Agent skill

Add Feature

Add new features to Syncpack including commands and validation logic.

MITAuto-check passedDevelopment

Install Add Feature

skills CLI

$ npx skills add JamieMason/syncpack --skill add-feature -a claude-code

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

GitHub CLI

$ gh skill install JamieMason/syncpack add-feature --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/JamieMason/syncpack.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/add-feature .claude/skills/add-feature && 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 "add-feature" agent skill from https://github.com/JamieMason/syncpack/tree/main/.claude/skills/add-feature into .claude/skills/add-feature/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-feature", 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/JamieMason/syncpack/tree/main/.claude/skills/add-feature

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 JamieMason/syncpack --skill add-feature -a codex

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

GitHub CLI

$ gh skill install JamieMason/syncpack add-feature --agent codex

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

Manual copy

$ git clone --depth 1 https://github.com/JamieMason/syncpack.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.claude/skills/add-feature .agents/skills/add-feature && 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 "add-feature" agent skill from https://github.com/JamieMason/syncpack/tree/main/.claude/skills/add-feature into .agents/skills/add-feature/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-feature", 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 JamieMason/syncpack --skill add-feature -a cursor

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

GitHub CLI

$ gh skill install JamieMason/syncpack add-feature --agent cursor

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

Manual copy

$ git clone --depth 1 https://github.com/JamieMason/syncpack.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.claude/skills/add-feature .cursor/skills/add-feature && 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 "add-feature" agent skill from https://github.com/JamieMason/syncpack/tree/main/.claude/skills/add-feature into .cursor/skills/add-feature/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-feature", 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/JamieMason/syncpack.git --path .claude/skills/add-feature

--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 JamieMason/syncpack --skill add-feature -a gemini-cli

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

GitHub CLI

$ gh skill install JamieMason/syncpack add-feature --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/JamieMason/syncpack.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.claude/skills/add-feature .gemini/skills/add-feature && 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 "add-feature" agent skill from https://github.com/JamieMason/syncpack/tree/main/.claude/skills/add-feature into .gemini/skills/add-feature/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-feature", 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 JamieMason/syncpack add-feature

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 JamieMason/syncpack --skill add-feature -a github-copilot

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

Manual copy

$ git clone --depth 1 https://github.com/JamieMason/syncpack.git skills-src && mkdir -p .github/skills && cp -r skills-src/.claude/skills/add-feature .github/skills/add-feature && 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 "add-feature" agent skill from https://github.com/JamieMason/syncpack/tree/main/.claude/skills/add-feature into .github/skills/add-feature/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-feature", 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 JamieMason/syncpack --skill add-feature -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 JamieMason/syncpack add-feature --agent opencode

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

Manual copy

$ git clone --depth 1 https://github.com/JamieMason/syncpack.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.claude/skills/add-feature .opencode/skills/add-feature && 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 "add-feature" agent skill from https://github.com/JamieMason/syncpack/tree/main/.claude/skills/add-feature into .opencode/skills/add-feature/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-feature", 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: add-feature
GitHub stars: 2.1k
Token cost: ~523 tokens
SKILL.md length: 221 words
Files: 3
Skills in repo: 11
Repo updated: Sep 26, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Add new features to Syncpack including commands and validation logic.

Works in 3 steps: Understand the 3-phase pattern: Create… → Know which phase your feature affects → Check if similar code exists (use…
Implementing new CLI commands
SKILL.md covers Quick Decision, Prerequisites, Feature Types and Common Workflow, plus 1 more section
Calls cargo and just

What it does

Add Feature is an agent skill from JamieMason/syncpack. Add new features to Syncpack including commands and validation logic. Use when implementing new CLI commands, adding InstanceState variants, or extending version group behaviour.

Its SKILL.md is about 520 tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files (for example `adding-command.md` and `adding-instance-state.md`).

It sits in Development. The repository describes itself as: Consistent dependency versions in large JavaScript Monorepos. The licence is MIT.

When your agent uses it

Implementing new CLI commands
Adding InstanceState variants
Extending version group behaviour

Example prompts

“/add-feature”

Workflow steps

3 steps, taken from the first numbered list in SKILL.md.

Understand the 3-phase pattern: Create Context → Inspect Context → Run Command
Know which phase your feature affects
Check if similar code exists (use ast-grep -p 'PATTERN' src/)

What it can do on your machine

Read from SKILL.md and the folder at commit 958d306. 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:
- cargo
- just
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
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

Add Feature loads about 523 tokens when it runs. Until then it costs about 48 tokens; SKILL.md has 221 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~48
When it runs · the whole SKILL.md, loaded when a task matches: ~523

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 JamieMason/syncpack at commit 958d306, republished under its MIT licence (© JamieMason). 221 words, ~523 tokens.

Download SKILL.mdSave it as .claude/skills/add-feature/SKILL.md (or your agent's skills folder). This skill also uses 2 other files; get the full folder from GitHub.

name: add-feature
description: Add new features to Syncpack including commands and validation logic. Use when implementing new CLI commands, adding InstanceState variants, or extending version group behaviour.

Add Feature

Guide for adding new functionality to Syncpack.

Quick Decision

What are you adding?

New CLI command (lint, fix, format, etc.) → See adding-command.md
New validation logic (InstanceState variant) → See adding-instance-state.md
Both → Start with instance state, then add command

Prerequisites

Before adding any feature:

Understand the 3-phase pattern: Create Context → Inspect Context → Run Command
Know which phase your feature affects
Check if similar code exists (use ast-grep -p 'PATTERN' src/)

Feature Types

Commands

Commands are user-facing operations (syncpack lint, syncpack fix, etc.).

When to create a new command:

New user-facing operation that doesn't fit existing commands
Different output format or behaviour needed

Registration points (all three required):

src/cli.rs - Add to Subcommand enum
src/main.rs - Add match arm for dispatch
src/commands/*.rs - Implement pub fn run(ctx: Context) -> i32

→ Full guide: adding-command.md

Instance States

InstanceState variants describe validation results (valid, fixable, unfixable, suspect).

When to add a new state:

New validation rule needed
New type of error/warning to report
New auto-fix capability

Location: src/instance_state.rs + src/visit_packages/*.rs

→ Full guide: adding-instance-state.md

Common Workflow

Write failing test using TestBuilder
Implement minimal code to pass
Run cargo clippy and fix warnings
Refactor if needed
Update documentation

Checklist

Before submitting:

Tests pass (just test)
Zero clippy warnings
Follows existing patterns
Registered in all required places (for commands)
Uses TDD approach

Files

SKILL.md and 2 other files in .claude/skills/add-feature of JamieMason/syncpack.

SKILL.md
adding-command.md
adding-instance-state.md

Open the folder on GitHubat commit 958d306

Compare with similar skills

Add Feature 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.

Add Feature compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Add Feature this skillJamieMason/syncpack	2.1k	—	~523	Automated safety check: Pass	MIT	12 days ago
Vercel Composition Patternssupabase/supabase	111k	58 repos	~726	Automated safety check: Pass	MIT	today
Finishing a Development Branchobra/superpowers	297k	5 repos	~1.9k	Automated safety check: Pass	MIT	today
Typescript Advanced Typesrolling-scopes/rsschool-app	10k	25 repos	~4.2k	Automated safety check: Pass	MPL-2.0	4 days ago
PR Babysitteropeninterpreter/openinterpreter	69k	3 repos	~4.2k	Automated safety check: Pass	Apache-2.0	2 days ago
Code Review ChecklistshareAI-lab/learn-claude-code	78k	5 repos	~1.1k	Automated safety check: Pass	MIT	10 days ago

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Questions about Add Feature

What does Add Feature do?

Add new features to Syncpack including commands and validation logic. Add Feature is an agent skill from JamieMason/syncpack. Add new features to Syncpack including commands and validation logic.

When should I use Add Feature?

Add Feature fits situations like: implementing new CLI commands; adding InstanceState variants; extending version group behaviour.

How do I install Add Feature in Claude Code?

Run `npx skills add JamieMason/syncpack --skill add-feature -a claude-code`. Or copy the skill folder (.claude/skills/add-feature in JamieMason/syncpack) into .claude/skills/add-feature in your project. Claude Code loads it when a task matches its description.

How do I install Add Feature in Codex?

Run `npx skills add JamieMason/syncpack --skill add-feature -a codex`. Or copy the skill folder (.claude/skills/add-feature in JamieMason/syncpack) into .agents/skills/add-feature in your project. Codex loads it when a task matches its description.

Can I use Add Feature 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 JamieMason/syncpack --skill add-feature -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/add-feature, .gemini/skills/add-feature, .github/skills/add-feature and .opencode/skills/add-feature in your project.

What does Add Feature need to run?

Going by SKILL.md and its folder, Add Feature needs the command-line tools its instructions call (cargo and just).

Does Add Feature access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Add Feature 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 Add Feature use?

Add Feature 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 Add Feature use?

About 523 tokens (SKILL.md is roughly 2.1k 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 Add Feature?

Skills that share tags, products or a category with Add Feature: Vercel Composition Patterns (supabase/supabase, 111k stars), Finishing a Development Branch (obra/superpowers, 297k stars), Typescript Advanced Types (rolling-scopes/rsschool-app, 10k stars) and PR Babysitter (openinterpreter/openinterpreter, 69k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Add Feature?

JamieMason (a GitHub user) maintains it in JamieMason/syncpack, which has 2,101 GitHub stars. The repository holds 11 skills in this directory. The repository was last updated on September 26, 2026.

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

Install Add Feature

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Add Feature

Quick Decision

Prerequisites

Feature Types

Commands

Instance States

Common Workflow

Checklist

Files

Compare with similar skills

Similar skills

More from JamieMason/syncpack

Related

Questions about Add Feature