How do I install the Extension Guide skill?

Run npx skillmds@latest add pacphi/extension-guide in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Extension Guide safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Extension Guide?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Extension Guide free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Extension Guide?

pacphi (@pacphi) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Extension Guide by pacphi — Agent Skill

Name: Extension Guide
Author: pacphi

Extension Guide

Guide users through creating Sindri extensions. Use when creating new extensions, understanding extension.yaml structure, or learning about the extension system. Asks user to choose V2 or V3 before delegating to specialized version-specific skills.

pacphi 83bc548 3.5 KB Updated Sep 17, 2026

File contents

Sindri Extension Guide

Sindri supports extensions for both V2 (Bash/Docker) and V3 (Rust CLI) platforms. Before proceeding with extension creation, you need to choose which platform you're targeting.

Version Differences at a Glance

Aspect	V2	V3
Implementation	Bash (~52K lines)	Rust (~11.2K lines)
Extension Directory	`v2/docker/lib/extensions/`	`v3/extensions/`
Schema Location	`v2/docker/lib/schemas/extension.schema.json`	`v3/schemas/extension.schema.json`
CLI	`./v2/cli/extension-manager`	`sindri extension`
Install Methods	6 (mise, apt, binary, npm, script, hybrid)	7 (adds npm-global)
Categories	11	12 (different set)
VisionFlow	Supported	Not available

V2 Categories

base, agile, language, dev-tools, infrastructure, ai, database, monitoring, mobile, desktop, utilities

V3 Categories

ai-agents, ai-dev, claude, cloud, desktop, devops, documentation, languages, mcp, productivity, research, testing

When to Choose V2

VisionFlow workflows - vf-* extensions only available in V2
Proven stability - Battle-tested codebase
Docker-first - Deep Docker/container integration
Team familiar with Bash - V2 scripts are all Bash

When to Choose V3

New projects - Modern architecture
Windows support - Native Windows binaries
Performance - 10-50x faster CLI operations
Advanced collision handling - Smart merge strategies for cloned projects
Project-context merging - CLAUDE.md file management

Required Action: Choose Version

Before creating an extension, use AskUserQuestion to determine:

Which Sindri version (V2 or V3)?
Basic extension details (name, category, purpose)

Then delegate to the appropriate specialist skill:

V2: Use /extension-guide-v2 skill
V3: Use /extension-guide-v3 skill

Slash Commands

Command	Description
`/extension-guide`	This router (choose version first)
`/extension-guide-v2`	V2-specific extension guide
`/extension-guide-v3`	V3-specific extension guide

Quick Decision Tree

Creating an extension?
    │
    ├── Need VisionFlow (vf-*)?
    │   └── V2 only
    │
    ├── New AI/Claude tool?
    │   └── V3 recommended (better categories, collision handling)
    │
    ├── Language runtime (Node, Python, etc.)?
    │   └── Either works (V3 preferred for new projects)
    │
    └── Windows support needed?
        └── V3 only

Shared Features (Both V2 and V3)

Both versions support the capabilities system for advanced extensions:

project-init - Commands to initialize projects
auth - API key and CLI authentication
hooks - Lifecycle hooks (pre/post install, pre/post project-init)
mcp - Model Context Protocol server registration
features - Feature flags for advanced functionality

Most extensions don't need capabilities - they're for extensions that manage project setup (like Claude Flow, Agentic QE, Spec-Kit).

Next Step: Ask the user which version they need, then invoke the appropriate specialist skill.

---name: extension-guidedescription: Guide users through creating Sindri extensions. Use when creating new extensions, understanding extension.yaml structure, or learning about the extension system. Asks user to choose V2 or V3 before delegating to specialized version-specific skills.---# Sindri Extension GuideSindri supports extensions for **both V2 (Bash/Docker)** and **V3 (Rust CLI)** platforms. Before proceeding with extension creation, you need to choose which platform you're targeting.## Version Differences at a Glance| Aspect | V2 | V3 ||--------|-----|-----|| **Implementation** | Bash (~52K lines) | Rust (~11.2K lines) || **Extension Directory** | `v2/docker/lib/extensions/` | `v3/extensions/` || **Schema Location** | `v2/docker/lib/schemas/extension.schema.json` | `v3/schemas/extension.schema.json` || **CLI** | `./v2/cli/extension-manager` | `sindri extension` || **Install Methods** | 6 (mise, apt, binary, npm, script, hybrid) | 7 (adds npm-global) || **Categories** | 11 | 12 (different set) || **VisionFlow** | Supported | Not available |### V2 Categories`base`, `agile`, `language`, `dev-tools`, `infrastructure`, `ai`, `database`, `monitoring`, `mobile`, `desktop`, `utilities`### V3 Categories`ai-agents`, `ai-dev`, `claude`, `cloud`, `desktop`, `devops`, `documentation`, `languages`, `mcp`, `productivity`, `research`, `testing`## When to Choose V2- **VisionFlow workflows** - vf-* extensions only available in V2- **Proven stability** - Battle-tested codebase- **Docker-first** - Deep Docker/container integration- **Team familiar with Bash** - V2 scripts are all Bash## When to Choose V3- **New projects** - Modern architecture- **Windows support** - Native Windows binaries- **Performance** - 10-50x faster CLI operations- **Advanced collision handling** - Smart merge strategies for cloned projects- **Project-context merging** - CLAUDE.md file management## Required Action: Choose Version**Before creating an extension, use AskUserQuestion to determine:**1. Which Sindri version (V2 or V3)?2. Basic extension details (name, category, purpose)Then delegate to the appropriate specialist skill:- **V2**: Use `/extension-guide-v2` skill- **V3**: Use `/extension-guide-v3` skill## Slash Commands| Command | Description ||---------|-------------|| `/extension-guide` | This router (choose version first) || `/extension-guide-v2` | V2-specific extension guide || `/extension-guide-v3` | V3-specific extension guide |## Quick Decision Tree```Creating an extension? │ ├── Need VisionFlow (vf-*)? │ └── V2 only │ ├── New AI/Claude tool? │ └── V3 recommended (better categories, collision handling) │ ├── Language runtime (Node, Python, etc.)? │ └── Either works (V3 preferred for new projects) │ └── Windows support needed? └── V3 only```## Shared Features (Both V2 and V3)Both versions support the **capabilities system** for advanced extensions:- **project-init** - Commands to initialize projects- **auth** - API key and CLI authentication- **hooks** - Lifecycle hooks (pre/post install, pre/post project-init)- **mcp** - Model Context Protocol server registration- **features** - Feature flags for advanced functionalityMost extensions don't need capabilities - they're for extensions that manage project setup (like Claude Flow, Agentic QE, Spec-Kit).---**Next Step:** Ask the user which version they need, then invoke the appropriate specialist skill.

Frequently asked questions