Add endpoint to get a single trade by ID

backend/routes/exchange.py

@@ -565,6 +565,29 @@ async def get_my_trades(
     return [_to_exchange_response(ex, current_user.email) for ex in exchanges]
 
 
+@trades_router.get("/{exchange_id}", response_model=ExchangeResponse)
+async def get_my_trade(
+    exchange_id: int,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(require_permission(Permission.VIEW_OWN_EXCHANGES)),
+) -> ExchangeResponse:
+    """Get a specific trade by ID. User can only access their own trades."""
+    result = await db.execute(
+        select(Exchange).where(
+            and_(Exchange.id == exchange_id, Exchange.user_id == current_user.id)
+        )
+    )
+    exchange = result.scalar_one_or_none()
+
+    if not exchange:
+        raise HTTPException(
+            status_code=404,
+            detail="Trade not found or you don't have permission to view it.",
+        )
+
+    return _to_exchange_response(exchange, current_user.email)
+
+
 @trades_router.post("/{exchange_id}/cancel", response_model=ExchangeResponse)
 async def cancel_my_trade(
     exchange_id: int,

backend/tests/test_exchange.py

@@ -646,6 +646,79 @@ class TestUserTrades:
         assert len(data) == 2
 
 
+class TestGetMyTrade:
+    """Test getting a single trade by ID."""
+
+    @pytest.mark.asyncio
+    async def test_get_my_trade_success(self, client_factory, regular_user, admin_user):
+        """Can get own trade by ID."""
+        target_date = await setup_availability_and_price(client_factory, admin_user)
+
+        with mock_price_fetcher(20000.0):
+            async with client_factory.create(cookies=regular_user["cookies"]) as client:
+                # Create a trade
+                create_response = await client.post(
+                    "/api/exchange",
+                    json={
+                        "slot_start": f"{target_date}T09:00:00Z",
+                        "direction": "buy",
+                        "bitcoin_transfer_method": "onchain",
+                        "eur_amount": 10000,
+                    },
+                )
+                assert create_response.status_code == 200
+                trade_id = create_response.json()["id"]
+
+                # Get the trade
+                get_response = await client.get(f"/api/trades/{trade_id}")
+
+        assert get_response.status_code == 200
+        data = get_response.json()
+        assert data["id"] == trade_id
+        assert data["direction"] == "buy"
+        assert data["bitcoin_transfer_method"] == "onchain"
+
+    @pytest.mark.asyncio
+    async def test_cannot_get_other_user_trade(
+        self, client_factory, regular_user, alt_regular_user, admin_user
+    ):
+        """Cannot get another user's trade."""
+        target_date = await setup_availability_and_price(client_factory, admin_user)
+
+        with mock_price_fetcher(20000.0):
+            # First user creates a trade
+            async with client_factory.create(cookies=regular_user["cookies"]) as client:
+                create_response = await client.post(
+                    "/api/exchange",
+                    json={
+                        "slot_start": f"{target_date}T09:00:00Z",
+                        "direction": "buy",
+                        "bitcoin_transfer_method": "onchain",
+                        "eur_amount": 10000,
+                    },
+                )
+                assert create_response.status_code == 200
+                trade_id = create_response.json()["id"]
+
+            # Second user tries to get it
+            async with client_factory.create(
+                cookies=alt_regular_user["cookies"]
+            ) as client:
+                get_response = await client.get(f"/api/trades/{trade_id}")
+
+        assert get_response.status_code == 404
+
+    @pytest.mark.asyncio
+    async def test_get_nonexistent_trade_returns_404(
+        self, client_factory, regular_user
+    ):
+        """Getting a nonexistent trade returns 404."""
+        async with client_factory.create(cookies=regular_user["cookies"]) as client:
+            response = await client.get("/api/trades/99999")
+
+        assert response.status_code == 404
+
+
 class TestCancelTrade:
     """Test cancelling trades."""