feat: instance embed SSE live push and lighter tab revisit

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_instance_live_push_lib.py

@@ -0,0 +1,20 @@
+"""instance_live_push_lib 单元测试。"""
+from __future__ import annotations
+
+import json
+
+from lib.instance.instance_live_push_lib import InstanceLivePush
+
+
+def test_tick_increments_version_and_connect_event() -> None:
+    push = InstanceLivePush()
+    v1 = push.tick("test")
+    v2 = push.tick("test")
+    assert v1 == 1
+    assert v2 == 2
+    gen = push.iter_sse()
+    first = next(gen)
+    assert first.startswith("event: live")
+    data = json.loads(first.split("data: ", 1)[1].strip())
+    assert data["live_version"] == 2
+    push.stop()