fix: change /watchlist api to utc format

frontend/src/api/stock.ts

@@ -33,7 +33,7 @@ export const useAddStockToWatchlist = () => {
 
   return useMutation({
     mutationFn: (ticker: Pick<Stock, "ticker">) =>
-      apiClient.post<ApiResponse<null>>("watchlist/stocks", ticker),
+      apiClient.post<ApiResponse<null>>("watchlist/asset", ticker),
     onSuccess: () => {
       // invalidate watchlist query cache to trigger re-fetch
       queryClient.invalidateQueries({

python/valuecell/server/api/routers/watchlist.py

@@ -1,10 +1,10 @@
 """Watchlist related API routes."""
 
-from datetime import datetime, timedelta
 from typing import List, Optional
 
 from fastapi import APIRouter, HTTPException, Path, Query
 
+from ....utils.i18n_utils import parse_and_validate_utc_dates
 from ...db.repositories.watchlist_repository import get_watchlist_repository
 from ...services.assets.asset_service import get_asset_service
 from ..schemas import (
@@ -301,7 +301,7 @@ async def get_watchlist(
         description="Create a new watchlist",
     )
     async def create_watchlist(
-        request: CreateWatchlistRequest = None,
+        request: CreateWatchlistRequest,
     ):
         """Create a new watchlist."""
         try:
@@ -341,7 +341,7 @@ async def create_watchlist(
         summary="Add asset to watchlist",
         description="Add a asset to a watchlist",
     )
-    async def add_asset_to_watchlist(request: AddAssetRequest = None):
+    async def add_asset_to_watchlist(request: AddAssetRequest):
         """Add a asset to a watchlist."""
         try:
             success = watchlist_repo.add_asset_to_watchlist(
@@ -453,8 +453,8 @@ async def delete_watchlist(
         description="Update notes for a asset in a watchlist",
     )
     async def update_asset_notes(
+        request: UpdateAssetNotesRequest,
         ticker: str = Path(..., description="Asset ticker"),
-        request: UpdateAssetNotesRequest = None,
         watchlist_name: Optional[str] = Query(
             None, description="Watchlist name (uses default if not provided)"
         ),
@@ -499,10 +499,12 @@ async def update_asset_notes(
     async def get_asset_historical_prices(
         ticker: str = Path(..., description="Asset ticker"),
         start_date: Optional[str] = Query(
-            None, description="Start date (YYYY-MM-DD), defaults to 30 days ago"
+            None,
+            description="Start date in UTC format (YYYY-MM-DDTHH:MM:SSZ or YYYY-MM-DDTHH:MM:SS.fffZ), defaults to 30 days ago",
         ),
         end_date: Optional[str] = Query(
-            None, description="End date (YYYY-MM-DD), defaults to today"
+            None,
+            description="End date in UTC format (YYYY-MM-DDTHH:MM:SSZ or YYYY-MM-DDTHH:MM:SS.fffZ), defaults to now",
         ),
         interval: str = Query("1d", description="Data interval (1d, 1h, 5m, etc.)"),
         language: Optional[str] = Query(
@@ -511,22 +513,8 @@ async def get_asset_historical_prices(
     ):
         """Get historical prices for a asset."""
         try:
-            # Parse dates
-            if end_date:
-                end_dt = datetime.strptime(end_date, "%Y-%m-%d")
-            else:
-                end_dt = datetime.now()
-
-            if start_date:
-                start_dt = datetime.strptime(start_date, "%Y-%m-%d")
-            else:
-                start_dt = end_dt - timedelta(days=30)
-
-            # Validate date range
-            if start_dt >= end_dt:
-                raise HTTPException(
-                    status_code=400, detail="Start date must be before end date"
-                )
+            # Parse and validate UTC dates using i18n_utils
+            start_dt, end_dt = parse_and_validate_utc_dates(start_date, end_date)
 
             # Get historical price data
             result = asset_service.get_historical_prices(
@@ -569,7 +557,7 @@ async def get_asset_historical_prices(
             raise
         except ValueError as e:
             raise HTTPException(
-                status_code=400, detail=f"Invalid date format: {str(e)}"
+                status_code=400, detail=f"Invalid UTC datetime format: {str(e)}"
             )
         except Exception as e:
             raise HTTPException(

python/valuecell/utils/i18n_utils.py

@@ -1,7 +1,7 @@
 """Internationalization utility functions for ValueCell application."""
 
 import re
-from datetime import datetime
+from datetime import datetime, timedelta
 from pathlib import Path
 from typing import Any, Dict, List, Optional
 
@@ -165,6 +165,111 @@ def convert_timezone(dt: datetime, from_tz: str, to_tz: str) -> datetime:
         return dt
 
 
+def parse_utc_datetime(date_str: str) -> datetime:
+    """Parse UTC datetime string into timezone-aware datetime object.
+
+    Args:
+        date_str: UTC datetime string in ISO format (YYYY-MM-DDTHH:MM:SSZ or YYYY-MM-DDTHH:MM:SS.fffZ)
+
+    Returns:
+        Timezone-aware datetime object in UTC
+
+    Raises:
+        ValueError: If date string format is invalid
+    """
+    # Try different UTC datetime formats
+    formats = [
+        "%Y-%m-%dT%H:%M:%SZ",  # 2023-12-01T10:30:00Z
+        "%Y-%m-%dT%H:%M:%S.%fZ",  # 2023-12-01T10:30:00.123Z
+        "%Y-%m-%dT%H:%M:%S.%f",  # 2023-12-01T10:30:00.123 (without Z)
+        "%Y-%m-%dT%H:%M:%S",  # 2023-12-01T10:30:00 (without Z)
+        "%Y-%m-%d",  # 2023-12-01 (date only)
+    ]
+
+    for fmt in formats:
+        try:
+            dt = datetime.strptime(date_str, fmt)
+            # If no timezone info, assume UTC
+            if dt.tzinfo is None:
+                dt = pytz.UTC.localize(dt)
+            return dt
+        except ValueError:
+            continue
+
+    raise ValueError(
+        f"Invalid UTC datetime format: {date_str}. Expected formats: YYYY-MM-DDTHH:MM:SSZ, YYYY-MM-DDTHH:MM:SS.fffZ, or YYYY-MM-DD"
+    )
+
+
+def format_utc_datetime(dt: datetime, format_type: str = "iso") -> str:
+    """Format datetime as UTC string.
+
+    Args:
+        dt: Datetime object to format
+        format_type: Format type ('iso', 'date', 'time', 'datetime')
+
+    Returns:
+        Formatted UTC datetime string
+    """
+    # Ensure datetime is in UTC
+    if dt.tzinfo is None:
+        dt = pytz.UTC.localize(dt)
+    elif dt.tzinfo != pytz.UTC:
+        dt = dt.astimezone(pytz.UTC)
+
+    if format_type == "iso":
+        return dt.strftime("%Y-%m-%dT%H:%M:%SZ")
+    elif format_type == "date":
+        return dt.strftime("%Y-%m-%d")
+    elif format_type == "time":
+        return dt.strftime("%H:%M:%SZ")
+    else:  # datetime
+        return dt.strftime("%Y-%m-%dT%H:%M:%SZ")
+
+
+def get_utc_now() -> datetime:
+    """Get current UTC datetime.
+
+    Returns:
+        Current datetime in UTC timezone
+    """
+    return datetime.now(pytz.UTC)
+
+
+def parse_and_validate_utc_dates(
+    start_date: Optional[str], end_date: Optional[str]
+) -> tuple[datetime, datetime]:
+    """Parse and validate UTC date parameters for API endpoints.
+
+    Args:
+        start_date: Start date string in UTC format (optional)
+        end_date: End date string in UTC format (optional)
+
+    Returns:
+        Tuple of (start_datetime, end_datetime) in UTC
+
+    Raises:
+        ValueError: If date format is invalid or start_date >= end_date
+    """
+    # Parse end date
+    if end_date:
+        end_dt = parse_utc_datetime(end_date)
+    else:
+        end_dt = get_utc_now()
+
+    # Parse start date
+    if start_date:
+        start_dt = parse_utc_datetime(start_date)
+    else:
+        start_dt = end_dt - timedelta(days=30)
+
+    # Validate date range
+    if start_dt >= end_dt:
+        raise ValueError("Start date must be before end date")
+
+    return start_dt, end_dt
+
+
 def format_file_size(size_bytes: int, language: Optional[str] = None) -> str:
     """Format file size according to language settings.