faf-rust-sdk v2

Persistent Project Context for Rust. Parse, validate, score, FAFb (binary).

FAF defines. MD instructs. AI codes.

High-performance Rust SDK for FAF (Foundational AI-context Format) — parsing, scoring, validation, and the FAFb binary format.

IANA Media Type: application/vnd.faf+yaml

v2 — The Definitive Edition

The definitive binary format for AI context. v2 ships FAFb — the compiled form of .faf files, future-proofed for any repo size, complexity, or organization. The FAF creator fell in love with IFF in the 90s — working with the Interchange File Format that Commodore created for the Amiga across early computer graphics engines and apps. That chunked binary architecture influenced everything that came after. Microsoft literally riffed on it with RIFF. IFF got it right the first time.

FAFb brings that same architecture into the AI era: a string table replacing the fixed enum, the same pattern ELF and IFF have used for decades. FAF creator realized every YAML key can just become a named section. No limits. No "Unknown" fallback. No artificial ceiling. Sections are classified as DNA (core identity), Context (supplementary), or Pointer (documentation). Works for a solo dev or a 680-engineer enterprise.

This is a significant free upgrade. The SDK is MIT, the format is an IANA-registered open standard, and the binary spec is public. We're making the standard bulletproof so everyone can build on it.

Installation

[dependencies]
faf-rust-sdk = "2.0"

Quick Start

use faf_rust_sdk::{parse, validate, compress, CompressionLevel};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let content = r#"
faf_version: 2.5.0
project:
  name: my-app
  goal: Build something great
instant_context:
  what_building: CLI tool
  tech_stack: Rust, Python
  key_files:
    - src/main.rs
stack:
  backend: Rust
"#;

    // Parse
    let faf = parse(content)?;

    // Access
    println!("Project: {}", faf.project_name());
    println!("Stack: {:?}", faf.tech_stack());

    // Validate
    let result = validate(&faf);
    println!("Valid: {}, Score: {}%", result.valid, result.score);

    // Compress for token optimization
    let minimal = compress(&faf, CompressionLevel::Minimal);

    Ok(())
}

FAFb Binary Format

Compile .faf YAML to a sealed binary. YAML is source code, FAFb is the compiled output.

use faf_rust_sdk::binary::{compile, decompile, CompileOptions};

// Compile YAML → binary
let yaml = "faf_version: 2.5.0\nproject:\n  name: my-project\n";
let opts = CompileOptions { use_timestamp: false };
let bytes = compile(yaml, &opts).unwrap();

// Decompile binary → structured result
let result = decompile(&bytes).unwrap();
let name = result.get_section_string_by_name("project").unwrap();

// Query by classification
let dna = result.dna_sections();         // Core identity sections
let ctx = result.context_sections();     // Supplementary sections
let ptr = result.pointer_section();      // Documentation references

Binary Layout

HEADER (32 bytes)       — Magic "FAFB", version, flags, CRC32 checksum
SECTION DATA (variable) — Each YAML key → one section, priority-ordered
STRING TABLE (appended) — Section name index, unlimited names, O(1) lookup
SECTION TABLE (at end)  — 16 bytes per entry: name, priority, offset, length, tokens, classification

Features

Parsing & Validation

use faf_rust_sdk::{parse, validate};

let faf = parse(content)?;
let result = validate(&faf);
println!("Score: {}%", result.score);

Compression Levels

Optimize for context window constraints:

use faf_rust_sdk::{compress, CompressionLevel};

let minimal = compress(&faf, CompressionLevel::Minimal);   // ~150 tokens
let standard = compress(&faf, CompressionLevel::Standard);  // ~400 tokens
let full = compress(&faf, CompressionLevel::Full);           // ~800 tokens

Axum Integration

Add FAF project context to any Axum server:

[dependencies]
faf-rust-sdk = { version = "2.0", features = ["axum"] }

use axum::{Router, routing::get};
use faf_rust_sdk::axum::{FafLayer, FafContext};

let app: Router = Router::new()
    .route("/", get(handler))
    .layer(FafLayer::new());

async fn handler(faf: FafContext) -> String {
    format!("Project: {}", faf.project_name())
}

The .faf file is parsed once at startup. Per-request cost is a single Arc::clone.

Testing

175 tests passing — WJTTC Championship-Grade coverage:

cargo test

See Also

• faf-wasm-sdk — Same FAFb format compiled to WASM for browsers and edge compute
• mcpaas — Stream FAF context live via Radio Protocol

Links

• faf.one — project home
• IANA Registration — application/vnd.faf+yaml
• FAF on Zenodo — academic paper
• FAF on Grokipedia — 28 citations

License

MIT

---

Get the CLI

faf-cli — The original AI-Context CLI. A must-have for every builder.

npx faf-cli auto

Anthropic MCP #2759 · IANA Registered: application/vnd.faf+yaml · faf.one · npm