/**
 * Validate a channel session folder name.
 *
 * We allow nested relative paths (e.g. "guild/general") but reject empty,
 * absolute, and traversing paths so channel state always stays under
 * config.sessionsDir.
 */
export declare function validateSessionFolder(folder: string): string;
/** Resolve a channel session folder to an absolute directory under sessionsDir. */
export declare function resolveChannelSessionDir(folder: string): string;
/** Resolve a media directory for a message under a validated channel session directory. */
export declare function resolveChannelMediaMessageDir(folder: string, messageId: string): string;
/** Rotate a channel session directory out of the active path without deleting it. */
export declare function rotateChannelSessionDir(folder: string): string | undefined;
/** Resolve the most recent active session file for a channel, if one exists. */
export declare function resolveLatestChannelSessionFile(folder: string): string | undefined;
/** Read the session creation timestamp from the metadata record at the start of a session file. */
export declare function readSessionCreatedAt(sessionFile: string): string | undefined;