fix: address code review findings

cmd/api/handlers.go

@@ -438,7 +438,7 @@ func adminAuth(hc *HandlerContext, w http.ResponseWriter, r *http.Request) bool
 	}
 	providedAPIKey := r.Header.Get("X-Admin-Api-Key")
 	if !hmac.Equal([]byte(providedAPIKey), []byte(expectedAPIKey)) {
-		http.Error(w, "unauthorized: admin API key required", http.StatusUnauthorized)
+		http.Error(w, "unauthorized: invalid admin API key", http.StatusUnauthorized)
 		return false
 	}
 	return true
@@ -574,11 +574,13 @@ func RemoveSavedCity(hc *HandlerContext, w http.ResponseWriter, r *http.Request)
 		userID = "default"
 	}
 
-	cityCode := strings.TrimPrefix(r.URL.Path, "/v1/preferences/saved-cities/")
-	if cityCode == "" || cityCode == "/v1/preferences/saved-cities/" {
+	parts := strings.Split(r.URL.Path, "/")
+	// Expected: /v1/preferences/saved-cities/{city_code} -> parts: ["", "v1", "preferences", "saved-cities", "{city_code}"]
+	if len(parts) < 5 {
 		http.Error(w, "missing city code", http.StatusBadRequest)
 		return
 	}
+	cityCode := parts[4]
 
 	if err := hc.Preferences.RemoveSavedCity(r.Context(), userID, cityCode); err != nil {
 		http.Error(w, "failed to remove saved city: "+err.Error(), http.StatusInternalServerError)
@@ -628,6 +630,12 @@ func AddSearchHistory(hc *HandlerContext, w http.ResponseWriter, r *http.Request
 		return
 	}
 
+	// Validate input length
+	if len(req.FromCity) > 100 || len(req.ToCity) > 100 || len(req.Date) > 20 {
+		http.Error(w, "invalid city or date format", http.StatusBadRequest)
+		return
+	}
+
 	if err := hc.Preferences.AddSearchHistory(r.Context(), userID, req.FromCity, req.ToCity, req.Date); err != nil {
 		http.Error(w, "failed to add search history: "+err.Error(), http.StatusInternalServerError)
 		return

internal/routing/graph.go

@@ -343,7 +343,9 @@ func (g *Graph) FindRoute(originID, destID string, opts SearchOptions, closedSta
 				}
 			}
 		}
-	} // Build adjacency list from edges
+	}
+
+	// Build adjacency list from edges
 	adj := g.buildAdjacencyList()
 
 	// BFS with transfer tracking
@@ -976,7 +978,7 @@ type HubStation struct {
 // rule from the transfer rules, or returns the default MCT.
 func getMCTForTransfer(optsMCT int, g *Graph) int {
 	// Default MCT if no rules match
-	defaultMCT := 1800 // 30 minutes
+	defaultMCT := storage.DefaultMCT // 30 minutes
 
 	// If the user explicitly set an MCT via SearchOptions, prefer that
 	if optsMCT > 0 {
@@ -984,11 +986,10 @@ func getMCTForTransfer(optsMCT int, g *Graph) int {
 	}
 
 	// Try to determine MCT from node types in the graph
-	// This is a simplified lookup; in a full implementation, this would
-	// query the transfer_rules table from the database
+	// In a full implementation, this would query the transfer_rules table
+	// from the database using storage.MinTransferTime(ruleKey, rules, defaultMCT)
+	// For now, return the default MCT.
 
-	// For now, return the default MCT. In a full implementation,
-	// this would query the transfer_rules table.
 	return defaultMCT
 }