/**
 * PID file management for the limps HTTP daemon.
 *
 * PID files are stored in OS-standard application directories:
 * - macOS: ~/Library/Application Support/limps/pids/
 * - Windows: %APPDATA%/limps/pids/
 * - Linux: $XDG_DATA_HOME/limps/pids/ or ~/.local/share/limps/pids/
 *
 * This allows system-wide awareness of which ports are in use.
 */
/**
 * Contents of a PID file.
 */
export interface PidFileContents {
    pid: number;
    port: number;
    host: string;
    startedAt: string;
    configPath?: string;
    logPath?: string;
}
/**
 * Get the system-wide PID directory.
 * Creates the directory if it doesn't exist.
 *
 * @returns Path to the system PID directory
 * @throws Error if directory cannot be created (e.g., permission denied, read-only filesystem)
 */
export declare function getSystemPidDir(): string;
/**
 * Get the PID file path for a given port.
 *
 * PID files are stored system-wide by port number to prevent
 * duplicate daemons on the same port across different projects.
 *
 * @param port - The HTTP server port
 * @returns Path to the PID file (e.g., ~/Library/Application Support/limps/pids/limps-4269.pid)
 */
export declare function getPidFilePath(port: number): string;
/**
 * Write a PID file.
 *
 * @param pidFilePath - Path to write the PID file
 * @param contents - PID file contents
 */
export declare function writePidFile(pidFilePath: string, contents: PidFileContents): void;
/**
 * Read a PID file.
 *
 * @param pidFilePath - Path to the PID file
 * @returns PID file contents, or null if file doesn't exist or is invalid
 */
export declare function readPidFile(pidFilePath: string): PidFileContents | null;
/**
 * Remove a PID file.
 *
 * @param pidFilePath - Path to the PID file
 */
export declare function removePidFile(pidFilePath: string): void;
/**
 * Check if a process is still running.
 *
 * @param pid - Process ID to check
 * @returns true if the process is running
 */
export declare function isProcessRunning(pid: number): boolean;
/**
 * Read PID file and check if the daemon is actually running.
 * Cleans up stale PID files automatically.
 *
 * @param pidFilePath - Path to the PID file
 * @returns PID file contents if daemon is running, null otherwise
 */
export declare function getRunningDaemon(pidFilePath: string): PidFileContents | null;
/**
 * Scan the system PID directory and return all running daemons.
 * Cleans up stale PID files automatically.
 *
 * @returns Array of PID file contents for all running daemons
 */
export declare function discoverRunningDaemons(): PidFileContents[];
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