Sindri Extension Development Guide

What's New: Extension Capabilities System

Recent Addition (Jan 2026): Sindri now supports an optional capabilities system for advanced extensions:

• Project Initialization - Commands to set up new projects (project-init)
• Multi-Method Authentication - Support both API key and CLI auth (auth)
• Lifecycle Hooks - Pre/post install and project-init hooks (hooks)
• MCP Integration - Register as Model Context Protocol servers (mcp)

Most extensions don't need capabilities - they're only for extensions that extend project management functionality (like Claude Flow, Agentic QE, Spec-Kit). Regular extensions (nodejs, python, docker) work exactly as before.

Slash Commands (Recommended)

For reliable extension creation with all documentation updates, use these commands:

Command	Purpose
/extension/new <name> [source]	Create new extension with complete documentation workflow
/extension/update-docs <name>	Update documentation for existing extension

Example:

/extension/new mdflow https://github.com/johnlindquist/mdflow
/extension/update-docs nodejs

These commands enforce the complete workflow including all required documentation updates.

---

Overview

This skill guides you through creating declarative YAML extensions for Sindri. Extensions are YAML files, not bash scripts - all configuration is driven by declarative YAML definitions.

Documentation Locations

IMPORTANT: After creating any extension, you must update the relevant documentation.

Key Documentation Files

Type	Path	Purpose
Schema	v2/docker/lib/schemas/extension.schema.json	Extension validation schema
Registry	v2/docker/lib/registry.yaml	Master extension registry
Profiles	v2/docker/lib/profiles.yaml	Extension profile definitions
Categories	v2/docker/lib/categories.yaml	Category definitions
Extension Docs	docs/extensions/{NAME}.md	Individual extension documentation
Catalog	v2/docs/EXTENSIONS.md	Overview of all extensions
Authoring Guide	v2/docs/EXTENSION_AUTHORING.md	Detailed authoring reference
Slides	docs/slides/extensions.html	Visual presentation

Quick Start Checklist

1. Create directory: v2/docker/lib/extensions/{name}/
2. Create extension.yaml with required sections
3. Add to v2/docker/lib/registry.yaml
4. Validate: ./v2/cli/extension-manager validate {name}
5. Test: ./v2/cli/extension-manager install {name}
6. Update documentation (see Post-Extension Checklist below)

Extension Directory Structure

v2/docker/lib/extensions/{extension-name}/
├── extension.yaml       # Required: Main definition
├── scripts/             # Optional: Custom scripts
│   ├── install.sh       # Custom installation
│   ├── uninstall.sh     # Custom removal
│   └── validate.sh      # Custom validation
├── templates/           # Optional: Config templates
│   └── config.template
└── mise.toml            # Optional: mise configuration

Minimal Extension Template

metadata:
  name: my-extension
  version: 1.0.0
  description: Brief description (10-200 chars)
  category: dev-tools
  dependencies: []

install:
  method: mise
  mise:
    configFile: mise.toml

validate:
  commands:
    - name: mytool
      versionFlag: --version
      expectedPattern: "v\\d+\\.\\d+\\.\\d+"

Extension YAML Sections

Extensions consist of required sections (metadata, install, validate) and optional sections (requirements, configure, remove, upgrade, bom, capabilities).

IMPORTANT: Capabilities are OPTIONAL - Most extensions (nodejs, python, docker, etc.) don't need capabilities. Only extensions requiring project initialization, authentication, lifecycle hooks, or MCP integration need the capabilities section.

1. Metadata (Required)

metadata:
  name: extension-name # lowercase with hyphens
  version: 1.0.0 # semantic versioning
  description: What it does # 10-200 characters
  category: dev-tools # see categories below
  author: Your Name # optional
  homepage: https://... # optional
  dependencies: # other extensions needed
    - nodejs
    - python

Valid Categories:

• base - Core system components
• language - Programming runtimes (Node.js, Python, etc.)
• dev-tools - Development tools (linters, formatters)
• infrastructure - Cloud/container tools (Docker, K8s, Terraform)
• ai - AI/ML tools and frameworks
• agile - Project management tools (Jira, Linear)
• database - Database servers
• monitoring - Observability tools
• mobile - Mobile SDKs
• desktop - GUI environments
• utilities - General tools

2. Requirements (Optional)

requirements:
  domains: # Network access needed
    - api.github.com
    - registry.npmjs.org
  diskSpace: 500 # MB required
  secrets: # Credentials needed
    - GITHUB_TOKEN

3. Install (Required)

Choose ONE installation method:

mise (recommended for language tools):

install:
  method: mise
  mise:
    configFile: mise.toml # Reference to mise config
    reshim: true # Rebuild shims after install

apt (system packages):

install:
  method: apt
  apt:
    repositories:
      - name: docker
        key: https://download.docker.com/linux/ubuntu/gpg
        url: https://download.docker.com/linux/ubuntu
        suite: jammy
        component: stable
    packages:
      - docker-ce
      - docker-ce-cli

binary (direct download):

install:
  method: binary
  binary:
    url: https://github.com/org/repo/releases/download/v1.0.0/tool-linux-amd64.tar.gz
    extract: tar.gz # tar.gz, zip, or none
    destination: ~/.local/bin/tool

npm (Node.js packages):

install:
  method: npm
  npm:
    packages:
      - typescript
      - eslint
    global: true

script (custom installation):

install:
  method: script
  script:
    path: scripts/install.sh
    timeout: 300 # seconds (default: 300)

hybrid (multiple methods):

install:
  method: hybrid
  hybrid:
    steps:
      - method: apt
        apt:
          packages: [build-essential]
      - method: script
        script:
          path: scripts/install.sh

4. Configure (Optional)

configure:
  templates:
    - source: templates/config.template
      destination: ~/.config/tool/config.yaml
      mode: overwrite # overwrite|append|merge|skip-if-exists
  environment:
    - key: TOOL_HOME
      value: $HOME/.tool
      scope: bashrc # bashrc|profile|session

5. Validate (Required)

validate:
  commands:
    - name: tool-name
      versionFlag: --version
      expectedPattern: "\\d+\\.\\d+\\.\\d+"
  mise:
    tools:
      - node
      - python
    minToolCount: 2
  script:
    path: scripts/validate.sh
    timeout: 60

6. Remove (Optional)

remove:
  confirmation: true
  mise:
    removeConfig: true
    tools: [node, python]
  apt:
    packages: [package-name]
    purge: false
  script:
    path: scripts/uninstall.sh
  paths:
    - ~/.config/tool
    - ~/.local/share/tool

7. Upgrade (Optional)

upgrade:
  strategy: automatic # automatic|manual|none
  mise:
    upgradeAll: true
  apt:
    packages: [package-name]
    updateFirst: true
  script:
    path: scripts/upgrade.sh

8. Bill of Materials (Optional but Recommended)

bom:
  tools:
    - name: node
      version: dynamic # or specific version
      source: mise
      type: runtime
      license: MIT
      homepage: https://nodejs.org

9. Capabilities (Optional - Advanced Extensions Only)

Use capabilities when your extension needs:

• Project initialization - Commands to set up a new project (e.g., claude-flow init, spec-kit init)
• Authentication - Validate API keys or CLI authentication before running
• Lifecycle hooks - Pre/post install or project-init commands
• MCP integration - Register as a Model Context Protocol server for Claude Code

Most extensions don't need capabilities. Only use this for extensions that extend project management functionality.

capabilities:
  # Project initialization (optional)
  project-init:
    enabled: true
    commands:
      - command: "mytool init --force"
        description: "Initialize mytool project"
        requiresAuth: anthropic # or: openai, github, none
        conditional: false # true = only run if condition met

    state-markers:
      - path: ".mytool"
        type: directory
        description: "Mytool configuration directory"
      - path: ".mytool/config.json"
        type: file
        description: "Mytool config file"

    validation:
      command: "mytool --version"
      expectedPattern: "^\\d+\\.\\d+\\.\\d+"
      expectedExitCode: 0

  # Authentication (optional)
  auth:
    provider: anthropic # or: openai, github, custom
    required: false # true = block installation without auth
    methods:
      - api-key # API key in environment variable
      - cli-auth # CLI authentication (e.g., Max/Pro plan)
    envVars:
      - ANTHROPIC_API_KEY
    validator:
      command: "claude --version"
      expectedExitCode: 0
    features:
      - name: agent-spawn
        requiresApiKey: false
        description: "CLI-based features"
      - name: api-integration
        requiresApiKey: true
        description: "Direct API features"

  # Lifecycle hooks (optional)
  hooks:
    pre-install:
      command: "echo 'Preparing installation...'"
      description: "Pre-installation checks"
    post-install:
      command: "mytool --version"
      description: "Verify installation"
    pre-project-init:
      command: "mytool doctor --check"
      description: "Pre-init health check"
    post-project-init:
      command: "echo 'Project initialized'"
      description: "Post-init notification"

  # MCP server registration (optional)
  mcp:
    enabled: true
    server:
      command: "npx"
      args:
        - "-y"
        - "@mytool/mcp-server"
        - "start"
      env:
        MYTOOL_MCP_MODE: "1"
    tools:
      - name: "mytool-action"
        description: "Perform mytool action"
      - name: "mytool-query"
        description: "Query mytool data"

  # Feature configuration (optional, V3+ extensions)
  features:
    core:
      daemon_autostart: true
      unified_config: true
    advanced:
      plugin_system: true
      security_scanning: false

Capability Guidelines:

1. Keep it simple - Only add capabilities you actually need
2. State markers - Define files/directories created by project-init for idempotency
3. Conditional commands - Use conditional: true for optional setup steps
4. Multi-method auth - Support both API key and CLI auth when possible
5. Feature-level auth - Some features may work without API key (use features array)

Adding to Registry

After creating your extension, add it to v2/docker/lib/registry.yaml:

extensions:
  my-extension:
    category: dev-tools
    description: Short description
    dependencies: [nodejs]
    protected: false

Validation Commands

# Validate single extension
./v2/cli/extension-manager validate my-extension

# Validate all extensions
./v2/cli/extension-manager validate-all

# Check extension info
./v2/cli/extension-manager info my-extension

# Test installation
./v2/cli/extension-manager install my-extension

# Check status
./v2/cli/extension-manager status my-extension

Common Patterns

Language Runtime (mise-based)

Best for: Node.js, Python, Go, Rust, Ruby

• Use method: mise with a mise.toml config file
• Set appropriate environment variables in configure section
• Validate with version command
• No capabilities needed - just install tools

Development Tool (npm-based)

Best for: TypeScript, ESLint, Prettier

• Depend on nodejs extension
• Use method: npm with global packages
• Add configuration templates

CLI Tool (binary download)

Best for: GitHub releases, standalone binaries

• Use method: binary with GitHub release URL
• Handle extraction (tar.gz, zip)
• Validate binary exists and runs

Complex Setup (hybrid)

Best for: Desktop environments, multi-step installs

• Use method: hybrid with ordered steps
• Combine apt + script for flexibility
• Include cleanup in remove section
• No capabilities needed unless it requires project initialization

AI/Project Management Tool (with capabilities)

Best for: Claude Flow, Agentic QE, Spec-Kit

• Use appropriate install method (mise, script, npm)
• Add capabilities section for project initialization
• Define state markers for idempotency (.claude/, .agentic-qe/, .github/spec.json)
• Include authentication configuration (anthropic, openai, github, or none)
• Add lifecycle hooks for post-install/post-init actions
• Register MCP server if extension provides Claude Code tools
• Example extensions: claude-flow-v3, spec-kit, agentic-qe

Current Extensions Using Capabilities:

Extension	project-init	auth	hooks	mcp	Notes
claude-flow-v2	✓	anthropic	✓	✓	Stable, 158+ aliases
claude-flow-v3	✓	anthropic	✓	✓	Alpha, 10x performance, 15 tools
agentic-qe	✓	anthropic	✓	✓	AI-powered testing
spec-kit	✓	none	✓	-	GitHub spec documentation
agentic-flow	✓	anthropic	✓	✓	Multi-agent workflows

Script Guidelines

All scripts must:

1. Start with #!/usr/bin/env bash
2. Include set -euo pipefail
3. Exit 0 on success, non-zero on failure
4. Use $HOME, $WORKSPACE environment variables
5. Log progress with echo statements

Example:

#!/usr/bin/env bash
set -euo pipefail

echo "Installing my-tool..."
# Installation commands here
echo "my-tool installed successfully"

Troubleshooting

Issue	Solution
Schema validation fails	Check YAML syntax, verify required fields
Dependencies not found	Add missing extensions to registry.yaml
Install times out	Increase timeout in script section
Validation fails	Check expectedPattern regex escaping
Permission denied	Scripts must be executable

---

Post-Extension Documentation Checklist

CRITICAL: After creating or modifying an extension, you MUST complete these documentation updates:

Required Updates (Always Do These)

• Registry Entry - Add to v2/docker/lib/registry.yaml

  extensions:
    my-extension:
      category: dev-tools
      description: Short description
      dependencies: []
  

• Extension Documentation - Create docs/extensions/{NAME}.md

  • Use UPPERCASE for filename (e.g., NODEJS.md, AI-TOOLKIT.md)
  • Include: overview, installation, configuration, usage examples
  • For VisionFlow: docs/extensions/vision-flow/VF-{NAME}.md

• Extension Catalog - Update v2/docs/EXTENSIONS.md

  • Add to appropriate category table
  • Include link to extension doc

Conditional Updates (When Applicable)

• Profiles - If adding extension to profiles:

  • Update v2/docker/lib/profiles.yaml
  • Update relevant profile descriptions in v2/docs/EXTENSIONS.md

• Categories - If adding new category:

  • Update v2/docker/lib/categories.yaml
  • Update v2/docker/lib/schemas/extension.schema.json (category enum)
  • Update category docs in v2/docs/EXTENSIONS.md

• Schema - If adding new extension fields:

  • Update v2/docker/lib/schemas/extension.schema.json
  • Update docs/SCHEMA.md
  • Update REFERENCE.md in this skill

• Slides - If extension is notable/featured:

  • Update docs/slides/extensions.html

VisionFlow-Specific Updates

• Update docs/extensions/vision-flow/README.md
• Update docs/extensions/vision-flow/CAPABILITY-CATALOG.md
• Update VisionFlow profile if applicable

Validation After Updates

# Validate YAML files
pnpm validate:yaml

# Lint markdown
pnpm lint:md

# Validate extension
./v2/cli/extension-manager validate {name}

---

Extension Documentation Template

When creating docs/extensions/{NAME}.md, use this template:

# {Extension Name}

{Brief description of what the extension provides.}

## Overview

{More detailed explanation of the extension's purpose and capabilities.}

## Installation

\`\`\`bash
extension-manager install {name}
\`\`\`

## What Gets Installed

- {Tool 1} - {purpose}
- {Tool 2} - {purpose}

## Configuration

{Any configuration options or environment variables.}

## Usage

{Usage examples.}

## Dependencies

{List any extension dependencies.}

## Requirements

- **Disk Space:** {X} MB
- **Network:** {domains accessed}
- **Secrets:** {optional secrets}

## Related Extensions

- {Related extension 1}
- {Related extension 2}

---

Reference Files

• Schema: v2/docker/lib/schemas/extension.schema.json
• Registry: v2/docker/lib/registry.yaml
• Categories: v2/docker/lib/categories.yaml
• Profiles: v2/docker/lib/profiles.yaml
• Examples: v2/docker/lib/extensions/*/extension.yaml

For detailed field reference, see REFERENCE.md. For complete examples, see EXAMPLES.md.

Tip: Use Glob and Grep tools to discover current documentation files dynamically:

# Find all extension docs
ls docs/extensions/*.md

# Find VisionFlow docs
ls docs/extensions/vision-flow/*.md