Fix AI API key not persisted in cache (#39)

The AI API key has a json:"-" tag for security (to prevent exposure in API
responses), but this caused it to be excluded when caching ChatbotSettings.

After the first message, settings were served from cache with an empty API key,
causing subsequent AI requests to fail with "AI not configured" error.

Solution: Create a chatbotSettingsCache wrapper struct that explicitly includes
the API key when caching, similar to how whatsAppAccountCache handles the
AccessToken field.

Fixes #38

Author: shridarpatil

internal/handlers/cache.go

@@ -31,6 +31,12 @@ const (
 	aiContextsCachePrefix      = "chatbot:ai_contexts:"
 )
 
+// chatbotSettingsCache is used for caching since AI.APIKey has json:"-" tag
+type chatbotSettingsCache struct {
+	models.ChatbotSettings
+	AIAPIKey string `json:"ai_api_key_cache"`
+}
+
 // getChatbotSettingsCached retrieves chatbot settings from cache or database
 func (a *App) getChatbotSettingsCached(orgID uuid.UUID, whatsAppAccount string) (*models.ChatbotSettings, error) {
 	ctx := context.Background()
@@ -39,9 +45,11 @@ func (a *App) getChatbotSettingsCached(orgID uuid.UUID, whatsAppAccount string)
 	// Try cache first
 	cached, err := a.Redis.Get(ctx, cacheKey).Result()
 	if err == nil && cached != "" {
-		var settings models.ChatbotSettings
-		if err := json.Unmarshal([]byte(cached), &settings); err == nil {
-			return &settings, nil
+		var cacheData chatbotSettingsCache
+		if err := json.Unmarshal([]byte(cached), &cacheData); err == nil {
+			// Restore the API key from the cache wrapper
+			cacheData.ChatbotSettings.AI.APIKey = cacheData.AIAPIKey
+			return &cacheData.ChatbotSettings, nil
 		}
 	}
 
@@ -56,8 +64,12 @@ func (a *App) getChatbotSettingsCached(orgID uuid.UUID, whatsAppAccount string)
 		return nil, result.Error
 	}
 
-	// Cache the result
-	if data, err := json.Marshal(settings); err == nil {
+	// Cache the result (include AI APIKey explicitly since it has json:"-" tag)
+	cacheData := chatbotSettingsCache{
+		ChatbotSettings: settings,
+		AIAPIKey:        settings.AI.APIKey,
+	}
+	if data, err := json.Marshal(cacheData); err == nil {
 		a.Redis.Set(ctx, cacheKey, data, settingsCacheTTL)
 	}