What is nix-scaffolding?

A guide for creating a new project with a Nix flake and development shell. A Nix flake records project setup, while a development shell provides the tools and dependencies used for development.

It helps scaffold Python, Python with machine learning, Rust, and web projects, including dependencies, system packages, environment variables, shell commands, and a pinned Nix package set.

It removes repetitive setup work and keeps the development environment defined in the project. It also helps configure language-specific dependencies and startup commands.

nix-scaffolding — Skill for Claude Code by breakds/claude.bds

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add breakds/claude.bds --skill nix-scaffolding

Clone the repo

git clone --depth 1 https://github.com/breakds/claude.bds

Made for: Claude Code.

Or install bds-dev, the plugin that ships this one along with the rest of its 2 skills, 3 commands.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/breakds/claude.bds/nix-scaffolding/github.svg)](https://agentmods.dev/skills/breakds/claude.bds/nix-scaffolding)

Your own site

<a href="https://agentmods.dev/skills/breakds/claude.bds/nix-scaffolding"><img src="https://agentmods.dev/badge/skills/breakds/claude.bds/nix-scaffolding/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/breakds/claude.bds/nix-scaffolding"><img src="https://agentmods.dev/badge/skills/breakds/claude.bds/nix-scaffolding.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 951 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00024	$0.00951
Opus 5.5	$0.00010	$0.00380
Sonnet 5.5	$0.00005	$0.00190
Haiku 4.5	$0.00002	$0.00095

Measured 2mo ago against content hash 2eef5a97c14d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

nix-scaffolding scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

bds-dev/skills/nix-scaffolding/SKILL.md · 98 lines

How it starts

The opening of the file, as written. The whole thing — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Nix Project Scaffolding

Create new projects with flake.nix and devshell for Python, Rust, or webapp stacks.

Workflow

Gather basic info:
- Project name (used for directory and shell name)
- Short description (for flake description)
- Project type: Python / Python+ML / Rust / Webapp
Gather project-specific details:
- Python/Python+ML: Initial Python dependencies to include (e.g., pandas, pytest, fastapi)
- Rust: Additional system dependencies for buildInputs (e.g., libva, glib.dev)
- Webapp: Any additional tools beyond Node.js + pnpm
- All: Custom shellHook commands, environment variables, or special configurations
Ask for nixpkgs pin:
- Ask user which nixpkgs commit to pin in flake.lock
- User may provide a commit hash or reference another project's lock
Create and customize project:
- Create project directory
- Copy appropriate template from templates/
- Replace {{PROJECT_NAME}} and {{PROJECT_DESCRIPTION}} placeholders
- Customize based on gathered details:
  - Add specified dependencies to packages list
  - Add any custom buildInputs or environment variables
  - Modify shellHook if needed
- Run git init
- Run nix flake lock --override-input nixpkgs github:NixOS/nixpkgs/<commit>

Templates

Template	Use when
`basic-python`	Pure Python projects without ML/CUDA needs
`basic-python-ml`	ML/robotics projects needing CUDA and ml-pkgs overlay
`basic-rust`	Rust projects (uses crane with full checks)
`basic-webapp`	Frontend apps with Node.js + pnpm
`pyo3-python`	Python library with Rust backend via PyO3/maturin
`esp32`	ESP32 embedded projects with ESP-IDF (C/C++)

Template Structure

All templates create:

<project>/
  flake.nix           # flake-parts based
  .envrc              # direnv integration (watch_dir nix, use flake)
  nix/
    development.nix   # devShell definition

Read the full file on GitHub · 98 lines

Files

What ships with it

24 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 98 lines · 24 tokens per session scan A 2eef5a97c14d

Subscribe to this mod's changes

nix-scaffolding is a skill published in the GitHub repository breakds/claude.bds (2 stars, last pushed 5mo ago), licensed MIT. It adds 24 tokens to every session and 951 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

nix-scaffolding next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
nix-scaffoldingbreakds/claude.bds	Skill	2	5mo ago	MIT	A	24	Claude Code
imagegenopenai/codex	Skill	134k	today	Apache-2.0	A	113	Codex
local-ai-agentsmicrosoft/ai-agents-for-beginners	Skill	79k	today	MIT	A	200	Claude Code, Codex
playwright-climicrosoft/playwright	Skill	99k	today	Apache-2.0	A	19	Claude Code
systematic-debuggingobra/superpowers	Skill	314k	4d ago	MIT	A	21	Claude Code
next-cache-components-adoptionvercel/next.js	Skill	143k	today	MIT	A	95	Claude Code
chat-pet-sprite-creationmicrosoft/vscode	Skill	195k	today	MIT	A	53	Claude Code, Codex