fix: allow initial_message_sequence to have assistant message (#1729)

Co-authored-by: Sarah Wooders <sarahwooders@gmail.com>
Co-authored-by: Kevin Lin <kl2806@columbia.edu>
Co-authored-by: Kevin Lin <klin5061@gmail.com>

tests/integration_test_initial_sequence.py

@@ -0,0 +1,65 @@
+import os
+import threading
+import time
+
+import pytest
+from dotenv import load_dotenv
+from letta_client import Letta, MessageCreate
+
+
+def run_server():
+    load_dotenv()
+
+    from letta.server.rest_api.app import start_server
+
+    print("Starting server...")
+    start_server(debug=True)
+
+
+@pytest.fixture(
+    scope="module",
+)
+def client(request):
+    # Get URL from environment or start server
+    server_url = os.getenv("LETTA_SERVER_URL", f"http://localhost:8283")
+    if not os.getenv("LETTA_SERVER_URL"):
+        print("Starting server thread")
+        thread = threading.Thread(target=run_server, daemon=True)
+        thread.start()
+        time.sleep(5)
+    print("Running client tests with server:", server_url)
+
+    # create the Letta client
+    yield Letta(base_url=server_url, token=None)
+
+
+def test_initial_sequence(client: Letta):
+    # create an agent
+    agent = client.agents.create(
+        memory_blocks=[{"label": "human", "value": ""}, {"label": "persona", "value": ""}],
+        model="letta/letta-free",
+        embedding="letta/letta-free",
+        initial_message_sequence=[
+            MessageCreate(
+                role="assistant",
+                content="Hello, how are you?",
+            ),
+            MessageCreate(role="user", content="I'm good, and you?"),
+        ],
+    )
+
+    # list messages
+    messages = client.agents.messages.list(agent_id=agent.id)
+    response = client.agents.messages.create(
+        agent_id=agent.id,
+        messages=[
+            MessageCreate(
+                role="user",
+                content="hello assistant!",
+            )
+        ],
+    )
+    assert len(messages) == 3
+    assert messages[0].message_type == "system_message"
+    assert messages[1].message_type == "assistant_message"
+    assert messages[2].message_type == "user_message"