Add sys import to test files and remove obsolete integration tests

- Add sys import to 29 test files across agent-coordinator, blockchain-event-bridge, blockchain-node, and coordinator-api
- Remove apps/blockchain-event-bridge/tests/test_integration.py (obsolete bridge integration tests)
- Remove apps/coordinator-api/tests/test_integration.py (obsolete API integration tests)
- Implement GPU registration in marketplace_gpu.py with GPURegistry model persistence

apps/exchange/tests/test_unit_exchange.py

@@ -0,0 +1,144 @@
+"""Unit tests for exchange service"""
+
+import pytest
+import sys
+import sys
+from pathlib import Path
+
+
+from exchange_api import app, OrderCreate, OrderResponse, TradeResponse, OrderBookResponse
+
+
+@pytest.mark.unit
+def test_app_initialization():
+    """Test that the FastAPI app initializes correctly"""
+    assert app is not None
+    assert app.title == "AITBC Trade Exchange API"
+    assert app.version == "1.0.0"
+
+
+@pytest.mark.unit
+def test_order_create_model():
+    """Test OrderCreate model"""
+    order = OrderCreate(
+        order_type="BUY",
+        amount=100.0,
+        price=0.00001
+    )
+    assert order.order_type == "BUY"
+    assert order.amount == 100.0
+    assert order.price == 0.00001
+
+
+@pytest.mark.unit
+def test_order_create_model_sell():
+    """Test OrderCreate model with SELL"""
+    order = OrderCreate(
+        order_type="SELL",
+        amount=50.0,
+        price=0.00002
+    )
+    assert order.order_type == "SELL"
+    assert order.amount == 50.0
+
+
+@pytest.mark.unit
+def test_order_response_model():
+    """Test OrderResponse model"""
+    from datetime import datetime
+    order = OrderResponse(
+        id=1,
+        order_type="BUY",
+        amount=100.0,
+        price=0.00001,
+        total=0.001,
+        filled=0.0,
+        remaining=100.0,
+        status="OPEN",
+        created_at=datetime.utcnow()
+    )
+    assert order.id == 1
+    assert order.order_type == "BUY"
+    assert order.amount == 100.0
+    assert order.status == "OPEN"
+
+
+@pytest.mark.unit
+def test_trade_response_model():
+    """Test TradeResponse model"""
+    from datetime import datetime
+    trade = TradeResponse(
+        id=1,
+        amount=50.0,
+        price=0.00001,
+        total=0.0005,
+        created_at=datetime.utcnow()
+    )
+    assert trade.id == 1
+    assert trade.amount == 50.0
+    assert trade.total == 0.0005
+
+
+@pytest.mark.unit
+def test_order_book_response_model():
+    """Test OrderBookResponse model"""
+    from datetime import datetime
+    buy_order = OrderResponse(
+        id=1,
+        order_type="BUY",
+        amount=100.0,
+        price=0.00001,
+        total=0.001,
+        filled=0.0,
+        remaining=100.0,
+        status="OPEN",
+        created_at=datetime.utcnow()
+    )
+    sell_order = OrderResponse(
+        id=2,
+        order_type="SELL",
+        amount=50.0,
+        price=0.00002,
+        total=0.001,
+        filled=0.0,
+        remaining=50.0,
+        status="OPEN",
+        created_at=datetime.utcnow()
+    )
+    orderbook = OrderBookResponse(buys=[buy_order], sells=[sell_order])
+    assert len(orderbook.buys) == 1
+    assert len(orderbook.sells) == 1
+
+
+@pytest.mark.unit
+def test_order_create_negative_amount():
+    """Test OrderCreate with negative amount"""
+    order = OrderCreate(
+        order_type="BUY",
+        amount=-10.0,
+        price=0.00001
+    )
+    assert order.amount == -10.0
+
+
+@pytest.mark.unit
+def test_order_create_zero_price():
+    """Test OrderCreate with zero price"""
+    order = OrderCreate(
+        order_type="BUY",
+        amount=100.0,
+        price=0.0
+    )
+    assert order.price == 0.0
+
+
+@pytest.mark.unit
+def test_order_create_invalid_type():
+    """Test OrderCreate with invalid order type"""
+    # Model accepts any string, validation happens at endpoint level
+    order = OrderCreate(
+        order_type="INVALID",
+        amount=100.0,
+        price=0.00001
+    )
+    assert order.order_type == "INVALID"