diff --git a/src/file-watcher.ts b/src/file-watcher.ts
new file mode 100644
index 0000000..760a623
--- /dev/null
+++ b/src/file-watcher.ts
@@ -0,0 +1,139 @@
+import { glob } from 'glob';
+import * as fs from 'fs';
+import * as path from 'path';
+import type { FSWatcher } from 'chokidar';
+
+export interface FileWatcherOptions {
+  patterns: string[];
+  ignored?: string[];
+  debounceMs?: number;
+}
+
+export type FileChangeCallback = (event: 'add' | 'change' | 'unlink', filePath: string) => void;
+
+export class FileWatcher {
+  private chokidar: typeof import('chokidar') | null = null;
+  private watcher: FSWatcher | null = null;
+  private options: Required<FileWatcherOptions>;
+  private callback: FileChangeCallback | null = null;
+  private debounceTimers: Map<string, NodeJS.Timeout> = new Map();
+
+  constructor(options: FileWatcherOptions) {
+    this.options = {
+      patterns: options.patterns,
+      ignored: options.ignored || ['node_modules/**', 'dist/**', '*.d.ts'],
+      debounceMs: options.debounceMs || 300,
+    };
+  }
+
+  async initialize(): Promise<void> {
+    const chokidarModule = await import('chokidar');
+    this.chokidar = chokidarModule;
+  }
+
+  start(callback: FileChangeCallback): void {
+    if (!this.chokidar) {
+      throw new Error('FileWatcher not initialized. Call initialize() first.');
+    }
+
+    this.callback = callback;
+    
+    this.watcher = this.chokidar.watch(this.options.patterns, {
+      ignored: this.options.ignored,
+      persistent: true,
+      awaitWriteFinish: {
+        stabilityThreshold: this.options.debounceMs,
+        pollInterval: 100,
+      },
+    });
+
+    this.watcher.on('add', (filePath: string) => this.handleEvent('add', filePath));
+    this.watcher.on('change', (filePath: string) => this.handleEvent('change', filePath));
+    this.watcher.on('unlink', (filePath: string) => this.handleEvent('unlink', filePath));
+  }
+
+  private handleEvent(event: 'add' | 'change' | 'unlink', filePath: string): void {
+    if (!this.callback) return;
+
+    const timerKey = filePath;
+    
+    if (this.debounceTimers.has(timerKey)) {
+      clearTimeout(this.debounceTimers.get(timerKey)!);
+    }
+
+    const timer = setTimeout(() => {
+      this.debounceTimers.delete(timerKey);
+      this.callback!(event, filePath);
+    }, this.options.debounceMs);
+
+    this.debounceTimers.set(timerKey, timer);
+  }
+
+  async findFiles(patterns: string[]): Promise<string[]> {
+    const allFiles: string[] = [];
+    
+    for (const pattern of patterns) {
+      const files = await glob(pattern, {
+        ignore: this.options.ignored,
+      });
+      allFiles.push(...files);
+    }
+
+    return [...new Set(allFiles)];
+  }
+
+  stop(): void {
+    if (this.watcher) {
+      this.watcher.close();
+      this.watcher = null;
+    }
+
+    for (const timer of this.debounceTimers.values()) {
+      clearTimeout(timer);
+    }
+    this.debounceTimers.clear();
+  }
+}
+
+export async function readJsonFile(filePath: string): Promise<unknown> {
+  const content = await fs.promises.readFile(filePath, 'utf-8');
+  return JSON.parse(content);
+}
+
+export async function writeDeclarationFile(
+  filePath: string,
+  content: string
+): Promise<void> {
+  const dir = path.dirname(filePath);
+  await fs.promises.mkdir(dir, { recursive: true });
+  await fs.promises.writeFile(filePath, content, 'utf-8');
+}
+
+export function getDeclarationPath(jsonPath: string, outputDir?: string): string {
+  const baseName = path.basename(jsonPath, path.extname(jsonPath));
+  const dir = outputDir || path.dirname(jsonPath);
+  return path.join(dir, `${baseName}.d.ts`);
+}
+
+export function getInterfaceName(filePath: string): string {
+  const baseName = path.basename(filePath, path.extname(filePath));
+  return toPascalCase(baseName);
+}
+
+export function toPascalCase(str: string): string {
+  return str
+    .replace(/[-_\s]+(.)?/g, (_, c) => (c ? c.toUpperCase() : ''))
+    .replace(/^(.)/, (c) => c.toUpperCase())
+    .replace(/[A-Z]/g, (c, i) => (i === 0 ? c : c));
+}
+
+export function extractJsonSamplesFromFile(filePath: string): unknown[] {
+  const content = fs.readFileSync(filePath, 'utf-8');
+  const data = JSON.parse(content);
+  
+  if (Array.isArray(data)) {
+    return data;
+  }
+  
+  return [data];
+}