diff --git a/services/search/providers.py b/services/search/providers.py
index 60daa4844..a812b79c4 100644
--- a/services/search/providers.py
+++ b/services/search/providers.py
@@ -305,23 +305,28 @@ def searxng_search_api(query: str, count: Optional[int] = None, categories: str
         return parsed
     except Exception as e:
         logger.warning(f"SearXNG JSON API search failed: {e}")
-        html_results = searxng_search(query, max_results=count)
+        html_results = searxng_search(query, max_results=count, search_params=active_params)
         if html_results:
             logger.info(f"SearXNG HTML fallback returned {len(html_results)} results for: {query}")
         return html_results
 
 
-def searxng_search(query, max_results=10):
+def searxng_search(query, max_results=10, *, search_params=None):
     """Search using SearXNG instance - parsing HTML."""
     instance = _get_search_instance()
     api_key = ""
     req_headers = {"User-Agent": WEB_FETCH_USER_AGENT}
     if api_key:
         req_headers["Authorization"] = f"Bearer {api_key}"
+    # Transport fallback must not change the user's retrieval constraints.
+    # In particular omit only JSON formatting, not publication time/category.
+    params = {key: value for key, value in (search_params or {}).items()
+              if key in {'categories', 'engines', 'language', 'time_range'}}
+    params.update({'q': query, 'safesearch': _safesearch_for('searxng')})
     try:
         response = httpx.get(
             f"{instance}/search",
-            params={"q": query, "safesearch": _safesearch_for("searxng")},
+            params=params,
             headers=req_headers,
             timeout=10,
         )
diff --git a/tests/test_service_search_provider_guards.py b/tests/test_service_search_provider_guards.py
index ca7973499..1277370a9 100644
--- a/tests/test_service_search_provider_guards.py
+++ b/tests/test_service_search_provider_guards.py
@@ -11,6 +11,27 @@ from services.search import core
 from services.search import providers
 
 
+def test_html_transport_fallback_preserves_query_constraints(monkeypatch):
+    seen = []
+    class Response:
+        is_success = True
+        text = '<article class="result"><h3><a href="https://example.org/report">Report</a></h3><p class="content">Evidence</p></article>'
+    def get(*args, **kwargs):
+        seen.append(dict(kwargs['params']))
+        if len(seen) == 1:
+            raise ValueError('JSON transport unavailable')
+        return Response()
+    monkeypatch.setattr(providers, '_get_search_instance', lambda: 'http://searx.test')
+    monkeypatch.setattr(providers, '_get_search_settings', lambda: {'search_safesearch': 'strict'})
+    monkeypatch.setattr(providers, '_get_provider_key', lambda name: '')
+    monkeypatch.setattr(providers.httpx, 'get', get)
+    results = providers.searxng_search_api('AI news site:example.org', time_filter='week', engines='test-engine')
+    assert len(results) == 1
+    assert len(seen) == 2
+    assert seen[1] == {k: v for k, v in seen[0].items() if k != 'format'}
+    assert seen[1]['time_range'] == 'week'
+
+
 @pytest.mark.parametrize('query,category', [
     ('AI developments this week', 'news'),
     ('recent developments in battery manufacturing', 'news'),