feat: add /readyz readiness probe with database check

Author: rubenhensen

src/routes/readyz/+server.ts

@@ -0,0 +1,19 @@
+import { json } from '@sveltejs/kit';
+import { sql } from 'drizzle-orm';
+import { db } from '$lib/server/db';
+import type { RequestHandler } from './$types';
+
+// Readiness probe: reports 200 only when the app can actually serve traffic
+// (i.e. the database is reachable). This is distinct from /health, which is a
+// pure liveness check. Orchestrator readiness gates should point here; the
+// container liveness HEALTHCHECK stays on /health.
+export const GET: RequestHandler = async () => {
+	try {
+		await db.execute(sql`select 1`);
+	} catch (err) {
+		console.error('[readyz] database check failed', err);
+		return json({ status: 'unavailable', checks: { database: 'down' } }, { status: 503 });
+	}
+
+	return json({ status: 'ready', checks: { database: 'ok' } });
+};

tests/e2e/readyz.e2e.ts

@@ -0,0 +1,9 @@
+import { test, expect } from '@playwright/test';
+
+test('readiness endpoint reports ready when the database is reachable', async ({ request }) => {
+	const response = await request.get('/readyz');
+	expect(response.status()).toBe(200);
+	const body = await response.json();
+	expect(body.status).toBe('ready');
+	expect(body.checks.database).toBe('ok');
+});