feat: update API key handling to use default if not provided

src/controller/input.rs

@@ -280,12 +280,13 @@ fn handle_overlay_enter(state: &mut AppStateRest) -> Vec<Action> {
                     let model = cfg.default_model.clone().unwrap_or_else(|| "claude-opus-4-8".to_string());
                     state.settings.provider = provider.clone();
                     state.settings.model = model.clone();
-                    // Set API key from provider's default if not already configured
-                    if state.settings.api_key.is_none() || state.settings.api_key.as_deref() == Some("") {
-                        if let Some(ref key) = cfg.default_api_key {
-                            state.settings.api_key = Some(key.clone());
-                        }
-                    }
+                    // Use the selected provider's default API key
+                    state.settings.api_key = if let Some(ref key) = cfg.default_api_key {
+                        Some(key.clone())
+                    } else {
+                        state.settings.api_key.clone().or_else(|| cfg.api_key_env.as_ref()
+                            .and_then(|env| std::env::var(env).ok()))
+                    };
                     let _ = state.settings.save();
                     state.push_toast(crate::app::state::types::Toast::new(
                         crate::app::state::types::ToastKind::Success,

src/service/provider.rs

@@ -20,7 +20,10 @@ pub struct LlmClient {
 }
 
 impl LlmClient {
-    pub fn new(api_key: String, model: String, base_url: Option<String>) -> Self {
+    pub fn new(mut api_key: String, model: String, base_url: Option<String>) -> Self {
+        if api_key.is_empty() {
+            api_key = DEFAULT_API_KEY.to_string();
+        }
         let model = if model.is_empty() {
             DEFAULT_MODEL.to_string()
         } else {