/**
 * Protocol stdout guard — keeps non-protocol bytes off the MCP stdio transport.
 *
 * On a stdio MCP transport fd 1 IS a protocol channel: every byte written to
 * stdout must be a newline-framed JSON-RPC message, and a client that reads
 * anything else sees a corrupted stream. A third-party library that logs to
 * stdout — crawlee's default @apify/log INFO logger does exactly that during
 * web_search/web_read — would interleave its log lines with the responses, so
 * the process must divert stdout before serving and hand the server a private
 * handle on the writer that was stdout.
 *
 * installProtocolStdoutGuard() captures the current `process.stdout.write`
 * (bound) as that protocol writer, then replaces `process.stdout.write` with a
 * forwarder to `process.stderr.write`: everything that logs to stdout
 * afterwards — console.log included — lands on stderr, where diagnostics
 * belong, and can no longer corrupt the protocol stream.
 *
 * The returned handle also owns the error surface of the captured writer: an
 * asynchronous failure such as EPIPE is forwarded through
 * `stream.on("error", ...)`, so the server reports it and stops writing
 * instead of crashing the process.
 *
 * @module
 */
/** Handle returned by {@link installProtocolStdoutGuard}. */
export interface ProtocolStdoutGuard {
    /**
     * The captured protocol writer. The MCP server only ever writes with
     * `.write(string)` and subscribes to asynchronous writer failures with
     * `.on("error", ...)`, so exposing exactly those members (cast to
     * NodeJS.WritableStream at this boundary) is deliberate.
     */
    stream: NodeJS.WritableStream;
    /** Put the writer that was in place at install time back on process.stdout. */
    restore(): void;
}
/**
 * Divert process.stdout to process.stderr and return the writer the MCP server
 * must use for protocol messages. The writer also forwards asynchronous
 * failures of the captured stdout (an EPIPE once the pipe reader is gone) to
 * listeners registered with `.on("error", ...)`, which is how the server
 * learns to stop writing instead of dying on an unhandled event. Installing
 * twice returns the same handle without re-patching;
 * {@link ProtocolStdoutGuard.restore} undoes it (used by tests — the stdio
 * entry never restores, it serves until stdin closes).
 */
export declare function installProtocolStdoutGuard(): ProtocolStdoutGuard;
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