fix: address code review findings

cmd/api/handlers.go

@@ -205,6 +205,18 @@ func RouteSearch(hc *HandlerContext, w http.ResponseWriter, r *http.Request) {
 		RankingMode: rankingMode,
 	}
 
+	// Determine if this is a far-term search (date is more than 7 days in the future)
+	if req.Date != "" {
+		requestDate, err := time.Parse("2006-01-02", req.Date)
+		if err == nil {
+			now := time.Now()
+			daysDiff := int(requestDate.Sub(now).Hours() / 24)
+			if daysDiff >= 7 {
+				opts.FarTerm = true
+			}
+		}
+	}
+
 	// Detect closed stations and get neighbors for fallback
 	closedStationsMap := make(map[string]bool)
 	neighborsMap := make(map[string][]storage.StationNeighbor)
@@ -431,7 +443,7 @@ func StationStatus(hc *HandlerContext, w http.ResponseWriter, r *http.Request) {
 func adminAuth(hc *HandlerContext, w http.ResponseWriter, r *http.Request) bool {
 	expectedAPIKey := os.Getenv("TRIP_PLANNER_ADMIN_API_KEY")
 	if expectedAPIKey == "" {
-		http.Error(w, "unauthorized", http.StatusUnauthorized)
+		http.Error(w, "server configuration error: TRIP_PLANNER_ADMIN_API_KEY is not set", http.StatusInternalServerError)
 		return false
 	}
 	providedAPIKey := r.Header.Get("X-Admin-Api-Key")

cmd/cron/station_status.go

@@ -131,12 +131,17 @@ func (sm *StationMonitor) updateStationStatus(ctx context.Context, tripCount int
 	zeroSinceData, err := sm.Cache.Get(ctx, zeroSinceKey)
 	var zeroSince time.Time
 	if err == nil && zeroSinceData != nil {
-		var zeroSinceUnix int64
-		_, parseErr := fmt.Sscanf(string(zeroSinceData), "%d", &zeroSinceUnix)
-		if parseErr == nil {
-			zeroSince = time.Unix(zeroSinceUnix, 0)
-		} else {
+		// Handle "0" marker for time.Time{} (no zero-since)
+		if string(zeroSinceData) == "0" {
 			zeroSince = time.Time{}
+		} else {
+			var zeroSinceUnix int64
+			_, parseErr := fmt.Sscanf(string(zeroSinceData), "%d", &zeroSinceUnix)
+			if parseErr == nil {
+				zeroSince = time.Unix(zeroSinceUnix, 0)
+			} else {
+				zeroSince = time.Time{}
+			}
 		}
 	}
 
@@ -184,7 +189,12 @@ func (sm *StationMonitor) updateStationStatus(ctx context.Context, tripCount int
 	}
 
 	// Write updated zero-since timestamp to cache with 24h TTL
-	if err := sm.Cache.Set(ctx, zeroSinceKey, []byte(fmt.Sprintf("%d", zeroSince.Unix())), 24*time.Hour); err != nil {
+	// Use "0" marker for time.Time{} to indicate no zero-since
+	zeroSinceStr := "0"
+	if !zeroSince.IsZero() {
+		zeroSinceStr = fmt.Sprintf("%d", zeroSince.Unix())
+	}
+	if err := sm.Cache.Set(ctx, zeroSinceKey, []byte(zeroSinceStr), 24*time.Hour); err != nil {
 		return newStatus, fmt.Errorf("cache set zero since: %w", err)
 	}