feat: replace MemorySaver with SqliteSaver for thread persistence

pyproject.toml

@@ -8,6 +8,8 @@ version = "0.0.0"
 requires-python = ">=3.11"
 dependencies = [
   "langgraph>=1.0,<2.0",
+  "langgraph-checkpoint-sqlite",
+  "langmem>=0.0.1",
   "langchain-core>=1.0,<2.0",
   "langchain-anthropic>=1.0,<2.0",
   "langchain-google-genai>=2.0.0,<5.0",

src/lilith_agent/app.py

@@ -8,7 +8,10 @@ from typing import Callable
 
 from langchain_core.messages import AIMessage, HumanMessage, ToolMessage
 from langchain_core.tools import BaseTool
-from langgraph.checkpoint.memory import MemorySaver
+from langgraph.checkpoint.sqlite import SqliteSaver
+import sqlite3
+import os
+from pathlib import Path
 from langgraph.graph import END, StateGraph
 from langgraph.graph.message import MessagesState, add_messages
 from typing import Annotated, TypedDict
@@ -592,5 +595,13 @@ def build_react_agent(cfg: Config):
     graph.add_edge("tools", "model")
     graph.add_edge("fail_safe", END)
 
-    compiled = graph.compile(checkpointer=MemorySaver())
+    # Setup SQLite Saver
+    lilith_home = Path(os.getenv("LILITH_HOME", ".lilith"))
+    lilith_home.mkdir(parents=True, exist_ok=True)
+    db_path = lilith_home / "threads.sqlite"
+    
+    conn = sqlite3.connect(str(db_path), check_same_thread=False)
+    memory_saver = SqliteSaver(conn)
+
+    compiled = graph.compile(checkpointer=memory_saver)
     return compiled.with_config({"recursion_limit": cfg.recursion_limit})

tests/test_memory_persistence.py

@@ -0,0 +1,20 @@
+import pytest
+from pathlib import Path
+from lilith_agent.config import Config
+from lilith_agent.app import build_react_agent
+
+def test_build_react_agent_uses_sqlite_saver(tmp_path):
+    cfg = Config.from_env()
+    
+    # Temporarily override where the agent looks for the .lilith dir
+    import os
+    os.environ["LILITH_HOME"] = str(tmp_path / ".lilith")
+    
+    agent = build_react_agent(cfg)
+    
+    assert agent.checkpointer is not None
+    assert type(agent.checkpointer).__name__ == "SqliteSaver"
+    
+    # Check if DB file was created
+    db_path = tmp_path / ".lilith" / "threads.sqlite"
+    assert db_path.exists()