feat: Add mermaid-fixer skill for automatic Mermaid syntax error correction

- Add skill that uses check-mermaid.js to validate Mermaid diagrams
- Skill guides Claude to parse error reports and apply intelligent fixes
- Fixes common Mermaid parser bugs (parentheses, brackets, braces in labels)
- Include demo scripts with test Markdown file for validation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

demo_scripts/check-mermaid.js

@@ -0,0 +1,128 @@
+#!/usr/bin/env node
+
+const fs = require('fs');
+const { execSync } = require('child_process');
+const path = require('path');
+const os = require('os');
+
+// 获取命令行传入的 Markdown 文件路径
+const fileArg = process.argv[2];
+if (!fileArg) {
+  console.error('❌ 请提供 Markdown 文件路径。用法: node check-mermaid.js <file.md>');
+  process.exit(1);
+}
+
+const filePath = path.resolve(fileArg);
+const fileName = path.basename(filePath);
+
+if (!fs.existsSync(filePath)) {
+  console.error(`❌ 文件不存在: ${filePath}`);
+  process.exit(1);
+}
+
+const content = fs.readFileSync(filePath, 'utf-8');
+
+// 正则匹配 ```mermaid ... ``` 代码块，兼容 Windows(\r\n) 和 Linux(\n)
+const mermaidRegex = /```mermaid\r?\n([\s\S]*?)```/g;
+let match;
+let blockCount = 0;
+let errorCount = 0;
+
+// 用于收集所有格式化后的错误报告块
+const errorReports = [];
+
+while ((match = mermaidRegex.exec(content)) !== null) {
+  blockCount++;
+  
+  const fullMatch = match[0];
+  const code = match[1];
+  
+  // 1. 计算在 Markdown 文件中的绝对行号
+  const textBeforeMatch = content.substring(0, match.index);
+  const startLine = textBeforeMatch.split(/\r?\n/).length;
+  const endLine = startLine + fullMatch.split(/\r?\n/).length - 1;
+
+  // 创建临时文件存放单个 Mermaid 代码
+  const tmpFile = path.join(os.tmpdir(), `mermaid-check-${Date.now()}-${blockCount}.mmd`);
+  fs.writeFileSync(tmpFile, code.trim());
+
+  try {
+    // 调用 mmdc 进行静默渲染检查
+    execSync(`npx mmdc -i "${tmpFile}" -o "${tmpFile}.svg" -q`, { stdio: 'pipe' });
+  } catch (error) {
+    errorCount++;
+    
+    // 2. 净化报错信息：剔除底层执行堆栈
+    const stderr = error.stderr ? error.stderr.toString() : error.message;
+    const errorLines = stderr.split(/\r?\n/);
+    const cleanErrorLines = [];
+    
+    for (const line of errorLines) {
+      if (line.trim().startsWith('at ') || 
+          line.includes('Parser3.parseError') || 
+          line.includes('fromText')) {
+        break;
+      }
+      cleanErrorLines.push(line);
+    }
+    const cleanErrorOutput = cleanErrorLines.join('\n').trim();
+
+    // 3. 截断代码内容：最少3行，最多6行
+    const codeLines = code.split(/\r?\n/).filter(l => l.trim() !== ''); 
+    let displayCode = '';
+    
+    if (codeLines.length <= 6) {
+      displayCode = codeLines.join('\n');
+    } else {
+      const head = codeLines.slice(0, 3).join('\n');
+      const tail = codeLines.slice(-3).join('\n');
+      displayCode = `${head}\n  ...\n  ... (中间省略 ${codeLines.length - 6} 行) ...\n  ...\n${tail}`;
+    }
+
+    // 4. 组装单个错误的 Markdown 块
+    errorReports.push(`### ❌ 错误 #${errorCount} (代码块 #${blockCount})
+
+- **文档位置：** 第 \`${startLine}\` 行至第 \`${endLine}\` 行
+
+#### 核心错误详情
+\`\`\`text
+${cleanErrorOutput}
+\`\`\`
+
+#### 代码内容片段
+\`\`\`text
+${displayCode}
+\`\`\``);
+
+  } finally {
+    // 清理临时文件
+    if (fs.existsSync(tmpFile)) fs.unlinkSync(tmpFile);
+    if (fs.existsSync(`${tmpFile}.svg`)) fs.unlinkSync(`${tmpFile}.svg`);
+  }
+}
+
+// ------------------------------------------------------------------
+// 生成最终的 Markdown 报告输出
+// ------------------------------------------------------------------
+
+if (errorCount > 0) {
+  // 存在错误的情况
+  console.log(`## 🚨 Mermaid 语法检查报告\n`);
+  console.log(`**检查文件：** \`${fileName}\``);
+  console.log(`**检查结果：** ❌ 发现 ${errorCount} 处语法错误 (共检测到 ${blockCount} 个代码块)\n`);
+  console.log(`---\n`);
+  console.log(errorReports.join('\n\n---\n\n'));
+  
+  // 返回非零状态码，确保在 CI/CD 或 Git Hook 中能够阻断流程
+  process.exit(1); 
+} else {
+  // 全部正确或没有代码块的情况
+  console.log(`## 🎉 Mermaid 语法检查报告\n`);
+  console.log(`**检查文件：** \`${fileName}\``);
+  if (blockCount === 0) {
+    console.log(`**检查结果：** ⚠️ 未检测到 Mermaid 代码块`);
+  } else {
+    console.log(`**检查结果：** ✅ 全部通过 (共检测到 ${blockCount} 个代码块)`);
+  }
+  process.exit(0);
+}