@sema-agent/core/dist/engine/lsp/frame-decoder.js

Stateless, task-oriented AI agent core

export function encodeFrame(json) {
    const payload = Buffer.from(json, "utf8");
    return Buffer.concat([Buffer.from(`Content-Length: ${payload.length}\r\n\r\n`, "ascii"), payload]);
}
export function createFrameDecoder(maxBytes = 50 * 1024 * 1024) {
    const HEADER_SLACK = 128;
    let buf = Buffer.alloc(0);
    return function decode(chunk) {
        const frames = [];
        buf = Buffer.concat([buf, chunk]);
        let awaiting;
        for (;;) {
            const he = buf.indexOf("\r\n\r\n");
            if (he === -1)
                break;
            const m = /Content-Length:\s*(\d+)/i.exec(buf.subarray(0, he).toString("ascii"));
            if (!m) {
                buf = buf.subarray(he + 4);
                continue;
            }
            const len = Number(m[1]);
            if (!Number.isFinite(len) || len < 0 || len > maxBytes) {
                buf = buf.subarray(he + 4);
                continue;
            }
            const start = he + 4;
            if (buf.length < start + len) {
                awaiting = start + len;
                break;
            }
            frames.push(buf.subarray(start, start + len).toString("utf8"));
            buf = buf.subarray(start + len);
        }
        if (buf.length > (awaiting ?? maxBytes + HEADER_SLACK))
            buf = Buffer.alloc(0);
        return frames;
    };
}