/** Input validation and sanitization utilities. */
/**
 * Reduce a sender-supplied attachment name to one that is safe to write.
 *
 * The name arrives in the message's Content-Disposition header, so anyone who
 * can email the user chooses it. Passed to `path.join` as-is, a name like
 * `../../../../.zshrc` escapes the destination directory entirely and
 * overwrites whatever sits there — and since the CLI defaults its destination
 * to the working directory, even a plain leading dot is enough to drop a file
 * that shell startup will read.
 *
 * The result is always a bare filename: no directory part, no control
 * characters, no leading dot, and never empty.
 */
export declare function safeAttachmentFilename(name: string): string;
/**
 * Validate and sanitize an IMAP mailbox name.
 * Rejects names containing IMAP wildcard characters (`*`, `%`) or empty strings.
 * @param name - The mailbox name to validate.
 * @returns The trimmed mailbox name.
 */
export declare function sanitizeMailboxName(name: string): string;
/**
 * Strip control characters from an IMAP search query.
 * Removes ASCII 0-31 except tab (0x09) and newline (0x0A).
 * @param query - The raw search query.
 * @returns The sanitized query string.
 */
export declare function sanitizeSearchQuery(query: string): string;
/**
 * Validate a webhook URL.
 * Ensures the URL uses http(s) and does not point to a private or loopback address.
 * @param url - The webhook URL to validate.
 */
export declare function validateWebhookUrl(url: string): void;
/**
 * Sanitize a value for use in a template.
 * When `html` is true, HTML-special characters are escaped.
 * @param value - The template variable value.
 * @param html - Whether to apply HTML escaping.
 * @returns The sanitized value.
 */
export declare function sanitizeTemplateVariable(value: string, html: boolean): string;
/**
 * Validate an email label name.
 * Rejects labels with control characters or that exceed 200 characters.
 * @param name - The label name to validate.
 * @returns The trimmed label name.
 */
export declare function validateLabelName(name: string): string;
/**
 * Validate that an input string does not exceed a maximum length.
 * @param input - The input string to check.
 * @param maxLength - The maximum allowed length.
 * @param fieldName - The field name for the error message.
 */
export declare function validateInputLength(input: string, maxLength: number, fieldName: string): void;
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