Plugin Extension Pattern

Extend marketplace plugins with project-specific context using .local.md files. These files bridge general plugin skills to a specific codebase.

When to Use This Skill

Apply this skill when:

• Installing a marketplace plugin in a project
• A plugin skill is generic but project-specific guidance is needed
• Documenting project-specific file paths, conventions, or workflows that relate to a plugin
• Setting up a new project that uses existing plugins

Key Distinction

.local.md files are agent context (for Claude), not human documentation (like READMEs or guides). Treat them like CLAUDE.md in purpose.

The Pattern

File Location and Naming

.claude/<plugin-name>.local.md

Examples:

• .claude/cc-governance-skills.local.md
• .claude/fvtt-skills.local.md

Structure

---
plugin: <plugin-name>
project: <project-name>
---

# <Plugin Name> - Project-Specific Context

This file extends the `<plugin-name>` plugin with <project>-specific information.

## <Section relevant to plugin's skills>

<Project-specific details>

YAML Frontmatter

What Belongs in Extension Files

DO Include

1. File paths - Where plugin patterns are implemented in this project

   markdownCopy

   | Skill | Implementation Files |
   |-------|---------------------|
   | `fvtt-performance-safe-updates` | `scripts/lib/update-queue.js`, `scripts/hooks.js` |
   

2. Project conventions - How general patterns apply here

   markdownCopy

   ### Actor Types
   - `character` - Player characters
   - `crew` - Crew sheets
   

3. Workflows - Project-specific processes

   markdownCopy

   ### Git Workflow
   - Feature branches → PR to `upstream/rc-1.1.0`
   - Use `--head ImproperSubset:branch-name` for cross-fork PRs
   

4. Build commands - Project-specific tooling

   markdownCopy

   ## Build Commands
   npm run build:css         # Compile SCSS
   npm run lint:css          # Stylelint
   

5. Reminders - Project-specific gotchas related to plugin skills

   markdownCopy

   ### Multi-Client Development
   Every update handler MUST have:
   1. Ownership guard
   2. No-op check
   3. Batched updates
   

DON'T Include

• Content that should be in the plugin itself (general patterns)
• Personal preferences (those stay gitignored in settings.local.json)
• Information unrelated to the plugin's skills

Version Control

Check In (Project Context)

Commit extension files containing project-specific context to the repository. This ensures all contributors using the plugins get the enhanced context.

# .gitignore - DON'T ignore project context
# .claude/*.local.md  <-- Remove this line

Gitignore (Personal Preferences)

Gitignore only personal settings:

# .gitignore
.claude/settings.local.json

Example: Complete Extension File

---
plugin: fvtt-skills
project: my-foundry-module
---

# FVTT Skills - Project-Specific Context

This file extends the `fvtt-skills` plugin with my-foundry-module-specific information.

## File Paths

| Skill | Implementation Files |
|-------|---------------------|
| `fvtt-performance-safe-updates` | `scripts/lib/update-queue.js` |
| `fvtt-version-compat` | `scripts/compat.js` |

## Project Conventions

### Document Types
- `character` - Player characters
- `npc` - Non-player characters

### Flag Namespace
```javascript
actor.getFlag("my-foundry-module", "flagName")

Build Commands

npm run build    # Build module
npm run test     # Run tests

## When NOT to Create Extension Files

- Plugin is used without project-specific customization
- Information belongs in CLAUDE.md (not plugin-specific)
- Content is personal preference (use `settings.local.json`)