Designing a portable proof format for signing files in JavaScript

I recently needed a consistent way to sign content across environments - specifically in both Node and the browser. Most existing approaches either rely on shelling out to system binaries or are tightly coupled to a particular runtime. I wanted something: JS-native Deterministic Portable With a clear, versioned proof format So I ended up designing a small proof primitive and extracting it into its own tool. The idea Given: A file Some text Or a directory The tool: Produces a deterministic representation Signs it locally Emits a versioned JSON proof That proof can be published alongside the content and verified later. It’s self-contained and runtime-agnostic. For directories, a stable manifest is generated first, so the proof reflects the structure and contents deterministically. Why JSON? The proof format is intentionally plain JSON. That makes it: Inspectable Easy to store Easy to transport Easy to verify across environments The same proof format is used in: A CLI A GitHub Action A Ja