中控总览改为后台常驻并行拉取热缓存，浏览器只读缓存并经 SSE 更新。

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

app.py

@@ -3,8 +3,6 @@ from __future__ import annotations
 
 import os
 import sys
-import threading
-import time
 from functools import wraps
 from pathlib import Path
 
@@ -19,6 +17,7 @@ from flask import (
     request,
     send_file,
     session,
+    stream_with_context,
     url_for,
 )
 
@@ -62,6 +61,7 @@ from lib.instances_lib import (
     list_instances,
     update_instance,
 )
+from lib.overview_cache_lib import overview_store
 from lib.sso_lib import build_embed_open_url
 from lib.stats_agg_lib import build_stats_curve, build_stats_summary, normalize_window
 from lib.wechat_lib import (
@@ -486,38 +486,54 @@ def desk():
     )
 
 
+def _on_overview_pulled(rows: list) -> None:
+    """常驻 pull 回调:健康巡检 + 余额采样(与浏览器是否打开无关)."""
+    try:
+        inspect_overview_rows(rows)
+    except Exception:
+        pass
+    try:
+        record_cash_samples_from_overview(rows)
+    except Exception:
+        pass
+
+
 @app.route("/api/overview")
 @login_required
 def api_overview():
-    rows = pull_all_enabled()
-    return jsonify({"ok": True, "instances": rows})
+    """只读热缓存;不在请求内现场拉实例(后台常驻并行 pull)."""
+    force = (request.args.get("force") or "").strip().lower() in ("1", "true", "yes")
+    if force:
+        overview_store.request_refresh()
+    return jsonify(overview_store.snapshot_dict())
 
 
-def _health_pull_interval_sec() -> float:
-    try:
-        return max(5.0, float(os.getenv("HUB_PULL_INTERVAL_SEC") or 10))
-    except (TypeError, ValueError):
-        return 10.0
+@app.route("/api/overview/refresh", methods=["POST"])
+@login_required
+def api_overview_refresh():
+    overview_store.request_refresh()
+    return jsonify({"ok": True, "msg": "已触发后台刷新"})
 
 
-def _health_watch_loop() -> None:
-    """后台巡检:即使无人打开总览也会告警;并采样余额曲线."""
-    while True:
-        try:
-            rows = pull_all_enabled()
-            inspect_overview_rows(rows)
-            record_cash_samples_from_overview(rows)
-        except Exception:
-            pass
-        time.sleep(_health_pull_interval_sec())
+@app.route("/api/overview/stream")
+@login_required
+def api_overview_stream():
+    return Response(
+        stream_with_context(overview_store.iter_sse()),
+        mimetype="text/event-stream",
+        headers={
+            "Cache-Control": "no-cache",
+            "Connection": "keep-alive",
+            "X-Accel-Buffering": "no",
+        },
+    )
 
 
-def start_health_watch() -> None:
-    t = threading.Thread(target=_health_watch_loop, name="hub-health-watch", daemon=True)
-    t.start()
+def start_overview_cache() -> None:
+    overview_store.start(pull_all_enabled, on_pull=_on_overview_pulled)
 
 
-start_health_watch()
+start_overview_cache()
 
 try:
     start_hub_backup_scheduler(