/**
 * Size-bounded log files: rotate `x.jsonl` -> `x.1.jsonl` -> … -> delete.
 *
 * Lives in `@fjall/util` because three packages write persistent logs into
 * the same state root and only one of them had a bound. The CLI's logger
 * owned this class privately; `components/infrastructure` could not reach
 * it across the package boundary, so its validation log had no cap at all
 * and grew to hundreds of megabytes on a developer machine over one release
 * cycle. A rotation policy that only one of several writers can reach is
 * not a policy.
 */
/** Construction options. */
export interface FileRotatorOptions {
    maxFiles: number;
}
export declare class FileRotator {
    private maxFiles;
    constructor(options: FileRotatorOptions);
    /**
     * Check if a file needs rotation based on size
     */
    needsRotation(filePath: string, maxFileSize: number): boolean;
    /** Rotate log files: current -> .1 -> .2 -> delete oldest */
    rotate(filePath: string): void;
    /** Check if rotation is needed and perform it if so */
    rotateIfNeeded(filePath: string, maxFileSize: number): boolean;
    /** Get all rotated file paths for a given log file */
    getRotatedFiles(filePath: string): string[];
    /** Clean up all log files (main and rotated) */
    cleanAll(filePath: string): void;
}
/**
 * The bound every Fjall log file shares.
 *
 * Coupled values: the CLI's `LOGGER_DEFAULTS` and the infrastructure
 * validation log both derive from here, so a change to the retention budget
 * cannot apply to one writer and silently miss the other.
 */
export declare const LOG_ROTATION_DEFAULTS: {
    readonly MAX_FILE_SIZE: number;
    readonly MAX_FILES: 5;
};
/** The resolved rotation budget one writer applies. */
export interface LogRotationBudget {
    maxFileSize: number;
    maxFiles: number;
}
/**
 * The rotation budget with its env overrides applied: `FJALL_LOG_MAX_SIZE`
 * (bytes per file) and `FJALL_LOG_MAX_FILES`. Invalid values — empty,
 * non-numeric, zero, negative — fall back to the defaults.
 *
 * Every writer that rotates against `LOG_ROTATION_DEFAULTS` must resolve
 * through here, or the overrides govern one log stream and silently miss
 * the other (the CLI honoured them while the infrastructure validation log
 * hardcoded the defaults). Resolved per call, never at module load: the
 * CDK subprocess imports its writer long before a command's environment is
 * readable.
 */
export declare function resolveLogRotationBudget(): LogRotationBudget;