             {/if}
+            <Table.TableCell class="max-w-[9rem] truncate font-mono text-xs text-muted-foreground" title={d.lastClientIP}>
+              {d.lastClientIP || '—'}
+            </Table.TableCell>
             <Table.TableCell class="text-right text-muted-foreground tabular-nums">
               {formatTime(d.lastSeen)}
             </Table.TableCell>