Added a lot of functionality. Bugfixes and changes

oAI/Models/Settings.swift

@@ -20,7 +20,8 @@ struct Settings: Codable {
     var streamEnabled: Bool
     var maxTokens: Int
     var systemPrompt: String?
-    
+    var customPromptMode: CustomPromptMode
+
     // Feature flags
     var onlineMode: Bool
     var memoryEnabled: Bool
@@ -58,7 +59,7 @@ struct Settings: Codable {
         case anthropicNative = "anthropic_native"
         case duckduckgo
         case google
-        
+
         var displayName: String {
             switch self {
             case .anthropicNative: return "Anthropic Native"
@@ -67,6 +68,25 @@ struct Settings: Codable {
             }
         }
     }
+
+    enum CustomPromptMode: String, Codable, CaseIterable {
+        case append = "append"
+        case replace = "replace"
+
+        var displayName: String {
+            switch self {
+            case .append: return "Append to Default"
+            case .replace: return "Replace Default (BYOP)"
+            }
+        }
+
+        var description: String {
+            switch self {
+            case .append: return "Your custom prompt will be added after the default system prompt"
+            case .replace: return "Only use your custom prompt (Bring Your Own Prompt)"
+            }
+        }
+    }
     
     // Default settings
     static let `default` = Settings(
@@ -79,6 +99,7 @@ struct Settings: Codable {
         streamEnabled: true,
         maxTokens: 4096,
         systemPrompt: nil,
+        customPromptMode: .append,
         onlineMode: false,
         memoryEnabled: true,
         mcpEnabled: false,