push updated state to clients over SSE (ISS-129)

e2e/events.spec.ts

@@ -0,0 +1,59 @@
+import { test, expect } from '@playwright/test';
+
+// ISS-129 (v0.57.0): /api/events pushes full state snapshots over SSE — the current snapshot on
+// connect, then one after every sim tick (~1 s; the background tick runs even while idle since
+// v0.56.0, so no scale hook is needed). Reached via the same base URL as playwright.config.ts
+// (E2E_BASE_URL, defaulting to the live instance) — node-side fetch, no browser involved.
+const baseUrl = process.env.E2E_BASE_URL ?? 'https://flight.dev.kkhost.pl';
+
+interface StateBody {
+  simState: { clockMs: number };
+}
+
+test('GET /api/events streams state snapshots over SSE', async () => {
+  const res = await fetch(`${baseUrl}/api/events`, { headers: { Accept: 'text/event-stream' } });
+  expect(res.status).toBe(200);
+  expect(res.headers.get('content-type')).toContain('text/event-stream');
+  expect(res.body).not.toBeNull();
+
+  const reader = res.body!.getReader();
+  const decoder = new TextDecoder();
+  let buffer = '';
+  const clocks: number[] = []; // simState.clockMs of each parsed snapshot event
+
+  try {
+    // Collect two snapshot events: the initial one, then at least one pushed by a background tick.
+    const deadline = Date.now() + 15_000;
+    while (clocks.length < 2 && Date.now() < deadline) {
+      let chunk: ReadableStreamReadResult<Uint8Array>;
+      try {
+        chunk = await Promise.race([
+          reader.read(),
+          new Promise<never>((_, reject) =>
+            setTimeout(() => reject(new Error('SSE stream stalled')), Math.max(1, deadline - Date.now())),
+          ),
+        ]);
+      } catch {
+        break; // stalled or past the deadline — let the length assertion report it
+      }
+      if (chunk.done) break; // stream ended early — same
+      buffer += decoder.decode(chunk.value, { stream: true });
+      let sep: number;
+      while ((sep = buffer.indexOf('\n\n')) >= 0) {
+        const frame = buffer.slice(0, sep);
+        buffer = buffer.slice(sep + 2);
+        for (const line of frame.split('\n')) {
+          if (!line.startsWith('data: ')) continue; // heartbeats are comment lines (" : ping")
+          const snap = JSON.parse(line.slice('data: '.length)) as StateBody;
+          clocks.push(snap.simState.clockMs);
+        }
+      }
+    }
+  } finally {
+    await reader.cancel(); // close the stream → server unsubscribes
+  }
+
+  // The initial snapshot arrives on connect; the second comes from a background tick within ~1 s.
+  expect(clocks.length).toBeGreaterThanOrEqual(2);
+  expect(clocks[1]).toBeGreaterThan(clocks[0]); // clock advanced between pushes — real updates, not replays
+});