Fix: failing p3 test for SDK/HTTP APIs (#13062)

### What problem does this PR solve?

Adjust highlight parsing, add row-count SQL override, tweak retrieval
thresholding, and update tests with engine-aware skips/utilities.

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

test/testcases/utils/engine_utils.py

@@ -0,0 +1,47 @@
+#
+#  Copyright 2025 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+import os
+import requests
+
+_DOC_ENGINE_CACHE = None
+
+
+def get_doc_engine(rag=None) -> str:
+    """Return lower-cased doc_engine from env, or from /system/status if env is unset."""
+    global _DOC_ENGINE_CACHE
+    env = (os.getenv("DOC_ENGINE") or "").strip().lower()
+    if env:
+        _DOC_ENGINE_CACHE = env
+        return env
+    if _DOC_ENGINE_CACHE:
+        return _DOC_ENGINE_CACHE
+    if rag is None:
+        return ""
+    try:
+        api_url = getattr(rag, "api_url", "")
+        if "/api/" in api_url:
+            base_url, version = api_url.rsplit("/api/", 1)
+            status_url = f"{base_url}/{version}/system/status"
+        else:
+            status_url = f"{api_url}/system/status"
+        headers = getattr(rag, "authorization_header", {})
+        res = requests.get(status_url, headers=headers).json()
+        engine = str(res.get("data", {}).get("doc_engine", {}).get("type", "")).lower()
+        if engine:
+            _DOC_ENGINE_CACHE = engine
+        return engine
+    except Exception:
+        return ""