feat: add Fabric patterns support

[OskarStark]

Summary

This PR implements support for Fabric patterns in LLM Chain, providing access to a comprehensive collection of pre-built, tested system prompts for common AI tasks.

Implementation Details

Core Components

1. Message::fabric() Factory Method

   • Simple API for using Fabric patterns: Message::fabric('create_summary')
   • Supports custom pattern locations
   • Automatically loads patterns from the php-llm/fabric-pattern package

2. FabricInputProcessor

   • Enables dynamic pattern loading via chain options
   • Usage: $chain->call($messages, ['fabric_pattern' => 'analyze_code'])
   • Can be configured with custom pattern repositories

3. FabricRepository

   • Manages pattern loading and caching
   • Validates pattern existence
   • Supports metadata loading (README.md, metadata.json)
   • Checks for php-llm/fabric-pattern package installation

4. Exception Handling

   • Clear error messages when the patterns package is not installed
   • PatternNotFoundException for missing patterns

Design Decisions

1. Separate Package Requirement

   • Fabric patterns are provided by the php-llm/fabric-pattern package
   • Keeps the main library lightweight
   • Users can opt-in to Fabric functionality
   • Clear error messages guide users to install the package

2. Multiple Usage Patterns

   • Factory method for simple, static usage
   • Input processor for dynamic, runtime pattern selection
   • Both approaches support custom pattern locations

3. Immutable Design

   • Follows the library's immutable patterns (e.g., MessageBag)
   • Repository uses internal caching for performance

Usage Examples

Via Factory Method

$messages = new MessageBag(
    Message::fabric('create_summary'),
    Message::ofUser($articleContent)
);
$response = $chain->call($messages);

Via Input Processor

$processor = new FabricInputProcessor();
$chain = new Chain($platform, $model, [$processor]);

$response = $chain->call($messages, ['fabric_pattern' => 'analyze_threat_report']);

Custom Pattern Location

$repository = new FabricRepository('/path/to/custom/patterns');
$processor = new FabricInputProcessor($repository);

Documentation

• Added comprehensive section to README.md
• Created example files in examples/fabric/
• Included PHPDoc comments with usage instructions

Testing

• Full test coverage for all new classes
• Tests handle the case when the patterns package is not installed
• Mock-friendly design (removed final from FabricRepository)

Available Patterns

Some popular patterns include:

• create_summary - Create comprehensive summaries
• analyze_claims - Fact-check and analyze claims
• extract_wisdom - Extract key insights
• improve_writing - Enhance writing quality
• analyze_code - Security and quality analysis

Closes #31

🤖 Generated with Claude Code

[chr-hertel]

Two things I struggle here with:

1. i'm not sure about this options way of using the prompts - I def favor the Message::fabric one over the option
2. i don't think we need the entire repository+prompt classes, since the lib itself provides already the logic to use the markdown files (new Pattern)->load('extract_wisdom')

[OskarStark]

any comments @chr-hertel ?

[chr-hertel]

only minor stuff :) 👍

[OskarStark]

Problem 1
- Root composer.json requires php-llm/fabric-pattern ^0.1 -> satisfiable by php-llm/fabric-pattern[0.1.4.51].
- php-llm/fabric-pattern 0.1.4.51 requires danielmiessler/fabric ^1.4 -> could not be found in any version, there may be a typo in the package name.

lets release a 1.0? 🤷

[chr-hertel]

Oooooh, no, if course ... my trick to install that python thingy doesn't work for transitive dependencies. php-llm/fabric-pattern 0.1.4.51 requires danielmiessler/fabric will always result in an error since that thing is not a real PHP package.

okay, we need a different approach anyways

[chr-hertel]

Let's first bring in a new approach to fabric into symfony/ai and then rebuild this please