snix Skill

"Nix, reimplemented in Rust." -- snix.dev

Trit: -1 (MINUS) - Build validation and rootfs construction

Overview

snix is a Rust reimplementation of Nix (forked from Tvix) with a bytecode VM evaluator, content-addressed store, and library-oriented architecture. It provides the build layer for the Minimum Viable Runtime (MVR) — creating minimal Linux rootfs images that run AI agent TUIs inside boxxy (Apple Virtualization.framework) VMs.

┌─────────────────────────────────────────────────────┐
│                    snix BUILD LAYER                  │
│              (content-addressed store)              │
└──────────────────────┬──────────────────────────────┘
                       │
       ┌───────────────┼───────────────┐
       │               │               │
┌──────▼──────┐ ┌──────▼──────┐ ┌──────▼──────┐
│  Evaluate   │ │   Build     │ │   Store     │
│  (bytecode) │ │   (daemon)  │ │   (CAS)     │
│  trit: -1   │ │   trit: 0   │ │   trit: +1  │
└─────────────┘ └─────────────┘ └─────────────┘
       │               │               │
       └───────────────┼───────────────┘
                       │
               ┌───────▼───────┐
               │   rootfs.img  │
               │   (~75-130MB) │
               └───────────────┘

Why snix

• Pure Rust embeds into boxxy's Go/Rust toolchain without C++ dependency
• Bytecode VM evaluator is faster than Nix's AST walker
• Content-addressed store enables deduped, granular rootfs images
• Library-oriented — callable from Rust code, not just CLI
• Fork of Tvix with dedicated CI and macOS support
• devenv switching to snix eval — ecosystem momentum

Installation

# Clone from Forgejo
git clone https://git.snix.dev/snix/snix ~/i/snix

# Or from GitHub mirror
git clone https://github.com/cachix/snix ~/i/snix

# Build from source (Rust toolchain required)
cd ~/i/snix
cargo build --release

# Components
ls target/release/snix-*
# snix-eval      -- Nix expression evaluator (bytecode VM)
# snix-build     -- Build orchestrator
# snix-store     -- Content-addressed store daemon
# snix-cli       -- Unified CLI

Minimal Rootfs Build

Flake for codex-rs VM

# flake.nix — snix-evaluable minimal codex-rs VM rootfs
{
  description = "Minimal aarch64-linux rootfs for codex-rs in boxxy";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
  };

  outputs = { self, nixpkgs }: let
    system = "aarch64-linux";
    pkgs = import nixpkgs {
      inherit system;
      crossSystem = { config = "aarch64-unknown-linux-musl"; };
    };
  in {
    packages.${system} = {
      rootfs = pkgs.dockerTools.buildImage {
        name = "codex-minimal";
        tag = "latest";
        copyToRoot = pkgs.buildEnv {
          name = "codex-rootfs";
          paths = [
            pkgs.busybox          # shell + coreutils (~1.5MB)
            pkgs.gitMinimal       # git without docs/perl (~15-30MB)
            pkgs.cacert           # TLS root certificates (~0.2MB)
          ];
        };
        runAsRoot = ''
          mkdir -p /tmp /proc /dev
          mknod -m 666 /dev/null c 1 3
          mknod -m 666 /dev/urandom c 1 9
        '';
      };

      diskImage = pkgs.vmTools.runInLinuxVM (pkgs.runCommand "codex-disk" {} ''
        mkdir -p $out
        dd if=/dev/zero of=$out/rootfs.img bs=1M count=256
        mkfs.ext4 $out/rootfs.img
      '');
    };
  };
}

Build with snix

# Evaluate the flake
snix eval .#packages.aarch64-linux.rootfs

# Build rootfs image
snix build .#packages.aarch64-linux.rootfs

# Inspect store paths
snix store ls /snix/store/<hash>-codex-rootfs

Rootfs Composition

Kernel Requirements (codex-rs sandbox)

Sandbox Layers (defense-in-depth)

1. macOS Virtualization.framework hypervisor (boxxy)
2. Landlock filesystem ACLs (/ = ro, writable_roots = rw)
3. seccomp-BPF syscall filter (blocks connect/accept/bind/listen/ptrace)
4. Mount namespace (.git dirs bind-mounted read-only)
5. User namespace (unprivileged, UID/GID mapping)
6. Process hardening (PR_SET_DUMPABLE=0, RLIMIT_CORE=0, LD_* stripped)

boxxy Boot Integration

;; ~/i/boxxy/examples/codex-vm.joke
;; Boot snix-built rootfs via Apple Virtualization.framework

(def codex-vm
  (vz/new-linux-vm-config
    {:kernel   "vmlinuz-6.7-aarch64"
     :initrd   "initrd-codex.img"
     :cmdline  "console=hvc0 root=/dev/vda rw quiet"
     :disk     "codex-rootfs.img"       ;; snix-built rootfs
     :memory   2                        ;; GB
     :cpus     4
     :network  {:nat true}}))           ;; NAT for API access

(println "Booting codex-rs VM...")
(vz/start-vm! codex-vm)

Agent TUI Matrix (toad)

Agents running inside snix-built rootfs, driven by toad:

toad -a claude

toad -a codex

toad -a goose

toad -a copilot

toad -a gemini

GF(3) check:

0 + (-1) + 1 + 0 + 1 = 1

GF(3) Triads

snix (-1) ⊗ world-runtime (0) ⊗ agent-o-rama (+1) = 0 ✓  [MVR Core]
snix (-1) ⊗ flox (0) ⊗ hvm-runtime (+1) = 0 ✓  [Build Chain]
snix (-1) ⊗ nix-acset-worlding (-1) ⊗ codex-self-rewriting (+1+1) — needs split
nix-acset-worlding (-1) ⊗ snix (-1) ⊗ true-alife (+1) — rebalance via:
  snix (-1) ⊗ acsets (0) ⊗ hvm-runtime (+1) = 0 ✓  [Store Verification]

MVR Triad (Minimum Viable Runtime)

         snix (-1)
        /         \
       /    MVR    \
      /      0      \
world-runtime (0) --- agent-o-rama (+1)
     BUILD ←→ RUN ←→ ORCHESTRATE

Content-Addressed Store

/snix/store/
├── <hash>-busybox-1.36.1/
│   └── bin/
│       └── busybox              # 1.5MB static binary
├── <hash>-git-minimal-2.43.0/
│   └── bin/
│       └── git                  # 15-30MB
├── <hash>-ca-certificates/
│   └── etc/ssl/certs/
│       └── ca-bundle.crt        # 0.2MB
└── <hash>-codex-rootfs/
    └── ...                      # Composed rootfs

Key properties:

• Content-addressed: paths keyed by cryptographic hash
• Deduplication: identical content shared across builds
• Reproducibility: same inputs always produce same outputs
• Granularity: individual packages, not monolithic images

Commands

# Build minimal rootfs
snix build .#packages.aarch64-linux.rootfs

# Evaluate without building
snix eval .#packages.aarch64-linux.rootfs

# Inspect store
snix store ls /snix/store/

# GC dead paths
snix store gc

# Boot in boxxy
cd ~/i/boxxy && ./boxxy boot codex-rootfs.img

# Run agents via toad
toad -a claude ~/i/soft-machine
toad -a codex ~/i/soft-machine
toad -a goose ~/i/soft-machine

See Also

• Minimum Viable Runtime — full MVR specification
• nix-acset-worlding — Nix store as ACSet
• flox — Nix environment management
• world-runtime — VM lifecycle coordination
• agent-o-rama — Agent orchestration
• codex-self-rewriting — Codex behavior patterns
• goose-introspection — Goose behavior analysis

References

1. snix — https://snix.dev / https://git.snix.dev/snix/snix
2. Tvix — https://tvix.dev (upstream before fork)
3. boxxy — https://github.com/bmorphism/boxxy (Apple Virtualization.framework)
4. codex-rs — https://github.com/openai/codex (Rust Codex CLI)
5. toad — https://github.com/batrachianai/toad (Agent TUI driver)
6. Landlock — https://landlock.io (Linux security module)

Scientific Skill Interleaving

This skill connects to the K-Dense-AI/claude-scientific-skills ecosystem:

Systems Programming

• nix-acset-worlding [-1] via store semantics
  • Nix store modeled as Attributed C-Set
• flox [0] via environment management
  • Nix-based dev environments
• world-runtime [0] via VM lifecycle
  • Firecracker + Morph Infinibranch execution substrate

Runtime Composition

• hvm-runtime [+1] via parallel reduction
  • GPU-accelerated interaction nets
• kinfer-runtime [-1] via inference
  • K-Scale robot inference runtime
• agent-o-rama [+1] via orchestration
  • Multi-agent coordination

Agent Behaviors

• codex-self-rewriting [0] via codex-rs integration
  • OpenAI Codex behavior patterns
• goose-introspection [0] via behavior analysis
  • Block/Goose agent introspection

Graph Theory

• networkx [0] via bicomodule
  • Universal graph hub

Bibliography References

• general

  : 734 citations in bib.duckdb

SDF Interleaving

This skill connects to Software Design for Flexibility (Hanson & Sussman, 2021):

Primary Chapter: 2. Domain-Specific Languages

Concepts: embedded DSL, combinator, wrapper, Nix expression language

GF(3) Balanced Triad

snix (-) + SDF.Ch2 (-) + [balancer] (+) — rebalance needed
snix (-) + SDF.Ch7.Propagators (0) + hvm-runtime (+) = 0 ✓

Skill Trit: -1 (MINUS - build validation)

Secondary Chapters

• Ch1: Flexibility through Abstraction
• Ch8: Degeneracy (fallback build strategies)

Connection Pattern

DSLs embed domain knowledge. snix embeds Nix semantics in Rust for reproducible builds.

Cat# Integration

This skill maps to Cat# = Comod(P) as a bicomodule in the equipment structure:

Trit: -1 (MINUS)
Home: Prof
Poly Op: ⊗
Kan Role: Ran (right Kan extension - verification)
Color: #D89B73

GF(3) Naturality

The skill participates in triads satisfying:

(-1) + (0) + (+1) ≡ 0 (mod 3)

Example balanced triads:

snix (-1) + world-runtime (0) + agent-o-rama (+1) = 0 ✓
snix (-1) + flox (0) + hvm-runtime (+1) = 0 ✓
snix (-1) + acsets (0) + true-alife (+1) = 0 ✓

This ensures compositional coherence in the Cat# equipment structure.