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# Configuration Management
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Configuration loading and validation for Svelte projects with support for multiple config file formats.
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## Capabilities
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### Load Config Function
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Loads and validates Svelte configuration from svelte.config.js or svelte.config.ts files.
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```typescript { .api }
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/**
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 * Loads and validates Svelte config file
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 * @param options - Configuration loading options
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 * @returns Promise resolving to Svelte configuration
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 */
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function load_config(options?: { cwd?: string }): Promise<Config>;
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interface Config {
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  extensions?: string[];
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  kit?: {
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    alias?: Record<string, string>;
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    files?: {
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      lib?: string;
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    };
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    outDir?: string;
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  };
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  preprocess?: PreprocessorGroup;
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}
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```
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**Usage Examples:**
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```typescript
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import { load_config } from "@sveltejs/package/src/config.js";
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// Load config from current directory
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const config = await load_config();
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// Load config from specific directory
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const config = await load_config({ cwd: "/path/to/project" });
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// Use config with build
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import { build } from "@sveltejs/package/src/index.js";
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await build({
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  cwd: process.cwd(),
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  input: config.kit?.files?.lib ?? "src/lib",
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  output: "dist",
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  preserve_output: false,
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  types: true,
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  config
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});
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```
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### Load Package JSON Function
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Loads package.json file from the specified directory.
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```typescript { .api }
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/**
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 * Load package.json file
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 * @param cwd - Directory to search for package.json (defaults to process.cwd())
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 * @returns Parsed package.json object or empty object if not found
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 */
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function load_pkg_json(cwd?: string): Record<string, any>;
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```
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**Usage Examples:**
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```typescript
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import { load_pkg_json } from "@sveltejs/package/src/config.js";
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// Load package.json from current directory
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const pkg = load_pkg_json();
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// Load package.json from specific directory
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const pkg = load_pkg_json("/path/to/project");
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// Access package information
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console.log(`Package name: ${pkg.name}`);
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console.log(`Version: ${pkg.version}`);
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```
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## Configuration File Discovery
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### Config File Resolution
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The system searches for configuration files in this order:
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1. `svelte.config.js`
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2. `svelte.config.ts`
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If multiple files exist, the first one found is used and a warning is displayed.
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### Configuration Loading Process
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1. **Discovery**: Search for config files in the specified directory
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2. **Selection**: Choose the first config file found
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3. **Import**: Dynamically import the config file with timestamp for cache busting
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4. **Validation**: Check for deprecated `config.package` field
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5. **Return**: Return the loaded configuration object
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## Configuration Structure
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### Extensions Configuration
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```typescript
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// svelte.config.js
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export default {
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  extensions: ['.svelte', '.svx'] // File extensions to process
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};
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```
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### Kit Configuration
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```typescript
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// svelte.config.js
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export default {
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  kit: {
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    // Path aliases for import resolution
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    alias: {
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      '$lib': 'src/lib',
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      '$utils': 'src/utils'
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    },
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    // File paths
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    files: {
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      lib: 'src/lib' // Library source directory
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    },
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    // Output directory for build artifacts
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    outDir: '.svelte-kit'
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  }
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};
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```
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### Preprocessing Configuration
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```typescript
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import { vitePreprocess } from '@sveltejs/vite-plugin-svelte';
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// svelte.config.js
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export default {
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  preprocess: vitePreprocess() // Svelte preprocessor
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};
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```
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## Error Handling
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### Deprecated Configuration
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The system will throw an error if the deprecated `config.package` field is found:
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```typescript
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// This will cause an error
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export default {
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  package: { // ❌ Deprecated
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    // ...
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  }
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};
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```
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### Missing Configuration
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If no configuration file is found, an empty configuration object is returned, allowing the system to use defaults.
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## Types
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```typescript { .api }
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interface Config {
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  extensions?: string[];
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  kit?: {
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    alias?: Record<string, string>;
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    files?: {
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      lib?: string;
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    };
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    outDir?: string;
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  };
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  preprocess?: PreprocessorGroup;
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}
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interface LoadConfigOptions {
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  cwd?: string;
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}
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```