first pass analytics redo

tests/stats-digest.test.ts

@@ -0,0 +1,77 @@
+import { describe, test, expect } from 'bun:test';
+import { composeDigest } from '$lib/server/stats/digest';
+import type { SnapshotPayload } from '$lib/types/stats';
+
+const payload: SnapshotPayload = {
+	asOfDate: '2026-09-14',
+	activity: {
+		dau: 102,
+		wau: 363,
+		mau: 852,
+		core: 61,
+		returningShare: 38,
+		newPlayers: 20,
+		resurrected: 4,
+		churned: 25,
+		netGrowth: -1,
+		corePrevious: 60,
+		previous: null
+	},
+	dailySeries: [],
+	kpis: {
+		d1Return: 12.2,
+		return7: 18,
+		overallReturnRate: 22.8,
+		completionRate: null,
+		shareRate: null,
+		firstTryRate: 33.7,
+		avgGuesses: 4.1
+	},
+	retention: { cohorts: [], curves: { d1: [], d7: [], d30: [] }, timeToSecondPlay: [], segmentMix: [] },
+	verseMix: {
+		coverage: [],
+		testamentMix: [],
+		entropy: [],
+		repeatIntervals: [],
+		firstTryByBook: [],
+		retentionByBook: [],
+		retentionByGuessBucket: [],
+		achievability: []
+	},
+	habit: { streakSurvival: [], streakLengths: [], calendar: [], weekdayHour: [] },
+	growth: { lifecycleFunnel: [], signups: [] },
+	totals: { completions: 31775, players: 6589, yesterdayCompletions: 102, yesterdayAvgGuesses: 4.1 },
+	signals: [
+		{
+			id: 'd1_return',
+			severity: 'bad',
+			title: 'D1 return',
+			detail: 'D1 return is 12.2%, below the 20% target.',
+			action: 'Test a "come back tomorrow" prompt.'
+		}
+	],
+	meta: { hasStartedData: false, hasShareData: false, firstEventDate: null }
+};
+
+describe('composeDigest', () => {
+	test('includes the core numbers in plain language', () => {
+		const message = composeDigest(payload);
+		expect(message).toContain('2026-09-14');
+		expect(message).toContain('363');
+		expect(message).toContain('12.2');
+		expect(message).toContain('Top signal: D1 return');
+		expect(message).toContain('/admin/stats?date=2026-09-14');
+	});
+
+	test('is at most a handful of lines', () => {
+		expect(composeDigest(payload).split('\n').length).toBeLessThanOrEqual(6);
+	});
+
+	test('shows an em-dash for missing metrics', () => {
+		const message = composeDigest({
+			...payload,
+			kpis: { ...payload.kpis, d1Return: null, return7: null }
+		});
+		expect(message).toContain('D1 return —%');
+	});
+});