diff --git a/src/clean_agent_preview.py b/src/clean_agent_preview.py
index 6d7b5e230..98ca99bd5 100644
--- a/src/clean_agent_preview.py
+++ b/src/clean_agent_preview.py
@@ -3459,9 +3459,13 @@ def preserve_requested_web_recency(name, args, *, user_text='', prior_search_int
     user = str(user_text or '')
     query = str(args.get('query') or '').strip()
     if not query:
-        query = re.sub(r'\s+', ' ', user).strip().rstrip('?.!')
         if prior_search_intents:
-            query += ' corroborating analysis authoritative sources'
+            raise ValueError(
+                'web_search requires an explicit query for a follow-up. Supply a '
+                'specific missing fact, entity, or corroboration question based on '
+                'the evidence already returned; do not repeat the original query.'
+            )
+        query = re.sub(r'\s+', ' ', user).strip().rstrip('?.!')
         if not query:
             return args
     normalized = dict(args)
diff --git a/tests/test_clean_agent_preview.py b/tests/test_clean_agent_preview.py
index 28c36a7ed..13a1034ff 100644
--- a/tests/test_clean_agent_preview.py
+++ b/tests/test_clean_agent_preview.py
@@ -2017,17 +2017,14 @@ def test_current_search_arguments_repair_stale_year_and_add_freshness():
     assert args['time_filter'] == 'day'
 
 
-def test_missing_refinement_query_is_grounded_in_user_request():
-    args = preserve_requested_web_recency(
-        'web_search',
-        {'time_filter': 'day'},
-        user_text='What are the latest important AI developments?',
-        prior_search_intents=['important ai developments'],
-    )
-
-    assert 'AI developments' in args['query']
-    assert 'corroborating analysis' in args['query']
-    assert args['time_filter'] == 'day'
+@pytest.mark.parametrize('missing_query', [{}, {'query': ''}, {'query': '  ', 'time_filter': 'day'}])
+def test_missing_refinement_query_is_not_fabricated(missing_query):
+    with pytest.raises(ValueError, match='explicit query for a follow-up'):
+        preserve_requested_web_recency(
+            'web_search', missing_query,
+            user_text='serch latest ai news pls',
+            prior_search_intents=['ai news'],
+        )
 
 
 def test_official_manual_does_not_invent_pdf_requirement():