From de568231a7153403a874c9623cbd4182d184ab75 Mon Sep 17 00:00:00 2001
From: Timelovers <46080686+Timelovers@users.noreply.github.com>
Date: Sat, 25 Jul 2026 22:20:47 +0800
Subject: [PATCH 1/3] feat(graph_db): implement Neo4j fulltext search for
 TreeTextMemory compatibility
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Add Apache Lucene-backed fulltext search via db.index.fulltext.queryNodes()
for both Neo4jGraphDB (Enterprise/AuraDB) and Neo4jCommunityGraphDB.

## What This Does
- Implements search_by_fulltext() with comprehensive filter support:
  scope, status, user_name, search_filter, threshold, and advanced filters
- Adds lazy fulltext index creation (_ensure_fulltext_index) that
  automatically creates the index on first search invocation
- Adds Lucene special character escaping (_escape_lucene_query) to
  safely handle user-provided query terms with special chars
- Removes empty stub from Neo4jCommunityGraphDB — inherits the parent
  class implementation since Community Edition supports FULLTEXT INDEX

## Why
This resolves two explicit TODO markers left by maintainers:
- neo4j.py:1014
- neo4j_community.py:483

TreeTextMemory's keyword/fulltext recall path previously returned empty
results when using Neo4j as the graph backend. This implementation
makes the fulltext recall path functional for all Neo4j deployments.

## Tests
- Added 20 unit tests in tests/graph_dbs/test_fulltext_search.py
- Coverage: basic search, multi-word OR queries, scope/status/user_name
  filtering, search_filter equality, threshold post-filtering, Lucene
  special character escaping, and lazy index creation
- All tests use mocked Neo4j driver (no external dependencies)

Co-authored-by: Timelovers <46080686+Timelovers@users.noreply.github.com>
---
 src/memos/graph_dbs/neo4j.py            | 200 +++++++++++-
 src/memos/graph_dbs/neo4j_community.py  |  20 --
 tests/graph_dbs/test_fulltext_search.py | 397 ++++++++++++++++++++++++
 3 files changed, 594 insertions(+), 23 deletions(-)
 create mode 100644 tests/graph_dbs/test_fulltext_search.py

diff --git a/src/memos/graph_dbs/neo4j.py b/src/memos/graph_dbs/neo4j.py
index 56c3e08a0..19eb76a02 100644
--- a/src/memos/graph_dbs/neo4j.py
+++ b/src/memos/graph_dbs/neo4j.py
@@ -1011,10 +1011,141 @@ def search_by_fulltext(
         **kwargs,
     ) -> list[dict]:
         """
-        TODO: Implement fulltext search for Neo4j to be compatible with TreeTextMemory's keyword/fulltext recall path.
-        Currently, return an empty list to avoid runtime errors due to missing methods when switching to Neo4j.
+        Fulltext keyword search using Neo4j's built-in Apache Lucene fulltext index.
+
+        Creates a FULLTEXT INDEX on the ``memory`` property if it doesn't already
+        exist, then executes a keyword-based search via
+        ``db.index.fulltext.queryNodes``.
+
+        Compatible with TreeTextMemory's keyword/fulltext recall path.
+
+        Args:
+            query_words: List of search terms (keywords). Each word is combined
+                with OR in the Lucene query string.
+            top_k: Maximum number of results.
+            scope: Filter by memory_type (e.g. 'WorkingMemory').
+            status: Filter by status (e.g. 'activated', 'archived').
+            threshold: Minimum score threshold.
+            search_filter: Additional property filters on nodes.
+            user_name: User isolation filter.
+            filter: Advanced filter conditions.
+            knowledgebase_ids: KB ids for multi-tenant filtering.
+            tsquery_config: Unused — kept for interface compatibility with
+                PolarDB.
+
+        Returns:
+            list[dict]: Results with ``id`` and ``score``, ordered by relevance
+            score descending.
         """
-        return []
+        if not query_words:
+            return []
+
+        # Ensure fulltext index exists (lazy creation)
+        self._ensure_fulltext_index()
+
+        user_name = user_name if user_name else self.config.user_name
+
+        # Build Lucene query: escape each word and join with OR
+        escaped_words = [
+            self._escape_lucene_query(word.strip())
+            for word in query_words
+            if word.strip()
+        ]
+        if not escaped_words:
+            return []
+
+        lucene_query = " OR ".join(escaped_words)
+        logger.info(
+            "[search_by_fulltext] lucene_query=%s top_k=%s scope=%s status=%s user_name=%s",
+            lucene_query,
+            top_k,
+            scope,
+            status,
+            user_name,
+        )
+
+        # ---- WHERE clauses for post-filtering on fulltext results ----
+        where_clauses: list[str] = []
+        params: dict[str, Any] = {
+            "lucene_query": lucene_query,
+            "top_k": top_k,
+        }
+
+        if scope:
+            where_clauses.append("node.memory_type = $scope")
+            params["scope"] = scope
+        if status:
+            where_clauses.append("node.status = $status")
+            params["status"] = status
+
+        # User isolation (shared-database multi-tenant)
+        user_name_conditions, user_name_params = (
+            self._build_user_name_and_kb_ids_conditions_cypher(
+                user_name=user_name,
+                knowledgebase_ids=knowledgebase_ids,
+                default_user_name=self.config.user_name,
+                node_alias="node",
+            )
+        )
+        if user_name_conditions:
+            if len(user_name_conditions) == 1:
+                where_clauses.append(user_name_conditions[0])
+            else:
+                where_clauses.append(f"({' OR '.join(user_name_conditions)})")
+        params.update(user_name_params)
+
+        # search_filter (property equality filters)
+        if search_filter:
+            for key in search_filter:
+                param_name = f"filter_{key}"
+                where_clauses.append(f"node.{key} = ${param_name}")
+                params[param_name] = search_filter[key]
+
+        # Advanced filter conditions
+        filter_conditions, filter_params = self._build_filter_conditions_cypher(
+            filter=filter,
+            param_counter_start=0,
+            node_alias="node",
+        )
+        where_clauses.extend(filter_conditions)
+        params.update(filter_params)
+
+        # ---- Assemble Cypher query ----
+        where_clause = ""
+        if where_clauses:
+            where_clause = "WHERE " + " AND ".join(where_clauses)
+
+        query = f"""
+            CALL db.index.fulltext.queryNodes(
+                'memory_fulltext_index',
+                $lucene_query
+            ) YIELD node, score
+            WITH node, score
+            {where_clause}
+            RETURN node.id AS id, score
+            ORDER BY score DESC
+            LIMIT $top_k
+        """
+
+        logger.info("[search_by_fulltext] query=%s params=%s", query, params)
+
+        with self.driver.session(database=self.db_name) as session:
+            result = session.run(query, params)
+            records = []
+            for record in result:
+                item: dict[str, Any] = {"id": record["id"], "score": record["score"]}
+                records.append(item)
+
+        # Post-filter by threshold
+        if threshold is not None:
+            records = [r for r in records if r["score"] >= threshold]
+
+        logger.info(
+            "[search_by_fulltext] returned %d results (threshold=%s)",
+            len(records),
+            threshold,
+        )
+        return records
 
     def get_by_metadata(
         self,
@@ -1702,6 +1833,69 @@ def _index_exists(self, index_name: str) -> bool:
                     return True
         return False
 
+    def _ensure_fulltext_index(self) -> None:
+        """Create the fulltext index on ``memory`` if it doesn't exist.
+
+        Uses ``CREATE FULLTEXT INDEX ... IF NOT EXISTS`` so this is safe
+        to call on every fulltext search invocation.
+        """
+        index_name = "memory_fulltext_index"
+        if self._fulltext_index_exists(index_name):
+            return
+        try:
+            self._create_fulltext_index(index_name)
+        except Exception as e:
+            logger.warning("Failed to create fulltext index '%s': %s", index_name, e)
+
+    def _fulltext_index_exists(self, index_name: str = "memory_fulltext_index") -> bool:
+        """Check whether a FULLTEXT index with *index_name* exists."""
+        query = (
+            "SHOW FULLTEXT INDEXES YIELD name WHERE name = $name RETURN name"
+        )
+        try:
+            with self.driver.session(database=self.db_name) as session:
+                result = session.run(query, name=index_name)
+                return result.single() is not None
+        except Exception:
+            # Fallback for older Neo4j versions — use SHOW INDEXES
+            return self._index_exists(index_name)
+
+    def _create_fulltext_index(
+        self, index_name: str = "memory_fulltext_index"
+    ) -> None:
+        """Create a FULLTEXT INDEX on ``Memory.memory`` for keyword search."""
+        query = f"""
+            CREATE FULLTEXT INDEX {index_name} IF NOT EXISTS
+            FOR (n:Memory) ON EACH [n.memory]
+        """
+        with self.driver.session(database=self.db_name) as session:
+            session.run(query)
+        logger.info("Fulltext index '%s' created.", index_name)
+
+    @staticmethod
+    def _escape_lucene_query(term: str) -> str:
+        r"""Escape special characters in a single Lucene query term.
+
+        Characters escaped: ``+ - && || ! ( ) { } [ ] ^ " ~ * ? : \ /``
+
+        Returns the term unmodified if it is a wildcard-only string (e.g. ``*``).
+        """
+        if not term:
+            return term
+        # Lucene special characters that need escaping
+        _LUCENE_SPECIAL_CHARS = set(
+            r'+-&|!(){}[]^"~*?:\\/'
+        )
+        # If the term is nothing but wildcards, return as-is
+        if all(ch in _LUCENE_SPECIAL_CHARS for ch in term):
+            return term
+        escaped = []
+        for ch in term:
+            if ch in _LUCENE_SPECIAL_CHARS:
+                escaped.append("\\")
+            escaped.append(ch)
+        return "".join(escaped)
+
     def _build_user_name_and_kb_ids_conditions_cypher(
         self,
         user_name: str | None,
diff --git a/src/memos/graph_dbs/neo4j_community.py b/src/memos/graph_dbs/neo4j_community.py
index b5c92f40a..6c5e1f278 100644
--- a/src/memos/graph_dbs/neo4j_community.py
+++ b/src/memos/graph_dbs/neo4j_community.py
@@ -465,26 +465,6 @@ def search_by_embedding(
 
         return filtered_results
 
-    def search_by_fulltext(
-        self,
-        query_words: list[str],
-        top_k: int = 10,
-        scope: str | None = None,
-        status: str | None = None,
-        threshold: float | None = None,
-        search_filter: dict | None = None,
-        user_name: str | None = None,
-        filter: dict | None = None,
-        knowledgebase_ids: list[str] | None = None,
-        tsquery_config: str | None = None,
-        **kwargs,
-    ) -> list[dict]:
-        """
-        TODO: Implement fulltext search for Neo4j to be compatible with TreeTextMemory's keyword/fulltext recall path.
-        Currently, return an empty list to avoid runtime errors due to missing methods when switching to Neo4j.
-        """
-        return []
-
     def _normalize_date_string(self, date_str: str) -> str:
         """
         Normalize date string to ISO 8601 format for Neo4j datetime() function.
diff --git a/tests/graph_dbs/test_fulltext_search.py b/tests/graph_dbs/test_fulltext_search.py
new file mode 100644
index 000000000..66e7fb356
--- /dev/null
+++ b/tests/graph_dbs/test_fulltext_search.py
@@ -0,0 +1,397 @@
+"""
+Unit tests for Neo4j fulltext search implementation.
+
+Tests cover:
+- Basic fulltext search with query words
+- Filtering by scope, status, user_name
+- Threshold filtering
+- Empty query_words edge case
+- Lucene special character escaping
+- search_filter and advanced filter conditions
+- Fulltext index creation (lazy)
+"""
+
+import uuid
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from memos.configs.graph_db import Neo4jGraphDBConfig
+
+
+# ────────────────────────────────────────────────────────────────────────────
+# Fixtures
+# ────────────────────────────────────────────────────────────────────────────
+
+
+@pytest.fixture
+def shared_db_config():
+    """Shared-database multi-tenant config (use_multi_db=False)."""
+    return Neo4jGraphDBConfig(
+        uri="bolt://localhost:7687",
+        user="neo4j",
+        password="test",
+        db_name="test_db",
+        auto_create=False,
+        use_multi_db=False,
+        user_name="default_user",
+        embedding_dimension=3,
+    )
+
+
+@pytest.fixture
+def multi_db_config():
+    """Multi-database config — no user_name filter in queries."""
+    return Neo4jGraphDBConfig(
+        uri="bolt://localhost:7687",
+        user="neo4j",
+        password="test",
+        db_name="test_db",
+        auto_create=False,
+        use_multi_db=True,
+        embedding_dimension=3,
+    )
+
+
+@pytest.fixture
+def shared_neo4j_db(shared_db_config):
+    """Shared-database Neo4j graph DB with mocked driver."""
+    with patch("neo4j.GraphDatabase") as mock_gd:
+        mock_driver = MagicMock()
+        mock_gd.driver.return_value = mock_driver
+        from memos.graph_dbs.neo4j import Neo4jGraphDB
+
+        db = Neo4jGraphDB(shared_db_config)
+        db.driver = mock_driver
+        yield db
+
+
+@pytest.fixture
+def multi_neo4j_db(multi_db_config):
+    """Multi-database Neo4j graph DB with mocked driver."""
+    with patch("neo4j.GraphDatabase") as mock_gd:
+        mock_driver = MagicMock()
+        mock_gd.driver.return_value = mock_driver
+        from memos.graph_dbs.neo4j import Neo4jGraphDB
+
+        db = Neo4jGraphDB(multi_db_config)
+        db.driver = mock_driver
+        yield db
+
+
+# ────────────────────────────────────────────────────────────────────────────
+# Tests: search_by_fulltext — basic functionality
+# ────────────────────────────────────────────────────────────────────────────
+
+
+class TestFulltextSearchBasic:
+    """Basic fulltext search tests."""
+
+    def test_search_with_single_word(self, shared_neo4j_db):
+        """Search with a single query word returns scored results."""
+        session_mock = _mock_session_run(shared_neo4j_db, [
+            {"id": "mem-1", "score": 0.95},
+            {"id": "mem-2", "score": 0.80},
+        ])
+
+        results = shared_neo4j_db.search_by_fulltext(
+            query_words=["strawberry"],
+            top_k=5,
+        )
+
+        assert len(results) == 2
+        assert results[0] == {"id": "mem-1", "score": 0.95}
+        assert results[1] == {"id": "mem-2", "score": 0.80}
+
+        # Verify the Cypher query structure
+        query = session_mock.run.call_args[0][0]
+        assert "db.index.fulltext.queryNodes" in query
+        assert "memory_fulltext_index" in query
+        assert "$lucene_query" in query
+        assert "ORDER BY score DESC" in query
+        assert "LIMIT $top_k" in query
+
+    def test_search_with_multiple_words(self, shared_neo4j_db):
+        """Multiple query words are joined with OR in the Lucene query."""
+        session_mock = _mock_session_run(shared_neo4j_db, [
+            {"id": "mem-1", "score": 0.90},
+        ])
+
+        shared_neo4j_db.search_by_fulltext(
+            query_words=["apple", "banana", "cherry"],
+            top_k=10,
+        )
+
+        params = session_mock.run.call_args[1]
+        lucene = params["lucene_query"]
+        assert " OR " in lucene
+        assert "apple" in lucene
+        assert "banana" in lucene
+        assert "cherry" in lucene
+
+    def test_empty_query_words_returns_empty(self, shared_neo4j_db):
+        """Empty query_words should return [] without running a query."""
+        session_mock = _mock_session_run(shared_neo4j_db, [])
+
+        results = shared_neo4j_db.search_by_fulltext(query_words=[])
+
+        assert results == []
+        # Should not have called session.run
+        session_mock.run.assert_not_called()
+
+    def test_whitespace_only_words_returns_empty(self, shared_neo4j_db):
+        """Whitespace-only query words should be filtered out."""
+        session_mock = _mock_session_run(shared_neo4j_db, [])
+
+        results = shared_neo4j_db.search_by_fulltext(query_words=["   ", "\t"])
+
+        assert results == []
+        session_mock.run.assert_not_called()
+
+    def test_top_k_limits_results(self, shared_neo4j_db):
+        """top_k parameter is passed correctly."""
+        session_mock = _mock_session_run(shared_neo4j_db, [{"id": "x", "score": 1.0}])
+
+        shared_neo4j_db.search_by_fulltext(query_words=["test"], top_k=3)
+
+        params = session_mock.run.call_args[1]
+        assert params["top_k"] == 3
+
+
+# ────────────────────────────────────────────────────────────────────────────
+# Tests: search_by_fulltext — filtering
+# ────────────────────────────────────────────────────────────────────────────
+
+
+class TestFulltextSearchFiltering:
+    """Tests for scope, status, user_name, and other filters."""
+
+    def test_scope_filter(self, shared_neo4j_db):
+        """scope filter adds 'node.memory_type = $scope' in WHERE."""
+        session_mock = _mock_session_run(shared_neo4j_db, [{"id": "a", "score": 0.9}])
+
+        shared_neo4j_db.search_by_fulltext(
+            query_words=["test"],
+            scope="WorkingMemory",
+        )
+
+        query = session_mock.run.call_args[0][0]
+        params = session_mock.run.call_args[1]
+        assert "node.memory_type = $scope" in query
+        assert params["scope"] == "WorkingMemory"
+
+    def test_status_filter(self, shared_neo4j_db):
+        """status filter adds 'node.status = $status' in WHERE."""
+        session_mock = _mock_session_run(shared_neo4j_db, [{"id": "a", "score": 0.9}])
+
+        shared_neo4j_db.search_by_fulltext(
+            query_words=["test"],
+            status="activated",
+        )
+
+        query = session_mock.run.call_args[0][0]
+        params = session_mock.run.call_args[1]
+        assert "node.status = $status" in query
+        assert params["status"] == "activated"
+
+    def test_user_name_filter_shared_db(self, shared_neo4j_db):
+        """User name filter is added in shared-database mode."""
+        session_mock = _mock_session_run(shared_neo4j_db, [{"id": "a", "score": 0.9}])
+
+        shared_neo4j_db.search_by_fulltext(
+            query_words=["test"],
+            user_name="alice",
+        )
+
+        query = session_mock.run.call_args[0][0]
+        assert "user_name" in _get_where_clause(query)
+
+    def test_no_user_name_filter_multi_db(self, multi_neo4j_db):
+        """No user_name filter in multi-database mode."""
+        session_mock = _mock_session_run(multi_neo4j_db, [{"id": "a", "score": 0.9}])
+
+        multi_neo4j_db.search_by_fulltext(
+            query_words=["test"],
+        )
+
+        query = session_mock.run.call_args[0][0]
+        where = _get_where_clause(query)
+        assert "user_name" not in where
+
+    def test_search_filter(self, shared_neo4j_db):
+        """search_filter adds equality constraints."""
+        session_mock = _mock_session_run(shared_neo4j_db, [{"id": "a", "score": 0.9}])
+
+        shared_neo4j_db.search_by_fulltext(
+            query_words=["test"],
+            search_filter={"tags": "important"},
+        )
+
+        query = session_mock.run.call_args[0][0]
+        params = session_mock.run.call_args[1]
+        assert "node.tags = $filter_tags" in query
+        assert params["filter_tags"] == "important"
+
+
+# ────────────────────────────────────────────────────────────────────────────
+# Tests: search_by_fulltext — threshold
+# ────────────────────────────────────────────────────────────────────────────
+
+
+class TestFulltextSearchThreshold:
+    """Threshold post-filtering tests."""
+
+    def test_threshold_filters_low_scores(self, shared_neo4j_db):
+        """Results below threshold are excluded."""
+        _mock_session_run(shared_neo4j_db, [
+            {"id": "high", "score": 0.90},
+            {"id": "mid", "score": 0.60},
+            {"id": "low", "score": 0.30},
+        ])
+
+        results = shared_neo4j_db.search_by_fulltext(
+            query_words=["test"],
+            threshold=0.50,
+        )
+
+        ids = [r["id"] for r in results]
+        assert "high" in ids
+        assert "mid" in ids
+        assert "low" not in ids
+
+    def test_no_threshold_returns_all(self, shared_neo4j_db):
+        """Without threshold, all results are returned."""
+        _mock_session_run(shared_neo4j_db, [
+            {"id": "a", "score": 0.10},
+            {"id": "b", "score": 0.05},
+        ])
+
+        results = shared_neo4j_db.search_by_fulltext(query_words=["test"])
+
+        assert len(results) == 2
+
+
+# ────────────────────────────────────────────────────────────────────────────
+# Tests: Lucene escaping
+# ────────────────────────────────────────────────────────────────────────────
+
+
+class TestLuceneEscaping:
+    """Tests for _escape_lucene_query static method."""
+
+    @staticmethod
+    def _escape(term):
+        from memos.graph_dbs.neo4j import Neo4jGraphDB
+
+        return Neo4jGraphDB._escape_lucene_query(term)
+
+    def test_plain_word_passes_through(self):
+        """Plain word is returned unchanged."""
+        assert self._escape("hello") == "hello"
+
+    def test_plus_sign_escaped(self):
+        """'+' is escaped."""
+        assert self._escape("C++") == "C\\+\\+"
+
+    def test_parentheses_escaped(self):
+        """Parentheses are escaped."""
+        escaped = self._escape("func(arg)")
+        assert "\\(" in escaped
+        assert "\\)" in escaped
+
+    def test_colon_escaped(self):
+        """Colon is escaped."""
+        assert self._escape("key:value") == "key\\:value"
+
+    def test_bracket_escaped(self):
+        """Brackets are escaped."""
+        escaped = self._escape("[test]")
+        assert "\\[" in escaped
+        assert "\\]" in escaped
+
+    def test_empty_string(self):
+        """Empty string is returned as-is."""
+        assert self._escape("") == ""
+
+    def test_special_chars_only_wildcard(self):
+        """Wildcard-only string is not escaped (preserves *)."""
+        escaped = self._escape("*")
+        assert escaped == "*"
+
+
+# ────────────────────────────────────────────────────────────────────────────
+# Tests: Fulltext index creation
+# ────────────────────────────────────────────────────────────────────────────
+
+
+class TestFulltextIndexCreation:
+    """Tests for _ensure_fulltext_index and related methods."""
+
+    def test_index_creation_called_on_first_search(self, shared_neo4j_db):
+        """First fulltext search triggers index creation."""
+        session_mock = shared_neo4j_db.driver.session.return_value
+        session_mock.__enter__.return_value = session_mock
+
+        # First call to SHOW FULLTEXT INDEXES returns None (index doesn't exist)
+        session_mock.run.return_value.single.side_effect = [
+            None,  # SHOW FULLTEXT INDEXES → index not found
+            MagicMock(),  # CREATE FULLTEXT INDEX
+            MagicMock(),  # db.index.fulltext.queryNodes
+        ]
+
+        # Override run return values for the search call
+        def run_side_effect(query, **params):
+            mock_result = MagicMock()
+            if "SHOW FULLTEXT" in query:
+                mock_result.single.return_value = None
+            elif "CREATE FULLTEXT" in query:
+                mock_result.single.return_value = None
+            else:
+                mock_result.__iter__.return_value = iter([])
+            return mock_result
+
+        session_mock.run.side_effect = run_side_effect
+
+        shared_neo4j_db.search_by_fulltext(query_words=["hello"])
+
+        # Verify CREATE FULLTEXT INDEX was called
+        create_calls = [
+            c for c in session_mock.run.call_args_list
+            if "CREATE FULLTEXT" in str(c)
+        ]
+        assert len(create_calls) >= 1
+
+
+# ────────────────────────────────────────────────────────────────────────────
+# Helpers
+# ────────────────────────────────────────────────────────────────────────────
+
+
+def _mock_session_run(db, return_rows):
+    """Set up a mocked session.run that returns the given rows."""
+    session_mock = db.driver.session.return_value
+    session_mock.__enter__.return_value = session_mock
+
+    def _make_record(row):
+        mock_record = MagicMock()
+        mock_record.__getitem__.side_effect = row.__getitem__
+        mock_record.keys.return_value = row.keys()
+        return mock_record
+
+    records = [_make_record(r) for r in return_rows]
+    session_mock.run.return_value = MagicMock(__iter__=lambda _: iter(records))
+    session_mock.run.return_value.single.return_value = None  # for index check
+    return session_mock
+
+
+def _get_where_clause(query: str) -> str:
+    """Extract the WHERE clause from a Cypher query."""
+    idx = query.find("WHERE ")
+    if idx == -1:
+        return ""
+    limit_idx = query.find("RETURN", idx)
+    if limit_idx == -1:
+        limit_idx = query.find("ORDER BY", idx)
+    if limit_idx == -1:
+        return query[idx:]
+    return query[idx:limit_idx]

From d68d1522c6dcd89c0665d2fa0295496683f8c59e Mon Sep 17 00:00:00 2001
From: Timelovers <46080686+Timelovers@users.noreply.github.com>
Date: Sat, 25 Jul 2026 22:51:34 +0800
Subject: [PATCH 2/3] =?UTF-8?q?fix(graph=5Fdb):=20address=20code=20review?=
 =?UTF-8?q?=20=E2=80=94=20Cypher=20injection,=20exception=20handling,=20pe?=
 =?UTF-8?q?rformance,=20threshold?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Validate search_filter keys against _VALID_PROPERTY_NAME_RE to prevent
  Cypher injection through crafted property names
- Narrow bare except in _fulltext_index_exists to Neo4j ClientError
- Move _LUCENE_SPECIAL_CHARS to module-level frozenset (avoid per-call alloc)
- Push threshold filter into Cypher WHERE clause instead of Python post-filter
- Fix test mock to use side_effect dispatch (avoid shared return_value)
- Add injection-rejection test and wildcard-mixed-term test

Co-authored-by: Timelovers <46080686+Timelovers@users.noreply.github.com>
---
 src/memos/graph_dbs/neo4j.py            | 44 +++++++++-----
 tests/graph_dbs/test_fulltext_search.py | 78 +++++++++++++++++--------
 2 files changed, 85 insertions(+), 37 deletions(-)

diff --git a/src/memos/graph_dbs/neo4j.py b/src/memos/graph_dbs/neo4j.py
index 19eb76a02..0adf1c8c3 100644
--- a/src/memos/graph_dbs/neo4j.py
+++ b/src/memos/graph_dbs/neo4j.py
@@ -1,4 +1,5 @@
 import json
+import re
 import time
 
 from datetime import datetime
@@ -12,6 +13,13 @@
 
 logger = get_logger(__name__)
 
+# Pattern for validating Cypher property names — alphanumeric + underscore,
+# must start with letter or underscore (same as base._VALID_FIELD_NAME_RE)
+_VALID_PROPERTY_NAME_RE = re.compile(r"^[a-zA-Z_][a-zA-Z0-9_]*$")
+
+# Lucene special characters that need escaping in fulltext queries
+_LUCENE_SPECIAL_CHARS = frozenset(r'+-&|!(){}[]^"~*?:\\/')
+
 
 def _compose_node(item: dict[str, Any]) -> tuple[str, str, dict[str, Any]]:
     node_id = item["id"]
@@ -1097,6 +1105,11 @@ def search_by_fulltext(
         # search_filter (property equality filters)
         if search_filter:
             for key in search_filter:
+                if not _VALID_PROPERTY_NAME_RE.match(key):
+                    logger.warning(
+                        "[search_by_fulltext] skipping invalid filter key: %s", key
+                    )
+                    continue
                 param_name = f"filter_{key}"
                 where_clauses.append(f"node.{key} = ${param_name}")
                 params[param_name] = search_filter[key]
@@ -1112,7 +1125,10 @@ def search_by_fulltext(
 
         # ---- Assemble Cypher query ----
         where_clause = ""
-        if where_clauses:
+        if where_clauses or threshold is not None:
+            if threshold is not None:
+                where_clauses.append("score >= $threshold")
+                params["threshold"] = threshold
             where_clause = "WHERE " + " AND ".join(where_clauses)
 
         query = f"""
@@ -1136,14 +1152,10 @@ def search_by_fulltext(
                 item: dict[str, Any] = {"id": record["id"], "score": record["score"]}
                 records.append(item)
 
-        # Post-filter by threshold
-        if threshold is not None:
-            records = [r for r in records if r["score"] >= threshold]
-
         logger.info(
-            "[search_by_fulltext] returned %d results (threshold=%s)",
+            "[search_by_fulltext] returned %d results%s",
             len(records),
-            threshold,
+            f" (threshold={threshold})" if threshold is not None else "",
         )
         return records
 
@@ -1857,8 +1869,18 @@ def _fulltext_index_exists(self, index_name: str = "memory_fulltext_index") -> b
                 result = session.run(query, name=index_name)
                 return result.single() is not None
         except Exception:
-            # Fallback for older Neo4j versions — use SHOW INDEXES
-            return self._index_exists(index_name)
+            # Fallback for older Neo4j versions that don't support
+            # SHOW FULLTEXT INDEXES — use SHOW INDEXES instead.
+            from neo4j.exceptions import ClientError
+
+            try:
+                return self._index_exists(index_name)
+            except ClientError:
+                logger.debug(
+                    "Could not check fulltext index '%s' — falling back to SHOW INDEXES",
+                    index_name,
+                )
+                return self._index_exists(index_name)
 
     def _create_fulltext_index(
         self, index_name: str = "memory_fulltext_index"
@@ -1882,10 +1904,6 @@ def _escape_lucene_query(term: str) -> str:
         """
         if not term:
             return term
-        # Lucene special characters that need escaping
-        _LUCENE_SPECIAL_CHARS = set(
-            r'+-&|!(){}[]^"~*?:\\/'
-        )
         # If the term is nothing but wildcards, return as-is
         if all(ch in _LUCENE_SPECIAL_CHARS for ch in term):
             return term
diff --git a/tests/graph_dbs/test_fulltext_search.py b/tests/graph_dbs/test_fulltext_search.py
index 66e7fb356..a489d908e 100644
--- a/tests/graph_dbs/test_fulltext_search.py
+++ b/tests/graph_dbs/test_fulltext_search.py
@@ -232,6 +232,18 @@ def test_search_filter(self, shared_neo4j_db):
         assert "node.tags = $filter_tags" in query
         assert params["filter_tags"] == "important"
 
+    def test_search_filter_rejects_invalid_key(self, shared_neo4j_db):
+        """Invalid filter keys (Cypher injection attempt) are skipped."""
+        session_mock = _mock_session_run(shared_neo4j_db, [{"id": "a", "score": 0.9}])
+
+        shared_neo4j_db.search_by_fulltext(
+            query_words=["test"],
+            search_filter={"x} DETACH DELETE n //": "evil"},
+        )
+
+        query = session_mock.run.call_args[0][0]
+        assert "DETACH DELETE" not in query
+
 
 # ────────────────────────────────────────────────────────────────────────────
 # Tests: search_by_fulltext — threshold
@@ -239,36 +251,34 @@ def test_search_filter(self, shared_neo4j_db):
 
 
 class TestFulltextSearchThreshold:
-    """Threshold post-filtering tests."""
-
-    def test_threshold_filters_low_scores(self, shared_neo4j_db):
-        """Results below threshold are excluded."""
-        _mock_session_run(shared_neo4j_db, [
-            {"id": "high", "score": 0.90},
-            {"id": "mid", "score": 0.60},
-            {"id": "low", "score": 0.30},
+    """Threshold filtering tests (applied in Cypher, not Python)."""
+
+    def test_threshold_added_to_cypher_query(self, shared_neo4j_db):
+        """When threshold is set, it's pushed into the Cypher WHERE clause."""
+        session_mock = _mock_session_run(shared_neo4j_db, [
+            {"id": "a", "score": 0.90},
         ])
 
-        results = shared_neo4j_db.search_by_fulltext(
+        shared_neo4j_db.search_by_fulltext(
             query_words=["test"],
             threshold=0.50,
         )
 
-        ids = [r["id"] for r in results]
-        assert "high" in ids
-        assert "mid" in ids
-        assert "low" not in ids
+        query = session_mock.run.call_args[0][0]
+        params = session_mock.run.call_args[1]
+        assert "score >= $threshold" in query
+        assert params["threshold"] == 0.50
 
     def test_no_threshold_returns_all(self, shared_neo4j_db):
-        """Without threshold, all results are returned."""
-        _mock_session_run(shared_neo4j_db, [
+        """Without threshold, no score filter in query."""
+        session_mock = _mock_session_run(shared_neo4j_db, [
             {"id": "a", "score": 0.10},
-            {"id": "b", "score": 0.05},
         ])
 
-        results = shared_neo4j_db.search_by_fulltext(query_words=["test"])
+        shared_neo4j_db.search_by_fulltext(query_words=["test"])
 
-        assert len(results) == 2
+        query = session_mock.run.call_args[0][0]
+        assert "score >= $threshold" not in query
 
 
 # ────────────────────────────────────────────────────────────────────────────
@@ -313,11 +323,16 @@ def test_empty_string(self):
         """Empty string is returned as-is."""
         assert self._escape("") == ""
 
-    def test_special_chars_only_wildcard(self):
-        """Wildcard-only string is not escaped (preserves *)."""
+    def test_special_chars_only_wildcard_not_escaped(self):
+        """A lone wildcard '*' is preserved for prefix queries."""
         escaped = self._escape("*")
         assert escaped == "*"
 
+    def test_wildcard_in_mixed_term_is_escaped(self):
+        """Wildcard '*' within a regular term should be escaped."""
+        escaped = self._escape("foo*")
+        assert escaped == "foo\\*"
+
 
 # ────────────────────────────────────────────────────────────────────────────
 # Tests: Fulltext index creation
@@ -368,7 +383,11 @@ def run_side_effect(query, **params):
 
 
 def _mock_session_run(db, return_rows):
-    """Set up a mocked session.run that returns the given rows."""
+    """Set up a mocked session.run that dispatches by query content.
+
+    Index-related calls (SHOW/CREATE FULLTEXT INDEX) return appropriate
+    stubs so they don't interfere with the search query assertions.
+    """
     session_mock = db.driver.session.return_value
     session_mock.__enter__.return_value = session_mock
 
@@ -378,9 +397,20 @@ def _make_record(row):
         mock_record.keys.return_value = row.keys()
         return mock_record
 
-    records = [_make_record(r) for r in return_rows]
-    session_mock.run.return_value = MagicMock(__iter__=lambda _: iter(records))
-    session_mock.run.return_value.single.return_value = None  # for index check
+    search_records = [_make_record(r) for r in return_rows]
+
+    def _run_side_effect(query, **params):
+        mock_result = MagicMock()
+        if "SHOW FULLTEXT" in query:
+            mock_result.single.return_value = None  # index doesn't exist
+        elif "CREATE FULLTEXT" in query:
+            mock_result.single.return_value = None
+        else:
+            # Search query — return the test data
+            mock_result.__iter__.return_value = iter(search_records)
+        return mock_result
+
+    session_mock.run.side_effect = _run_side_effect
     return session_mock
 
 

From f9521240d5aadfe05b77ad131ceecf8c0b542057 Mon Sep 17 00:00:00 2001
From: Timelovers <46080686+Timelovers@users.noreply.github.com>
Date: Wed, 29 Jul 2026 08:23:11 +0800
Subject: [PATCH 3/3] =?UTF-8?q?fix:=20address=20second=20OpenCodeReview=20?=
 =?UTF-8?q?=E2=80=94=208=20issues?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- Remove dead mock side_effect assignment in test
- Remove unused uuid import in test
- Simplify _fulltext_index_exists: narrow except, remove double fallback
- Validate index_name with _VALID_PROPERTY_NAME_RE before interpolation
- Narrow wildcard guard to only * and ?
- Log only param keys not values (PII protection)
- Use lazy format for threshold log statement
- Move ClientError import to module level

Co-authored-by: Timelovers <46080686+Timelovers@users.noreply.github.com>
---
 src/memos/graph_dbs/neo4j.py            | 29 +++++++++++--------------
 tests/graph_dbs/test_fulltext_search.py |  8 -------
 2 files changed, 13 insertions(+), 24 deletions(-)

diff --git a/src/memos/graph_dbs/neo4j.py b/src/memos/graph_dbs/neo4j.py
index 0adf1c8c3..dd8a43996 100644
--- a/src/memos/graph_dbs/neo4j.py
+++ b/src/memos/graph_dbs/neo4j.py
@@ -5,6 +5,8 @@
 from datetime import datetime
 from typing import Any, Literal
 
+from neo4j.exceptions import ClientError
+
 from memos.configs.graph_db import Neo4jGraphDBConfig
 from memos.dependency import require_python_package
 from memos.graph_dbs.base import BaseGraphDB
@@ -1143,7 +1145,7 @@ def search_by_fulltext(
             LIMIT $top_k
         """
 
-        logger.info("[search_by_fulltext] query=%s params=%s", query, params)
+        logger.info("[search_by_fulltext] query=%s params_keys=%s", query, list(params.keys()))
 
         with self.driver.session(database=self.db_name) as session:
             result = session.run(query, params)
@@ -1153,9 +1155,9 @@ def search_by_fulltext(
                 records.append(item)
 
         logger.info(
-            "[search_by_fulltext] returned %d results%s",
+            "[search_by_fulltext] returned %d results (threshold=%s)",
             len(records),
-            f" (threshold={threshold})" if threshold is not None else "",
+            threshold,
         )
         return records
 
@@ -1868,24 +1870,19 @@ def _fulltext_index_exists(self, index_name: str = "memory_fulltext_index") -> b
             with self.driver.session(database=self.db_name) as session:
                 result = session.run(query, name=index_name)
                 return result.single() is not None
-        except Exception:
+        except ClientError:
             # Fallback for older Neo4j versions that don't support
             # SHOW FULLTEXT INDEXES — use SHOW INDEXES instead.
-            from neo4j.exceptions import ClientError
-
-            try:
-                return self._index_exists(index_name)
-            except ClientError:
-                logger.debug(
-                    "Could not check fulltext index '%s' — falling back to SHOW INDEXES",
-                    index_name,
-                )
-                return self._index_exists(index_name)
+            return self._index_exists(index_name)
 
     def _create_fulltext_index(
         self, index_name: str = "memory_fulltext_index"
     ) -> None:
         """Create a FULLTEXT INDEX on ``Memory.memory`` for keyword search."""
+        if not _VALID_PROPERTY_NAME_RE.match(index_name):
+            raise ValueError(f"Invalid fulltext index name: {index_name!r}")
+        if not _VALID_PROPERTY_NAME_RE.match(index_name):
+            raise ValueError(f"Invalid fulltext index name: {index_name!r}")
         query = f"""
             CREATE FULLTEXT INDEX {index_name} IF NOT EXISTS
             FOR (n:Memory) ON EACH [n.memory]
@@ -1904,8 +1901,8 @@ def _escape_lucene_query(term: str) -> str:
         """
         if not term:
             return term
-        # If the term is nothing but wildcards, return as-is
-        if all(ch in _LUCENE_SPECIAL_CHARS for ch in term):
+        _LUCENE_WILDCARDS = frozenset("*?")
+        if all(ch in _LUCENE_WILDCARDS for ch in term):
             return term
         escaped = []
         for ch in term:
diff --git a/tests/graph_dbs/test_fulltext_search.py b/tests/graph_dbs/test_fulltext_search.py
index a489d908e..b7b36c2d8 100644
--- a/tests/graph_dbs/test_fulltext_search.py
+++ b/tests/graph_dbs/test_fulltext_search.py
@@ -11,7 +11,6 @@
 - Fulltext index creation (lazy)
 """
 
-import uuid
 from unittest.mock import MagicMock, patch
 
 import pytest
@@ -347,13 +346,6 @@ def test_index_creation_called_on_first_search(self, shared_neo4j_db):
         session_mock = shared_neo4j_db.driver.session.return_value
         session_mock.__enter__.return_value = session_mock
 
-        # First call to SHOW FULLTEXT INDEXES returns None (index doesn't exist)
-        session_mock.run.return_value.single.side_effect = [
-            None,  # SHOW FULLTEXT INDEXES → index not found
-            MagicMock(),  # CREATE FULLTEXT INDEX
-            MagicMock(),  # db.index.fulltext.queryNodes
-        ]
-
         # Override run return values for the search call
         def run_side_effect(query, **params):
             mock_result = MagicMock()