feat: add writeToDisk option for dev server support

- Add writeToDisk option to write .d.ts files directly to disk
- Useful for rsbuild/rspack dev server which uses in-memory FS
- Set writeToDisk: true in dev mode to see generated types

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

src/csv-loader/loader.ts

@@ -3,6 +3,7 @@ import { parse } from 'csv-parse/sync';
 import { parseSchema, createValidator, parseValue } from '../index.js';
 import type { Schema } from '../types.js';
 import * as path from 'path';
+import * as fs from 'fs';
 
 export interface CsvLoaderOptions {
   delimiter?: string;
@@ -15,6 +16,8 @@ export interface CsvLoaderOptions {
   emitTypes?: boolean;
   /** Output directory for generated type files (relative to output path) */
   typesOutputDir?: string;
+  /** Write .d.ts files to disk (useful for dev server) */
+  writeToDisk?: boolean;
 }
 
 interface PropertyConfig {
@@ -91,6 +94,7 @@ export default function csvLoader(
   const trim = options?.trim ?? true;
   const emitTypes = options?.emitTypes ?? true;
   const typesOutputDir = options?.typesOutputDir ?? '';
+  const writeToDisk = options?.writeToDisk ?? false;
 
   const records = parse(content, {
     delimiter,
@@ -162,15 +166,23 @@ export default function csvLoader(
       relativePath = relativePath.substring(1);
     }
     relativePath = relativePath.replace(/\\/g, '/');
-    
+
     // Replace .csv with .d.ts for the output filename
     const dtsFileName = relativePath.replace(/\.csv$/, '.d.ts');
-    const outputPath = typesOutputDir 
+    const outputPath = typesOutputDir
       ? path.join(typesOutputDir, dtsFileName)
       : dtsFileName;
     const dtsContent = generateTypeDefinition(this.resourcePath, propertyConfigs, `./${relativePath}`);
 
-    this.emitFile?.(outputPath, dtsContent);
+    if (writeToDisk) {
+      // Write directly to disk (useful for dev server)
+      const absolutePath = path.join(this.context || process.cwd(), typesOutputDir || '', dtsFileName);
+      fs.mkdirSync(path.dirname(absolutePath), { recursive: true });
+      fs.writeFileSync(absolutePath, dtsContent);
+    } else {
+      // Emit to in-memory filesystem (for production build)
+      this.emitFile?.(outputPath, dtsContent);
+    }
   }
 
   return `export default ${json};`;