/**
 * A single-line terminal progress bar for long waits (editor startup, builds).
 *
 * Everything goes to stderr: stdout is the MCP stdio channel and a stray byte
 * there corrupts the protocol. On a TTY the line rewrites in place; when the
 * output is piped or logged (CI, an agent transcript) it degrades to one plain
 * line per change, so a log does not fill with escape codes.
 */
export interface ProgressState {
    /** 0..1, or null when the work has no measurable fraction yet. */
    fraction: number | null;
    /** Short label: what is happening right now. */
    message: string;
    /** Optional right-hand detail (module counts, elapsed time). */
    detail?: string;
}
export interface ProgressBar {
    update(state: ProgressState): void;
    /** Stop rendering. `finalLine`, if given, is left on screen. */
    stop(finalLine?: string): void;
}
/**
 * Start a progress bar. Returns a handle even when stderr is not a TTY, so
 * callers never branch on it.
 */
export declare function startProgress(title: string): ProgressBar;