feat: settings for default model

MLXServer/MLXServerApp.swift

@@ -14,8 +14,8 @@ struct MLXServerApp: App {
             ContentView()
                 .environment(modelManager)
                 .task {
-                    // Auto-load last used model (or default)
-                    let modelId = Preferences.lastModelId ?? ModelConfig.default.id
+                    // Auto-load: configured default → last used → built-in default
+                    let modelId = Preferences.defaultModelId ?? Preferences.lastModelId ?? ModelConfig.default.id
                     if let config = ModelConfig.availableModels.first(where: { $0.id == modelId }) {
                         await modelManager.loadModel(config)
                     }

MLXServer/Utilities/Preferences.swift

@@ -13,6 +13,15 @@ enum Preferences {
         set { defaults.set(newValue, forKey: lastModelKey) }
     }
 
+    // MARK: - Default startup model
+
+    private static let defaultModelKey = "defaultModelId"
+
+    static var defaultModelId: String? {
+        get { defaults.string(forKey: defaultModelKey) }
+        set { defaults.set(newValue, forKey: defaultModelKey) }
+    }
+
     // MARK: - System prompt
 
     private static let systemPromptKey = "systemPrompt"

MLXServer/Views/SettingsView.swift

@@ -5,9 +5,25 @@ struct SettingsView: View {
     @State private var apiPort: String = String(Preferences.apiPort)
     @State private var apiAutoStart: Bool = Preferences.apiAutoStart
     @State private var idleUnloadMinutes: String = String(Preferences.idleUnloadMinutes)
+    @State private var defaultModelId: String = Preferences.defaultModelId ?? ModelConfig.default.id
 
     var body: some View {
         Form {
+            Section("Startup") {
+                Picker("Default model", selection: $defaultModelId) {
+                    ForEach(ModelConfig.availableModels) { model in
+                        Text(model.displayName).tag(model.id)
+                    }
+                }
+                .onChange(of: defaultModelId) {
+                    Preferences.defaultModelId = defaultModelId
+                }
+
+                Text("The model to load automatically when the app starts.")
+                    .font(.caption)
+                    .foregroundStyle(.secondary)
+            }
+
             Section("System Prompt") {
                 TextEditor(text: $systemPrompt)
                     .font(.body.monospaced())
@@ -59,6 +75,6 @@ struct SettingsView: View {
             }
         }
         .formStyle(.grouped)
-        .frame(width: 450, height: 380)
+        .frame(width: 450, height: 460)
     }
 }