expect(stream.postId()).toBeUndefined();

});

it("truncates on a code-point boundary so a straddling emoji is dropped whole", async () => {

const { client, calls } = createMockClient();

// maxChars=12 => cut point is maxChars-3=9. The emoji 😀 occupies UTF-16

// indices 8-9, so a raw slice(0,9) would keep the lone high surrogate at

// index 8 and drop its low surrogate at index 9, leaking a dangling half.

const stream = createMattermostDraftStream({

client,

channelId: "channel-1",

throttleMs: 0,

maxChars: 12,

});

const input = `${"a".repeat(8)}\u{1F600}${"b".repeat(5)}`;

stream.update(input);

await stream.flush();

expect(calls).toHaveLength(1);

const message = parseRequestJson(calls[0]?.init).message;

expect(typeof message).toBe("string");

const sent = message as string;

// The straddling emoji must be dropped whole, leaving no dangling surrogate half.

expect(/[\uD800-\uDFFF]/u.test(sent)).toBe(false);

expect(sent.length).toBeLessThanOrEqual(12);

expect(sent).toBe("aaaaaaaa...");

});

it("does not resend after an update failure followed by stop", async () => {

const warn = vi.fn();

const calls: RequestRecord[] = [];

// Mattermost plugin module implements draft stream behavior.

import { createFinalizableDraftLifecycle } from "openclaw/plugin-sdk/channel-outbound";

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

import {

createMattermostPost,

deleteMattermostPost,

if (trimmed.length <= maxChars) {

return trimmed;

}

return `${trimmed.slice(0, Math.max(0, maxChars - 3)).trimEnd()}...`;

return `${sliceUtf16Safe(trimmed, 0, Math.max(0, maxChars - 3)).trimEnd()}...`;

}

export function createMattermostDraftStream(params: {