Fix control status: do not treat /health as fleet (missing positions).

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

control/backend/app/api/nodes.py

@@ -51,10 +51,6 @@ def _raise_node_error(code: int, data: Any) -> None:
     )
 
 
-def _health_looks_like_fleet(health: Any) -> bool:
-    return isinstance(health, dict) and "strategy" in health and "mode" in health
-
-
 async def _collect_one_status(
     node: dict[str, Any],
     *,
@@ -63,10 +59,10 @@ async def _collect_one_status(
     probe = await probe_health(node, timeout=timeout)
     item: dict[str, Any] = {**_public_node(node), **probe}
     if probe.get("online") and node.get("token_sealed"):
-        health = probe.get("health")
-        # probe_health 在 /health 失败时可能已用 fleet/status 回填到 health
-        if _health_looks_like_fleet(health):
-            code, data = 200, health
+        # /health 也有 mode+strategy，但不能当 fleet（无持仓详情）。
+        # 仅当 probe 已用 fleet 回退时复用，否则必须再拉 /api/fleet/status。
+        if probe.get("from_fleet") and isinstance(probe.get("health"), dict):
+            code, data = 200, probe["health"]
         else:
             code, data = await call_node(
                 node, "GET", "/api/fleet/status", timeout=timeout