diff --git a/backend/packages/harness/deerflow/agents/memory/backends/deermem/deermem/core/storage.py b/backend/packages/harness/deerflow/agents/memory/backends/deermem/deermem/core/storage.py
index 9f38aef87c..bdf2c9cc27 100644
--- a/backend/packages/harness/deerflow/agents/memory/backends/deermem/deermem/core/storage.py
+++ b/backend/packages/harness/deerflow/agents/memory/backends/deermem/deermem/core/storage.py
@@ -1974,8 +1974,11 @@ class FileMemoryStorage(MemoryStorage):
             return []
         results: list[dict[str, Any]] = []
         for scope in scopes:
-            facts = self.list_facts(filters=filters, **self._scope_kwargs(scope))
-            for fact in facts:
+            # The ranking covers the whole scope, so read the complete scope
+            # rather than a list_facts page.
+            for fact in self.load(**self._scope_kwargs(scope)).get("facts", []):
+                if filters and not all(key in fact and fact.get(key) == value for key, value in filters.items()):
+                    continue
                 content = fact.get("content")
                 if isinstance(content, str) and query_lower in content.lower():
                     # 0.0 is a persisted confidence _normalize_fact accepts; only unset/null defaults.
diff --git a/backend/tests/test_memory_retrieval_adapter.py b/backend/tests/test_memory_retrieval_adapter.py
index b47cb0dea9..ef8cea92bf 100644
--- a/backend/tests/test_memory_retrieval_adapter.py
+++ b/backend/tests/test_memory_retrieval_adapter.py
@@ -318,3 +318,29 @@ def test_substring_fallback_keeps_zero_confidence_weight(tmp_path: Path) -> None
         assert scores == {"zero": 0.0, "half": 0.5}
     finally:
         storage.close()
+
+
+def test_substring_fallback_searches_every_fact_of_a_large_scope(tmp_path: Path) -> None:
+    """The fallback must read the whole scope, not the first page of 100 facts.
+
+    With 150 facts (max_facts allows up to 500) and no retrieval adapter, a
+    top_k of 200 returned only the first 100 matches: the fallback iterated
+    list_facts' default page instead of the complete scope, so facts past
+    the page silently vanished from search results.
+    """
+    storage = FileMemoryStorage(DeerMemConfig(storage_path=str(tmp_path), max_facts=200))
+    scope = {"userId": "alice", "agentName": "agent-a"}
+    try:
+        facts = [_fact(f"fact-{index:03d}", f"zeta common memory number {index:03d}") for index in range(1, 151)]
+        storage.apply_changes({"upserts": facts}, user_id="alice", agent_name="agent-a")
+
+        results = storage.search_facts("zeta", scopes=[scope], top_k=200)
+
+        assert len(results) == 150
+        returned_ids = {item["fact"]["id"] for item in results}
+        # fact-001..fact-100 sat inside the old first page too (``matched[0:100]``
+        # in insertion order), so fact-101 and fact-150 are the ids only a
+        # complete-scope read can return.
+        assert {"fact-101", "fact-150"} <= returned_ids
+    finally:
+        storage.close()