feat: add POST /rebalance/calculate endpoint with manual prices

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/api/portfolio.py

@@ -16,6 +16,7 @@ from app.schemas.portfolio import (
     HoldingCreate, HoldingResponse, HoldingWithValue,
     TransactionCreate, TransactionResponse,
     RebalanceResponse, RebalanceSimulationRequest, RebalanceSimulationResponse,
+    RebalanceCalculateRequest, RebalanceCalculateResponse,
 )
 from app.services.rebalance import RebalanceService
 
@@ -319,6 +320,31 @@ async def simulate_rebalance(
     return service.calculate_rebalance(portfolio, additional_amount=data.additional_amount)
 
 
+@router.post("/{portfolio_id}/rebalance/calculate", response_model=RebalanceCalculateResponse)
+async def calculate_rebalance_manual(
+    portfolio_id: int,
+    data: RebalanceCalculateRequest,
+    current_user: CurrentUser,
+    db: Session = Depends(get_db),
+):
+    """Calculate rebalancing with manual prices and strategy selection."""
+    portfolio = _get_portfolio(db, portfolio_id, current_user.id)
+
+    if data.strategy == "additional_buy" and not data.additional_amount:
+        raise HTTPException(
+            status_code=400,
+            detail="additional_amount is required for additional_buy strategy"
+        )
+
+    service = RebalanceService(db)
+    return service.calculate_with_prices(
+        portfolio,
+        strategy=data.strategy,
+        manual_prices=data.prices,
+        additional_amount=data.additional_amount,
+    )
+
+
 @router.get("/{portfolio_id}/detail", response_model=PortfolioDetail)
 async def get_portfolio_detail(
     portfolio_id: int,

backend/tests/e2e/test_rebalance_flow.py

@@ -51,7 +51,7 @@ def test_calculate_rebalance_with_manual_prices(client: TestClient, auth_headers
     assert response.status_code == 200
     data = response.json()
     assert data["portfolio_id"] == pid
-    assert data["total_assets"] > 0
+    assert float(data["total_assets"]) > 0
     assert len(data["items"]) == 2
     # Verify items have required fields
     item = data["items"][0]
@@ -78,8 +78,8 @@ def test_calculate_additional_buy_strategy(client: TestClient, auth_headers):
     )
     assert response.status_code == 200
     data = response.json()
-    assert data["total_assets"] > 0
-    assert data["available_to_buy"] == 1000000
+    assert float(data["total_assets"]) > 0
+    assert float(data["available_to_buy"]) == 1000000
     # Additional buy should never have "sell" actions
     for item in data["items"]:
         assert item["action"] in ("buy", "hold")