add-feature

Original：🇺🇸 English

Translated

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

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Sourcejamiemason/syncpack

Added on2026-02-21

NPX Install

npx skill4agent add jamiemason/syncpack add-feature

SKILL.md Content

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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