# Task ID: 74

**Title:** Implement Content Type Detection

**Status:** done

**Dependencies:** None

**Priority:** high

**Description:** Create a utility that detects content type (JSON, YAML, XML, code, prose) for structural splitting in the section-split stage.

**Details:**

Create `src/mcplocal/src/proxymodel/content-detection.ts`:

```typescript
export type ContentType = 'json' | 'yaml' | 'xml' | 'code' | 'prose';

export function detectContentType(content: string): ContentType {
  const trimmed = content.trimStart();
  
  // JSON detection
  if (trimmed.startsWith('{') || trimmed.startsWith('[')) {
    try {
      JSON.parse(content);
      return 'json';
    } catch { /* not valid JSON, continue */ }
  }
  
  // XML detection
  if (trimmed.startsWith('<?xml') || /^<[a-zA-Z][^>]*>/.test(trimmed)) {
    return 'xml';
  }
  
  // YAML detection (key: value at start of lines)
  if (/^[a-zA-Z_][a-zA-Z0-9_]*:\s/m.test(trimmed) && !trimmed.includes('{')) {
    return 'yaml';
  }
  
  // Code detection (common patterns)
  const codePatterns = [
    /^(function |class |def |const |let |var |import |export |package |pub fn |fn |impl )/m,
    /^#include\s+[<"]/m,
    /^(public |private |protected )?(static )?(void |int |string |bool )/m,
  ];
  if (codePatterns.some(p => p.test(trimmed))) {
    return 'code';
  }
  
  return 'prose';
}
```

**Test Strategy:**

Unit tests with sample content for each type: valid JSON objects/arrays, XML documents, YAML configs, code snippets in multiple languages (JS, Python, Rust, Go, Java), and prose markdown. Edge cases: JSON-like strings that aren't valid JSON, mixed content.