Improve application responsiveness and background processing

tests/unit/ui-server-clock.test.ts

@@ -67,6 +67,34 @@ async function setup() {
 }
 
 describe('Fleet report clock', () => {
+    it('accepts newer navigation snapshots while keeping stream evidence newer than the snapshot', async () => {
+        const { fleetServers, hydrateFleet } = await setup();
+        await vi.advanceTimersByTimeAsync(2000);
+        emit(epoch + 2000, [status(epoch + 2000, { players: 3 })]);
+        const integrations = { rcon: true, komodo: false, rconTimeoutMs: 3000, defaultRconHost: '' };
+        hydrateFleet({ serverNow: epoch + 1000, servers: [server(epoch + 1000), server(epoch, { name: 'two' })], operations: [], integrations });
+        expect(get(fleetServers)).toHaveLength(2);
+        expect(get(fleetServers)[0].last_players).toBe(3);
+        hydrateFleet({ serverNow: epoch, servers: [], operations: [], integrations });
+        expect(get(fleetServers)).toHaveLength(2);
+    });
+    it('merges partial events without dropping other servers or repainting unchanged elapsed ticks', async () => {
+        snapshot.servers = [server(), server(epoch, { name: 'two' })];
+        const { fleetServers, statusByServer } = await setup();
+        emit(epoch, [status(epoch), status(epoch, { server: 'two' })]);
+        await vi.advanceTimersByTimeAsync(1000);
+        source.dispatchEvent(new MessageEvent('server-status', { data: JSON.stringify({
+            delta: true, serverNow: epoch + 1000, entries: [status(epoch + 1000, { players: 2 })]
+        }) }));
+        expect(get(statusByServer).size).toBe(2);
+        expect(get(fleetServers).find(server => server.name === 't5_zombie_theater_1')?.last_players).toBe(2);
+        const changes = vi.fn();
+        const unsubscribe = fleetServers.subscribe(changes);
+        changes.mockClear();
+        await vi.advanceTimersByTimeAsync(5000);
+        expect(changes).not.toHaveBeenCalled();
+        unsubscribe();
+    });
     it('keeps persisted occupancy and match anchors through live reports before the next status poll', async () => {
         const at = (seconds: number) => new Date(epoch + seconds * 1000).toISOString();
         snapshot.servers = [server(epoch, { container_state: 'running', container_checked_at: at(0) })];