The Kernel Router

Why This Exists

FAF has a Rust WASM compiler (faf-wasm-sdk). It works. But every consumer — bun-sticky, builder.faf.one, and eventually faf-cli — was wiring up the WASM differently. Loading the binary, calling the bindings, parsing the JSON results. Same boilerplate, every time.

Worse: when Zig Cascade arrives (2.7KB, sub-microsecond scoring), every consumer would need to add a second loading path. Two kernels, two APIs, divergence.

The Interface

Every kernel implements FafKernel:

import { init } from "faf-wasm-core";

const kernel = await init("rust");  // or "zig" when Cascade ships
const result = kernel.score(yaml);

// result.score = 100
// result.populated = 11
// result.ignored = 10
// result.active = 11

That's it. The consumer doesn't know or care which WASM binary is running underneath. The interface is the contract.

Full Kernel Contract

interface FafKernel {
  score(yaml: string): ScoreResult;
  scoreEnterprise(yaml: string): ScoreResult;
  validate(yaml: string): boolean;
  compile(yaml: string): Uint8Array;
  decompile(bytes: Uint8Array): FafbInfo;
  scoreBinary(bytes: Uint8Array): ScoreBinaryResult;
  binaryInfo(bytes: Uint8Array): FafbInfo;
  version(): string;
  readonly engine: "rust" | "zig";
  readonly engineVersion: string;
}

Capabilities

Not every kernel supports every method. Rust Mk4 has the full suite. Zig Cascade (when it ships) will start with scoring only. The rest throws KernelCapabilityError.

Query capabilities at runtime with capabilities(). No surprises.

Who Embeds This

faf-wasm-core is infrastructure. It's not a CLI. It's not a service. It's the engine that other tools embed:

• bun-sticky — Bun CLI, embeds core directly (v2.0.0, shipped same day)
• builder.faf.one — Browser scorer, runs WASM client-side
• faf-cli — Universal CLI (next consumer, replacing inline scoring)
• mcpaas.live — Badge service (future, server-side WASM)

One kernel. Every tool gets the same score. No divergence.

WASM Roundup

The FAF WASM stack, top to bottom:

sdk is the compiler. core wraps it behind an interface. bun-sticky embeds core. builder.faf.one runs both Rust and Zig in the browser.

Try It

The Numbers

• v1.0.0 — Released March 20, 2026
• 36/36 — Tests passing
• 284μs — Per score (Mk4, Rust)
• 322KB — Embedded WASM binary
• 0 dependencies — Zero
• 100% — Trophy score