diff --git a/src/typeagent/storage/sqlite/related_terms_index.py b/src/typeagent/storage/sqlite/related_terms_index.py
index d918fd6c..81550457 100644
--- a/src/typeagent/storage/sqlite/related_terms_index.py
+++ b/src/typeagent/storage/sqlite/related_terms_index.py
@@ -159,6 +159,7 @@ def __init__(self, db: sqlite3.Connection, settings: TextEmbeddingIndexSettings)
             for term, blob in rows:
                 assert blob is not None, term
                 self._terms_list.append(term)
+                self._added_terms.add(term)
                 embeddings.append(deserialize_embedding(blob))
             # Bulk add embeddings to VectorBase
             self._vector_base.add_embeddings(None, np.array(embeddings))
@@ -202,6 +203,9 @@ async def remove_term(self, term: str) -> None:
     async def clear(self) -> None:
         cursor = self.db.cursor()
         cursor.execute("DELETE FROM RelatedTermsFuzzy")
+        self._vector_base.clear()
+        self._terms_list.clear()
+        self._added_terms.clear()
 
     async def size(self) -> int:
         return self._size()
@@ -292,6 +296,7 @@ async def deserialize(self, data: TextEmbeddingIndexData) -> None:
         cursor.execute("DELETE FROM RelatedTermsFuzzy")
 
         # Clear local mappings
+        self._vector_base.clear()
         self._terms_list.clear()
         self._added_terms.clear()
 
diff --git a/tests/test_sqlite_indexes.py b/tests/test_sqlite_indexes.py
index c7c9af01..30875859 100644
--- a/tests/test_sqlite_indexes.py
+++ b/tests/test_sqlite_indexes.py
@@ -442,6 +442,65 @@ async def test_fuzzy_serialize(
         embeddings = data["embeddings"]
         assert embeddings is not None
 
+    @pytest.mark.asyncio
+    async def test_fuzzy_clear_resets_lookup_state(
+        self,
+        sqlite_db: sqlite3.Connection,
+        embedding_settings: TextEmbeddingIndexSettings,
+    ):
+        """clear() forgets cleared terms, so re-adding them stores them again."""
+        index = SqliteRelatedTermsFuzzy(sqlite_db, embedding_settings)
+        await index.add_terms(["apple"])
+
+        await index.clear()
+        assert await index.lookup_term("apple", min_score=0.0) == []
+        assert index.serialize()["textItems"] == []
+
+        await index.add_terms(["apple"])
+        assert await index.get_terms() == ["apple"]
+        assert [t.text for t in await index.lookup_term("apple", min_score=0.0)] == [
+            "apple"
+        ]
+
+    @pytest.mark.asyncio
+    async def test_fuzzy_empty_deserialize_resets_lookup_state(
+        self,
+        sqlite_db: sqlite3.Connection,
+        embedding_settings: TextEmbeddingIndexSettings,
+    ):
+        """Terms added after deserializing empty data map to the right embeddings."""
+        index = SqliteRelatedTermsFuzzy(sqlite_db, embedding_settings)
+        await index.add_terms(["pear"])
+
+        await index.deserialize({"textItems": [], "embeddings": None})
+        await index.add_terms(["kiwi"])
+
+        results = await index.lookup_term("kiwi", max_hits=1, min_score=0.0)
+        assert [t.text for t in results] == ["kiwi"]
+        assert await index.get_terms() == ["kiwi"]
+
+    @pytest.mark.asyncio
+    async def test_fuzzy_reopen_does_not_duplicate_existing_terms(
+        self,
+        sqlite_db: sqlite3.Connection,
+        embedding_settings: TextEmbeddingIndexSettings,
+        temp_db_path: str,
+    ):
+        """Terms loaded from an existing database count as already added."""
+        index = SqliteRelatedTermsFuzzy(sqlite_db, embedding_settings)
+        await index.add_terms(["plum"])
+        sqlite_db.commit()
+
+        reopened_db = sqlite3.connect(temp_db_path)
+        try:
+            reopened = SqliteRelatedTermsFuzzy(reopened_db, embedding_settings)
+            await reopened.add_terms(["plum"])
+            results = await reopened.lookup_term("plum", min_score=0.0)
+            assert [t.text for t in results] == ["plum"]
+            assert reopened.serialize()["textItems"] == ["plum"]
+        finally:
+            reopened_db.close()
+
 
 class TestSqliteRelatedTermsIndex:
     """Test SqliteRelatedTermsIndex combined functionality."""