Improve application responsiveness and background processing

tests/unit/report-workers.test.ts

@@ -0,0 +1,27 @@
+import { afterEach, beforeEach, expect, it, vi } from 'vitest';
+import { newFixture, type Fixture } from '../helpers/fixture.js';
+import { parseMetricsQuery } from '../../src/lib/metrics.js';
+
+let fixture: Fixture;
+beforeEach(async () => { vi.resetModules(); fixture = await newFixture([]); });
+afterEach(async () => { vi.restoreAllMocks(); await fixture.cleanup(); });
+
+it('runs reports off the request thread and invalidates cached history after writes', async () => {
+    const { db } = await import('../../src/lib/server/db/index.js');
+    const { recordMetrics, readMetrics } = await import('../../src/lib/server/fleet/metrics.js');
+    const { metricsReport } = await import('../../src/lib/server/reports/index.js');
+    const now = Date.UTC(2026, 9, 4, 12);
+    vi.spyOn(Date, 'now').mockReturnValue(now);
+    const sample = { server: 'one', game: 't5', map: 'Moon', players: 1, capacity: 4 };
+    recordMetrics([sample], now - 30_000);
+    const query = parseMetricsQuery(new URLSearchParams('days=1'));
+    const first = metricsReport(query);
+    const winner = await Promise.race([first.then(() => 'report'), new Promise<string>(resolve => setTimeout(() => resolve('timer'), 0))]);
+    expect(winner).toBe('timer');
+    expect(await first).toEqual(readMetrics(query, now));
+    expect(await metricsReport(query)).toEqual(await first);
+    db().prepare('UPDATE metric_samples SET players=3').run();
+    const changed = await metricsReport(query);
+    expect(changed).toEqual(readMetrics(query, now));
+    expect(changed.summary.playerHours).toBeCloseTo((await first).summary.playerHours * 3);
+});