feat(gateway): add sender presence tracking

src/gateway/handlers/handlers.test.ts

@@ -64,6 +64,57 @@ describe('system handlers', () => {
       { name: 'cron', type: 'automation', status: 'configured', description: 'Cron scheduler', itemCount: 2 },
     ]);
   });
+
+  it('system.presence returns empty result when getPresence is not provided', async () => {
+    const req: GatewayRequest = { id: 4, method: 'system.presence' };
+    const result = await handlers['system.presence'](req) as GatewayResponse;
+    expect(result.id).toBe(4);
+    expect((result.result as any).presence).toEqual([]);
+    expect((result.result as any).summary).toEqual({ total: 0, online: 0, offline: 0 });
+  });
+
+  it('system.presence returns filtered presence entries', async () => {
+    const handlers = createSystemHandlers({
+      ...deps,
+      getPresence: ({ channel, status, limit } = {}) => {
+        const all = [
+          {
+            channel: 'telegram',
+            senderId: '1',
+            senderName: 'alice',
+            firstSeenAt: 1000,
+            lastSeenAt: 2000,
+            messageCount: 3,
+            status: 'online' as const,
+          },
+          {
+            channel: 'discord',
+            senderId: '2',
+            senderName: 'bob',
+            firstSeenAt: 1000,
+            lastSeenAt: 1500,
+            messageCount: 1,
+            status: 'offline' as const,
+          },
+        ];
+
+        return all
+          .filter((entry) => !channel || entry.channel === channel)
+          .filter((entry) => !status || entry.status === status)
+          .slice(0, limit ?? 100);
+      },
+    });
+
+    const req: GatewayRequest = {
+      id: 5,
+      method: 'system.presence',
+      params: { channel: 'telegram', status: 'online', limit: 10 },
+    };
+    const result = await handlers['system.presence'](req) as GatewayResponse;
+    expect((result.result as any).presence).toHaveLength(1);
+    expect((result.result as any).presence[0].channel).toBe('telegram');
+    expect((result.result as any).summary).toEqual({ total: 1, online: 1, offline: 0 });
+  });
 });
 
 describe('system.tokenUsage handler', () => {