@compdict/core

Node.js primitives for RFC 9842 Compression Dictionary Transport:

• Use-As-Dictionary, Available-Dictionary, and Dictionary-ID
• URL pattern matching and dictionary selection
• dcb and dcz framing and window inspection
• bundled Brotli and Zstandard codecs
• stream and captured-HTTP validation
• build-time encoding and baseline measurement

Requires Node.js 22 or later.

npm install @compdict/core

Validate a stream

import { validateStream } from '@compdict/core';
import { readFile } from 'node:fs/promises';

const [stream, dictionary, original] = await Promise.all([
  readFile('app.v2.js.dcb'),
  readFile('app.v1.js'),
  readFile('app.v2.js'),
]);

const result = await validateStream({
  stream,
  dictionary,
  original,
  expectedEncoding: 'dcb',
});

for (const finding of result.findings) {
  if (finding.kind === 'conformance') {
    console.log(
      `${finding.code} RFC 9842 §${finding.rfc.section}: ${finding.message}`,
    );
  }
}

A conformance finding always carries an RFC 9842 citation. Network, input, and codec failures are separate operational findings, so an incomplete test is not reported as a server violation.

Encode an artifact

import { encodeStream } from '@compdict/core';
import { readFile, writeFile } from 'node:fs/promises';

const input = await readFile('app.v2.js');
const dictionary = await readFile('app.v1.js');
const encoded = await encodeStream(input, {
  encoding: 'dcz',
  dictionary,
});

if (encoded.verified !== true) throw new Error('round-trip failed');
await writeFile('app.v2.js.dcz', encoded.stream);

Round-trip verification is on by default.

The main entry point does not load a wasm binary until an operation needs one. Direct codec access is available through:

• @compdict/core/codec/brotli
• @compdict/core/codec/zstd

The WebAssembly artifacts are built from pinned upstream commits. Codec choice and URLPattern behaviour therefore do not depend on the host's Node build. urlpattern-polyfill is the package's only runtime dependency.

For the command-line tool, install compdict.

• API reference
• Conformance matrix
• JSON report format
• RFC 9842

Apache-2.0.