@humanspeak/svelte-markdown/dist/utils/streaming-chunks.js

Markdown and HTML renderer for Svelte 5 — built for rendering streaming AI agent output from Claude Code, ChatGPT, and agentic workflows. XSS-safe defaults, streaming-aware sanitization, token caching, TypeScript types, and Svelte 5 runes.

export const STREAM_BATCH_FALLBACK_MS = 16;
export const STREAM_BATCH_MAX_CHARS = 256;
// Largest gap an offset chunk may open before it is treated as malformed.
export const STREAM_MAX_OFFSET_GAP = 1_000_000;
/**
 * Checks whether a streaming chunk uses offset-based patching.
 *
 * @param chunk Streaming chunk passed to the imperative streaming API.
 * @returns True when the chunk has an `offset` field.
 */
export const isStreamingOffsetChunk = (chunk) => typeof chunk === 'object' && chunk !== null && 'offset' in chunk;
export const getStreamingChunkInstruction = (chunk, currentMode, { currentBufferLength = 0, maxOffsetGap = STREAM_MAX_OFFSET_GAP } = {}) => {
    if (typeof chunk === 'string') {
        if (currentMode === 'offset') {
            return {
                kind: 'drop',
                message: 'offset mode active, string chunk dropped. Call resetStream() before switching streaming input modes.'
            };
        }
        return { kind: 'append', value: chunk, nextMode: 'append' };
    }
    if (!isStreamingOffsetChunk(chunk) || typeof chunk.value !== 'string') {
        return {
            kind: 'drop',
            message: 'Invalid chunk object passed to writeChunk(); expected { value: string, offset: number }.'
        };
    }
    if (!Number.isSafeInteger(chunk.offset) || chunk.offset < 0) {
        return {
            kind: 'drop',
            message: 'Invalid offset chunk passed to writeChunk(); offset must be a non-negative safe integer.'
        };
    }
    if (currentMode === 'append') {
        return {
            kind: 'drop',
            message: 'append mode active, offset chunk dropped. Call resetStream() before switching streaming input modes.'
        };
    }
    if (chunk.offset - currentBufferLength > maxOffsetGap) {
        return {
            kind: 'drop',
            message: `offset chunk skipped: offset ${chunk.offset} is more than ` +
                `${maxOffsetGap} chars beyond the current buffer length ` +
                `(${currentBufferLength}).`
        };
    }
    return { kind: 'offset', chunk, nextMode: 'offset' };
};
export const appendStreamingChunk = (pendingBuffer, value) => pendingBuffer + value;
export const commitStreamingAppendBuffer = (sourceBuffer, pendingBuffer) => {
    if (pendingBuffer === '') {
        return { committed: false, sourceBuffer, pendingBuffer };
    }
    return {
        committed: true,
        sourceBuffer: sourceBuffer + pendingBuffer,
        pendingBuffer: ''
    };
};
export const shouldFlushStreamingAppendBuffer = (pendingBuffer, maxChars = STREAM_BATCH_MAX_CHARS) => pendingBuffer.length >= maxChars;
export const applyStreamingOffsetChunk = (source, { value, offset }, { maxOffsetGap = STREAM_MAX_OFFSET_GAP } = {}) => {
    const gap = Math.max(0, offset - source.length);
    const boundedGap = Math.min(gap, Math.max(0, maxOffsetGap));
    const effectiveOffset = offset > source.length ? source.length + boundedGap : offset;
    const padded = boundedGap > 0 ? source + ' '.repeat(boundedGap) : source;
    const prefix = padded.slice(0, effectiveOffset);
    const suffix = padded.slice(effectiveOffset + value.length);
    return prefix + value + suffix;
};