/**
 * Strict UTF-8 validation on a buffer.
 * TextDecoder with fatal: true throws an error on invalid UTF-8 sequences.
 */
export declare function isValidUTF8(buffer: Buffer): boolean;
/**
 * Returns true if the file consistently uses CRLF.
 * Consistently means it contains at least one CRLF, and no LF without a preceding CR.
 */
export declare function isConsistentlyCRLF(text: string): boolean;
/**
 * Preservation of BOM and line endings.
 */
export declare function applyEncodingPreservation(existingContent: string, newContent: string): string;
/**
 * Get the byte length of a string in UTF-8.
 */
export declare function utf8ByteLength(text: string): number;
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