perf: skulpt 改为按需加载，client-zip 换成 fflate

skulpt 此前被 SubmitCode.vue 静态引用，945K 的 chunk 落在做题页首屏，
学生打开任何一道题都要下 233KB gzip，只为提交时拿一个语法错误行号。
改成 import() 懒加载并在语言切到 Python3 时预取，加载失败放行提交、
交给后端判题兜底。构建产物确认该 chunk 只剩一处 import() 引用，
index.html 不再引用。

client-zip 的能力 fflate 已经覆盖（utils/functions.ts 本就在用 zlibSync），
新增 createZipBlob 统一两处测试用例打包，删掉该依赖。压缩方式由 store
变为 deflate，Python zipfile 透明解压，后端不受影响。

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/admin/problem/components/SQLTestcaseEditor.vue

@@ -1,6 +1,6 @@
 <script setup lang="ts">
-import { downloadZip } from "client-zip"
 import type { LANGUAGE, SQLDisplay, Testcase } from "utils/types"
+import { createZipBlob } from "utils/functions"
 import SQLDataTable from "oj/problem/components/SQLDataTable.vue"
 import {
   generateSQLTestcase,
@@ -156,15 +156,13 @@ async function preview() {
 async function upload() {
   isUploading.value = true
   try {
-    const now = new Date()
     const data = scripts.value
       .filter((s) => s.sql.trim())
       .map((s, i) => ({
         name: `${i + 1}.sql`,
-        input: s.sql,
-        lastModified: now,
+        content: s.sql,
       }))
-    const blob = await downloadZip(data).blob()
+    const blob = createZipBlob(data)
     const file = new File([blob], "testcase.zip", { type: "application/zip" })
 
     const res = await uploadTestcases(file, { sql: true })

src/admin/problem/components/TestcaseGenerator.vue

@@ -1,6 +1,6 @@
 <script setup lang="ts">
-import { downloadZip } from "client-zip"
 import type { LANGUAGE, Testcase } from "utils/types"
+import { createZipBlob } from "utils/functions"
 import { createTestSubmission } from "utils/judge"
 import { uploadTestcases } from "../../api"
 
@@ -158,15 +158,14 @@ async function run() {
 async function upload() {
   isUploading.value = true
   try {
-    const now = new Date()
     const data = files.value
       .filter((f) => f.in.trim() && f.out && !f.error)
       .flatMap((f, i) => [
-        { name: `${i + 1}.in`, input: f.in, lastModified: now },
-        { name: `${i + 1}.out`, input: f.out, lastModified: now },
+        { name: `${i + 1}.in`, content: f.in },
+        { name: `${i + 1}.out`, content: f.out },
       ])
 
-    const blob = await downloadZip(data).blob()
+    const blob = createZipBlob(data)
     const file = new File([blob], "testcase.zip", { type: "application/zip" })
 
     const res = await uploadTestcases(file)

src/oj/problem/components/SubmitCode.vue

@@ -17,7 +17,10 @@ import SubmissionResult from "./SubmissionResult.vue"
 import { getSubmitButtonState } from "./submitButtonState"
 import { useBreakpoints } from "shared/composables/breakpoints"
 import { useUserStore } from "shared/store/user"
-import { checkPythonSyntax } from "oj/problem/utils/pythonSyntaxCheck"
+import {
+  checkPythonSyntax,
+  prefetchPythonSyntaxChecker,
+} from "oj/problem/utils/pythonSyntaxCheck"
 
 // ==================== 异步组件 ====================
 const ProblemComment = defineAsyncComponent(
@@ -50,6 +53,16 @@ const showResult = ref(false)
 const isFormatting = ref(false)
 const isSubmittingRequest = ref(false)
 
+// ==================== Python 语法检测器预取 ====================
+// 选中 Python3 时就把 Skulpt 拉下来，避免点提交时才开始下载
+watch(
+  () => codeStore.code.language,
+  (language) => {
+    if (language === "Python3") prefetchPythonSyntaxChecker()
+  },
+  { immediate: true },
+)
+
 // ==================== 提交冷却 ====================
 const { start: startCooldown, isPending: isCooldown } = useTimeout(5000, {
   controls: true,
@@ -99,7 +112,7 @@ async function submit() {
 
   // 0. Python3 语法检测
   if (codeStore.code.language === "Python3") {
-    const syntaxError = checkPythonSyntax(codeStore.code.value)
+    const syntaxError = await checkPythonSyntax(codeStore.code.value)
     if (syntaxError) {
       message.warning(`第 ${syntaxError.line} 行存在语法错误，请修正后再提交`)
       return

src/oj/problem/utils/pythonSyntaxCheck.ts

@@ -1,15 +1,47 @@
-// @ts-ignore - skulpt has no type definitions
-import Sk from "skulpt"
-
 export interface PythonSyntaxError {
   line: number
 }
 
+let skulptPromise: Promise<any> | null = null
+
+/**
+ * 按需加载 Skulpt（约 233KB gzip），只在提交 Python3 代码时才下载。
+ * 结果缓存，同一页面只加载一次。
+ */
+function loadSkulpt(): Promise<any> {
+  if (!skulptPromise) {
+    // @ts-ignore - skulpt has no type definitions
+    skulptPromise = import("skulpt").then((m) => m.default ?? m)
+  }
+  return skulptPromise
+}
+
+/**
+ * 提前把 Skulpt 拉下来，避免点提交时才开始下载。
+ * 失败不影响功能，提交时会再试一次。
+ */
+export function prefetchPythonSyntaxChecker() {
+  loadSkulpt().catch(() => {
+    skulptPromise = null
+  })
+}
+
 /**
  * 用 Skulpt 检测 Python 代码中的语法错误。
  * 只编译不执行，不受 input() 等 IO 调用影响。
+ * 加载失败时返回 null（放行提交），交给后端判题兜底。
  */
-export function checkPythonSyntax(code: string): PythonSyntaxError | null {
+export async function checkPythonSyntax(
+  code: string,
+): Promise<PythonSyntaxError | null> {
+  let Sk: any
+  try {
+    Sk = await loadSkulpt()
+  } catch {
+    skulptPromise = null
+    return null
+  }
+
   Sk.configure({ output: () => {} })
   try {
     Sk.compile(code, "prog.py", "exec")

src/utils/functions.ts

@@ -1,7 +1,14 @@
 import { getTime, intervalToDuration, parseISO, type Duration } from "date-fns"
 import { User } from "./types"
 import { USER_TYPE } from "./constants"
-import { strFromU8, strToU8, unzlibSync, zlibSync } from "fflate"
+import {
+  strFromU8,
+  strToU8,
+  unzlibSync,
+  zipSync,
+  zlibSync,
+  type Zippable,
+} from "fflate"
 import copyTextFallback from "copy-text-to-clipboard"
 import { customAlphabet } from "nanoid"
 
@@ -208,6 +215,22 @@ export function atou(base64: string): string {
   return strFromU8(unzipped)
 }
 
+/**
+ * 把若干文本文件打包成 zip Blob
+ * @param files 文件名和文本内容
+ * @param mtime 归档内的修改时间，默认当前时间
+ */
+export function createZipBlob(
+  files: { name: string; content: string }[],
+  mtime: Date = new Date(),
+): Blob {
+  const entries: Zippable = {}
+  for (const f of files) {
+    entries[f.name] = strToU8(f.content)
+  }
+  return new Blob([zipSync(entries, { mtime })], { type: "application/zip" })
+}
+
 /**
  * 复制文本到剪贴板
  * 优先使用 Clipboard API（支持在 modal 中使用），失败时回退到 copy-text-to-clipboard