/**
 * parsePiThought turns ONE line of Pi's `--mode json` JSONL stream into a short
 * label of what the agent is currently *saying or reasoning* — the live "watch
 * Pi think" signal, distinct from `parsePiActivity` (which surfaces TOOL use).
 *
 * Pi streams assistant output as `message_update` events whose
 * `assistantMessageEvent` is a `text_delta` or `thinking_delta` carrying a
 * `delta` string (shape verified against @earendil-works/pi-ai types.d.ts —
 * `AssistantMessageEvent`). Only those two delta kinds yield a label; every
 * other event (tool deltas, starts/ends, non-JSON noise) yields undefined so
 * the caller keeps the last known line or shows none.
 *
 * Pure (no I/O) and total (never throws): a malformed line, missing delta, or
 * empty delta degrades to undefined. The label is whitespace-collapsed and
 * clipped so it never blows up the single live line on a phone or narrow term.
 */
export declare function parsePiThought(line: string): string | undefined;