diff --git a/tests/test_integration.py b/tests/test_integration.py
new file mode 100644
index 00000000..ed376b93
--- /dev/null
+++ b/tests/test_integration.py
@@ -0,0 +1,78 @@
+"""End-to-end integration tests for Polymarket agent."""
+from unittest.mock import MagicMock, patch
+
+
+def test_graph_compiles_with_all_analysts():
+    """Verify the graph compiles without errors."""
+    with patch("tradingagents.graph.trading_graph.create_llm_client") as mock_client:
+        mock_llm = MagicMock()
+        mock_client.return_value = MagicMock(get_llm=lambda: mock_llm)
+
+        from tradingagents.graph.trading_graph import TradingAgentsGraph
+        graph = TradingAgentsGraph(
+            selected_analysts=["odds", "social", "news", "event"],
+            debug=False,
+        )
+        assert graph.graph is not None
+
+
+def test_graph_compiles_with_single_analyst():
+    """Verify the graph works with a single analyst."""
+    with patch("tradingagents.graph.trading_graph.create_llm_client") as mock_client:
+        mock_llm = MagicMock()
+        mock_client.return_value = MagicMock(get_llm=lambda: mock_llm)
+
+        from tradingagents.graph.trading_graph import TradingAgentsGraph
+        graph = TradingAgentsGraph(
+            selected_analysts=["odds"],
+            debug=False,
+        )
+        assert graph.graph is not None
+
+
+def test_initial_state_has_correct_fields():
+    """Verify initial state matches AgentState schema."""
+    from tradingagents.graph.propagation import Propagator
+    prop = Propagator()
+    state = prop.create_initial_state("test-event-id", "Will X happen?", "2026-03-21")
+
+    assert state["event_id"] == "test-event-id"
+    assert state["event_question"] == "Will X happen?"
+    assert state["odds_report"] == ""
+    assert state["event_report"] == ""
+    assert state["trader_plan"] == ""
+    assert state["final_decision"] == ""
+    assert "timing_history" in state["investment_debate_state"]
+    assert "latest_speaker" in state["investment_debate_state"]
+    assert state["investment_debate_state"]["count"] == 0
+
+
+def test_initial_state_has_no_old_fields():
+    """Verify old stock-related fields are absent."""
+    from tradingagents.graph.propagation import Propagator
+    prop = Propagator()
+    state = prop.create_initial_state("evt", "Q?", "2026-01-01")
+
+    assert "company_of_interest" not in state
+    assert "market_report" not in state
+    assert "fundamentals_report" not in state
+    assert "trader_investment_plan" not in state
+    assert "final_trade_decision" not in state
+
+
+def test_signal_processor_json_output():
+    """Verify signal processor returns valid JSON."""
+    import json
+    from tradingagents.graph.signal_processing import SignalProcessor
+
+    mock_llm = MagicMock()
+    mock_llm.invoke.return_value = MagicMock(
+        content='{"action": "YES", "confidence": 0.8, "edge": 0.15, "position_size": 0.05, "reasoning": "Strong evidence", "time_horizon": "2 weeks"}'
+    )
+
+    processor = SignalProcessor(mock_llm)
+    result = processor.process_signal("Analysis text")
+    parsed = json.loads(result)
+    assert parsed["action"] == "YES"
+    assert parsed["confidence"] == 0.8
+    assert "edge" in parsed