export declare const STREAM_END_MARKER = "[[END]]";
/**
 * Builds a stateful delta filter that streams the value of the top-level
 * `"answer"` key of a `finish` action, decoding JSON string escapes on the fly.
 *
 * The model keeps emitting strict JSON (`{"action":"finish","answer":"..."}`),
 * so `enforceJsonOutput` can stay ON — there is no plain-text "tail" format and
 * no way for protocol JSON or reasoning to leak into the stream: only the
 * characters inside the `answer` string are forwarded to `onToken`, as soon as
 * each delta arrives (the only buffered part is the `{"action":..,"answer":"`
 * envelope prefix).
 *
 * Steps without a top-level `answer` key (describe/call/abort) emit nothing,
 * which makes the filter self-gating across the whole reasoning chain.
 *
 * Create a fresh filter per LLM call — state is not meant to be reused.
 */
export declare const createAnswerStreamFilter: (onToken: (token: string) => void) => (delta: string) => void;