// Slack tests cover truncate plugin behavior.

import { describe, expect, it } from "vitest";

import { truncateSlackText } from "./truncate.js";

describe("truncateSlackText", () => {

it("drops a surrogate-pair emoji whole when it straddles the limit", () => {

// "abc😀def": 😀 (U+1F600) sits at the cut point. Slicing by UTF-16 code unit

// would keep only its high surrogate — a lone \uD83D — before the ellipsis,

// which serializes to an invalid character in the Slack payload.

const out = truncateSlackText("abc😀def", 5);

expect(out).toBe("abc…");

// No dangling high surrogate (a high surrogate not followed by a low one).

expect(/[\uD800-\uDBFF](?![\uDC00-\uDFFF])/.test(out)).toBe(false);

});

it("truncates plain BMP text unchanged", () => {

expect(truncateSlackText("hello world", 5)).toBe("hell…");

});

it("keeps an emoji that fits before the cut", () => {

expect(truncateSlackText("😀abcdef", 5)).toBe("😀ab…");

});

it("returns the trimmed input unchanged when it fits", () => {

expect(truncateSlackText("ab😀cd", 10)).toBe("ab😀cd");

});

});

// Slack plugin module implements truncate behavior.

import { sliceUtf16Safe } from "openclaw/plugin-sdk/text-utility-runtime";

export function truncateSlackText(value: string, max: number): string {

const trimmed = value.trim();

if (trimmed.length <= max) {

return trimmed;

}

// Slice on a code-point boundary so a surrogate pair (emoji / astral char)

// straddling the limit is dropped whole, instead of leaving a lone surrogate

// half that serializes to an invalid `\uD83D` in the Slack payload.

if (max <= 1) {

return trimmed.slice(0, max);

return sliceUtf16Safe(trimmed, 0, max);

}

return `${trimmed.slice(0, max - 1)}…`;

return `${sliceUtf16Safe(trimmed, 0, max - 1)}…`;

}