Fix city selector fallback coverage

frontend/components/dashboard/ScanTerminalDashboard.tsx

@@ -50,7 +50,10 @@ import { KoyfinRowsTable } from "@/components/dashboard/scan-terminal/KoyfinRows
 import { rowName, pct, money, temp, edgeClass } from "@/components/dashboard/scan-terminal/utils";
 import { CitySelectorDropdown } from "@/components/dashboard/scan-terminal/CitySelectorDropdown";
 import { GridLayoutSelector } from "@/components/dashboard/scan-terminal/GridLayoutSelector";
-import { cityListItemsToScanRows } from "@/components/dashboard/scan-terminal/city-fallback-rows";
+import {
+  cityListItemsToScanRows,
+  mergeScanRowsWithCityFallbackRows,
+} from "@/components/dashboard/scan-terminal/city-fallback-rows";
 
 function createEmptyAccess(loading = true): ProAccessState {
   return {
@@ -1107,7 +1110,9 @@ function ScanTerminalScreen() {
   const rows = useMemo(
     () => {
       const scanRows = terminalData?.rows || [];
-      return sortRowsByUserTime(scanRows.length ? scanRows : cityFallbackRows);
+      return sortRowsByUserTime(
+        mergeScanRowsWithCityFallbackRows(scanRows, cityFallbackRows),
+      );
     },
     [cityFallbackRows, terminalData?.rows],
   );

frontend/components/dashboard/scan-terminal/__tests__/cityFallbackRows.test.ts

@@ -1,4 +1,7 @@
-import { cityListItemsToScanRows } from "@/components/dashboard/scan-terminal/city-fallback-rows";
+import {
+  cityListItemsToScanRows,
+  mergeScanRowsWithCityFallbackRows,
+} from "@/components/dashboard/scan-terminal/city-fallback-rows";
 import type { CityListItem } from "@/lib/dashboard-types";
 
 function assert(condition: unknown, message: string) {
@@ -49,6 +52,68 @@ export function runTests() {
   assert(rows[0].temp_symbol === "°C", "celsius cities should use °C");
   assert(rows[1].trading_region === "north_america", "known cities should keep their configured product region");
   assert(rows[1].temp_symbol === "°F", "fahrenheit cities should use °F");
+
+  const scanRows = [
+    {
+      id: "scan:paris",
+      city: "paris",
+      city_display_name: "Paris",
+      current_temp: 31,
+      deb_prediction: 30.5,
+      temp_symbol: "°C",
+    },
+  ] as any[];
+  const fallbackRows = cityListItemsToScanRows([
+    {
+      airport: "Paris Le Bourget",
+      display_name: "Paris",
+      icao: "LFPB",
+      lat: 48.97,
+      lon: 2.44,
+      name: "paris",
+      risk_level: "medium",
+      temp_unit: "celsius",
+      utc_offset_seconds: 7200,
+    },
+    {
+      airport: "Munich Airport",
+      display_name: "Munich",
+      icao: "EDDM",
+      lat: 48.35,
+      lon: 11.78,
+      name: "munich",
+      risk_level: "medium",
+      temp_unit: "celsius",
+      utc_offset_seconds: 7200,
+    },
+    {
+      airport: "Cape Town International",
+      display_name: "Cape Town",
+      icao: "FACT",
+      lat: -33.97,
+      lon: 18.6,
+      name: "cape town",
+      risk_level: "medium",
+      temp_unit: "celsius",
+      utc_offset_seconds: 7200,
+    },
+  ]);
+  const merged = mergeScanRowsWithCityFallbackRows(scanRows, fallbackRows);
+  const mergedCities = merged.map((row) => row.city);
+
+  assert(merged.length === 3, "city selector data should include scan rows plus missing registry cities");
+  assert(mergedCities.includes("paris"), "merged rows should keep scan city");
+  assert(mergedCities.includes("munich"), "merged rows should include missing registry city");
+  assert(mergedCities.includes("cape town"), "merged rows should include another missing registry city");
+  assert(
+    merged.filter((row) => row.city === "paris").length === 1,
+    "merged rows should not duplicate cities already present in scan rows",
+  );
+  assert(
+    merged.find((row) => row.city === "paris")?.current_temp === 31,
+    "scan rows should win over fallback rows for cities already present",
+  );
+
   assert(
     dashboardSource.includes("cityListItemsToScanRows") &&
       dashboardSource.includes("/api/cities") &&

frontend/components/dashboard/scan-terminal/city-fallback-rows.ts

@@ -61,3 +61,25 @@ export function cityListItemsToScanRows(cities: CityListItem[]): ScanOpportunity
       };
     });
 }
+
+export function mergeScanRowsWithCityFallbackRows(
+  scanRows: ScanOpportunityRow[],
+  fallbackRows: ScanOpportunityRow[],
+): ScanOpportunityRow[] {
+  const merged = [...(scanRows || [])];
+  const seen = new Set<string>();
+
+  for (const row of merged) {
+    const key = normalizeCityKey(row.city || row.city_display_name || row.display_name || "");
+    if (key) seen.add(key);
+  }
+
+  for (const row of fallbackRows || []) {
+    const key = normalizeCityKey(row.city || row.city_display_name || row.display_name || "");
+    if (!key || seen.has(key)) continue;
+    seen.add(key);
+    merged.push(row);
+  }
+
+  return merged;
+}