fix(acp): prevent unnecessary credential cache clearing on re-authent… (#9410)

Co-authored-by: Tommaso Sciortino <sciortino@gmail.com>

packages/cli/src/zed-integration/zedIntegration.ts

@@ -113,8 +113,16 @@ export class GeminiAgent {
 
   async authenticate({ methodId }: acp.AuthenticateRequest): Promise<void> {
     const method = z.nativeEnum(AuthType).parse(methodId);
+    const selectedAuthType = this.settings.merged.security?.auth?.selectedType;
 
-    await clearCachedCredentialFile();
+    // Only clear credentials when switching to a different auth method
+    if (selectedAuthType && selectedAuthType !== method) {
+      await clearCachedCredentialFile();
+    }
+
+    // Refresh auth with the requested method
+    // This will reuse existing credentials if they're valid,
+    // or perform new authentication if needed
     await this.config.refreshAuth(method);
     this.settings.setValue(
       SettingScope.User,