Initial commit of 001code-html Scratch frontend project.

Includes scratch-gui, scratch-vm, scratch-blocks, scratch-render, scratch-l10n, and deployment config.

Co-authored-by: Cursor <cursoragent@cursor.com>

scratch-vm/test/integration/tw_add_builtin_extension.js

@@ -0,0 +1,60 @@
+const fs = require('fs');
+const path = require('path');
+const {test} = require('tap');
+const VM = require('../../src/virtual-machine');
+const Scratch = require('../../src/extension-support/tw-extension-api-common');
+
+class TestBuiltinExtension {
+    getInfo () {
+        return {
+            id: 'testbuiltin',
+            name: 'Test Builtin',
+            blocks: [
+                {
+                    opcode: 'test',
+                    blockType: Scratch.BlockType.REPORTER,
+                    text: 'test'
+                }
+            ]
+        };
+    }
+    test () {
+        return 'It works! 123';
+    }
+}
+
+test('addBuiltingExtension', t => {
+    const vm = new VM();
+
+    t.equal(vm.extensionManager.isBuiltinExtension('testbuiltin'), false, 'extension is not known');
+    t.equal(vm.extensionManager.isExtensionLoaded('testbuiltin'), false, 'extension is not loaded');
+
+    vm.extensionManager.addBuiltinExtension('testbuiltin', TestBuiltinExtension);
+    t.equal(vm.extensionManager.isBuiltinExtension('testbuiltin'), true, 'extension is now known');
+    t.equal(vm.extensionManager.isExtensionLoaded('testbuiltin'), false, 'extension is still not loaded');
+
+    const fixture = fs.readFileSync(path.join(__dirname, '..', 'fixtures', 'tw-add-builtin-extension.sb3'));
+    vm.loadProject(fixture).then(() => {
+        t.equal(vm.extensionManager.isExtensionLoaded('testbuiltin'), true, 'extension was loaded automatically');
+
+        vm.runtime.on('SAY', (target, type, text) => {
+            t.equal(text, 'It works! 123', 'said value from extension');
+            t.end();
+        });
+
+        vm.greenFlag();
+        vm.runtime._step();
+    });
+});
+
+test('each runtime has own set of extensions', t => {
+    const vm1 = new VM();
+    const vm2 = new VM();
+
+    vm1.extensionManager.addBuiltinExtension('testbuiltin', TestBuiltinExtension);
+
+    t.ok(vm1.extensionManager.isBuiltinExtension('testbuiltin'));
+    t.notOk(vm2.extensionManager.isBuiltinExtension('testbuiltin'));
+
+    t.end();
+});