diff --git a/Dockerfile b/Dockerfile
index ff8c30b..931d6d0 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -12,23 +12,29 @@ FROM python:3.9-slim
 # Set working directory
 WORKDIR /app
 
-# Install system dependencies (if needed for TA-Lib or others)
-# RUN apt-get update && apt-get install -y gcc ...
+# Install system dependencies
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    gcc \
+    python3-dev \
+    && rm -rf /var/lib/apt/lists/*
 
 # Copy backend requirements
 COPY ./backend/requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 
-# Copy backend code
-COPY ./backend ./backend
+# Copy backend code (contents of backend folder to /app)
+COPY ./backend/ .
 
-# Copy frontend build artifacts to backend static folder
-COPY --from=frontend-build /app/frontend/dist ./backend/static
+# Copy frontend build artifacts to /app/static
+COPY --from=frontend-build /app/frontend/dist ./static
+
+# Ensure data directory exists
+RUN mkdir -p /app/data
 
 # Environment variables
 ENV PORT=80
 EXPOSE 80
 
 # Run FastAPI server
-# Assuming main.py is in backend folder and app object is named 'app'
-CMD ["uvicorn", "backend.app.main:app", "--host", "0.0.0.0", "--port", "80"]
\ No newline at end of file
+# Since app/ is now directly in /app, uvicorn app.main:app works
+CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "80"]
\ No newline at end of file
diff --git a/backend/app/__pycache__/main.cpython-312.pyc b/backend/app/__pycache__/main.cpython-312.pyc
index 48ae108..1c04938 100644
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diff --git a/backend/app/api/__pycache__/api.cpython-312.pyc b/backend/app/api/__pycache__/api.cpython-312.pyc
new file mode 100644
index 0000000..992e641
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diff --git a/backend/app/api/api.py b/backend/app/api/api.py
index 6b8a69c..c550aad 100644
--- a/backend/app/api/api.py
+++ b/backend/app/api/api.py
@@ -1,8 +1,16 @@
 from fastapi import APIRouter
-from app.api.endpoints import settings, kis
+from app.api.endpoints import settings, kis, account, watchlist, discovery, news, trade, auto_trade
 
 api_router = APIRouter()
 
 api_router.include_router(settings.router, prefix="/settings", tags=["settings"])
 api_router.include_router(kis.router, prefix="/kis", tags=["kis"])
-# api_router.include_router(trade.router, prefix="/trade", tags=["trade"])
+api_router.include_router(account.router, prefix="/account", tags=["account"])
+api_router.include_router(watchlist.router, prefix="/watchlists", tags=["watchlists"])
+api_router.include_router(discovery.router, prefix="/discovery", tags=["discovery"])
+api_router.include_router(discovery.router, prefix="/stocks", tags=["stocks"]) # Alias for search
+api_router.include_router(news.router, prefix="/news", tags=["news"])
+api_router.include_router(trade.router, prefix="/trade", tags=["trade"])
+api_router.include_router(trade.router, prefix="/history", tags=["history"]) # Alias
+api_router.include_router(trade.router, prefix="/reserved-orders", tags=["reserved"]) # Alias
+api_router.include_router(auto_trade.router, prefix="/auto-trade", tags=["auto-trade"])
diff --git a/backend/app/api/endpoints/__pycache__/kis.cpython-312.pyc b/backend/app/api/endpoints/__pycache__/kis.cpython-312.pyc
new file mode 100644
index 0000000..e67f928
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diff --git a/backend/app/api/endpoints/__pycache__/settings.cpython-312.pyc b/backend/app/api/endpoints/__pycache__/settings.cpython-312.pyc
new file mode 100644
index 0000000..65e3433
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diff --git a/backend/app/api/endpoints/account.py b/backend/app/api/endpoints/account.py
new file mode 100644
index 0000000..7aa6967
--- /dev/null
+++ b/backend/app/api/endpoints/account.py
@@ -0,0 +1,54 @@
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select
+from typing import List
+
+from app.db.database import get_db
+from app.db.models import AccountStatus, Holding
+from pydantic import BaseModel
+
+router = APIRouter()
+
+class AccountStatusSchema(BaseModel):
+    totalAssets: float
+    buyingPower: float
+    dailyProfit: float
+    dailyProfitRate: float
+    
+    class Config:
+        from_attributes = True
+
+class HoldingSchema(BaseModel):
+    stockCode: str
+    stockName: str
+    quantity: int
+    avgPrice: float
+    currentPrice: float
+    profit: float
+    profitRate: float
+    marketValue: float
+
+    class Config:
+        from_attributes = True
+
+@router.get("/summary", response_model=AccountStatusSchema)
+async def get_account_summary(db: AsyncSession = Depends(get_db)):
+    stmt = select(AccountStatus).where(AccountStatus.id == 1)
+    result = await db.execute(stmt)
+    status = result.scalar_one_or_none()
+    
+    if not status:
+        # Return default zeroed if not initialized
+        return AccountStatusSchema(totalAssets=0, buyingPower=0, dailyProfit=0, dailyProfitRate=0)
+    
+    return status
+
+@router.get("/holdings", response_model=List[HoldingSchema])
+async def get_holdings(market: str = None, db: AsyncSession = Depends(get_db)):
+    # TODO: Filter by market if Holding table supports it. 
+    # Current Holding model doesn't have 'market' column explicitly, but we can assume mixed or add it.
+    # For now, return all.
+    stmt = select(Holding)
+    result = await db.execute(stmt)
+    holdings = result.scalars().all()
+    return holdings
diff --git a/backend/app/api/endpoints/auto_trade.py b/backend/app/api/endpoints/auto_trade.py
new file mode 100644
index 0000000..25cbbce
--- /dev/null
+++ b/backend/app/api/endpoints/auto_trade.py
@@ -0,0 +1,87 @@
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select, delete
+from typing import List, Optional
+from pydantic import BaseModel
+from datetime import datetime
+
+from app.db.database import get_db
+from app.db.models import AutoTradeRobot
+
+router = APIRouter()
+
+# --- Schema ---
+class AutoTradeConfigSchema(BaseModel):
+    id: str
+    stockCode: str
+    stockName: str
+    groupId: Optional[str] = None
+    type: str
+    frequency: str
+    executionTime: str
+    market: str
+    quantity: int
+    specificDay: Optional[int] = None
+    trailingPercent: Optional[float] = None
+    active: bool = True
+    
+    class Config:
+        from_attributes = True
+
+# --- Endpoints ---
+@router.get("/configs", response_model=List[AutoTradeConfigSchema])
+async def get_auto_configs(db: AsyncSession = Depends(get_db)):
+    stmt = select(AutoTradeRobot)
+    res = await db.execute(stmt)
+    return res.scalars().all()
+
+@router.post("/configs")
+async def create_auto_config(config: AutoTradeConfigSchema, db: AsyncSession = Depends(get_db)):
+    # Check exists? Upsert? 
+    # Frontend generates ID usually or we do. Schema has ID.
+    # We will upsert (merge) or just add.
+    
+    # Check if exists
+    stmt = select(AutoTradeRobot).where(AutoTradeRobot.id == config.id)
+    res = await db.execute(stmt)
+    existing = res.scalar_one_or_none()
+    
+    if existing:
+        # Update
+        existing.stockCode = config.stockCode
+        existing.stockName = config.stockName
+        existing.groupId = config.groupId
+        existing.type = config.type
+        existing.frequency = config.frequency
+        existing.executionTime = config.executionTime
+        existing.market = config.market
+        existing.quantity = config.quantity
+        existing.specificDay = config.specificDay
+        existing.trailingPercent = config.trailingPercent
+        existing.active = config.active
+    else:
+        # Create
+        new_obj = AutoTradeRobot(
+            id=config.id,
+            stockCode=config.stockCode,
+            stockName=config.stockName,
+            groupId=config.groupId,
+            type=config.type,
+            frequency=config.frequency,
+            executionTime=config.executionTime,
+            market=config.market,
+            quantity=config.quantity,
+            specificDay=config.specificDay,
+            trailingPercent=config.trailingPercent,
+            active=config.active
+        )
+        db.add(new_obj)
+        
+    await db.commit()
+    return {"status": "saved", "id": config.id}
+
+@router.delete("/configs/{config_id}")
+async def delete_auto_config(config_id: str, db: AsyncSession = Depends(get_db)):
+    await db.execute(delete(AutoTradeRobot).where(AutoTradeRobot.id == config_id))
+    await db.commit()
+    return {"status": "deleted"}
diff --git a/backend/app/api/endpoints/discovery.py b/backend/app/api/endpoints/discovery.py
new file mode 100644
index 0000000..1230792
--- /dev/null
+++ b/backend/app/api/endpoints/discovery.py
@@ -0,0 +1,68 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select
+from typing import List
+from pydantic import BaseModel
+
+from app.db.database import get_db
+from app.db.models import MasterStock, DiscoveryRankingCache, StockItem
+
+router = APIRouter()
+
+class StockItemSchema(BaseModel):
+    code: str
+    name: str
+    market: str
+    class Config:
+        from_attributes = True
+        
+class RankingItemSchema(BaseModel):
+    code: str
+    name: str
+    price: float
+    change: float
+    changePercent: float
+    class Config:
+        from_attributes = True
+
+@router.get("/rankings", response_model=List[RankingItemSchema])
+async def get_rankings(type: str = "rise", limit: int = 10, db: AsyncSession = Depends(get_db)):
+    """
+    Get Top Rankings based on cached StockItem data.
+    type: 'rise' (Top Gainers), 'fall' (Top Losers), 'volume' (Not impl yet)
+    """
+    stmt = select(StockItem)
+    
+    if type == "fall":
+        stmt = stmt.order_by(StockItem.changePercent.asc())
+    else:
+        stmt = stmt.order_by(StockItem.changePercent.desc())
+        
+    stmt = stmt.limit(limit)
+    res = await db.execute(stmt)
+    items = res.scalars().all()
+    
+    return items
+
+@router.get("/stocks/search", response_model=List[StockItemSchema])
+async def search_stocks(query: str, db: AsyncSession = Depends(get_db)):
+    # Search by name or code
+    stmt = select(MasterStock).where(
+        (MasterStock.name.like(f"%{query}%")) | (MasterStock.code.like(f"%{query}%"))
+    ).limit(20)
+    result = await db.execute(stmt)
+    stocks = result.scalars().all()
+    return stocks
+
+from app.services.master_service import master_service
+
+@router.get("/kis/master-stocks")
+async def sync_master_stocks(db: AsyncSession = Depends(get_db)):
+    # Trigger Sync
+    # Ideally should be BackgroundTasks, but for now await to show result
+    await master_service.sync_master_data(db)
+    
+    # Return count
+    stmt = select(MasterStock).limit(1)
+    # Just return status
+    return {"status": "Sync Complete"}
diff --git a/backend/app/api/endpoints/kis.py b/backend/app/api/endpoints/kis.py
index 17ece84..4fa0fc3 100644
--- a/backend/app/api/endpoints/kis.py
+++ b/backend/app/api/endpoints/kis.py
@@ -3,8 +3,10 @@ from pydantic import BaseModel
 from typing import Literal
 
 from app.services.kis_client import kis_client
+import logging
 
 router = APIRouter()
+logger = logging.getLogger("KisAPI")
 
 class OrderRequest(BaseModel):
     market: Literal["Domestic", "Overseas"]
@@ -13,6 +15,15 @@ class OrderRequest(BaseModel):
     quantity: int
     price: float = 0 # 0 for Market Price (if supported)
 
+class ModifyOrderRequest(BaseModel):
+    market: Literal["Domestic", "Overseas"]
+    order_no: str
+    code: str
+    quantity: int
+    price: float = 0
+    type: str = "00"
+    is_cancel: bool = False # True = Cancel, False = Modify
+
 @router.get("/price")
 async def get_current_price(market: Literal["Domestic", "Overseas"], code: str):
     """
@@ -29,11 +40,22 @@ async def get_balance(market: Literal["Domestic", "Overseas"]):
     try:
         data = await kis_client.get_balance(market)
         return data
+        raise HTTPException(status_code=500, detail=str(e))
+
+@router.put("/order")
+async def modify_order(req: ModifyOrderRequest):
+    logger.info(f"Received Modify/Cancel Request: {req}")
+    try:
+        res = await kis_client.modify_order(
+            req.market, req.order_no, req.code, req.quantity, req.price, req.type, req.is_cancel
+        )
+        return res
     except Exception as e:
         raise HTTPException(status_code=500, detail=str(e))
 
 @router.post("/order")
 async def place_order(order: OrderRequest):
+    logger.info(f"Received Order Request: {order}")
     try:
         res = await kis_client.place_order(order.market, order.side, order.code, order.quantity, order.price)
         return res
diff --git a/backend/app/api/endpoints/news.py b/backend/app/api/endpoints/news.py
new file mode 100644
index 0000000..36a1208
--- /dev/null
+++ b/backend/app/api/endpoints/news.py
@@ -0,0 +1,29 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select
+from typing import List
+from pydantic import BaseModel
+
+from app.db.database import get_db
+from app.db.models import NewsCache
+
+router = APIRouter()
+
+class NewsItemSchema(BaseModel):
+    news_id: str
+    title: str
+    description: str
+    pubDate: str
+    sentiment: str | None
+    class Config:
+        from_attributes = True
+
+@router.get("/", response_model=List[NewsItemSchema])
+async def get_news(query: str = None, limit: int = 50, db: AsyncSession = Depends(get_db)):
+    stmt = select(NewsCache).order_by(NewsCache.pubDate.desc()).limit(limit)
+    if query:
+        stmt = stmt.where(NewsCache.title.like(f"%{query}%"))
+        
+    result = await db.execute(stmt)
+    news = result.scalars().all()
+    return news
diff --git a/backend/app/api/endpoints/settings.py b/backend/app/api/endpoints/settings.py
index 20fdaf9..be90518 100644
--- a/backend/app/api/endpoints/settings.py
+++ b/backend/app/api/endpoints/settings.py
@@ -6,8 +6,10 @@ from pydantic import BaseModel
 from app.db.database import get_db
 from app.db.models import ApiSettings
 from app.services.kis_auth import kis_auth
+import logging
 
 router = APIRouter()
+logger = logging.getLogger("SettingsAPI")
 
 class SettingsSchema(BaseModel):
     # Partial schema for updates
@@ -50,6 +52,7 @@ async def get_settings(db: AsyncSession = Depends(get_db)):
 
 @router.put("/", response_model=SettingsSchema)
 async def update_settings(payload: SettingsSchema, db: AsyncSession = Depends(get_db)):
+    logger.info("Updating API Settings...")
     stmt = select(ApiSettings).where(ApiSettings.id == 1)
     result = await db.execute(stmt)
     settings = result.scalar_one_or_none()
diff --git a/backend/app/api/endpoints/trade.py b/backend/app/api/endpoints/trade.py
new file mode 100644
index 0000000..35bfde2
--- /dev/null
+++ b/backend/app/api/endpoints/trade.py
@@ -0,0 +1,100 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select
+from typing import List
+from pydantic import BaseModel
+from datetime import datetime
+
+from app.db.database import get_db
+from app.db.models import TradeHistory, AutoTradeRobot, ReservedOrder
+
+router = APIRouter()
+
+# --- Schemas ---
+class TradeOrderSchema(BaseModel):
+    id: str
+    stockName: str
+    type: str
+    quantity: int
+    price: float
+    timestamp: datetime
+    status: str
+    class Config:
+        from_attributes = True
+        
+class ReservedOrderSchema(BaseModel):
+    id: str
+    stockName: str
+    stockCode: str
+    monitoringType: str
+    status: str
+    class Config:
+        from_attributes = True
+
+class CreateReservedOrderRequest(BaseModel):
+    stockCode: str
+    stockName: str
+    monitoringType: str # PRICE_TRIGGER
+    triggerPrice: float
+    orderType: str # BUY, SELL
+    quantity: int
+    price: float = 0 # Limit price (0 = Market)
+    
+    # Trailing Stop Options
+    trailingType: str | None = None # AMOUNT, PERCENT
+    trailingValue: float | None = None
+    stopLossValue: float | None = None
+
+class ReservedOrderResponse(BaseModel):
+    id: str
+    status: str
+
+# --- Endpoints ---
+
+@router.get("/history/orders", response_model=List[TradeOrderSchema])
+async def get_trade_history(limit: int = 100, db: AsyncSession = Depends(get_db)):
+    stmt = select(TradeHistory).order_by(TradeHistory.timestamp.desc()).limit(limit)
+    result = await db.execute(stmt)
+    return result.scalars().all()
+
+@router.get("/reserved-orders", response_model=List[ReservedOrderSchema])
+async def get_reserved_orders(db: AsyncSession = Depends(get_db)):
+    stmt = select(ReservedOrder)
+    result = await db.execute(stmt)
+    return result.scalars().all()
+
+@router.post("/reserved-orders")
+async def create_reserved_order(req: CreateReservedOrderRequest, db: AsyncSession = Depends(get_db)):
+    import uuid
+    new_id = str(uuid.uuid4())
+    
+    order = ReservedOrder(
+        id=new_id,
+        stockCode=req.stockCode,
+        stockName=req.stockName,
+        monitoringType=req.monitoringType,
+        triggerPrice=req.triggerPrice,
+        type=req.orderType, # BUY/SELL
+        quantity=req.quantity,
+        price=req.price,
+        
+        # TS Fields
+        trailingType=req.trailingType,
+        trailingValue=req.trailingValue,
+        stopLossValue=req.stopLossValue,
+        highestPrice=0, # Init
+        lowestPrice=99999999, # Init
+        
+        status="MONITORING",
+        created_at=datetime.now()
+    )
+    db.add(order)
+    await db.commit()
+    return {"id": new_id, "status": "MONITORING"}
+
+@router.delete("/reserved-orders/{order_id}")
+async def delete_reserved_order(order_id: str, db: AsyncSession = Depends(get_db)):
+    from sqlalchemy import delete
+    await db.execute(delete(ReservedOrder).where(ReservedOrder.id == order_id))
+    await db.commit()
+    return {"status": "Deleted"}
diff --git a/backend/app/api/endpoints/watchlist.py b/backend/app/api/endpoints/watchlist.py
new file mode 100644
index 0000000..e9dc16b
--- /dev/null
+++ b/backend/app/api/endpoints/watchlist.py
@@ -0,0 +1,95 @@
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select, delete
+from sqlalchemy.orm import selectinload
+from typing import List
+from pydantic import BaseModel
+from datetime import datetime
+import uuid
+
+from app.db.database import get_db
+from app.db.models import WatchlistGroup, WatchlistItem
+
+router = APIRouter()
+
+# --- Schemas ---
+class WatchlistItemSchema(BaseModel):
+    stock_code: str
+    added_at: datetime
+    class Config:
+        from_attributes = True
+
+class WatchlistGroupSchema(BaseModel):
+    id: str
+    name: str
+    market: str
+    items: List[WatchlistItemSchema] = []
+    class Config:
+        from_attributes = True
+
+class CreateGroupRequest(BaseModel):
+    name: str
+    market: str
+    codes: List[str] = []
+
+class UpdateGroupRequest(BaseModel):
+    name: str | None = None
+    codes: List[str] | None = None
+
+# --- Endpoints ---
+
+@router.get("/", response_model=List[WatchlistGroupSchema])
+async def get_watchlists(db: AsyncSession = Depends(get_db)):
+    # Load groups with items (Need relationship setup? 
+    # Current models.py WatchlistGroup doesn't have `items` relationship defined explicitly in snippet provided?
+    # Let's assume we need to join manually or update models.
+    # Checking models.py... WatchlistItem has foreign key.
+    # Ideally should add `items = relationship("WatchlistItem")` to WatchlistGroup.
+    # For now, let's just fetch items separately or via join.
+    pass
+    # Creating relationship on the fly or assuming simple manual join for safety.
+    
+    stmt = select(WatchlistGroup)
+    result = await db.execute(stmt)
+    groups = result.scalars().all()
+    
+    resp = []
+    for g in groups:
+        # Fetch items
+        stmt_items = select(WatchlistItem).where(WatchlistItem.group_id == g.id)
+        res_items = await db.execute(stmt_items)
+        items = res_items.scalars().all()
+        
+        g_schema = WatchlistGroupSchema(
+            id=g.id, name=g.name, market=g.market,
+            items=[WatchlistItemSchema.model_validate(i) for i in items]
+        )
+        resp.append(g_schema)
+        
+    return resp
+
+@router.post("/", response_model=WatchlistGroupSchema)
+async def create_watchlist(req: CreateGroupRequest, db: AsyncSession = Depends(get_db)):
+    gid = str(uuid.uuid4())
+    group = WatchlistGroup(id=gid, name=req.name, market=req.market)
+    db.add(group)
+    
+    items = []
+    for code in req.codes:
+        item = WatchlistItem(group_id=gid, stock_code=code)
+        db.add(item)
+        items.append(item)
+        
+    await db.commit()
+    return WatchlistGroupSchema(
+        id=gid, name=req.name, market=req.market,
+        items=[WatchlistItemSchema(stock_code=i.stock_code, added_at=i.added_at) for i in items]
+    )
+
+@router.delete("/{group_id}")
+async def delete_watchlist(group_id: str, db: AsyncSession = Depends(get_db)):
+    # Delete items first (Cascade usually handls this but explicit is safe)
+    await db.execute(delete(WatchlistItem).where(WatchlistItem.group_id == group_id))
+    await db.execute(delete(WatchlistGroup).where(WatchlistGroup.id == group_id))
+    await db.commit()
+    return {"status": "deleted"}
diff --git a/backend/app/core/__pycache__/crypto.cpython-312.pyc b/backend/app/core/__pycache__/crypto.cpython-312.pyc
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diff --git a/backend/app/core/__pycache__/rate_limiter.cpython-312.pyc b/backend/app/core/__pycache__/rate_limiter.cpython-312.pyc
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diff --git a/backend/app/core/startup.py b/backend/app/core/startup.py
new file mode 100644
index 0000000..4f8c3f5
--- /dev/null
+++ b/backend/app/core/startup.py
@@ -0,0 +1,69 @@
+import logging
+import asyncio
+from sqlalchemy import select
+from app.db.database import SessionLocal
+from app.db.models import ApiSettings
+from app.core.config import settings
+from app.services.kis_auth import kis_auth
+from app.services.sync_service import sync_service
+
+logger = logging.getLogger(__name__)
+
+async def run_startup_sequence():
+    """
+    Executes the Phase 1~4 startup sequence defined in ReadMe.md.
+    """
+    logger.info("=== Starting System Initialization Sequence ===")
+    
+    async with SessionLocal() as db_session:
+        # Phase 1: DB & Settings Load
+        stmt = select(ApiSettings).where(ApiSettings.id == 1)
+        result = await db_session.execute(stmt)
+        settings_obj = result.scalar_one_or_none()
+        
+        if not settings_obj:
+            settings_obj = ApiSettings(id=1)
+            db_session.add(settings_obj)
+            await db_session.commit()
+            logger.info("Created Default ApiSettings.")
+            
+        # Phase 2: KIS Connectivity
+        if not settings_obj.appKey or not settings_obj.appSecret:
+            logger.warning(">> [Phase 2] KIS Credentials (appKey/Secret) NOT FOUND in DB.")
+            logger.warning("   Please configure them via the Settings Page.")
+            logger.warning("   Skipping Token Issue & Realtime Connection.")
+        else:
+            logger.info(">> [Phase 2] KIS Credentials Found. Attempting Authentication...")
+            try:
+                # 1. Access Token
+                token = await kis_auth.get_access_token(db_session)
+                masked_token = token[:10] + "..." if token else "None"
+                logger.info(f"   [OK] Access Token Valid (Starts with: {masked_token})")
+                
+                # 2. Approval Key (Optional, lazy load usually, but good to check)
+                # approval_key = await kis_auth.get_approval_key(db_session)
+                # logger.info("   [OK] WebSocket Approval Key Issued.")
+                
+            except Exception as e:
+                logger.error(f"   [FAILED] Authentication Failed: {e}")
+                logger.error("   Please check your AppKey/Secret and ensure KIS API Server is reachable.")
+
+        # Phase 2.5: Telegram (Placeholder)
+        if settings_obj.useTelegram and settings_obj.telegramToken:
+            logger.info(">> [Phase 2] Telegram Token Found. Sending Startup Message...")
+            # TODO: Implement Telegram Sender
+        else:
+            logger.info(">> [Phase 2] Telegram Disabled or Token missing.")
+
+        # Phase 3: Data Sync (Master Stocks & Account)
+        logger.info(">> [Phase 3-1] Syncing Account Data...")
+        await sync_service.sync_account(db_session)
+        
+        logger.info(">> [Phase 3-2] Syncing Master Data (This may take a while)...")
+        from app.services.master_service import master_service
+        await master_service.sync_master_data(db_session)
+        
+        # Phase 4: Scheduler
+        # (Scheduler is started in main.py)
+        
+    logger.info("=== System Initialization Complete ===")
diff --git a/backend/app/main.py b/backend/app/main.py
index 3e666a8..5c69a71 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -9,14 +9,31 @@ from app.core.config import settings
 from app.db.init_db import init_db
 from app.workers.scheduler import start_scheduler
 
+import logging
+
+# Configure Logging
+logging.basicConfig(
+    level=logging.INFO,
+    format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
+)
+logger = logging.getLogger(__name__)
+
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     # Startup: Initialize DB
+    logger.info("Initializing Database...")
     await init_db()
+    
+    # Startup Sequence (Auth, Checks)
+    await run_startup_sequence()
+    
+    logger.info("Starting Background Scheduler...")
     start_scheduler()
-    print("Database & Scheduler Initialized")
+    
+    logger.info("Application Startup Complete.")
     yield
-    # Shutdown: Cleanup if needed
+    # Shutdown
+    logger.info("Application Shutdown.")
 
 app = FastAPI(
     title=settings.PROJECT_NAME,
@@ -59,4 +76,4 @@ STATIC_DIR = BASE_DIR / "static"
 if STATIC_DIR.exists():
     app.mount("/", StaticFiles(directory=str(STATIC_DIR), html=True), name="static")
 else:
-    print(f"Warning: Static directory not found at {STATIC_DIR}")
+    logger.warning(f"Static directory not found at {STATIC_DIR}")
diff --git a/backend/app/services/__pycache__/kis_auth.cpython-312.pyc b/backend/app/services/__pycache__/kis_auth.cpython-312.pyc
new file mode 100644
index 0000000..e1b0688
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diff --git a/backend/app/services/__pycache__/kis_client.cpython-312.pyc b/backend/app/services/__pycache__/kis_client.cpython-312.pyc
new file mode 100644
index 0000000..178daa4
Binary files /dev/null and b/backend/app/services/__pycache__/kis_client.cpython-312.pyc differ
diff --git a/backend/app/services/__pycache__/realtime_manager.cpython-312.pyc b/backend/app/services/__pycache__/realtime_manager.cpython-312.pyc
new file mode 100644
index 0000000..df918d5
Binary files /dev/null and b/backend/app/services/__pycache__/realtime_manager.cpython-312.pyc differ
diff --git a/backend/app/services/kis_auth.py b/backend/app/services/kis_auth.py
index fa17e67..2ca2866 100644
--- a/backend/app/services/kis_auth.py
+++ b/backend/app/services/kis_auth.py
@@ -5,13 +5,14 @@ from app.db.database import SessionLocal
 from app.db.models import ApiSettings 
 from app.db.models import ApiSettings 
 from app.core.crypto import decrypt_str, encrypt_str
+import logging
 
 class KisAuth:
     BASE_URL_REAL = "https://openapi.koreainvestment.com:9443"
     # BASE_URL_VIRTUAL = "https://openapivts.koreainvestment.com:29443"
     
     def __init__(self):
-        pass
+        self.logger = logging.getLogger(self.__class__.__name__)
 
     async def get_access_token(self, db_session=None) -> str:
         """
@@ -37,9 +38,11 @@ class KisAuth:
                  token_dec = decrypt_str(settings_obj.accessToken)
                  if token_dec and token_dec != "[Decryption Failed]":
                      if settings_obj.tokenExpiry > datetime.now() + timedelta(minutes=10):
+                         # self.logger.debug("Using cached Access Token.") # Too verbose?
                          return token_dec
             
             # 3. Issue New Token
+            self.logger.info("Access Token Expired or Missing. Issuing New Token...")
             app_key_dec = decrypt_str(settings_obj.appKey)
             app_secret_dec = decrypt_str(settings_obj.appSecret)
             token_data = await self._issue_token(app_key_dec, app_secret_dec)
diff --git a/backend/app/services/kis_client.py b/backend/app/services/kis_client.py
index 78e4f3b..6d2204f 100644
--- a/backend/app/services/kis_client.py
+++ b/backend/app/services/kis_client.py
@@ -6,6 +6,7 @@ from app.db.database import SessionLocal
 from app.db.models import ApiSettings 
 from sqlalchemy import select
 from app.core.crypto import decrypt_str
+import logging
 
 class KisClient:
     """
@@ -15,16 +16,19 @@ class KisClient:
     
     # Domestic URLs
     URL_DOMESTIC_ORDER = "/uapi/domestic-stock/v1/trading/order-cash"
+    URL_DOMESTIC_MODIFY = "/uapi/domestic-stock/v1/trading/order-rvsecncl"
     URL_DOMESTIC_PRICE = "/uapi/domestic-stock/v1/quotations/inquire-price"
     URL_DOMESTIC_BALANCE = "/uapi/domestic-stock/v1/trading/inquire-balance"
     
     # Overseas URLs
     URL_OVERSEAS_ORDER = "/uapi/overseas-stock/v1/trading/order"
+    URL_OVERSEAS_MODIFY = "/uapi/overseas-stock/v1/trading/order-rvsecncl"
     URL_OVERSEAS_PRICE = "/uapi/overseas-price/v1/quotations/price"
     URL_OVERSEAS_BALANCE = "/uapi/overseas-stock/v1/trading/inquire-balance"
 
     def __init__(self):
         pass
+        self.logger = logging.getLogger(self.__class__.__name__)
 
     async def _get_settings(self):
         async with SessionLocal() as session:
@@ -60,6 +64,7 @@ class KisClient:
         }
         
         full_url = f"{base_url}{url_path}"
+        # self.logger.debug(f"API Calling: {method} {url_path} (TR_ID: {tr_id})")
         
         async with httpx.AsyncClient() as client:
             if method == "GET":
@@ -178,6 +183,7 @@ class KisClient:
                 "ORD_QTY": str(quantity),
                 "ORD_UNPR": str(int(price)), # Cash Order requires integer price string
             }
+            self.logger.info(f"Ordering Domestic: {side} {code} {quantity}qty @ {price}")
             return await self._call_api("POST", self.URL_DOMESTIC_ORDER, tr_id, data=data)
             
         elif market == "Overseas":
@@ -197,4 +203,52 @@ class KisClient:
              }
              return await self._call_api("POST", self.URL_OVERSEAS_ORDER, tr_id, data=data)
 
+    async def modify_order(self, market: str, order_no: str, code: str, quantity: int, price: float, type: str = "00", cancel: bool = False) -> Dict:
+        """
+        Cancel or Modify Order.
+        cancel=True -> Cancel
+        """
+        settings = await self._get_settings()
+        acc_no_str = decrypt_str(settings.accountNumber)
+        
+        if '-' in acc_no_str:
+            cano, prdt = acc_no_str.split('-')
+        else:
+            cano = acc_no_str[:8]
+            prdt = acc_no_str[8:]
+            
+        if market == "Domestic":
+            # TR_ID: TTTC0803U (Modify/Cancel)
+            data = {
+                "CANO": cano,
+                "ACNT_PRDT_CD": prdt,
+                "KRX_FWDG_ORD_ORGNO": "", # Exchange Node? Usually empty or "00950"
+                "ORGN_ODNO": order_no,
+                "ORD_DVSN": type, 
+                "RVSE_CNCL_DVSN_CD": "02" if cancel else "01", # 01: Modify, 02: Cancel
+                "ORD_QTY": str(quantity),
+                "ORD_UNPR": str(int(price)),
+                "QTY_ALL_ORD_YN": "Y" if quantity == 0 else "N", # 0 means cancel all?
+            }
+            # Note: KRX_FWDG_ORD_ORGNO is tricky. Usually 5 digit branch code. Defaulting to "" might fail.
+            # Using '06010' (Online) or leaving blank depending on API.
+            # KIS API Doc: "주문상태조회"에서 얻은 ORGNO 사용해야 함.
+            # For this impl, we assume user knows or simple default.
+            
+            return await self._call_api("POST", self.URL_DOMESTIC_MODIFY, "TTTC0803U", data=data)
+            
+        elif market == "Overseas":
+            # MCCL: TTTT1004U
+             data = {
+                "CANO": cano,
+                "ACNT_PRDT_CD": prdt,
+                "OVRS_EXCG_CD": "NASD", 
+                "PDNO": code,
+                "ORGN_ODNO": order_no,
+                "RVSE_CNCL_DVSN_CD": "02" if cancel else "01",
+                "ORD_QTY": str(quantity),
+                "OVRS_ORD_UNPR": str(price),
+             }
+             return await self._call_api("POST", self.URL_OVERSEAS_MODIFY, "TTTT1004U", data=data)
+
 kis_client = KisClient()
diff --git a/backend/app/services/master_service.py b/backend/app/services/master_service.py
new file mode 100644
index 0000000..31cc143
--- /dev/null
+++ b/backend/app/services/master_service.py
@@ -0,0 +1,112 @@
+import os
+import zipfile
+import httpx
+import logging
+import asyncio
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import delete
+from app.db.models import MasterStock
+from app.db.database import SessionLocal
+
+logger = logging.getLogger(__name__)
+
+class MasterService:
+    BASE_URL = "https://new.real.download.dws.co.kr/common/master"
+    FILES = {
+        "KOSPI": "kospi_code.mst.zip",
+        "KOSDAQ": "kosdaq_code.mst.zip"
+    }
+    TMP_DIR = "./tmp_master"
+
+    async def sync_master_data(self, db: AsyncSession):
+        """
+        Download and parse KOSPI/KOSDAQ master files.
+        Populate MasterStock table.
+        """
+        logger.info("MasterService: Starting Master Data Sync...")
+        os.makedirs(self.TMP_DIR, exist_ok=True)
+        
+        try:
+            # Clear existing data? Or Upsert?
+            # For simplicity, Clear and Re-insert (Full Sync)
+            # await db.execute(delete(MasterStock)) # Optional: Clear all
+            
+            total_count = 0
+            
+            async with httpx.AsyncClient(verify=False) as client:
+                for market, filename in self.FILES.items():
+                    url = f"{self.BASE_URL}/{filename}"
+                    dest = os.path.join(self.TMP_DIR, filename)
+                    
+                    # 1. Download
+                    logger.info(f"Downloading {market} from {url}...")
+                    try:
+                        resp = await client.get(url, timeout=60.0)
+                        resp.raise_for_status()
+                        with open(dest, "wb") as f:
+                            f.write(resp.content)
+                    except Exception as e:
+                        logger.error(f"Failed to download {market}: {e}")
+                        continue
+
+                    # 2. Unzip & Parse
+                    count = await self._process_zip(dest, market, db)
+                    total_count += count
+            
+            await db.commit()
+            logger.info(f"MasterService: Sync Complete. Total {total_count} stocks.")
+            
+            # Cleanup
+            # shutil.rmtree(self.TMP_DIR) 
+
+        except Exception as e:
+            logger.error(f"MasterService: Fatal Error: {e}")
+            await db.rollback()
+
+    async def _process_zip(self, zip_path: str, market: str, db: AsyncSession) -> int:
+        try:
+            with zipfile.ZipFile(zip_path, 'r') as zf:
+                mst_filename = zf.namelist()[0] # Usually only one .mst file
+                zf.extract(mst_filename, self.TMP_DIR)
+                mst_path = os.path.join(self.TMP_DIR, mst_filename)
+                
+                return await self._parse_mst(mst_path, market, db)
+        except Exception as e:
+            logger.error(f"Error processing ZIP {zip_path}: {e}")
+            return 0
+
+    async def _parse_mst(self, mst_path: str, market: str, db: AsyncSession) -> int:
+        count = 0
+        batch = []
+        
+        # Encoding is usually cp949 for KIS files
+        with open(mst_path, "r", encoding="cp949", errors="replace") as f:
+            for line in f:
+                # Format:
+                # row[0:9] : Short Code (Example: "005930   ")
+                # row[9:21] : Standard Code
+                # row[21:len-222] : Name
+                
+                if len(line) < 250: continue # Invalid line
+                
+                short_code = line[0:9].strip()
+                # standard_code = line[9:21].strip()
+                name_part = line[21:len(line)-222].strip()
+                
+                if not short_code or not name_part: continue
+                
+                # Check for ETF/ETN? (Usually included)
+                
+                obj = MasterStock(
+                    code=short_code,
+                    name=name_part,
+                    market=market
+                )
+                db.add(obj)
+                count += 1
+                
+                # Batch commit? session.add is fast, commit at end.
+                
+        return count
+
+master_service = MasterService()
diff --git a/backend/app/services/realtime_manager.py b/backend/app/services/realtime_manager.py
index 6ee075c..5b6b852 100644
--- a/backend/app/services/realtime_manager.py
+++ b/backend/app/services/realtime_manager.py
@@ -3,6 +3,7 @@ import json
 import websockets
 import logging
 from typing import Dict, Set, Callable, Optional
+from datetime import datetime
 
 from app.services.kis_auth import kis_auth
 from app.core.crypto import aes_cbc_base64_dec
@@ -21,134 +22,113 @@ class RealtimeManager:
     def __init__(self):
         self.ws: Optional[websockets.WebSocketClientProtocol] = None
         self.approval_key: Optional[str] = None
-        self.subscribed_codes: Set[str] = set()
-        self.running = False
-        self.data_map: Dict[str, Dict] = {} # Store IV/Key for encrypted TRs
-
-    async def start(self):
-        """
-        Main loop: Connect -> Authenticate -> Listen
-        """
-        self.running = True
-        while self.running:
-            try:
-                # 1. Get Approval Key
-                self.approval_key = await kis_auth.get_approval_key()
-                
-                logger.info(f"Connecting to KIS WS: {self.WS_URL_REAL}")
-                async with websockets.connect(self.WS_URL_REAL, ping_interval=None) as websocket:
-                    self.ws = websocket
-                    logger.info("Connected.")
-                    
-                    # 2. Resubscribe if recovering connection
-                    if self.subscribed_codes:
-                        await self._resubscribe_all()
-
-                    # 3. Listen Loop
-                    await self._listen()
-                    
-            except Exception as e:
-                logger.error(f"WS Connection Error: {e}. Retrying in 5s...")
-                await asyncio.sleep(5)
-
-    async def stop(self):
-        self.running = False
-        if self.ws:
-            await self.ws.close()
-
-    async def subscribe(self, stock_code: str, type="price"):
-        """
-        Subscribe to a stock.
-        type: 'price' (H0STCNT0 - 체결가)
-        """
-        if not self.ws or not self.approval_key:
-            logger.warning("WS not ready. Adding to pending list.")
-            self.subscribed_codes.add(stock_code)
-            return
-
-        # Domestic Realtime Price TR ID: H0STCNT0
-        tr_id = "H0STCNT0" 
-        tr_key = stock_code
         
+        # Reference Counting: Code -> Set of Sources
+        # e.g. "005930": {"HOLDING", "FRONTEND_DASHBOARD"}
+        self.subscriptions: Dict[str, Set[str]] = {} 
+        
+        self.running = False
+        self.data_map: Dict[str, Dict] = {} 
+        
+        # Realtime Data Cache (Code -> DataDict)
+        # Used by Scheduler to persist data periodically
+        self.price_cache: Dict[str, Dict] = {} 
+
+    async def add_subscription(self, code: str, source: str):
+        """
+        Request subscription. Increments reference count for the code.
+        """
+        if code not in self.subscriptions:
+            self.subscriptions[code] = set()
+            
+        if not self.subscriptions[code]:
+            # First subscriber, Send WS Command
+            await self._send_subscribe(code, "1") # 1=Register
+            
+        self.subscriptions[code].add(source)
+        logger.info(f"Subscribed {code} by {source}. RefCount: {len(self.subscriptions[code])}")
+
+    async def remove_subscription(self, code: str, source: str):
+        """
+        Remove subscription. Decrements reference count.
+        """
+        if code in self.subscriptions and source in self.subscriptions[code]:
+            self.subscriptions[code].remove(source)
+            logger.info(f"Unsubscribed {code} by {source}. RefCount: {len(self.subscriptions[code])}")
+            
+            if not self.subscriptions[code]:
+                # No more subscribers, Send WS Unsubscribe
+                await self._send_subscribe(code, "2") # 2=Unregister
+                del self.subscriptions[code]
+
+    async def _send_subscribe(self, code: str, tr_type: str):
+        if not self.ws or not self.approval_key:
+            return # Will resubscribe on connect
+            
         payload = {
             "header": {
                 "approval_key": self.approval_key,
                 "custtype": "P",
-                "tr_type": "1", # 1=Register, 2=Unregister
+                "tr_type": tr_type,
                 "content-type": "utf-8"
             },
             "body": {
                 "input": {
-                    "tr_id": tr_id,
-                    "tr_key": tr_key
+                    "tr_id": "H0STCNT0",
+                    "tr_key": code
                 }
             }
         }
-        
         await self.ws.send(json.dumps(payload))
-        self.subscribed_codes.add(stock_code)
-        logger.info(f"Subscribed to {stock_code}")
 
     async def _resubscribe_all(self):
-        for code in self.subscribed_codes:
-            await self.subscribe(code)
+        for code in list(self.subscriptions.keys()):
+            await self._send_subscribe(code, "1")
 
     async def _listen(self):
         async for message in self.ws:
             try:
-                # Message can be plain text provided by library, or bytes
-                if isinstance(message, bytes):
-                    message = message.decode('utf-8')
-
-                # KIS sends data in specific formats.
-                # 1. JSON (Control Messages, PINGPONG, Subscription Ack)
-                # 2. Text/Pipe separated (Real Data) - Usually starts with 0 or 1
+                if isinstance(message, bytes): message = message.decode('utf-8')
                 
                 first_char = message[0]
-                
-                if first_char in ['{', '[']: 
-                    # JSON Message
-                    data = json.loads(message)
-                    header = data.get('header', {})
-                    tr_id = header.get('tr_id')
-
-                    if tr_id == "PINGPONG":
-                        await self.ws.send(message) # Echo back
-                        logger.debug("PINGPONG handled")
-                        
-                    elif 'body' in data:
-                        # Subscription Ack
-                        # Store IV/Key if encryption is enabled (msg1 often contains 'ENCRYPT')
-                        # But for Brokerage API, H0STCNT0 is usually plaintext unless configured otherwise.
-                        # If encrypted, 'iv' and 'key' are in body['output']
-                        pass
-                        
-                elif first_char in ['0', '1']:
-                    # Real Data: 0|TR_ID|DATA_CNT|DATA...
+                if first_char in ['0', '1']:
+                    # Real Data
                     parts = message.split('|')
-                    if len(parts) < 4:
-                        continue
-                        
+                    if len(parts) < 4: continue
                     tr_id = parts[1]
                     raw_data = parts[3]
                     
-                    # Decryption Check
-                    # If this tr_id was registered as encrypted, decrypt it.
-                    # For now assuming Plaintext for H0STCNT0 as per standard Personal API.
-                    
-                    # Parse Data
-                    if tr_id == "H0STCNT0": # Domestic Price
-                        # Data format: TIME^PRICE^...
-                        # We need to look up format spec.
-                        # Simple implementation: just log or split
-                        fields = raw_data.split('^')
-                        if len(fields) > 2:
-                            current_price = fields[2] # Example index
-                            # TODO: Update DB
-                            # print(f"Price Update: {current_price}")
-                            pass
-                            
+                    if tr_id == "H0STCNT0":
+                        await self._parse_domestic_price(raw_data)
+                        
+                elif first_char == '{':
+                    data = json.loads(message)
+                    if data.get('header', {}).get('tr_id') == "PINGPONG":
+                        await self.ws.send(message)
+                        
             except Exception as e:
-                logger.error(f"Error processing WS message: {e}")
+                logger.error(f"WS Error: {e}")
 
+    async def _parse_domestic_price(self, raw_data: str):
+        # Format: MKSC_SHRN_ISCD^EXEC_TIME^CURRENT_PRICE^...
+        fields = raw_data.split('^')
+        if len(fields) < 3: return
+        
+        code = fields[0]
+        curr_price = fields[2]
+        change = fields[4]
+        change_rate = fields[5]
+        
+        # Create lightweight update object (Dict)
+        update_data = {
+            "code": code,
+            "price": curr_price,
+            "change": change,
+            "rate": change_rate,
+            "timestamp": datetime.now().isoformat()
+        }
+        
+        # Update Cache
+        self.price_cache[code] = update_data
+        # logger.debug(f"Price Update: {code} {curr_price}")
 realtime_manager = RealtimeManager()
diff --git a/backend/app/services/sync_service.py b/backend/app/services/sync_service.py
new file mode 100644
index 0000000..9cdc78c
--- /dev/null
+++ b/backend/app/services/sync_service.py
@@ -0,0 +1,104 @@
+import logging
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select, delete
+from datetime import datetime
+
+from app.db.database import SessionLocal
+from app.db.models import AccountStatus, Holding
+from app.services.kis_client import kis_client
+
+logger = logging.getLogger(__name__)
+
+class SyncService:
+    async def sync_account(self, db: AsyncSession):
+        """
+        Fetches balance from KIS and updates DB (AccountStatus & Holdings).
+        Currently supports Domestic only.
+        """
+        logger.info("SyncService: Starting Account Sync...")
+        try:
+            # 1. Fetch Domestic Balance
+            # kis_client.get_balance returns dict with 'output1', 'output2' or None
+            res = await kis_client.get_balance("Domestic")
+            if not res:
+                logger.error("SyncService: Failed to fetch balance (API Error or No Data).")
+                return
+
+            # output1: Holdings List
+            # output2: Account Summary
+            output1 = res.get('output1', [])
+            output2 = res.get('output2', [])
+            
+            # KIS API returns output2 as a LIST of 1 dict usually
+            summary_data = output2[0] if output2 else {}
+            
+            # --- Update AccountStatus ---
+            # Map KIS fields to AccountStatus model
+            # tot_evlu_amt: 총평가금액 (Total Assets)
+            # dnca_tot_amt: 예수금총액 (Buying Power)
+            # evlu_pfls_smt_tl: 평가손익합계 (Daily Profit - approximation)
+            # evlu_pfls_rt: 수익률
+            
+            total_assets = float(summary_data.get('tot_evlu_amt', 0) or 0)
+            buying_power = float(summary_data.get('dnca_tot_amt', 0) or 0)
+            daily_profit = float(summary_data.get('evlu_pfls_smt_tl', 0) or 0)
+            
+            # Calculate daily profit rate if not provided directly
+            # profit_rate = float(summary_data.get('evlu_pfls_rt', 0)) # Sometimes available
+            daily_profit_rate = 0.0
+            if total_assets > 0:
+                daily_profit_rate = (daily_profit / total_assets) * 100
+
+            # Upsert AccountStatus (ID=1)
+            stmt = select(AccountStatus).where(AccountStatus.id == 1)
+            result = await db.execute(stmt)
+            status = result.scalar_one_or_none()
+            
+            if not status:
+                status = AccountStatus(id=1)
+                db.add(status)
+            
+            status.totalAssets = total_assets
+            status.buyingPower = buying_power
+            status.dailyProfit = daily_profit
+            status.dailyProfitRate = daily_profit_rate
+            
+            # --- Update Holdings ---
+            # Strategy: Delete all existing holdings (refresh) or Upsert?
+            # Refresh is safer to remove sold items.
+            await db.execute(delete(Holding))
+            
+            for item in output1:
+                # Map fields
+                # pdno: 종목번호
+                # prdt_name: 종목명
+                # hldg_qty: 보유수량
+                # pchs_avg_pric: 매입평균가격
+                # prpr: 현재가
+                # evlu_pfls_amt: 평가손익금액
+                # evlu_pfls_rt: 평가손익율
+                # evlu_amt: 평가금액
+                
+                code = item.get('pdno')
+                if not code: continue
+                
+                h = Holding(
+                    stockCode=code,
+                    stockName=item.get('prdt_name', 'Unknown'),
+                    quantity=int(item.get('hldg_qty', 0) or 0),
+                    avgPrice=float(item.get('pchs_avg_pric', 0) or 0),
+                    currentPrice=float(item.get('prpr', 0) or 0),
+                    profit=float(item.get('evlu_pfls_amt', 0) or 0),
+                    profitRate=float(item.get('evlu_pfls_rt', 0) or 0),
+                    marketValue=float(item.get('evlu_amt', 0) or 0)
+                )
+                db.add(h)
+                
+            await db.commit()
+            logger.info(f"SyncService: Account Sync Complete. Assets: {total_assets}, Holdings: {len(output1)}")
+            
+        except Exception as e:
+            await db.rollback()
+            logger.error(f"SyncService: Error during sync: {e}")
+
+sync_service = SyncService()
diff --git a/backend/app/workers/__pycache__/scheduler.cpython-312.pyc b/backend/app/workers/__pycache__/scheduler.cpython-312.pyc
index 8f0e95b..cf4314d 100644
Binary files a/backend/app/workers/__pycache__/scheduler.cpython-312.pyc and b/backend/app/workers/__pycache__/scheduler.cpython-312.pyc differ
diff --git a/backend/app/workers/scheduler.py b/backend/app/workers/scheduler.py
index 74ea6a8..4898890 100644
--- a/backend/app/workers/scheduler.py
+++ b/backend/app/workers/scheduler.py
@@ -2,7 +2,11 @@ from apscheduler.schedulers.asyncio import AsyncIOScheduler
 from app.core.market_schedule import market_schedule
 from app.services.kis_client import kis_client
 from app.services.realtime_manager import realtime_manager
+from app.db.database import SessionLocal
+from app.db.models import StockItem, ReservedOrder
+from sqlalchemy import select, update
 import logging
+from datetime import datetime
 
 logger = logging.getLogger(__name__)
 
@@ -12,32 +16,160 @@ async def market_check_job():
     """
     Periodic check to ensure Realtime Manager is connected when market is open.
     """
+    logger.info("Scheduler: Market Check Job Running...")
     is_domestic_open = market_schedule.is_market_open("Domestic")
     # is_overseas_open = market_schedule.is_market_open("Overseas")
     
     # If market is open and WS is not running, start it
     if is_domestic_open and not realtime_manager.running:
         logger.info("Market is Open! Starting Realtime Manager.")
-        # This is a blocking call if awaited directly in job? NO, start() has a loop.
-        # We should start it as a task if it's not running.
-        # But realtime_manager.start() is a loop.
-        # Better to have it managed by FastAPI startup, and this job just checks.
-        pass
+    else:
+        logger.info(f"Market Status: Domestic={is_domestic_open}, RealtimeManager={realtime_manager.running}")
+
+async def persist_market_data_job():
+    """
+    Flushes realtime_manager.price_cache to DB (StockItem).
+    """
+    if not realtime_manager.price_cache:
+        return
+
+    # Snapshot and clear (thread-safe ish in async single loop)
+    # Or just iterate. Python dict iteration is safe if not modifying keys.
+    # We'll take keys copy.
+    codes_to_process = list(realtime_manager.price_cache.keys())
+    
+    if not codes_to_process:
+        return
+        
+    async with SessionLocal() as session:
+        count = 0
+        for code in codes_to_process:
+            data = realtime_manager.price_cache.get(code)
+            if not data: continue
+            
+            # Upsert StockItem?
+            # Or just update if exists. StockItem generally exists if synced.
+            # If not exists, we might create it.
+            
+            price = float(data['price'])
+            change = float(data['change'])
+            rate = float(data['rate'])
+            
+            # Simple Update
+            stmt = update(StockItem).where(StockItem.code == code).values(
+                price=price,
+                change=change,
+                changePercent=rate
+            )
+            await session.execute(stmt)
+            count += 1
+            
+        await session.commit()
+    
+    # logger.debug(f"Persisted {count} stock prices to DB.")
 
 async def news_scrap_job():
     # Placeholder for News Scraper
-    # logger.info("Scraping Naver News...")
+    logger.info("Scheduler: Scraping Naver News (Placeholder)...")
     pass
 
 async def auto_trade_scan_job():
-    # Placeholder for Auto Trading Scanner (Check Reserved Orders)
-    # logger.info("Scanning Reserved Orders...")
-    pass
+    """
+    Scans ReservedOrders and triggers actions if conditions are met.
+    """
+    async with SessionLocal() as session:
+        # Fetch Monitoring Orders
+        stmt = select(ReservedOrder).where(ReservedOrder.status == "MONITORING")
+        result = await session.execute(stmt)
+        orders = result.scalars().all()
+        
+        for order in orders:
+            # Check Price
+            current_price = 0
+            
+            # 1. Try Realtime Cache
+            if order.stockCode in realtime_manager.price_cache:
+                current_price = float(realtime_manager.price_cache[order.stockCode]['price'])
+            else:
+                # 2. Try DB (StockItem)
+                # ... (omitted for speed, usually Cache covers if monitored)
+                pass
+                
+            if current_price <= 0: continue
+            
+            # Trigger Logic (Simple)
+            triggered = False
+            if order.monitoringType == "PRICE_TRIGGER":
+                # Buy if Price <= Trigger (Dip Buy) ?? OR Buy if Price >= Trigger (Breakout)?
+                # Usually define "Condition". Assuming Buy Lower for now or User defined.
+                # Let's assume TriggerPrice is "Target".
+                # If BUY -> Price <= Trigger?
+                # If SELL -> Price >= Trigger?
+                
+                if order.type == "BUY" and current_price <= order.triggerPrice:
+                    triggered = True
+                elif order.type == "SELL" and current_price >= order.triggerPrice:
+                    triggered = True
+            
+            elif order.monitoringType == "TRAILING_STOP":
+                if order.type == "SELL":
+                    # Trailing Sell (High Water Mark)
+                    if not order.highestPrice or current_price > order.highestPrice:
+                        order.highestPrice = current_price
+                    
+                    if order.highestPrice > 0 and order.trailingValue:
+                        drop = order.highestPrice - current_price
+                        triggered = False
+                        
+                        if order.trailingType == "PERCENT":
+                            drop_rate = (drop / order.highestPrice) * 100
+                            if drop_rate >= order.trailingValue: triggered = True
+                        else: # AMOUNT
+                            if drop >= order.trailingValue: triggered = True
+                            
+                        if triggered:
+                            logger.info(f"TS SELL Triggered: High={order.highestPrice}, Curr={current_price}")
+
+                elif order.type == "BUY":
+                    # Trailing Buy (Low Water Mark / Rebound)
+                    # Initialize lowest if 0 (assuming stock price never 0, or use 99999999 default)
+                    if not order.lowestPrice or order.lowestPrice == 0:
+                        order.lowestPrice = current_price
+                        
+                    if current_price < order.lowestPrice:
+                        order.lowestPrice = current_price
+                        
+                    if order.lowestPrice > 0 and order.trailingValue:
+                        rise = current_price - order.lowestPrice
+                        triggered = False
+                        
+                        if order.trailingType == "PERCENT":
+                            rise_rate = (rise / order.lowestPrice) * 100
+                            if rise_rate >= order.trailingValue: triggered = True
+                        else:
+                            if rise >= order.trailingValue: triggered = True
+                            
+                        if triggered:
+                            logger.info(f"TS BUY Triggered: Low={order.lowestPrice}, Curr={current_price}")
+            
+            if triggered:
+                    
+            if triggered:
+                logger.info(f"Order TRIGGERED! {order.stockName} {order.type} @ {current_price} (Target: {order.triggerPrice})")
+                
+                # Execute Order
+                # res = await kis_client.place_order(...)
+                # Update Status
+                # order.status = "TRIGGERED" (or "COMPLETED" after exec)
+                pass
+                
+        await session.commit()
 
 def start_scheduler():
     scheduler.add_job(market_check_job, 'interval', minutes=5)
     scheduler.add_job(news_scrap_job, 'interval', minutes=10)
     scheduler.add_job(auto_trade_scan_job, 'interval', minutes=1)
+    scheduler.add_job(persist_market_data_job, 'interval', seconds=10) # Persist every 10s
     
     scheduler.start()
     logger.info("Scheduler Started.")
diff --git a/backend/kis_stock.db b/backend/kis_stock.db
new file mode 100644
index 0000000..02fe0b5
Binary files /dev/null and b/backend/kis_stock.db differ
diff --git a/services/config.ts b/services/config.ts
new file mode 100644
index 0000000..acac598
--- /dev/null
+++ b/services/config.ts
@@ -0,0 +1,8 @@
+export const API_BASE_URL = "http://localhost:8000/api";
+
+export const getHeaders = () => {
+  return {
+    "Content-Type": "application/json",
+    // "Authorization": "Bearer ..." // If we implement Auth later
+  };
+};
diff --git a/services/dbService.ts b/services/dbService.ts
index 486dace..57cbaef 100644
--- a/services/dbService.ts
+++ b/services/dbService.ts
@@ -1,5 +1,5 @@
-
 import { TradeOrder, OrderType, MarketType, AutoTradeConfig, WatchlistGroup, ReservedOrder, StockTick } from '../types';
+import { API_BASE_URL, getHeaders } from './config';
 
 export interface HoldingItem {
   code: string;
@@ -7,178 +7,152 @@ export interface HoldingItem {
   avgPrice: number;
   quantity: number;
   market: MarketType;
+  currentPrice: number; // Added
+  profit: number; // Added
+  profitRate: number; // Added
 }
 
 export class DbService {
-  private holdingsKey = 'batchukis_sqlite_holdings';
-  private configsKey = 'batchukis_sqlite_configs';
-  private watchlistGroupsKey = 'batchukis_sqlite_watchlist_groups';
-  private reservedOrdersKey = 'batchukis_sqlite_reserved_orders';
-  private ticksPrefix = 'batchukis_ticks_';
-
-  constructor() {
-    this.initDatabase();
-  }
-
-  private initDatabase() {
-    if (!localStorage.getItem(this.holdingsKey)) {
-      const initialHoldings: HoldingItem[] = [
-        { code: '005930', name: '삼성전자', avgPrice: 68500, quantity: 150, market: MarketType.DOMESTIC },
-        { code: 'AAPL', name: 'Apple Inc.', avgPrice: 175.20, quantity: 25, market: MarketType.OVERSEAS },
-      ];
-      localStorage.setItem(this.holdingsKey, JSON.stringify(initialHoldings));
-    }
-    if (!localStorage.getItem(this.configsKey)) {
-      localStorage.setItem(this.configsKey, JSON.stringify([]));
-    }
-    if (!localStorage.getItem(this.watchlistGroupsKey)) {
-      const initialGroups: WatchlistGroup[] = [
-        { id: 'grp1', name: '핵심 우량주', codes: ['005930', '000660'], market: MarketType.DOMESTIC },
-        { id: 'grp2', name: 'AI 포트폴리오', codes: ['NVDA', 'TSLA'], market: MarketType.OVERSEAS },
-        { id: 'grp3', name: '미국 빅테크', codes: ['AAPL'], market: MarketType.OVERSEAS }
-      ];
-      localStorage.setItem(this.watchlistGroupsKey, JSON.stringify(initialGroups));
-    }
-    if (!localStorage.getItem(this.reservedOrdersKey)) {
-      localStorage.setItem(this.reservedOrdersKey, JSON.stringify([]));
-    }
-  }
-
-  // 시계열 데이터 저장 (무제한)
-  async saveStockTick(tick: StockTick) {
-    const key = this.ticksPrefix + tick.code;
-    const existing = localStorage.getItem(key);
-    const ticks: StockTick[] = existing ? JSON.parse(existing) : [];
-    ticks.push(tick);
-    localStorage.setItem(key, JSON.stringify(ticks));
-  }
-
-  async getStockTicks(code: string): Promise<StockTick[]> {
-    const key = this.ticksPrefix + code;
-    const data = localStorage.getItem(key);
-    return data ? JSON.parse(data) : [];
-  }
+  constructor() {}
 
+  // --- Holdings ---
   async getHoldings(): Promise<HoldingItem[]> {
-    const data = localStorage.getItem(this.holdingsKey);
-    return data ? JSON.parse(data) : [];
-  }
-
-  async syncOrderToHolding(order: TradeOrder) {
-    const holdings = await this.getHoldings();
-    const existingIdx = holdings.findIndex(h => h.code === order.stockCode);
-
-    if (order.type === OrderType.BUY) {
-      if (existingIdx > -1) {
-        const h = holdings[existingIdx];
-        const newQty = h.quantity + order.quantity;
-        const newAvg = ((h.avgPrice * h.quantity) + (order.price * order.quantity)) / newQty;
-        holdings[existingIdx] = { ...h, quantity: newQty, avgPrice: newAvg };
-      } else {
-        holdings.push({
-          code: order.stockCode,
-          name: order.stockName,
-          avgPrice: order.price,
-          quantity: order.quantity,
-          market: order.stockCode.length > 6 ? MarketType.OVERSEAS : MarketType.DOMESTIC
-        });
-      }
-    } else {
-      if (existingIdx > -1) {
-        holdings[existingIdx].quantity -= order.quantity;
-        if (holdings[existingIdx].quantity <= 0) {
-          holdings.splice(existingIdx, 1);
-        }
-      }
+    try {
+      const res = await fetch(`${API_BASE_URL}/account/holdings`);
+      if (!res.ok) return [];
+      const data = await res.json();
+      // Map API response to HoldingItem
+      // API returns: { stockCode, stockName, quantity, avgPrice, currentPrice, profit, profitRate }
+      return data.map((h: any) => ({
+        code: h.stockCode,
+        name: h.stockName,
+        avgPrice: h.avgPrice,
+        quantity: h.quantity,
+        market: h.stockCode.length > 6 ? MarketType.OVERSEAS : MarketType.DOMESTIC,
+        currentPrice: h.currentPrice,
+        profit: h.profit,
+        profitRate: h.profitRate
+      }));
+    } catch (e) {
+      console.error("Failed to fetch holdings", e);
+      return [];
     }
-    localStorage.setItem(this.holdingsKey, JSON.stringify(holdings));
-    return holdings;
-  }
-
-  async getWatchlistGroups(): Promise<WatchlistGroup[]> {
-    const data = localStorage.getItem(this.watchlistGroupsKey);
-    return data ? JSON.parse(data) : [];
-  }
-
-  async saveWatchlistGroup(group: WatchlistGroup) {
-    const groups = await this.getWatchlistGroups();
-    groups.push(group);
-    localStorage.setItem(this.watchlistGroupsKey, JSON.stringify(groups));
-  }
-
-  async updateWatchlistGroup(group: WatchlistGroup) {
-    const groups = await this.getWatchlistGroups();
-    const idx = groups.findIndex(g => g.id === group.id);
-    if (idx > -1) {
-      groups[idx] = group;
-      localStorage.setItem(this.watchlistGroupsKey, JSON.stringify(groups));
-    }
-  }
-
-  async deleteWatchlistGroup(id: string) {
-    const groups = await this.getWatchlistGroups();
-    const filtered = groups.filter(g => g.id !== id);
-    localStorage.setItem(this.watchlistGroupsKey, JSON.stringify(filtered));
-  }
-
-  async getAutoConfigs(): Promise<AutoTradeConfig[]> {
-    const data = localStorage.getItem(this.configsKey);
-    return data ? JSON.parse(data) : [];
-  }
-
-  async saveAutoConfig(config: AutoTradeConfig) {
-    const configs = await this.getAutoConfigs();
-    configs.push(config);
-    localStorage.setItem(this.configsKey, JSON.stringify(configs));
-  }
-
-  async updateAutoConfig(config: AutoTradeConfig) {
-    const configs = await this.getAutoConfigs();
-    const idx = configs.findIndex(c => c.id === config.id);
-    if (idx > -1) {
-      configs[idx] = config;
-      localStorage.setItem(this.configsKey, JSON.stringify(configs));
-    }
-  }
-
-  async deleteAutoConfig(id: string) {
-    const configs = await this.getAutoConfigs();
-    const filtered = configs.filter(c => c.id !== id);
-    localStorage.setItem(this.configsKey, JSON.stringify(filtered));
-  }
-
-  async getReservedOrders(): Promise<ReservedOrder[]> {
-    const data = localStorage.getItem(this.reservedOrdersKey);
-    return data ? JSON.parse(data) : [];
-  }
-
-  async saveReservedOrder(order: ReservedOrder) {
-    const orders = await this.getReservedOrders();
-    orders.push(order);
-    localStorage.setItem(this.reservedOrdersKey, JSON.stringify(orders));
-  }
-
-  async updateReservedOrder(order: ReservedOrder) {
-    const orders = await this.getReservedOrders();
-    const idx = orders.findIndex(o => o.id === order.id);
-    if (idx > -1) {
-      orders[idx] = order;
-      localStorage.setItem(this.reservedOrdersKey, JSON.stringify(orders));
-    }
-  }
-
-  async deleteReservedOrder(id: string) {
-    const orders = await this.getReservedOrders();
-    const filtered = orders.filter(o => o.id !== id);
-    localStorage.setItem(this.reservedOrdersKey, JSON.stringify(filtered));
   }
 
   async getAccountSummary() {
-    const holdings = await this.getHoldings();
-    const totalEval = holdings.reduce((acc, h) => acc + (h.avgPrice * h.quantity), 0);
-    return {
-      totalAssets: totalEval + 45800000,
-      buyingPower: 45800000
-    };
+      try {
+          const res = await fetch(`${API_BASE_URL}/account/balance?market=Domestic`); // Default
+          if (!res.ok) return { totalAssets: 0, buyingPower: 0 };
+          const data = await res.json();
+          // API returns complex object. We might need to simplify or use /account/summary if exists.
+          // Or calculate from holdings + cash?
+          // Using a simplified assumption or endpoints.
+          // Let's assume we use the totalAssets from the API if available, or fetch from Status endpoint.
+          // Actually, we verified /account/balance returns KIS raw data.
+          // We should implemented a summary endpoint or parse raw data.
+          // For now, let's return a basic structure.
+          return {
+             totalAssets: parseFloat(data.output2?.tot_evlu_amt || "0"),
+             buyingPower: parseFloat(data.output2?.dnca_tot_amt || "0")
+          };
+      } catch (e) {
+          return { totalAssets: 0, buyingPower: 0 };
+      }
+  }
+
+  // --- Reserved Orders ---
+  async getReservedOrders(): Promise<ReservedOrder[]> {
+    const res = await fetch(`${API_BASE_URL}/reserved-orders`);
+    if (!res.ok) return [];
+    return await res.json();
+  }
+
+  async saveReservedOrder(order: ReservedOrder) {
+      // POST
+      // Map Frontend Order to Backend Request
+      const payload = {
+          stockCode: order.stockCode,
+          stockName: order.stockName,
+          monitoringType: order.monitoringType,
+          triggerPrice: order.triggerPrice,
+          orderType: order.type,
+          quantity: order.quantity,
+          price: order.price || 0,
+          trailingType: order.trailingType,
+          trailingValue: order.trailingValue,
+          stopLossValue: order.stopLossValue
+      };
+      
+      const res = await fetch(`${API_BASE_URL}/reserved-orders`, {
+          method: 'POST',
+          headers: getHeaders(),
+          body: JSON.stringify(payload)
+      });
+      return await res.json();
+  }
+
+  async deleteReservedOrder(id: string) {
+      await fetch(`${API_BASE_URL}/reserved-orders/${id}`, {
+          method: 'DELETE'
+      });
+  }
+  
+  // --- Auto Trade Configs ---
+  async getAutoConfigs(): Promise<AutoTradeConfig[]> {
+      const res = await fetch(`${API_BASE_URL}/auto-trade/configs`);
+      if (!res.ok) return [];
+      return await res.json();
+  }
+  
+  async saveAutoConfig(config: AutoTradeConfig) {
+      await fetch(`${API_BASE_URL}/auto-trade/configs`, {
+          method: 'POST',
+          headers: getHeaders(),
+          body: JSON.stringify(config)
+      });
+  }
+  
+  async deleteAutoConfig(id: string) {
+      await fetch(`${API_BASE_URL}/auto-trade/configs/${id}`, {
+          method: 'DELETE'
+      });
+  }
+
+  // --- Watchlist Groups ---
+  async getWatchlistGroups(): Promise<WatchlistGroup[]> {
+      const res = await fetch(`${API_BASE_URL}/watchlists/groups`);
+      if (!res.ok) return [];
+      return await res.json();
+  }
+
+  // --- Ticks (Optional, might be local only or via API) ---
+  // If backend doesn't support generic tick history per session, keep local or ignore.
+  async saveStockTick(tick: StockTick) {
+      // No-op or keep local? 
+      // Keeping Local storage for ticks is fine for detailed charts if backend doesn't persist ticks.
+      // Backend persists ticks to StockItem but not history properly yet (except daily).
+  }
+  
+  async getStockTicks(code: string): Promise<StockTick[]> {
+      return []; 
+  }
+  
+  // Helpers not needed with real API usually
+  async syncOrderToHolding(order: TradeOrder) {
+      // Refresh holdings from server instead of calculating
+      return await this.getHoldings();
+  }
+  
+  // Write-only wrappers
+  async updateWatchlistGroup(group: WatchlistGroup) {
+      // Use PUT if available or POST
+  }
+  
+  async saveWatchlistGroup(group: WatchlistGroup) {
+       // POST
+  }
+  
+  async deleteWatchlistGroup(id: string) {
+      // DELETE
   }
 }
diff --git a/services/kisService.ts b/services/kisService.ts
index e86ca5d..bf01bd5 100644
--- a/services/kisService.ts
+++ b/services/kisService.ts
@@ -1,61 +1,105 @@
 
 import { ApiSettings, MarketType, OrderType, StockItem } from '../types';
+import { API_BASE_URL, getHeaders } from './config';
 
 /**
  * Korea Investment & Securities (KIS) Open API Service
+ * Now connected to Real Backend
  */
 export class KisService {
   private settings: ApiSettings;
-  private accessToken: string | null = null;
 
   constructor(settings: ApiSettings) {
     this.settings = settings;
   }
 
   async issueAccessToken() {
-    this.accessToken = "mock_token_" + Math.random().toString(36).substr(2);
-    return this.accessToken;
+    // Backend manages token automatically.
+    return "backend-managed-token";
   }
 
   async inquirePrice(code: string): Promise<number> {
-    const basePrice = code.startsWith('0') ? 70000 : 150;
-    return Math.floor(basePrice + Math.random() * 5000);
+    // Default to Domestic for now, or infer from code length
+    const market = code.length === 6 ? "Domestic" : "Overseas";
+    try {
+        const res = await fetch(`${API_BASE_URL}/kis/price?market=${market}&code=${code}`);
+        if (!res.ok) return 0;
+        const data = await res.json();
+        return parseFloat(data.price) || 0;
+    } catch (e) {
+        return 0;
+    }
   }
 
   /**
-   * 서버로부터 전체 종목 마스터 리스트를 가져오는 Mock 함수
+   * Fetch Market Data
    */
   async fetchMasterStocks(market: MarketType): Promise<StockItem[]> {
-    console.log(`KIS: Fetching master stocks for ${market}...`);
-    // 백엔드 구현 전까지는 시뮬레이션 데이터를 반환합니다.
-    if (market === MarketType.DOMESTIC) {
-      return [
-        { code: '005930', name: '삼성전자', price: 73200, change: 800, changePercent: 1.1, market: MarketType.DOMESTIC, volume: 15234000, aiScoreBuy: 85, aiScoreSell: 20, themes: ['반도체', 'AI', '스마트폰'] },
-        { code: '000660', name: 'SK하이닉스', price: 124500, change: -1200, changePercent: -0.96, market: MarketType.DOMESTIC, volume: 2100000, aiScoreBuy: 65, aiScoreSell: 45, themes: ['반도체', 'HBM'] },
-        { code: '035420', name: 'NAVER', price: 215000, change: 4500, changePercent: 2.14, market: MarketType.DOMESTIC, volume: 850000, aiScoreBuy: 72, aiScoreSell: 30, themes: ['플랫폼', 'AI'] },
-        { code: '035720', name: '카카오', price: 58200, change: 300, changePercent: 0.52, market: MarketType.DOMESTIC, volume: 1200000, aiScoreBuy: 50, aiScoreSell: 50, themes: ['플랫폼', '모빌리티'] },
-        { code: '005380', name: '현대차', price: 245000, change: 2000, changePercent: 0.82, market: MarketType.DOMESTIC, volume: 450000, aiScoreBuy: 78, aiScoreSell: 25, themes: ['자동차', '전기차'] },
-      ];
-    } else {
-      return [
-        { code: 'AAPL', name: 'Apple Inc.', price: 189.43, change: 1.25, changePercent: 0.66, market: MarketType.OVERSEAS, volume: 45000000, aiScoreBuy: 90, aiScoreSell: 15, themes: ['빅테크', '스마트폰'] },
-        { code: 'TSLA', name: 'Tesla Inc.', price: 234.12, change: -4.50, changePercent: -1.89, market: MarketType.OVERSEAS, volume: 110000000, aiScoreBuy: 40, aiScoreSell: 75, themes: ['전기차', '자율주행'] },
-        { code: 'NVDA', name: 'NVIDIA Corp.', price: 485.12, change: 12.30, changePercent: 2.6, market: MarketType.OVERSEAS, volume: 32000000, aiScoreBuy: 95, aiScoreSell: 10, themes: ['반도체', 'AI'] },
-        { code: 'MSFT', name: 'Microsoft Corp.', price: 402.12, change: 3.45, changePercent: 0.86, market: MarketType.OVERSEAS, volume: 22000000, aiScoreBuy: 88, aiScoreSell: 12, themes: ['소프트웨어', 'AI'] },
-        { code: 'GOOGL', name: 'Alphabet Inc.', price: 145.12, change: 0.55, changePercent: 0.38, market: MarketType.OVERSEAS, volume: 18000000, aiScoreBuy: 75, aiScoreSell: 20, themes: ['검색', 'AI'] },
-      ];
+    try {
+        // Use Rankings as the default "List"
+        const marketParam = market === MarketType.DOMESTIC ? "Domestic" : "Overseas";
+        const res = await fetch(`${API_BASE_URL}/discovery/rankings?limit=50`);
+        if (!res.ok) return [];
+        const data = await res.json();
+        
+        // Transform logic if needed. Ranking API returns StockItem which matches frontend type mostly.
+        return data.map((item: any) => ({
+            code: item.code,
+            name: item.name,
+            price: item.price,
+            change: item.change,
+            changePercent: item.changePercent,
+            market: market,
+            volume: 0, // Rankings might not return volume yet, or it does if enabled
+            aiScoreBuy: 50, // Placeholder as backend doesn't have AI score in StockItem yet
+            aiScoreSell: 50,
+            themes: []
+        }));
+    } catch (e) {
+        return [];
     }
   }
 
   async orderCash(code: string, type: OrderType, quantity: number, price: number = 0) {
-    return { success: true, orderId: "ORD-" + Math.random().toString(36).substr(2, 9) };
+    return this._placeOrder("Domestic", code, type, quantity, price);
   }
 
   async orderOverseas(code: string, type: OrderType, quantity: number, price: number) {
-    return { success: true, orderId: "OS-ORD-" + Math.random().toString(36).substr(2, 9) };
+    return this._placeOrder("Overseas", code, type, quantity, price);
+  }
+  
+  private async _placeOrder(market: string, code: string, type: OrderType, quantity: number, price: number) {
+      const payload = {
+          market: market,
+          side: type === OrderType.BUY ? "buy" : "sell",
+          code: code,
+          quantity: quantity,
+          price: price
+      };
+      
+      const res = await fetch(`${API_BASE_URL}/kis/order`, {
+          method: 'POST',
+          headers: getHeaders(),
+          body: JSON.stringify(payload)
+      });
+      
+      if (!res.ok) {
+          const err = await res.json();
+          throw new Error(err.detail || "Order Failed");
+      }
+      return await res.json();
   }
 
   async inquireBalance() {
-    return { output1: [], output2: { tot_evlu_amt: "124500000", nass_amt: "45800000" } };
+    // Default Domestic
+    const res = await fetch(`${API_BASE_URL}/kis/balance?market=Domestic`);
+    if (!res.ok) return { output1: [], output2: {} };
+    return await res.json();
+  }
+  
+  async inquireBalanceOverseas() {
+      const res = await fetch(`${API_BASE_URL}/kis/balance?market=Overseas`);
+      if (!res.ok) return { output1: [], output2: {} };
+      return await res.json();
   }
 }