/**
 * log.ts — File logging for @ericzhaozzz/wechat-channel.
 *
 * The extension runs *inside* the pi process, which owns the terminal. A
 * console.log from here is written straight into the TUI's frame and
 * corrupts the display, so extension-side logging must go to a file.
 * The worker is a separate process and logs to its own stderr, which the
 * extension pipes into this same file (see startWorker).
 *
 * Only one process writes the file, so rotation needs no locking.
 */
export declare const MAX_LOG_BYTES: number;
export interface Logger {
    /** Informational line. */
    info(...args: unknown[]): void;
    /** Something notable that is not a failure (a dropped sender, a retry). */
    warn(...args: unknown[]): void;
    /** Failure line; same destination, marked ERROR. */
    error(...args: unknown[]): void;
    /** Write text that already carries its own formatting (piped stderr). */
    raw(text: string): void;
    /** Absolute path of the file being written. */
    readonly file: string;
}
/**
 * The last `count` non-empty lines of `text`.
 *
 * `/wechat log` could only ever print a path, which means the answer to
 * "why did that message not come through" lives in a second terminal the
 * operator has to go open. Pure so the slicing is testable without a file.
 */
export declare function tailLines(text: string, count: number): string[];
/**
 * Create a logger appending to `file`. Never throws: logging must not be
 * able to take down the channel, and there is nowhere to report a logging
 * failure to anyway.
 */
export declare function createLogger(file: string, tag: string): Logger;
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