Core Pattern Finder

Search Drupal core for implementation patterns and return file references.

Activation

Activate when you detect:

• “How does core do X?”
• “Find core example of X”
• “Show me core’s implementation of X”
• Need a reference implementation for a Drupal pattern

Quick Reference

Check these common patterns first before searching:

Forms

Entities

Services

Plugins

Controllers

Workflow

1. Check Quick Reference

If pattern matches table above, return that path immediately.

2. Search Core

If not in quick reference, search using these strategies:

For class/interface patterns:

Use Grep with pattern: "class {PatternName}" or "interface {PatternName}"
Path: core/

For specific implementations:

Use Grep with pattern: "extends {BaseClass}" or "implements {Interface}"
Path: core/modules/

For service patterns:

Use Glob with pattern: core/modules/*/src/*Manager.php
or: core/lib/Drupal/Core/*/*.php

3. Read and Extract Key Sections

Once file found, use Read tool and identify:

• Key methods to study
• Relevant line numbers
• Dependencies injected

4. Return Structured Response

Format your response as:

## Core Pattern: {Pattern Name}

### Primary Example
`{file_path}`

**Key methods:**
- `{method1}()` (line {X}): {what it does}
- `{method2}()` (line {Y}): {what it does}

**Dependencies:**
- {service_name}: {purpose}

### Additional Examples
- `{path2}` - {variation description}
- `{path3}` - {variation description}

### Usage Notes
{Any gotchas or important considerations}

Stop Points

STOP and ask user:

• If pattern is ambiguous (multiple interpretations)
• If no matching pattern found in core
• Before reading more than 3 files (ask which to prioritize)