Wire database-backed demo account into API

app/main.py

@@ -1,11 +1,13 @@
 import asyncio
 from pathlib import Path
-from fastapi import FastAPI, HTTPException, WebSocket, WebSocketDisconnect
+from fastapi import Depends, FastAPI, HTTPException, WebSocket, WebSocketDisconnect
 from fastapi.responses import FileResponse
 from fastapi.staticfiles import StaticFiles
+from sqlalchemy.orm import Session
 
 from app.coinex import CoinExClient
 from app.core import get_settings
+from app.db import SessionLocal, get_db, init_db
 from app.demo_account import DemoAccountService
 
 settings = get_settings()
@@ -17,6 +19,11 @@ static_dir = Path(__file__).parent / 'static'
 app.mount('/static', StaticFiles(directory=static_dir), name='static')
 
 
+@app.on_event('startup')
+def on_startup() -> None:
+    init_db()
+
+
 @app.get('/')
 async def dashboard() -> FileResponse:
     return FileResponse(static_dir / 'index.html')
@@ -35,19 +42,26 @@ async def health() -> dict:
 
 
 @app.get('/api/v1/demo/account')
-async def demo_account() -> dict:
+async def demo_account(db: Session = Depends(get_db)) -> dict:
-    return demo_service.snapshot().model_dump(mode='json')
+    return demo_service.snapshot(db).model_dump(mode='json')
 
 
 @app.post('/api/v1/demo/reset')
-async def reset_demo_account() -> dict:
+async def reset_demo_account(db: Session = Depends(get_db)) -> dict:
-    return demo_service.reset().model_dump(mode='json')
+    return demo_service.reset(db).model_dump(mode='json')
 
 
 @app.post('/api/v1/demo/trades')
-async def create_demo_trade(market: str, side: str, price: float, amount: float, reason: str = 'manual demo trade') -> dict:
+async def create_demo_trade(
+    market: str,
+    side: str,
+    price: float,
+    amount: float,
+    reason: str = 'manual demo trade',
+    db: Session = Depends(get_db),
+) -> dict:
     try:
-        trade = demo_service.add_demo_trade(market=market, side=side, price=price, amount=amount, reason=reason)
+        trade = demo_service.add_demo_trade(db=db, market=market, side=side, price=price, amount=amount, reason=reason)
         return trade.model_dump(mode='json')
     except ValueError as exc:
         raise HTTPException(status_code=400, detail=str(exc)) from exc
@@ -69,11 +83,13 @@ async def market_stream(websocket: WebSocket, market: str) -> None:
     try:
         while True:
             ticker = await coinex.get_ticker(market)
+            with SessionLocal() as db:
+                account = demo_service.snapshot(db).model_dump(mode='json')
             await websocket.send_json({
                 'type': 'ticker',
                 'market': market.upper(),
                 'data': ticker,
-                'demo_account': demo_service.snapshot().model_dump(mode='json'),
+                'demo_account': account,
             })
             await asyncio.sleep(3)
     except WebSocketDisconnect: