@lynfe/xpatchlib (wasm)

Deterministic binary delta patches for app update bundles — producer side of the xpatchlib toolchain. Runs in Node during the build/publish step to generate XPDL patches that Android, iOS and HarmonyOS clients replay bit-for-bit.

Install

npm install --save-dev @lynfe/xpatchlib

Usage

import { algorithms, createPatch, applyPatch, patchInfo } from '@lynfe/xpatchlib';

// oldBundle: bytes of the previously published bundle
// newBundle: bytes of the bundle about to be published
const patch = createPatch('bsdiff', oldBundle, newBundle);

// catalog metadata for the client's pre-flight checks
const info = patchInfo(patch); // { algorithm, baseSize, resultSize, payloadLen, baseHash, resultHash }

// sanity check that the patch replays (same core as the mobile clients)
const restored = applyPatch(patch, oldBundle);

Algorithms: bsdiff (smallest patches), zdict (fastest), block (middle ground), full (recompressed baseline — use it to decide when a delta is not worth shipping).

Patches are byte-for-byte deterministic for identical input: safe to store in content-addressed object stores. The envelope pins SHA-256 of both the base and the result; clients verify both before and after replay.

License

MIT