Add realtime watcher+SSE transport with tests and lock-retry read path

tests/api/events-route.test.ts

@@ -0,0 +1,34 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+
+import { GET as eventsGet } from '../../src/app/api/events/route';
+import { getIssuesWatchManager } from '../../src/lib/watcher';
+
+test.after(async () => {
+  await getIssuesWatchManager().stopAll();
+});
+
+test('events route returns SSE response with expected headers', async () => {
+  const response = await eventsGet(new Request('http://localhost/api/events?projectRoot=C:/Repo/Test'));
+
+  assert.equal(response.status, 200);
+  assert.equal(response.headers.get('content-type')?.includes('text/event-stream'), true);
+  assert.equal(response.headers.get('cache-control')?.includes('no-cache'), true);
+
+  const reader = response.body?.getReader();
+  if (reader) {
+    await reader.cancel();
+  }
+});
+
+test('events route emits initial connected frame', async () => {
+  const response = await eventsGet(new Request('http://localhost/api/events?projectRoot=C:/Repo/Test'));
+  const reader = response.body?.getReader();
+  assert.equal(Boolean(reader), true);
+
+  const first = await reader!.read();
+  const chunk = new TextDecoder().decode(first.value);
+  assert.equal(chunk.includes(': connected'), true);
+
+  await reader!.cancel();
+});