fix: refine agent image attachments and restore Korean filenames

scripts/test-agent-request-payload.cjs

@@ -19,6 +19,20 @@ function visit(node) {
 visit(source)
 assert.ok(payloadExpression, 'Agent request JSON serialization must exist')
 
+test('user messages preserve only typed text while attachments remain separate metadata', () => {
+  let initializer
+  function find(node) {
+    if (ts.isVariableDeclaration(node) && node.name.getText(source) === 'userMessage') initializer = node.initializer.getText(source)
+    ts.forEachChild(node, find)
+  }
+  find(source)
+  assert.ok(initializer)
+  for (const request of ['이 이미지에서 슬램에 필요한 모듈만 골라봐', '첫 줄\n첨부 파일: 직접 입력한 내용']) {
+    const message = vm.runInNewContext(`(${initializer})`, { request, options: { attachments: [{ name: '스크린샷.png' }] } })
+    assert.equal(message.content, request)
+  }
+})
+
 function serialize(attachments, finalize = false, request = '설정 위치 알려줘', imageTokens = []) {
   return JSON.parse(vm.runInNewContext(payloadExpression, {
     courseId: 'course-1', weekNumber: 3, request, options: { attachments }, finalize,