diff --git a/apps/web/src/shared/composables/useMermaid.ts b/apps/web/src/shared/composables/useMermaid.ts
index c7039a0..ddda49a 100644
--- a/apps/web/src/shared/composables/useMermaid.ts
+++ b/apps/web/src/shared/composables/useMermaid.ts
@@ -6,6 +6,8 @@
  * pele 的版本号锁死（不带 ^）：项目 2026-10 才开，小版本也在改排版。
  */
 
+import { normalizeLegacyFlowchart } from "utils/legacyFlowchart"
+
 const semanticNodeClasses = [
   "startNode",
   "endNode",
@@ -135,7 +137,8 @@ export function useMermaid() {
     try {
       // pele/lazy 按图的类型现拉对应的模块，题目里绝大多数是流程图，只拉那一块
       const { renderAsync } = await import("pele/lazy")
-      const { svg } = await renderAsync(mermaidCode, {
+      // 老师手写的老参考图一个框的种类都没标，先按标准符号重排（见 legacyFlowchart.ts）
+      const { svg } = await renderAsync(normalizeLegacyFlowchart(mermaidCode), {
         // 量字宽用页面真实的字体，否则框会比字窄或宽
         fontFamily: getComputedStyle(container).fontFamily,
         // 题目是老师写的、提交是学生写的，图里的链接和外链图片一律不画
diff --git a/apps/web/src/utils/legacyFlowchart.ts b/apps/web/src/utils/legacyFlowchart.ts
new file mode 100644
index 0000000..3e1cc24
--- /dev/null
+++ b/apps/web/src/utils/legacyFlowchart.ts
@@ -0,0 +1,113 @@
+/**
+ * 老师手写的老参考流程图，显示前按标准符号重排。
+ *
+ * 现在的流程图（学生的画布、出题页的参考图）都由结构树生成，每个框带 `class nX input` 这样的
+ * 种类，useMermaid 按种类上标准的形状和颜色。2026-10 之前老师直接手写 Mermaid 的参考图
+ * （库里 36 张，全是这种）一个种类都没标：输入写成普通方框 `B[输入n]`、开始写成正圆，
+ * 显示时只能按框里的字分彩色，和学生图上的标准符号对不上。
+ *
+ * 这里只处理**一个种类都没标**的图（学生的老提交全都标了，不受影响），按写法和字认框：
+ * 花括号是判断；字是「开始 / 结束」的是起止；以「输入」「输出」「打印」开头（或者直接写着
+ * input( / print(）的是输入输出框；其余是处理框。认出来就换成标准形状、补上种类。靠字猜的：「a = 输入」会被当成处理框。
+ * 数据不动，只改显示。
+ */
+
+const SEMANTIC_CLASS =
+  /^\s*class\s+[\w,-]+\s+(startNode|endNode|startEnd|input|output|process|decision|loop)\s*;?\s*$/m
+
+/** 节点的开口和对应的收口，长的在前（`((` 要先于 `(` 认） */
+const SHAPES: [string, string][] = [
+  ["((", "))"],
+  ["([", "])"],
+  ["[[", "]]"],
+  ["[(", ")]"],
+  ["{{", "}}"],
+  ["[/", "/]"],
+  ["[\\", "\\]"],
+  ["[", "]"],
+  ["(", ")"],
+  ["{", "}"],
+]
+
+/** 这些开头的行不是节点：声明、分组、样式 */
+const SKIP_LINE = /^\s*(graph|flowchart|subgraph|end\s*$|class|classDef|style|linkStyle|click|%%)/
+
+const START = /^(开始|start)$/i
+const END = /^(结束|end)$/i
+const INPUT = /^(输入|读入|读取|input)/i
+const OUTPUT = /^(输出|打印|显示|print|output)/i
+
+type Kind = "startNode" | "endNode" | "input" | "output" | "process" | "decision"
+
+function plain(body: string) {
+  const text = body.trim()
+  return text.startsWith('"') && text.endsWith('"') && text.length >= 2 ? text.slice(1, -1) : text
+}
+
+function kindOf(open: string, text: string): Kind {
+  const word = text.replace(/<br\s*\/?>/gi, " ").trim()
+  if (START.test(word)) return "startNode"
+  if (END.test(word)) return "endNode"
+  if (open === "{" || open === "{{") return "decision"
+  // 有老师直接写代码：「a = float(input())」是读数据
+  if (INPUT.test(word) || /\binput\s*\(/.test(word)) return "input"
+  if (OUTPUT.test(word)) return "output"
+  return "process"
+}
+
+function shaped(kind: Kind, text: string) {
+  const label = `"${text.replace(/"/g, "#quot;")}"`
+  if (kind === "startNode" || kind === "endNode") return `([${label}])`
+  if (kind === "decision") return `{${label}}`
+  if (kind === "input" || kind === "output") return `[/${label}/]`
+  return `[${label}]`
+}
+
+/** 从 start 起找收口，引号里的不算 */
+function closeAt(line: string, start: number, close: string) {
+  let quoted = false
+  for (let i = start; i < line.length; i++) {
+    if (line[i] === '"') quoted = !quoted
+    else if (!quoted && line.startsWith(close, i)) return i
+  }
+  return -1
+}
+
+function rewriteLine(line: string, kinds: Map<string, Kind>) {
+  let out = ""
+  let i = 0
+  while (i < line.length) {
+    const id = /^[A-Za-z_][\w-]*/.exec(line.slice(i))
+    const prev = i > 0 ? line[i - 1]! : " "
+    if (!id || /[\w-]/.test(prev)) {
+      out += line[i]
+      i++
+      continue
+    }
+    const after = i + id[0].length
+    const shape = SHAPES.find(([open]) => line.startsWith(open, after))
+    const end = shape ? closeAt(line, after + shape[0].length, shape[1]) : -1
+    if (!shape || end < 0) {
+      out += id[0]
+      i = after
+      continue
+    }
+    const text = plain(line.slice(after + shape[0].length, end))
+    const kind = kindOf(shape[0], text)
+    kinds.set(id[0], kind)
+    out += id[0] + shaped(kind, text)
+    i = end + shape[1].length
+  }
+  return out
+}
+
+export function normalizeLegacyFlowchart(code: string) {
+  if (!/^\s*(graph|flowchart)\b/.test(code) || SEMANTIC_CLASS.test(code) || code.includes(":::"))
+    return code
+  const kinds = new Map<string, Kind>()
+  const lines = code
+    .split("\n")
+    .map((line) => (SKIP_LINE.test(line) ? line : rewriteLine(line, kinds)))
+  if (!kinds.size) return code
+  return [...lines, "", ...[...kinds].map(([id, kind]) => `    class ${id} ${kind}`)].join("\n")
+}