Agent skill

Working With Nix

A skill your agent uses when working with Nix flakes, selecting devShells, debugging environment issues, or understanding Nix infrastructure - covers shell selection, environment detection, common…

MITAuto-check passedDevelopment

Install Working With Nix

skills CLI

$ npx skills add xmtp/libxmtp --skill working-with-nix -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install xmtp/libxmtp working-with-nix --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/xmtp/libxmtp.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/working-with-nix .claude/skills/working-with-nix && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "working-with-nix" agent skill from https://github.com/xmtp/libxmtp/tree/main/.claude/skills/working-with-nix into .claude/skills/working-with-nix/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "working-with-nix", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/xmtp/libxmtp/tree/main/.claude/skills/working-with-nix

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add xmtp/libxmtp --skill working-with-nix -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install xmtp/libxmtp working-with-nix --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/xmtp/libxmtp.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.claude/skills/working-with-nix .agents/skills/working-with-nix && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "working-with-nix" agent skill from https://github.com/xmtp/libxmtp/tree/main/.claude/skills/working-with-nix into .agents/skills/working-with-nix/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "working-with-nix", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add xmtp/libxmtp --skill working-with-nix -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install xmtp/libxmtp working-with-nix --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/xmtp/libxmtp.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.claude/skills/working-with-nix .cursor/skills/working-with-nix && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "working-with-nix" agent skill from https://github.com/xmtp/libxmtp/tree/main/.claude/skills/working-with-nix into .cursor/skills/working-with-nix/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "working-with-nix", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/xmtp/libxmtp.git --path .claude/skills/working-with-nix

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add xmtp/libxmtp --skill working-with-nix -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install xmtp/libxmtp working-with-nix --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/xmtp/libxmtp.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.claude/skills/working-with-nix .gemini/skills/working-with-nix && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "working-with-nix" agent skill from https://github.com/xmtp/libxmtp/tree/main/.claude/skills/working-with-nix into .gemini/skills/working-with-nix/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "working-with-nix", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install xmtp/libxmtp working-with-nix

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add xmtp/libxmtp --skill working-with-nix -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/xmtp/libxmtp.git skills-src && mkdir -p .github/skills && cp -r skills-src/.claude/skills/working-with-nix .github/skills/working-with-nix && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "working-with-nix" agent skill from https://github.com/xmtp/libxmtp/tree/main/.claude/skills/working-with-nix into .github/skills/working-with-nix/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "working-with-nix", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add xmtp/libxmtp --skill working-with-nix -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install xmtp/libxmtp working-with-nix --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/xmtp/libxmtp.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.claude/skills/working-with-nix .opencode/skills/working-with-nix && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "working-with-nix" agent skill from https://github.com/xmtp/libxmtp/tree/main/.claude/skills/working-with-nix into .opencode/skills/working-with-nix/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "working-with-nix", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: working-with-nix
GitHub stars: 121
Token cost: ~1.4k tokens
SKILL.md length: 382 words
Files: 9
Skills in repo: 2
Repo updated: Oct 9, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

A skill your agent uses when working with Nix flakes, selecting devShells, debugging environment issues, or understanding Nix infrastructure - covers shell selection, environment detection, common…

Working with Nix flakes
SKILL.md covers Quick Shell Selection, Environment Detection, Critical Constraints and Shell Architecture, plus 4 more sections
Calls nix and git; reaches xmtp.cachix.org
Selecting devShells

What it does

Working With Nix is an agent skill from xmtp/libxmtp. Use when working with Nix flakes, selecting devShells, debugging environment issues, or understanding Nix infrastructure - covers shell selection, environment detection, common commands, and project-specific constraints like pinned Rust versions

Its SKILL.md is about 1.4k tokens, which your agent loads only when the skill is triggered. The skill folder holds 9 other files (for example `packages.md`, `shells/android.md` and `shells/default.md`).

It sits in Development. It works with Rust, iOS, Playwright and Android. The repository describes itself as: shared library bindings & reference implementation of XMTP (X-tensible Message Transport Protocol). The licence is MIT.

When your agent uses it

Working with Nix flakes
Selecting devShells
Debugging environment issues
Understanding Nix infrastructure - covers shell selection

Example prompts

“/working-with-nix”

Requirements

Node.js

What it can do on your machine

Read from SKILL.md and the folder at commit cc87802. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
- nix
- git
From the folder's file list and the shell code blocks in SKILL.md.
Network
Hosts in commands or code, which the agent is likely to contact:
- xmtp.cachix.org
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Working With Nix loads about 1.4k tokens when it runs. Until then it costs about 66 tokens; SKILL.md has 382 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~66
When it runs · the whole SKILL.md, loaded when a task matches: ~1.4k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from xmtp/libxmtp at commit cc87802, republished under its MIT licence (© xmtp). 382 words, ~1,424 tokens.

Download SKILL.mdSave it as .claude/skills/working-with-nix/SKILL.md (or your agent's skills folder). This skill also uses 8 other files; get the full folder from GitHub.

name: working-with-nix
description: Use when working with Nix flakes, selecting devShells, debugging environment issues, or understanding Nix infrastructure - covers shell selection, environment detection, common commands, and project-specific constraints like pinned Rust versions

Working with Nix in libxmtp

Quick Shell Selection

Task	Shell	Command
Focused Rust crates/bindings work	rust	`nix develop .#rust`
Full local development (default)	local	`nix develop`
Android builds/testing	android	`nix develop .#android`
iOS builds/testing	ios	`nix develop .#ios`
JavaScript/Node.js	js	`nix develop .#js`
WebAssembly builds	wasm	`nix develop .#wasm`

Environment Detection

bash

echo $XMTP_NIX_ENV     # "yes" if in any Rust-based Nix shell
echo $XMTP_DEV_SHELL   # "local", "android", "ios", or unset

Critical Constraints

Rust Version is Pinned — Do Not Change

Rust is pinned via flake.nix → rust-manifest (1.97.1 as of 2026-07; check with nix develop .#rust -c rustc --version). All shells use xmtp.mkToolchain. Never modify without project-wide coordination.

Playwright Versions Must Match EXACTLY

The playwright pin in bindings/wasm/package.json (=X.Y.Z) must equal nixpkgs' playwright version. The js shell provides browsers via PLAYWRIGHT_BROWSERS_PATH (nix/js.nix), and npm playwright looks them up by its own per-version browser revisions — any skew fails WASM tests with browserType.launch: Executable doesn't exist at .../chromium_headless_shell-NNNN/....

After every nixpkgs (flake.lock) bump:

bash

nix eval --raw .#devShells.x86_64-linux.js.PLAYWRIGHT_VERSION
# If it differs from the package.json pin: update the pin, then
# (cd bindings/wasm && yarn install)

iOS Shell is macOS Only

The .#ios shell only works on Darwin. Requires Xcode 16+ for Swift 6.1.

Untracked Files are Invisible to Flakes

bash

git add <new-file>  # Then rebuild — flakes only see git-tracked files

Cachix

Verify the binary cache is active: nix config show | grep substituters — should include https://xmtp.cachix.org.

Shell Architecture

Shells are independent — they compose from shared building blocks, not from each other:

shell-common.nix   → shared building blocks (rustBase, wasmEnv, tool groups)
  ├── rust.nix     → focused Rust shell (crates/bindings, lint, test)
  ├── local.nix    → full local dev (default) = all targets + debug + misc
  ├── android.nix  → Android cross-compilation
  └── ios.nix      → iOS cross-compilation (macOS only)
js.nix             → JavaScript/browser testing (no Rust)
package/wasm.nix   → WASM shell + package build

Essential Commands

bash

# Enter shells
nix develop              # Default shell
nix develop .#rust       # Focused Rust shell
nix develop .#android    # Android shell
nix develop .#ios        # iOS shell (macOS only)
nix develop .#js         # JavaScript shell
nix develop .#wasm       # WASM shell

# Build packages
nix build .#wasm-bindings                    # WASM compiled bindings
nix build .#node-bindings-fast               # Host-matching .node binary
nix build .#node-bindings-js                 # Generated JS/TS bindings
nix build .#node-bindings-linux-x64-gnu      # Per-target .node (example)
nix build .#android-libs                     # All Android targets
nix build .#ios-libs                         # All iOS targets (macOS only)

# Explore
nix flake show           # List all outputs
nix flake metadata       # Show inputs and versions

# Debug
nix develop --show-trace  # Verbose error output

Platform Support

Platform	Shells Available
macOS (aarch64-darwin)	rust, default, android, ios, js, wasm
Linux (x86_64-linux)	rust, default, android, js, wasm

Show full SKILL.md (166 more words)Show less

Key Files

File	Purpose
`flake.nix`	DevShell + package definitions, input pinning, cachix
`nix/lib/default.nix`	Overlay wiring — exposes `xmtp.*` to all Nix files
`nix/lib/shell-common.nix`	Shared building blocks (rustBase, wasmEnv, tool groups)
`nix/lib/mkToolchain.nix`	Rust version pinning logic
`nix/lib/filesets.nix`	Source file filtering for hermetic builds
`nix/lib/mobile-common.nix`	Shared mobile (iOS/Android) build args
`nix/lib/android-env.nix`	Android SDK config, targets, emulator script
`nix/lib/ios-env.nix`	iOS targets, dynamic Xcode resolution
`nix/lib/node-env.nix`	Node targets, NAPI name mapping, cross-compilation
`nix/shells/rust.nix`	Focused Rust dev shell
`nix/shells/local.nix`	Full local dev shell (default)
`nix/shells/android.nix`	Android dev shell
`nix/shells/ios.nix`	iOS dev shell (macOS only)
`nix/js.nix`	JavaScript shell
`nix/package/wasm.nix`	WASM shell + package build
`nix/package/node.nix`	Node.js per-target builds + JS/TS generation
`nix/package/android.nix`	Android release build derivation
`nix/package/ios.nix`	iOS release build derivation
`dev/nix-up`	Installation script for Nix and direnv

Further Reference

Shell: Default — Full local dev shell reference
Shell: Rust — Focused Rust shell reference
Shell: Android — Android shell reference
Shell: iOS — iOS shell reference
Shell: JavaScript — JavaScript shell reference
Shell: WASM — WASM shell reference
Nix Build Packages — All nix build .#<package> outputs
Troubleshooting — Common issues and solutions

Files

SKILL.md and 8 other files in .claude/skills/working-with-nix of xmtp/libxmtp.

SKILL.md
packages.md
shells/android.md
shells/default.md
shells/ios.md
shells/js.md
shells/rust.md
shells/wasm.md
troubleshooting.md

Open the folder on GitHubat commit cc87802

Compare with similar skills

Working With Nix next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Working With Nix compared with similar skills
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Makepad Deploymentsickn33/agentic-awesome-skills	47k	2 repos	~3k	Automated safety check: Notes	MIT	today
jscpd Code Migration Trackerkucherenko/jscpd	6.4k	—	~5k	Automated safety check: Pass	MIT	today
E2Ecallstack/react-native-pager-view	3.4k	1 repos	~2.1k	Automated safety check: Pass	MIT	yesterday
UI Testingchampionswimmer/TwoFac	130	—	~215	Automated safety check: Pass	None	4 mo ago
Dep Validateblokadaorg/blokada	3.3k	—	~5.7k	Automated safety check: Notes	MPL-2.0	today

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Questions about Working With Nix

What does Working With Nix do?

A skill your agent uses when working with Nix flakes, selecting devShells, debugging environment issues, or understanding Nix infrastructure - covers shell selection, environment detection, common…. Working With Nix is an agent skill from xmtp/libxmtp.

When should I use Working With Nix?

Working With Nix fits situations like: working with Nix flakes; selecting devShells; debugging environment issues; understanding Nix infrastructure - covers shell selection.

How do I install Working With Nix in Claude Code?

Run `npx skills add xmtp/libxmtp --skill working-with-nix -a claude-code`. Or copy the skill folder (.claude/skills/working-with-nix in xmtp/libxmtp) into .claude/skills/working-with-nix in your project. Claude Code loads it when a task matches its description.

How do I install Working With Nix in Codex?

Run `npx skills add xmtp/libxmtp --skill working-with-nix -a codex`. Or copy the skill folder (.claude/skills/working-with-nix in xmtp/libxmtp) into .agents/skills/working-with-nix in your project. Codex loads it when a task matches its description.

Can I use Working With Nix in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add xmtp/libxmtp --skill working-with-nix -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/working-with-nix, .gemini/skills/working-with-nix, .github/skills/working-with-nix and .opencode/skills/working-with-nix in your project.

What does Working With Nix need to run?

Going by SKILL.md and its folder, Working With Nix needs the command-line tools its instructions call (nix and git). Our summary lists: Node.js.

Does Working With Nix access the network?

SKILL.md names 1 domain. In commands or code: xmtp.cachix.org; the agent is likely to contact it when it follows the instructions. This is read from the text; nothing was executed.

Is Working With Nix safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Working With Nix use?

Working With Nix is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Working With Nix use?

About 1.4k tokens (SKILL.md is roughly 5.7k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Working With Nix?

Skills that share tags, products or a category with Working With Nix: Makepad Deployment (sickn33/agentic-awesome-skills, 47k stars), jscpd Code Migration Tracker (kucherenko/jscpd, 6.4k stars), E2E (callstack/react-native-pager-view, 3.4k stars) and UI Testing (championswimmer/TwoFac, 130 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Working With Nix?

xmtp (a GitHub organization) maintains it in xmtp/libxmtp, which has 121 GitHub stars. The repository holds 2 skills in this directory. The repository was last updated on October 9, 2026.

Source: xmtp/libxmtp on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Working With Nix

Facts

At a glance

What it does

When your agent uses it

Example prompts

Requirements

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Working with Nix in libxmtp

Quick Shell Selection

Environment Detection

Critical Constraints

Rust Version is Pinned — Do Not Change

Playwright Versions Must Match EXACTLY

iOS Shell is macOS Only

Untracked Files are Invisible to Flakes

Cachix

Shell Architecture

Essential Commands

Platform Support

Key Files

Further Reference

Files

Compare with similar skills

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Makepad Deployment

jscpd Code Migration Tracker

E2E

UI Testing

Dep Validate

Ksafe

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Related

Questions about Working With Nix