清理时区逻辑：TRADING_REGIONS→REGIONS，移除 detectLocalRegion/TZ fallback，用 CITY_REGION 硬编码替代

frontend/components/dashboard/ScanTerminalDashboard.tsx

@@ -27,9 +27,9 @@ import {
   getGapColor,
   getSignalLabel,
   getSignalState,
-  resolveTradingRegionKey,
-  TRADING_REGIONS,
-  detectLocalRegion,
+  getCityRegion,
+  REGIONS,
+  getDefaultRegion,
 } from "@/components/dashboard/scan-terminal/continent-grouping";
 import { MobileCityCard } from "@/components/dashboard/scan-terminal/MobileCityCard";
 import { MobileRegionTabs } from "@/components/dashboard/scan-terminal/MobileRegionTabs";
@@ -290,7 +290,7 @@ function PolyWeatherTerminal({
 
   const filteredRegionRows = useMemo(() => {
     return rows.filter(
-      (row) => resolveTradingRegionKey(row) === selectedRegionKey,
+      (row) => getCityRegion(row) === selectedRegionKey,
     );
   }, [rows, selectedRegionKey]);
 
@@ -504,7 +504,7 @@ function PolyWeatherTerminal({
             <>
               {/* Region tabs */}
               <div className="flex shrink-0 items-center gap-1 overflow-x-auto rounded-[4px] border border-[#cfd6df] bg-white p-1 mb-2 scrollbar-none">
-                {TRADING_REGIONS.filter((r) => visibleRegions.has(r.key)).map((r) => ({
+                {REGIONS.filter((r) => visibleRegions.has(r.key)).map((r) => ({
                     key: r.key,
                     labelEn: r.labelEn.toUpperCase(),
                     labelZh: r.labelZh,
@@ -540,7 +540,7 @@ function PolyWeatherTerminal({
                     id="region-selector-popover"
                     className="hidden absolute right-0 top-full mt-1 z-50 bg-white border border-slate-200 rounded-lg shadow-lg p-2 min-w-[180px]"
                   >
-                    {TRADING_REGIONS.map((r) => {
+                    {REGIONS.map((r) => {
                       const checked = visibleRegions.has(r.key);
                       return (
                         <label
@@ -649,7 +649,7 @@ function ScanTerminalScreen() {
       const stored = localStorage.getItem("polyweather_visible_regions");
       if (stored) return new Set(JSON.parse(stored));
     } catch {}
-    return new Set(TRADING_REGIONS.map((r) => r.key));
+    return new Set(REGIONS.map((r) => r.key));
   });
   const toggleRegion = useCallback((key: string) => {
     setVisibleRegions((prev) => {
@@ -734,7 +734,7 @@ function ScanTerminalScreen() {
   }, []);
 
   useEffect(() => {
-    setSelectedRegionKey(detectLocalRegion());
+    setSelectedRegionKey(getDefaultRegion());
     setLocalTimezoneOffsetSeconds(-new Date().getTimezoneOffset() * 60);
   }, []);
 

frontend/components/dashboard/scan-terminal/LiveTemperatureThresholdChart.tsx

@@ -13,7 +13,14 @@ import {
   XAxis,
   YAxis,
 } from "recharts";
-import type { AmosData, AirportCurrentConditions, CityDetail, ScanOpportunityRow } from "@/lib/dashboard-types";
+import type {
+  AmosData,
+  AirportCurrentConditions,
+  CityDetail,
+  ScanOpportunityRow,
+  ForecastDay,
+  DailyModelForecast,
+} from "@/lib/dashboard-types";
 import { buildDebBaselinePath } from "@/lib/temperature-chart-paths";
 import { Panel } from "@/components/dashboard/scan-terminal/Panel";
 import { rowName, temp } from "@/components/dashboard/scan-terminal/utils";

frontend/components/dashboard/scan-terminal/continent-grouping.ts

@@ -1,6 +1,6 @@
 import type { ScanOpportunityRow } from "@/lib/dashboard-types";
 
-export const TRADING_REGIONS = [
+export const REGIONS = [
   { key: "east_asia", labelEn: "East Asia", labelZh: "东亚", sort: 1 },
   { key: "southeast_asia", labelEn: "Southeast Asia", labelZh: "东南亚", sort: 2 },
   { key: "central_asia", labelEn: "Central / South Asia", labelZh: "中亚 / 南亚", sort: 3 },
@@ -10,23 +10,11 @@ export const TRADING_REGIONS = [
   { key: "north_america", labelEn: "North America", labelZh: "北美", sort: 7 },
 ] as const;
 
-export type TradingRegionKey = (typeof TRADING_REGIONS)[number]["key"];
+export type RegionKey = (typeof REGIONS)[number]["key"];
 
-/** Map browser timezone offset (hours) to the closest trading region. */
-export function detectLocalRegion(): TradingRegionKey {
-  const offset = -new Date().getTimezoneOffset() / 60; // UTC offset in hours
-  if (offset >= 8) return "east_asia";
-  if (offset >= 7) return "southeast_asia";
-  if (offset >= 4.5) return "central_asia";
-  if (offset >= 2) return "west_asia";
-  if (offset >= -2) return "europe_africa";
-  if (offset >= -4) return "south_america";
-  return "north_america";
-}
+const REGION_KEYS = new Set<string>(REGIONS.map((r) => r.key));
 
-const TRADING_REGION_KEYS = new Set<string>(TRADING_REGIONS.map((region) => region.key));
-
-const CITY_REGION_FALLBACK: Record<string, TradingRegionKey> = {
+const CITY_REGION: Record<string, RegionKey> = {
   beijing: "east_asia",
   busan: "east_asia",
   chengdu: "east_asia",
@@ -79,51 +67,23 @@ const CITY_REGION_FALLBACK: Record<string, TradingRegionKey> = {
   wellington: "east_asia",
 };
 
-function normalizeRegionValue(value?: string | null) {
-  return String(value || "")
-    .trim()
-    .toLowerCase()
-    .replace(/[-\s]+/g, "_");
+function normalizeCity(value?: string | null) {
+  return String(value || "").trim().toLowerCase()
+    .replace(/[_-]+/g, " ").replace(/\s+/g, " ");
 }
 
-function normalizeCityValue(value?: string | null) {
-  return String(value || "")
-    .trim()
-    .toLowerCase()
-    .replace(/[_-]+/g, " ")
-    .replace(/\s+/g, " ");
+export function getCityRegion(row: ScanOpportunityRow): RegionKey | null {
+  const key = normalizeCity(row.city || row.city_display_name || row.display_name);
+  return CITY_REGION[key] || null;
 }
 
-function finiteNumber(value: unknown) {
-  const numeric = Number(value);
-  return Number.isFinite(numeric) ? numeric : null;
-}
-
-export function resolveTradingRegionKey(row: ScanOpportunityRow): TradingRegionKey | null {
-  const direct = normalizeRegionValue(row.trading_region);
-  if (TRADING_REGION_KEYS.has(direct)) return direct as TradingRegionKey;
-
-  const cityKey = normalizeCityValue(row.city || row.city_display_name || row.display_name);
-  const cityRegion = CITY_REGION_FALLBACK[cityKey];
-  if (cityRegion) return cityRegion;
-
-  const offset = finiteNumber(row.tz_offset_seconds);
-  if (offset !== null) {
-    const hours = offset / 3600;
-    if (hours >= 8) return "east_asia";
-    if (hours >= 7) return "southeast_asia";
-    if (hours >= 4.5) return "central_asia";
-    if (hours >= 2) return "west_asia";
-    if (hours >= -2) return "europe_africa";
-    if (hours >= -4) return "south_america";
-    return "north_america";
-  }
-
-  return null;
+/** Default region on first load — East Asia. */
+export function getDefaultRegion(): RegionKey {
+  return "east_asia";
 }
 
 export interface ContinentGroup {
-  key: TradingRegionKey | "active_signals";
+  key: RegionKey | "active_signals";
   labelEn: string;
   labelZh: string;
   sort: number;
@@ -203,7 +163,7 @@ export function buildContinentGroups(rows: ScanOpportunityRow[], isEn: boolean):
   const regionMap = new Map<string, ScanOpportunityRow[]>();
 
   for (const row of rows) {
-    const region = resolveTradingRegionKey(row) || "unknown";
+    const region = getCityRegion(row) || "unknown";
     if (!regionMap.has(region)) regionMap.set(region, []);
     regionMap.get(region)!.push(row);
   }
@@ -229,7 +189,7 @@ export function buildContinentGroups(rows: ScanOpportunityRow[], isEn: boolean):
     });
   }
 
-  for (const region of TRADING_REGIONS) {
+  for (const region of REGIONS) {
     const regionRows = regionMap.get(region.key) || [];
     if (regionRows.length === 0) continue;