feat(gateway): add system.sessionAnalytics usage snapshot RPC

src/gateway/handlers/handlers.test.ts

@@ -327,6 +327,65 @@ describe('system.tokenUsage handler', () => {
   });
 });
 
+describe('system.sessionAnalytics handler', () => {
+  it('returns empty analytics when callback is not provided', async () => {
+    const handlers = createSystemHandlers({
+      startTime: Date.now(),
+      version: '0.1.0',
+      getSessionCount: () => 0,
+      getToolCount: () => 0,
+      getConnectionCount: () => 0,
+    });
+
+    const req: GatewayRequest = { id: 3, method: 'system.sessionAnalytics' };
+    const result = await handlers['system.sessionAnalytics'](req) as GatewayResponse;
+
+    expect(result.id).toBe(3);
+    const r = result.result as {
+      daily: unknown[];
+      topSessions: unknown[];
+      averageMessagesPerSession: number;
+      totalSessions: number;
+      totalMessages: number;
+    };
+    expect(r.daily).toEqual([]);
+    expect(r.topSessions).toEqual([]);
+    expect(r.averageMessagesPerSession).toBe(0);
+    expect(r.totalSessions).toBe(0);
+    expect(r.totalMessages).toBe(0);
+  });
+
+  it('returns analytics from callback', async () => {
+    const getSessionAnalytics = vi.fn(() => ({
+      daily: [{ day: '2026-02-16', sessions: 2, messages: 8 }],
+      topSessions: [{ sessionId: 'telegram:1', messages: 5, lastActivity: 1708080000 }],
+      averageMessagesPerSession: 4,
+      totalSessions: 2,
+      totalMessages: 8,
+    }));
+
+    const handlers = createSystemHandlers({
+      startTime: Date.now(),
+      version: '0.1.0',
+      getSessionCount: () => 2,
+      getToolCount: () => 0,
+      getConnectionCount: () => 1,
+      getSessionAnalytics,
+    });
+
+    const req: GatewayRequest = {
+      id: 4,
+      method: 'system.sessionAnalytics',
+      params: { days: 7, topLimit: 5 },
+    };
+    const result = await handlers['system.sessionAnalytics'](req) as GatewayResponse;
+
+    expect(getSessionAnalytics).toHaveBeenCalledWith({ days: 7, topLimit: 5 });
+    expect(getPath(result.result, 'totalSessions')).toBe(2);
+    expect(getPath(result.result, 'daily')).toEqual([{ day: '2026-02-16', sessions: 2, messages: 8 }]);
+  });
+});
+
 describe('session handlers', () => {
   const mockHistory = [
     { role: 'user' as const, content: 'hello' },