/**
 * Code-point-safe text helpers shared by chat-style communication adapters,
 * which had each copied the same chunker, tail preview, and trailing
 * normalizer. Pure and transport-agnostic.
 */
/** Default per-message character budget for chat transports. */
export declare const DEFAULT_MAX_MESSAGE_CHARS = 3800;
/** Default placeholder used when a finished response has no text. */
export declare const DEFAULT_EMPTY_FINAL_TEXT = "No response text was returned.";
/** Trim trailing whitespace, falling back to a placeholder when empty. */
export declare function normalizeTrailing(text: string, fallback: string): string;
/**
 * Split text into chunks of at most `maxChars` Unicode code points, so
 * multi-byte characters are never cut in half.
 */
export declare function splitTextByCodePoints(text: string, maxChars: number): string[];
/**
 * Split text into chunks of at most `maxChars` code points, cutting at a
 * paragraph, line, or word boundary when one is available near the end of the
 * window and falling back to a blind cut when none is.
 *
 * This is what a chat transport should use for a finished answer:
 * {@link splitTextByCodePoints} cuts mid-sentence, and leaving the text
 * unchunked hands the boundary to the channel — Slack silently breaks a long
 * `chat.postMessage` into several messages of its own choosing and returns only
 * the last fragment's id.
 *
 * Whitespace AT a chosen boundary is consumed, so a chunk never begins with the
 * newline it was split on. Every other character survives, in order, and the
 * indentation of the line after a break is preserved.
 */
export declare function splitTextForChat(text: string, maxChars: number): string[];
/**
 * Build a bounded "tail" preview for streaming edits: when text exceeds
 * `maxChars`, show a `prefix` marker followed by the most recent code points.
 */
export declare function buildStreamingTailPreview(text: string, maxChars: number, prefix?: string): string;
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