fix: aggregate presence samples every five minutes with seven-day retention

tests/analytics-sampling.test.ts

@@ -0,0 +1,36 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import type { AnalyticsStore } from '../src/server/analytics-store.js';
+import { Analytics } from '../src/server/analytics.js';
+import { ManualClock } from './helpers.js';
+
+test('ten-second observations preserve a brief peak in one five-minute write and flush the final partial interval', async () => {
+  const clock = new ManualClock();
+  const writes: Parameters<AnalyticsStore['sample']>[] = [];
+  const store = {
+    sample: async (...args: Parameters<AnalyticsStore['sample']>) => { writes.push(args); },
+    cleanup: async () => {},
+  } as unknown as AnalyticsStore;
+  const analytics = new Analytics(store, clock);
+  try {
+    analytics.states.set('visitor', { visible: true, lastAt: clock.now(), metadata: { device: 'pc', browser: 'Other', source: 'direct_or_unknown', invitation: false } });
+    await clock.advance(290000);
+    assert.equal(writes.length, 0);
+    assert.equal(analytics.live().active, 0);
+    await clock.advance(10000);
+    assert.equal(writes.length, 1);
+    assert.equal(writes[0][1].active, 1);
+    assert.equal(writes[0][4], 30);
+    await clock.advance(300000);
+    assert.equal(writes.length, 2);
+    assert.equal(writes[1][1].active, 0);
+    assert.equal(writes[1][4], 30);
+    await clock.advance(20000);
+    assert.equal(writes.length, 2);
+    await analytics.close();
+    assert.equal(writes.length, 3);
+    assert.equal(writes[2][4], 2);
+    await analytics.close();
+    assert.equal(writes.length, 3);
+  } finally { await analytics.close(); }
+});