Plugin Settings

What this skill does

# Plugin Settings Pattern for Claude Code Plugins

## Overview

Plugins can store user-configurable settings and state in `.claude/plugin-name.local.md` files within the project directory. This pattern uses YAML frontmatter for structured configuration and markdown content for prompts or additional context.

**Key characteristics:**
- File location: `.claude/plugin-name.local.md` in project root
- Structure: YAML frontmatter + markdown body
- Purpose: Per-project plugin configuration and state
- Usage: Read from hooks, commands, and agents
- Lifecycle: User-managed (not in git, should be in `.gitignore`)

## File Structure

### Basic Template

```markdown
---
enabled: true
setting1: value1
setting2: value2
numeric_setting: 42
list_setting: ["item1", "item2"]
---

# Additional Context

This markdown body can contain:
- Task descriptions
- Additional instructions
- Prompts to feed back to Claude
- Documentation or notes
```

### Example: Plugin State File

**.claude/my-plugin.local.md:**
```markdown
---
enabled: true
strict_mode: false
max_retries: 3
notification_level: info
coordinator_session: team-leader
---

# Plugin Configuration

This plugin is configured for standard validation mode.
Contact @team-lead with questions.
```

## Reading Settings Files

### From Hooks (Bash Scripts)

**Pattern: Check existence and parse frontmatter**

```bash
#!/bin/bash
set -euo pipefail

# Define state file path
STATE_FILE=".claude/my-plugin.local.md"

# Quick exit if file doesn't exist
if [[ ! -f "$STATE_FILE" ]]; then
  exit 0  # Plugin not configured, skip
fi

# Parse YAML frontmatter (between --- markers)
FRONTMATTER=$(sed -n '/^---$/,/^---$/{ /^---$/d; p; }' "$STATE_FILE")

# Extract individual fields
ENABLED=$(echo "$FRONTMATTER" | grep '^enabled:' | sed 's/enabled: *//' | sed 's/^"\(.*\)"$/\1/')
STRICT_MODE=$(echo "$FRONTMATTER" | grep '^strict_mode:' | sed 's/strict_mode: *//' | sed 's/^"\(.*\)"$/\1/')

# Check if enabled
if [[ "$ENABLED" != "true" ]]; then
  exit 0  # Disabled
fi

# Use configuration in hook logic
if [[ "$STRICT_MODE" == "true" ]]; then
  # Apply strict validation
  # ...
fi
```

See `examples/read-settings-hook.sh` for complete working example.

### From Commands

Commands can read settings files to customize behavior:

```markdown
---
description: Process data with plugin
allowed-tools: ["Read", "Bash"]
---

# Process Command

Steps:
1. Check if settings exist at `.claude/my-plugin.local.md`
2. Read configuration using Read tool
3. Parse YAML frontmatter to extract settings
4. Apply settings to processing logic
5. Execute with configured behavior
```

### From Agents

Agents can reference settings in their instructions:

```markdown
---
name: configured-agent
description: Agent that adapts to project settings
---

Check for plugin settings at `.claude/my-plugin.local.md`.
If present, parse YAML frontmatter and adapt behavior according to:
- enabled: Whether plugin is active
- mode: Processing mode (strict, standard, lenient)
- Additional configuration fields
```

## Parsing Techniques

### Extract Frontmatter

```bash
# Extract everything between --- markers
FRONTMATTER=$(sed -n '/^---$/,/^---$/{ /^---$/d; p; }' "$FILE")
```

### Read Individual Fields

**String fields:**
```bash
VALUE=$(echo "$FRONTMATTER" | grep '^field_name:' | sed 's/field_name: *//' | sed 's/^"\(.*\)"$/\1/')
```

**Boolean fields:**
```bash
ENABLED=$(echo "$FRONTMATTER" | grep '^enabled:' | sed 's/enabled: *//')
# Compare: if [[ "$ENABLED" == "true" ]]; then
```

**Numeric fields:**
```bash
MAX=$(echo "$FRONTMATTER" | grep '^max_value:' | sed 's/max_value: *//')
# Use: if [[ $MAX -gt 100 ]]; then
```

### Read Markdown Body

Extract content after second `---`:

```bash
# Get everything after closing ---
BODY=$(awk '/^---$/{i++; next} i>=2' "$FILE")
```

## Common Patterns

### Pattern 1: Temporarily Active Hooks

Use settings file to control hook activation:

```bash
#!/bin/bash
STATE_FILE=".claude/security-scan.local.md"

# Quick exit if not configured
if [[ ! -f "$STATE_FILE" ]]; then
  exit 0
fi

# Read enabled flag
FRONTMATTER=$(sed -n '/^---$/,/^---$/{ /^---$/d; p; }' "$STATE_FILE")
ENABLED=$(echo "$FRONTMATTER" | grep '^enabled:' | sed 's/enabled: *//')

if [[ "$ENABLED" != "true" ]]; then
  exit 0  # Disabled
fi

# Run hook logic
# ...
```

**Use case:** Enable/disable hooks without editing hooks.json (requires restart).

### Pattern 2: Agent State Management

Store agent-specific state and configuration:

**.claude/multi-agent-swarm.local.md:**
```markdown
---
agent_name: auth-agent
task_number: 3.5
pr_number: 1234
coordinator_session: team-leader
enabled: true
dependencies: ["Task 3.4"]
---

# Task Assignment

Implement JWT authentication for the API.

**Success Criteria:**
- Authentication endpoints created
- Tests passing
- PR created and CI green
```

Read from hooks to coordinate agents:

```bash
AGENT_NAME=$(echo "$FRONTMATTER" | grep '^agent_name:' | sed 's/agent_name: *//')
COORDINATOR=$(echo "$FRONTMATTER" | grep '^coordinator_session:' | sed 's/coordinator_session: *//')

# Send notification to coordinator
tmux send-keys -t "$COORDINATOR" "Agent $AGENT_NAME completed task" Enter
```

### Pattern 3: Configuration-Driven Behavior

**.claude/my-plugin.local.md:**
```markdown
---
validation_level: strict
max_file_size: 1000000
allowed_extensions: [".js", ".ts", ".tsx"]
enable_logging: true
---

# Validation Configuration

Strict mode enabled for this project.
All writes validated against security policies.
```

Use in hooks or commands:

```bash
LEVEL=$(echo "$FRONTMATTER" | grep '^validation_level:' | sed 's/validation_level: *//')

case "$LEVEL" in
  strict)
    # Apply strict validation
    ;;
  standard)
    # Apply standard validation
    ;;
  lenient)
    # Apply lenient validation
    ;;
esac
```

## Creating Settings Files

### From Commands

Commands can create settings files:

```markdown
# Setup Command

Steps:
1. Ask user for configuration preferences
2. Create `.claude/my-plugin.local.md` with YAML frontmatter
3. Set appropriate values based on user input
4. Inform user that settings are saved
5. Remind user to restart Claude Code for hooks to recognize changes
```

### Template Generation

Provide template in plugin README:

```markdown
## Configuration

Create `.claude/my-plugin.local.md` in your project:

\`\`\`markdown
---
enabled: true
mode: standard
max_retries: 3
---

# Plugin Configuration

Your settings are active.
\`\`\`

After creating or editing, restart Claude Code for changes to take effect.
```

## Best Practices

### File Naming

✅ **DO:**
- Use `.claude/plugin-name.local.md` format
- Match plugin name exactly
- Use `.local.md` suffix for user-local files

❌ **DON'T:**
- Use different directory (not `.claude/`)
- Use inconsistent naming
- Use `.md` without `.local` (might be committed)

### Gitignore

Always add to `.gitignore`:

```gitignore
.claude/*.local.md
.claude/*.local.json
```

Document this in plugin README.

### Defaults

Provide sensible defaults when settings file doesn't exist:

```bash
if [[ ! -f "$STATE_FILE" ]]; then
  # Use defaults
  ENABLED=true
  MODE=standard
else
  # Read from file
  # ...
fi
```

### Validation

Validate settings values:

```bash
MAX=$(echo "$FRONTMATTER" | grep '^max_value:' | sed 's/max_value: *//')

# Validate numeric range
if ! [[ "$MAX" =~ ^[0-9]+$ ]] || [[ $MAX -lt 1 ]] || [[ $MAX -gt 100 ]]; then
  echo "⚠️  Invalid max_value in settings (must be 1-100)" >&2
  MAX=10  # Use default
fi
```

### Restart Requirement

**Important:** Settings changes require Claude Code restart.

Document in your README:

```markdown
## Changing Settings

After editing `.claude/my-plugin.local.md`:
1. Save the file
2. Exit Claude Code
3. Restart: `claude` or `cc`
4. New settings will be loaded
```

Hooks cannot be hot-swapped within a session.

## Security Considerations

### Sanitize User Input

When writing settings files from user input:

```bash
# Escape quotes in user input
SAFE_VALUE=$(ec