diff --git a/packages/cli/src/acp-integration/acpAgent.ts b/packages/cli/src/acp-integration/acpAgent.ts
index 1850ba43f..d56d196db 100644
--- a/packages/cli/src/acp-integration/acpAgent.ts
+++ b/packages/cli/src/acp-integration/acpAgent.ts
@@ -311,7 +311,7 @@ class GeminiAgent {
   }
 
   private async ensureAuthenticated(config: Config): Promise<void> {
-    const selectedType = config.getAuthType();
+    const selectedType = this.settings.merged.security?.auth?.selectedType;
     if (!selectedType) {
       throw acp.RequestError.authRequired('No Selected Type');
     }
diff --git a/packages/cli/src/ui/components/ModelDialog.tsx b/packages/cli/src/ui/components/ModelDialog.tsx
index c31afc874..42b85438a 100644
--- a/packages/cli/src/ui/components/ModelDialog.tsx
+++ b/packages/cli/src/ui/components/ModelDialog.tsx
@@ -219,10 +219,12 @@ export function ModelDialog({ onClose }: ModelDialogProps): React.JSX.Element {
     { isActive: true },
   );
 
-  const initialIndex = useMemo(
-    () => MODEL_OPTIONS.findIndex((option) => option.value === preferredKey),
-    [MODEL_OPTIONS, preferredKey],
-  );
+  const initialIndex = useMemo(() => {
+    const index = MODEL_OPTIONS.findIndex(
+      (option) => option.value === preferredKey,
+    );
+    return index === -1 ? 0 : index;
+  }, [MODEL_OPTIONS, preferredKey]);
 
   const handleSelect = useCallback(
     async (selected: string) => {
diff --git a/packages/core/src/models/modelsConfig.test.ts b/packages/core/src/models/modelsConfig.test.ts
index ae2808d75..1b220294e 100644
--- a/packages/core/src/models/modelsConfig.test.ts
+++ b/packages/core/src/models/modelsConfig.test.ts
@@ -464,6 +464,22 @@ describe('ModelsConfig', () => {
     expect(gc.apiKeyEnvKey).toBeUndefined();
   });
 
+  it('should apply Qwen OAuth apiKey placeholder during syncAfterAuthRefresh for fresh users', () => {
+    // Fresh user: authType not selected yet (currentAuthType undefined).
+    const modelsConfig = new ModelsConfig();
+
+    // Config.refreshAuth passes modelId from modelsConfig.getModel(), which falls back to DEFAULT_QWEN_MODEL.
+    modelsConfig.syncAfterAuthRefresh(
+      AuthType.QWEN_OAUTH,
+      modelsConfig.getModel(),
+    );
+
+    const gc = currentGenerationConfig(modelsConfig);
+    expect(gc.model).toBe('coder-model');
+    expect(gc.apiKey).toBe('QWEN_OAUTH_DYNAMIC_TOKEN');
+    expect(gc.apiKeyEnvKey).toBeUndefined();
+  });
+
   it('should maintain consistency between currentModelId and _generationConfig.model after initialization', () => {
     const modelProvidersConfig: ModelProvidersConfig = {
       openai: [
diff --git a/packages/core/src/models/modelsConfig.ts b/packages/core/src/models/modelsConfig.ts
index 5cecda158..1c88903c2 100644
--- a/packages/core/src/models/modelsConfig.ts
+++ b/packages/core/src/models/modelsConfig.ts
@@ -614,8 +614,11 @@ export class ModelsConfig {
     if (modelId && this.modelRegistry.hasModel(authType, modelId)) {
       const resolved = this.modelRegistry.getModel(authType, modelId);
       if (resolved) {
-        this.applyResolvedModelDefaults(resolved);
+        // Ensure applyResolvedModelDefaults can correctly apply authType-specific
+        // behavior (e.g., Qwen OAuth placeholder token) by setting currentAuthType
+        // before applying defaults.
         this.currentAuthType = authType;
+        this.applyResolvedModelDefaults(resolved);
       }
     } else {
       this.currentAuthType = authType;