Merge pull request #136 from igorls/fix/kg-hardening

fix: enable SQLite WAL mode and add consistent LIMIT to KG timeline

mempalace/knowledge_graph.py

@@ -87,7 +87,9 @@ class KnowledgeGraph:
         conn.close()
 
     def _conn(self):
-        return sqlite3.connect(self.db_path, timeout=10)
+        conn = sqlite3.connect(self.db_path, timeout=10)
+        conn.execute("PRAGMA journal_mode=WAL")
+        return conn
 
     def _entity_id(self, name: str) -> str:
         return name.lower().replace(" ", "_").replace("'", "")
@@ -284,6 +286,7 @@ class KnowledgeGraph:
                 JOIN entities o ON t.object = o.id
                 WHERE (t.subject = ? OR t.object = ?)
                 ORDER BY t.valid_from ASC NULLS LAST
+                LIMIT 100
             """,
                 (eid, eid),
             ).fetchall()

tests/test_knowledge_graph.py

@@ -107,6 +107,23 @@ class TestTimeline:
         tl = kg.timeline()
         assert len(tl) == 100  # LIMIT 100
 
+    def test_timeline_entity_has_limit(self, kg):
+        # Add > 100 triples all connected to a single entity
+        for i in range(105):
+            kg.add_triple(
+                "hub", "connects_to", f"spoke_{i}", valid_from=f"2025-01-{(i % 28) + 1:02d}"
+            )
+        tl = kg.timeline("hub")
+        assert len(tl) == 100  # LIMIT 100 on entity-filtered branch
+
+
+class TestWALMode:
+    def test_wal_mode_enabled(self, kg):
+        conn = kg._conn()
+        mode = conn.execute("PRAGMA journal_mode").fetchone()[0]
+        conn.close()
+        assert mode == "wal"
+
 
 class TestStats:
     def test_stats_empty(self, kg):