/**
 * Format a skill (or pipeline stage) invocation `output` for terminal display.
 *
 * The server typed `output` as `string`, but at runtime a structured skill
 * returns an object/array/null. `${result.invocation.output}` then coerced
 * that to `"[object Object]"` — "request paid, result unreadable" is the
 * worst possible failure mode, because it looks like success. This helper
 * prints each runtime case in a human-readable form and bounds the size so
 * a fat response doesn't lock up the user's terminal.
 *
 * Cases:
 *   - string                       → verbatim (the dominant case; no transform)
 *   - object / array               → JSON.stringify(_, null, 2)
 *   - null                         → "<null>"          (sentinel: empty block
 *                                                          would look like a
 *                                                          missing field)
 *   - undefined                    → "<undefined>"
 *   - number / boolean / bigint    → String(_)         (so 42 prints "42",
 *                                                          not "[object Object]")
 *
 * Truncation: when the rendered string exceeds `maxBytes` (default 16 KB),
 * append `\n… [+N chars truncated]` — the same convention `commands/run.ts`
 * uses for debug previews. The marker tells the reader the output is not the
 * whole thing, and the count lets them react.
 */
/**
 * Default ceiling for the printed output, in characters (after rendering).
 *
 * 16 KB is well above the 2 KB / 4 KB limits `commands/run.ts` already uses
 * for LLM-response previews: skill output IS the product, not a debug aid,
 * so it warrants a larger budget. 16 KB is still small enough to keep the
 * terminal responsive on a fat JSON dump.
 */
export declare const MAX_OUTPUT_BYTES: number;
export interface FormatOutputOptions {
    /** Override the truncation limit (in rendered characters). Test-only. */
    maxBytes?: number;
}
/** Render an invocation output for human reading, with a bounded budget. */
export declare function formatSkillOutput(value: unknown, opts?: FormatOutputOptions): string;