diff --git a/tests/api/test_agent.py b/tests/api/test_agent.py
new file mode 100644
index 0000000..8eb0ea7
--- /dev/null
+++ b/tests/api/test_agent.py
@@ -0,0 +1,56 @@
+import pytest
+from fastapi.testclient import TestClient
+from unittest.mock import MagicMock, patch, AsyncMock
+from ea_chatbot.api.main import app
+from ea_chatbot.api.dependencies import get_current_user
+from ea_chatbot.history.models import User
+from ea_chatbot.api.utils import create_access_token
+
+client = TestClient(app)
+
+@pytest.fixture
+def mock_user():
+    return User(id="user-123", username="test@example.com", display_name="Test User")
+
+@pytest.fixture
+def auth_header(mock_user):
+    app.dependency_overrides[get_current_user] = lambda: mock_user
+    token = create_access_token(data={"sub": mock_user.username, "user_id": mock_user.id})
+    yield {"Authorization": f"Bearer {token}"}
+    app.dependency_overrides.clear()
+
+def test_stream_agent_unauthorized():
+    """Test that streaming requires authentication."""
+    response = client.post("/chat/stream", json={"message": "hello"})
+    assert response.status_code == 401
+
+@pytest.mark.asyncio
+async def test_stream_agent_success(auth_header):
+    """Test successful agent streaming with SSE."""
+    # We need to mock the LangGraph app.astream_events
+    mock_events = [
+        {"event": "on_chat_model_start", "name": "gpt-5", "data": {"input": "..."}},
+        {"event": "on_chat_model_stream", "name": "gpt-5", "data": {"chunk": "Hello"}},
+        {"event": "on_chain_end", "name": "agent", "data": {"output": "..."}}
+    ]
+    
+    async def mock_astream_events(*args, **kwargs):
+        for event in mock_events:
+            yield event
+
+    with patch("ea_chatbot.api.routers.agent.app.astream_events", side_effect=mock_astream_events), \
+         patch("ea_chatbot.api.routers.agent.get_checkpointer") as mock_cp:
+        
+        mock_cp.return_value.__aenter__.return_value = AsyncMock()
+        
+        # Using TestClient with a stream context
+        with client.stream("POST", "/chat/stream", 
+                          json={"message": "hello", "thread_id": "t1"}, 
+                          headers=auth_header) as response:
+            assert response.status_code == 200
+            assert response.headers["content-type"] == "text/event-stream"
+            
+            lines = list(response.iter_lines())
+            # Each event should start with 'data: ' and be valid JSON
+            data_lines = [line for line in lines if line.startswith("data: ")]
+            assert len(data_lines) >= len(mock_events)