test: preserve empty selections against configured extension defaults

crates/goose/src/acp/server.rs

@@ -2925,7 +2925,9 @@ extensions:
 
     #[test]
     fn empty_recipe_extensions_do_not_override_explicit_empty_extensions() {
-        let (config, _c, _s) = config_with_yaml("");
+        let (config, _c, _s) = config_with_yaml(
+            "extensions:\n  developer:\n    enabled: true\n    type: builtin\n    name: developer\n",
+        );
         let project_root = tempfile::tempdir().unwrap();
         let extensions = initial_session_extensions(
             &config,
@@ -2937,6 +2939,16 @@ extensions:
         )
         .unwrap();
         assert!(extensions.is_empty());
+        let defaults = initial_session_extensions(
+            &config,
+            &default_builtin("developer"),
+            project_root.path(),
+            vec![],
+            None,
+            Some(&[]),
+        )
+        .unwrap();
+        assert!(has_developer(&defaults));
     }
 
     #[test]

crates/goose/src/session/extension_data.rs

@@ -204,6 +204,17 @@ mod tests {
         expected: Option<Vec<ExtensionConfig>>,
     ) {
         let config = test_config();
+        config
+            .set_param(
+                "extensions",
+                json!({"developer": {"enabled": true, "type": "builtin", "name": "developer", "description": "dev"}}),
+            )
+            .unwrap();
+        assert!(
+            crate::config::extensions::get_enabled_extensions_with_config(&config)
+                .iter()
+                .any(|extension| extension.name() == "developer"),
+        );
         let expected = expected.unwrap_or_else(|| {
             crate::config::extensions::get_enabled_extensions_with_config(&config)
         });
@@ -213,6 +224,47 @@ mod tests {
         );
     }
 
+    #[tokio::test]
+    async fn persisted_empty_extensions_override_configured_defaults() {
+        let config = test_config();
+        config
+            .set_param(
+                "extensions",
+                json!({"developer": {"enabled": true, "type": "builtin", "name": "developer", "description": "dev"}}),
+            )
+            .unwrap();
+        let defaults = crate::config::extensions::get_enabled_extensions_with_config(&config);
+        assert!(defaults
+            .iter()
+            .any(|extension| extension.name() == "developer"));
+        let directory = tempfile::tempdir().unwrap();
+        let manager = SessionManager::new(directory.path().to_path_buf());
+        let session = manager
+            .create_session(
+                directory.path().to_path_buf(),
+                "extension selection".to_string(),
+                crate::session::SessionType::User,
+                crate::config::GooseMode::default(),
+            )
+            .await
+            .unwrap();
+        assert_eq!(
+            EnabledExtensionsState::for_session(&manager, &session.id, &config).await,
+            defaults,
+        );
+        manager
+            .update(&session.id)
+            .extension_data(extension_data_with(vec![]))
+            .apply()
+            .await
+            .unwrap();
+        assert!(
+            EnabledExtensionsState::for_session(&manager, &session.id, &config)
+                .await
+                .is_empty()
+        );
+    }
+
     #[test]
     fn test_extension_data_basic_operations() {
         let mut extension_data = ExtensionData::new();

ui/desktop/src/__tests__/createSession.test.ts

@@ -47,7 +47,10 @@ vi.mock('../acp/capabilities', () => ({
   getAcpFeatureCapabilities: vi.fn(),
 }));
 
-const testRecipe = vi.hoisted(() => ({ title: 'Test recipe', description: 'Recipe used in tests' }));
+const testRecipe = vi.hoisted(() => ({
+  title: 'Test recipe',
+  description: 'Recipe used in tests',
+}));
 
 const testSession: Session = {
   id: 'session-1',