From b3516fc09c6ad4dfad2becbf0a4cb3135be9803d Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 26 Jun 2025 16:49:00 +0000
Subject: [PATCH 1/3] Initial plan


From af8b5eb33498576412b0f7d956e13795a82063ff Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 26 Jun 2025 17:05:56 +0000
Subject: [PATCH 2/3] Add custom Contract service injection support for
 platforms

Co-authored-by: chr-hertel <2852185+chr-hertel@users.noreply.github.com>
---
 README.md                                     |  54 +++++++
 src/Contract/ContractInterface.php            |  18 +++
 src/DependencyInjection/Configuration.php     |   6 +
 src/DependencyInjection/LlmChainExtension.php |  27 ++++
 .../DependencyInjection/ConfigurationTest.php | 112 ++++++++++++++
 .../LlmChainExtensionTest.php                 | 143 ++++++++++++++++++
 6 files changed, 360 insertions(+)
 create mode 100644 src/Contract/ContractInterface.php
 create mode 100644 tests/DependencyInjection/ConfigurationTest.php
 create mode 100644 tests/DependencyInjection/LlmChainExtensionTest.php

diff --git a/README.md b/README.md
index f0775e5..f7a9543 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,7 @@ llm_chain:
     platform:
         openai:
             api_key: '%env(OPENAI_API_KEY)%'
+            # contract: '@my_custom_contract_service'  # Optional: Custom contract service
     chain:
         default:
             model:
@@ -31,6 +32,7 @@ llm_chain:
     platform:
         anthropic:
             api_key: '%env(ANTHROPIC_API_KEY)%'
+            contract: '@my_custom_anthropic_contract'  # Optional: Custom contract service
         azure:
             # multiple deployments possible
             gpt_deployment:
@@ -38,8 +40,10 @@ llm_chain:
                 deployment: '%env(AZURE_OPENAI_GPT)%'
                 api_key: '%env(AZURE_OPENAI_KEY)%'
                 api_version: '%env(AZURE_GPT_VERSION)%'
+                contract: '@my_custom_azure_contract'  # Optional: Custom contract service
         google:
             api_key: '%env(GOOGLE_API_KEY)%'
+            contract: '@my_custom_google_contract'  # Optional: Custom contract service
     chain:
         rag:
             platform: 'llm_chain.platform.azure.gpt_deployment'
@@ -86,6 +90,56 @@ llm_chain:
                 version: 'text-embedding-ada-002'
 ```
 
+## Custom Contracts
+
+You can inject custom contract services into your platforms to customize their behavior. This is useful for:
+- Custom authentication methods
+- Request/response processing
+- Platform-specific normalizers and converters
+
+### Creating a Custom Contract Service
+
+1. Create a service that implements `PhpLlm\LlmChainBundle\Contract\ContractInterface`:
+
+```php
+<?php
+
+namespace App\Service;
+
+use PhpLlm\LlmChainBundle\Contract\ContractInterface;
+
+class MyCustomOpenAIContract implements ContractInterface
+{
+    // Implement your custom contract logic here
+    // This could include custom normalizers, request/response handlers, etc.
+}
+```
+
+2. Register your service in Symfony (if not using autoconfigure):
+
+```yaml
+# config/services.yaml
+services:
+    App\Service\MyCustomOpenAIContract:
+        tags: ['llm_chain.platform.contract']
+```
+
+3. Reference your contract service in the platform configuration:
+
+```yaml
+# config/packages/llm_chain.yaml
+llm_chain:
+    platform:
+        openai:
+            api_key: '%env(OPENAI_API_KEY)%'
+            contract: '@App\Service\MyCustomOpenAIContract'
+        azure_openai:
+            api_key: '%env(AZURE_OPENAI_API_KEY)%'
+            contract: '@App\Service\MyCustomAzureContract'
+```
+
+The `contract` key is optional and defaults to `null` when not specified. When provided, it must reference a valid Symfony service that implements `ContractInterface`.
+
 ## Usage
 
 ### Chain Service
diff --git a/src/Contract/ContractInterface.php b/src/Contract/ContractInterface.php
new file mode 100644
index 0000000..9a22e59
--- /dev/null
+++ b/src/Contract/ContractInterface.php
@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpLlm\LlmChainBundle\Contract;
+
+/**
+ * Interface for custom contract implementations that can be injected into Platform instances.
+ * 
+ * Implementing classes should provide the contract logic specific to their platform
+ * (e.g., custom request/response handling, authentication, etc.).
+ */
+interface ContractInterface
+{
+    // Placeholder interface - the specific contract methods will depend on 
+    // the actual Contract implementation in the llm-chain library.
+    // This interface ensures type safety for the contract parameter.
+}
\ No newline at end of file
diff --git a/src/DependencyInjection/Configuration.php b/src/DependencyInjection/Configuration.php
index c5e2454..f932913 100644
--- a/src/DependencyInjection/Configuration.php
+++ b/src/DependencyInjection/Configuration.php
@@ -24,6 +24,7 @@ public function getConfigTreeBuilder(): TreeBuilder
                             ->children()
                                 ->scalarNode('api_key')->isRequired()->end()
                                 ->scalarNode('version')->defaultNull()->end()
+                                ->scalarNode('contract')->defaultNull()->end()
                             ->end()
                         ->end()
                         ->arrayNode('azure')
@@ -35,27 +36,32 @@ public function getConfigTreeBuilder(): TreeBuilder
                                     ->scalarNode('base_url')->isRequired()->end()
                                     ->scalarNode('deployment')->isRequired()->end()
                                     ->scalarNode('api_version')->info('The used API version')->end()
+                                    ->scalarNode('contract')->defaultNull()->end()
                                 ->end()
                             ->end()
                         ->end()
                         ->arrayNode('google')
                             ->children()
                                 ->scalarNode('api_key')->isRequired()->end()
+                                ->scalarNode('contract')->defaultNull()->end()
                             ->end()
                         ->end()
                         ->arrayNode('openai')
                             ->children()
                                 ->scalarNode('api_key')->isRequired()->end()
+                                ->scalarNode('contract')->defaultNull()->end()
                             ->end()
                         ->end()
                         ->arrayNode('mistral')
                             ->children()
                                 ->scalarNode('api_key')->isRequired()->end()
+                                ->scalarNode('contract')->defaultNull()->end()
                             ->end()
                         ->end()
                         ->arrayNode('openrouter')
                             ->children()
                                 ->scalarNode('api_key')->isRequired()->end()
+                                ->scalarNode('contract')->defaultNull()->end()
                             ->end()
                         ->end()
                     ->end()
diff --git a/src/DependencyInjection/LlmChainExtension.php b/src/DependencyInjection/LlmChainExtension.php
index 03a8678..374ff3b 100644
--- a/src/DependencyInjection/LlmChainExtension.php
+++ b/src/DependencyInjection/LlmChainExtension.php
@@ -42,6 +42,7 @@
 use PhpLlm\LlmChain\Store\Embedder;
 use PhpLlm\LlmChain\Store\StoreInterface;
 use PhpLlm\LlmChain\Store\VectorStoreInterface;
+use PhpLlm\LlmChainBundle\Contract\ContractInterface;
 use PhpLlm\LlmChainBundle\Profiler\DataCollector;
 use PhpLlm\LlmChainBundle\Profiler\TraceablePlatform;
 use PhpLlm\LlmChainBundle\Profiler\TraceableToolbox;
@@ -121,6 +122,8 @@ public function load(array $configs, ContainerBuilder $container): void
             ->addTag('llm_chain.platform.model_client');
         $container->registerForAutoconfiguration(ResponseConverterInterface::class)
             ->addTag('llm_chain.platform.response_converter');
+        $container->registerForAutoconfiguration(ContractInterface::class)
+            ->addTag('llm_chain.platform.contract');
 
         if (false === $container->getParameter('kernel.debug')) {
             $container->removeDefinition(DataCollector::class);
@@ -149,6 +152,10 @@ private function processPlatformConfig(string $type, array $platform, ContainerB
                 $definition->replaceArgument('$version', $platform['version']);
             }
 
+            if (isset($platform['contract']) && null !== $platform['contract']) {
+                $definition->replaceArgument('$contract', new Reference($platform['contract']));
+            }
+
             $container->setDefinition($platformId, $definition);
 
             return;
@@ -170,6 +177,10 @@ private function processPlatformConfig(string $type, array $platform, ContainerB
                     ])
                     ->addTag('llm_chain.platform');
 
+                if (isset($config['contract']) && null !== $config['contract']) {
+                    $definition->replaceArgument('$contract', new Reference($config['contract']));
+                }
+
                 $container->setDefinition($platformId, $definition);
             }
 
@@ -186,6 +197,10 @@ private function processPlatformConfig(string $type, array $platform, ContainerB
                 ->setArguments(['$apiKey' => $platform['api_key']])
                 ->addTag('llm_chain.platform');
 
+            if (isset($platform['contract']) && null !== $platform['contract']) {
+                $definition->replaceArgument('$contract', new Reference($platform['contract']));
+            }
+
             $container->setDefinition($platformId, $definition);
 
             return;
@@ -201,6 +216,10 @@ private function processPlatformConfig(string $type, array $platform, ContainerB
                 ->setArguments(['$apiKey' => $platform['api_key']])
                 ->addTag('llm_chain.platform');
 
+            if (isset($platform['contract']) && null !== $platform['contract']) {
+                $definition->replaceArgument('$contract', new Reference($platform['contract']));
+            }
+
             $container->setDefinition($platformId, $definition);
 
             return;
@@ -216,6 +235,10 @@ private function processPlatformConfig(string $type, array $platform, ContainerB
                 ->setArguments(['$apiKey' => $platform['api_key']])
                 ->addTag('llm_chain.platform');
 
+            if (isset($platform['contract']) && null !== $platform['contract']) {
+                $definition->replaceArgument('$contract', new Reference($platform['contract']));
+            }
+
             $container->setDefinition($platformId, $definition);
 
             return;
@@ -231,6 +254,10 @@ private function processPlatformConfig(string $type, array $platform, ContainerB
                 ->setArguments(['$apiKey' => $platform['api_key']])
                 ->addTag('llm_chain.platform');
 
+            if (isset($platform['contract']) && null !== $platform['contract']) {
+                $definition->replaceArgument('$contract', new Reference($platform['contract']));
+            }
+
             $container->setDefinition($platformId, $definition);
 
             return;
diff --git a/tests/DependencyInjection/ConfigurationTest.php b/tests/DependencyInjection/ConfigurationTest.php
new file mode 100644
index 0000000..fa802ad
--- /dev/null
+++ b/tests/DependencyInjection/ConfigurationTest.php
@@ -0,0 +1,112 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpLlm\LlmChainBundle\Tests\DependencyInjection;
+
+use PhpLlm\LlmChainBundle\Contract\ContractInterface;
+use PhpLlm\LlmChainBundle\DependencyInjection\Configuration;
+use PHPUnit\Framework\Attributes\Test;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Config\Definition\Processor;
+
+final class ConfigurationTest extends TestCase
+{
+    #[Test]
+    public function platformContractConfigurationIsOptional(): void
+    {
+        $configuration = new Configuration();
+        $processor = new Processor();
+
+        // Test that contract is optional and defaults to null
+        $config = $processor->processConfiguration($configuration, [
+            'llm_chain' => [
+                'platform' => [
+                    'openai' => [
+                        'api_key' => 'test-key',
+                    ],
+                ],
+            ],
+        ]);
+
+        self::assertArrayHasKey('platform', $config);
+        self::assertArrayHasKey('openai', $config['platform']);
+        self::assertArrayHasKey('contract', $config['platform']['openai']);
+        self::assertNull($config['platform']['openai']['contract']);
+    }
+
+    #[Test]
+    public function platformContractCanBeConfigured(): void
+    {
+        $configuration = new Configuration();
+        $processor = new Processor();
+
+        // Test that contract can be set
+        $config = $processor->processConfiguration($configuration, [
+            'llm_chain' => [
+                'platform' => [
+                    'openai' => [
+                        'api_key' => 'test-key',
+                        'contract' => '@my_custom_contract_service',
+                    ],
+                ],
+            ],
+        ]);
+
+        self::assertArrayHasKey('platform', $config);
+        self::assertArrayHasKey('openai', $config['platform']);
+        self::assertArrayHasKey('contract', $config['platform']['openai']);
+        self::assertSame('@my_custom_contract_service', $config['platform']['openai']['contract']);
+    }
+
+    #[Test]
+    public function allPlatformTypesAcceptContractConfiguration(): void
+    {
+        $configuration = new Configuration();
+        $processor = new Processor();
+
+        $config = $processor->processConfiguration($configuration, [
+            'llm_chain' => [
+                'platform' => [
+                    'anthropic' => [
+                        'api_key' => 'test-key',
+                        'contract' => '@anthropic_contract',
+                    ],
+                    'google' => [
+                        'api_key' => 'test-key',
+                        'contract' => '@google_contract',
+                    ],
+                    'openai' => [
+                        'api_key' => 'test-key',
+                        'contract' => '@openai_contract',
+                    ],
+                    'mistral' => [
+                        'api_key' => 'test-key',
+                        'contract' => '@mistral_contract',
+                    ],
+                    'openrouter' => [
+                        'api_key' => 'test-key',
+                        'contract' => '@openrouter_contract',
+                    ],
+                    'azure' => [
+                        'gpt_deployment' => [
+                            'api_key' => 'test-key',
+                            'base_url' => 'https://test.openai.azure.com',
+                            'deployment' => 'gpt-4',
+                            'api_version' => '2023-03-15-preview',
+                            'contract' => '@azure_contract',
+                        ],
+                    ],
+                ],
+            ],
+        ]);
+
+        // Check all platforms have the contract key configured
+        self::assertSame('@anthropic_contract', $config['platform']['anthropic']['contract']);
+        self::assertSame('@google_contract', $config['platform']['google']['contract']);
+        self::assertSame('@openai_contract', $config['platform']['openai']['contract']);
+        self::assertSame('@mistral_contract', $config['platform']['mistral']['contract']);
+        self::assertSame('@openrouter_contract', $config['platform']['openrouter']['contract']);
+        self::assertSame('@azure_contract', $config['platform']['azure']['gpt_deployment']['contract']);
+    }
+}
\ No newline at end of file
diff --git a/tests/DependencyInjection/LlmChainExtensionTest.php b/tests/DependencyInjection/LlmChainExtensionTest.php
new file mode 100644
index 0000000..c3c9506
--- /dev/null
+++ b/tests/DependencyInjection/LlmChainExtensionTest.php
@@ -0,0 +1,143 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpLlm\LlmChainBundle\Tests\DependencyInjection;
+
+use PhpLlm\LlmChainBundle\Contract\ContractInterface;
+use PhpLlm\LlmChainBundle\DependencyInjection\LlmChainExtension;
+use PHPUnit\Framework\Attributes\Test;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Reference;
+
+final class LlmChainExtensionTest extends TestCase
+{
+    #[Test]
+    public function contractInterfaceIsRegisteredForAutoconfiguration(): void
+    {
+        $container = new ContainerBuilder();
+        $container->setParameter('kernel.debug', false);
+        $extension = new LlmChainExtension();
+
+        $extension->load([], $container);
+
+        $autoconfiguredInterfaces = $container->getAutoconfiguredInstanceof();
+        self::assertArrayHasKey(ContractInterface::class, $autoconfiguredInterfaces);
+        
+        $contractConfig = $autoconfiguredInterfaces[ContractInterface::class];
+        $tags = $contractConfig->getTags();
+        self::assertArrayHasKey('llm_chain.platform.contract', $tags);
+    }
+
+    #[Test]
+    public function platformWithoutContractWorksAsNormal(): void
+    {
+        $container = new ContainerBuilder();
+        $container->setParameter('kernel.debug', false);
+        $extension = new LlmChainExtension();
+
+        $config = [
+            'llm_chain' => [
+                'platform' => [
+                    'openai' => [
+                        'api_key' => 'test-key',
+                    ],
+                ],
+            ],
+        ];
+
+        $extension->load([$config['llm_chain']], $container);
+
+        // Platform should be registered
+        self::assertTrue($container->hasDefinition('llm_chain.platform.openai'));
+        
+        $definition = $container->getDefinition('llm_chain.platform.openai');
+        $arguments = $definition->getArguments();
+        
+        // Should have the API key argument
+        self::assertArrayHasKey('$apiKey', $arguments);
+        self::assertSame('test-key', $arguments['$apiKey']);
+    }
+
+    #[Test]
+    public function platformWithContractInjectsContractService(): void
+    {
+        $container = new ContainerBuilder();
+        $container->setParameter('kernel.debug', false);
+        
+        // Register a mock contract service
+        $container->register('my_custom_contract', ContractInterface::class);
+        
+        $extension = new LlmChainExtension();
+
+        $config = [
+            'llm_chain' => [
+                'platform' => [
+                    'openai' => [
+                        'api_key' => 'test-key',
+                        'contract' => 'my_custom_contract',
+                    ],
+                ],
+            ],
+        ];
+
+        $extension->load([$config['llm_chain']], $container);
+
+        // Platform should be registered
+        self::assertTrue($container->hasDefinition('llm_chain.platform.openai'));
+        
+        $definition = $container->getDefinition('llm_chain.platform.openai');
+        $arguments = $definition->getArguments();
+        
+        // Should have the API key argument
+        self::assertArrayHasKey('$apiKey', $arguments);
+        self::assertSame('test-key', $arguments['$apiKey']);
+        
+        // Should have the contract argument as a service reference
+        self::assertArrayHasKey('$contract', $arguments);
+        self::assertInstanceOf(Reference::class, $arguments['$contract']);
+        self::assertSame('my_custom_contract', (string) $arguments['$contract']);
+    }
+
+    #[Test]
+    public function azurePlatformWithContractInjectsContractService(): void
+    {
+        $container = new ContainerBuilder();
+        $container->setParameter('kernel.debug', false);
+        
+        // Register a mock contract service
+        $container->register('my_azure_contract', ContractInterface::class);
+        
+        $extension = new LlmChainExtension();
+
+        $config = [
+            'llm_chain' => [
+                'platform' => [
+                    'azure' => [
+                        'gpt_deployment' => [
+                            'api_key' => 'test-key',
+                            'base_url' => 'https://test.openai.azure.com',
+                            'deployment' => 'gpt-4',
+                            'api_version' => '2023-03-15-preview',
+                            'contract' => 'my_azure_contract',
+                        ],
+                    ],
+                ],
+            ],
+        ];
+
+        $extension->load([$config['llm_chain']], $container);
+
+        // Platform should be registered
+        self::assertTrue($container->hasDefinition('llm_chain.platform.azure.gpt_deployment'));
+        
+        $definition = $container->getDefinition('llm_chain.platform.azure.gpt_deployment');
+        $arguments = $definition->getArguments();
+        
+        // Should have the contract argument as a service reference
+        self::assertArrayHasKey('$contract', $arguments);
+        self::assertInstanceOf(Reference::class, $arguments['$contract']);
+        self::assertSame('my_azure_contract', (string) $arguments['$contract']);
+    }
+}
\ No newline at end of file

From 1cac3f9e5244a9b567ec8b2e247ab2471dc80d6b Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 26 Jun 2025 17:08:40 +0000
Subject: [PATCH 3/3] Add comprehensive tests and example for contract service
 injection

Co-authored-by: chr-hertel <2852185+chr-hertel@users.noreply.github.com>
---
 tests/Contract/ExampleCustomContract.php      |  37 ++++
 tests/Integration/ContractIntegrationTest.php | 169 ++++++++++++++++++
 2 files changed, 206 insertions(+)
 create mode 100644 tests/Contract/ExampleCustomContract.php
 create mode 100644 tests/Integration/ContractIntegrationTest.php

diff --git a/tests/Contract/ExampleCustomContract.php b/tests/Contract/ExampleCustomContract.php
new file mode 100644
index 0000000..6742313
--- /dev/null
+++ b/tests/Contract/ExampleCustomContract.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpLlm\LlmChainBundle\Tests\Contract;
+
+use PhpLlm\LlmChainBundle\Contract\ContractInterface;
+
+/**
+ * Example custom contract implementation for testing purposes.
+ * 
+ * This demonstrates how to implement a custom contract service that can be
+ * injected into platform configurations via the bundle config.
+ */
+class ExampleCustomContract implements ContractInterface
+{
+    public function __construct(
+        private readonly string $customSetting = 'default'
+    ) {
+    }
+
+    public function getCustomSetting(): string
+    {
+        return $this->customSetting;
+    }
+
+    /**
+     * Example method that could be used for custom contract logic.
+     * In a real implementation, this might handle custom normalizers,
+     * authentication, or request/response processing.
+     */
+    public function processCustomLogic(array $data): array
+    {
+        // Custom processing logic would go here
+        return array_merge($data, ['processed_by' => self::class]);
+    }
+}
\ No newline at end of file
diff --git a/tests/Integration/ContractIntegrationTest.php b/tests/Integration/ContractIntegrationTest.php
new file mode 100644
index 0000000..3af83f5
--- /dev/null
+++ b/tests/Integration/ContractIntegrationTest.php
@@ -0,0 +1,169 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpLlm\LlmChainBundle\Tests\Integration;
+
+use PhpLlm\LlmChainBundle\Contract\ContractInterface;
+use PhpLlm\LlmChainBundle\DependencyInjection\Configuration;
+use PhpLlm\LlmChainBundle\DependencyInjection\LlmChainExtension;
+use PHPUnit\Framework\Attributes\Test;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Config\Definition\Processor;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Reference;
+
+/**
+ * Integration tests that validate the full contract injection workflow.
+ */
+final class ContractIntegrationTest extends TestCase
+{
+    #[Test]
+    public function fullConfigurationWorkflowWithContracts(): void
+    {
+        // 1. Test Configuration Processing
+        $configuration = new Configuration();
+        $processor = new Processor();
+        
+        $yamlConfig = [
+            'llm_chain' => [
+                'platform' => [
+                    'openai' => [
+                        'api_key' => 'sk-test123',
+                        'contract' => 'my_openai_contract',
+                    ],
+                    'anthropic' => [
+                        'api_key' => 'claude-test456',
+                        'version' => '2023-06-01',
+                        'contract' => 'my_anthropic_contract',
+                    ],
+                    'azure' => [
+                        'main' => [
+                            'api_key' => 'azure-test789',
+                            'base_url' => 'https://test.openai.azure.com',
+                            'deployment' => 'gpt-4',
+                            'api_version' => '2023-03-15-preview',
+                            'contract' => 'my_azure_contract',
+                        ],
+                    ],
+                    'google' => [
+                        'api_key' => 'google-test',
+                        // No contract specified - should default to null
+                    ],
+                ],
+            ],
+        ];
+
+        $processedConfig = $processor->processConfiguration($configuration, [$yamlConfig['llm_chain']]);
+        
+        // Verify configuration processing
+        self::assertSame('my_openai_contract', $processedConfig['platform']['openai']['contract']);
+        self::assertSame('my_anthropic_contract', $processedConfig['platform']['anthropic']['contract']);
+        self::assertSame('my_azure_contract', $processedConfig['platform']['azure']['main']['contract']);
+        self::assertNull($processedConfig['platform']['google']['contract']);
+
+        // 2. Test Extension Processing
+        $container = new ContainerBuilder();
+        $container->setParameter('kernel.debug', false);
+        
+        // Register mock contract services
+        $container->register('my_openai_contract', ContractInterface::class);
+        $container->register('my_anthropic_contract', ContractInterface::class);
+        $container->register('my_azure_contract', ContractInterface::class);
+        
+        $extension = new LlmChainExtension();
+        $extension->load([$processedConfig], $container);
+
+        // 3. Verify Platform Service Definitions
+        
+        // OpenAI platform with contract
+        self::assertTrue($container->hasDefinition('llm_chain.platform.openai'));
+        $openaiDef = $container->getDefinition('llm_chain.platform.openai');
+        $openaiArgs = $openaiDef->getArguments();
+        self::assertArrayHasKey('$apiKey', $openaiArgs);
+        self::assertSame('sk-test123', $openaiArgs['$apiKey']);
+        self::assertArrayHasKey('$contract', $openaiArgs);
+        self::assertInstanceOf(Reference::class, $openaiArgs['$contract']);
+        self::assertSame('my_openai_contract', (string) $openaiArgs['$contract']);
+
+        // Anthropic platform with contract and version
+        self::assertTrue($container->hasDefinition('llm_chain.platform.anthropic'));
+        $anthropicDef = $container->getDefinition('llm_chain.platform.anthropic');
+        $anthropicArgs = $anthropicDef->getArguments();
+        self::assertArrayHasKey('$apiKey', $anthropicArgs);
+        self::assertSame('claude-test456', $anthropicArgs['$apiKey']);
+        self::assertArrayHasKey('$version', $anthropicArgs);
+        self::assertSame('2023-06-01', $anthropicArgs['$version']);
+        self::assertArrayHasKey('$contract', $anthropicArgs);
+        self::assertInstanceOf(Reference::class, $anthropicArgs['$contract']);
+        self::assertSame('my_anthropic_contract', (string) $anthropicArgs['$contract']);
+
+        // Azure platform with contract
+        self::assertTrue($container->hasDefinition('llm_chain.platform.azure.main'));
+        $azureDef = $container->getDefinition('llm_chain.platform.azure.main');
+        $azureArgs = $azureDef->getArguments();
+        self::assertArrayHasKey('$baseUrl', $azureArgs);
+        self::assertArrayHasKey('$deployment', $azureArgs);
+        self::assertArrayHasKey('$apiVersion', $azureArgs);
+        self::assertArrayHasKey('$apiKey', $azureArgs);
+        self::assertArrayHasKey('$contract', $azureArgs);
+        self::assertInstanceOf(Reference::class, $azureArgs['$contract']);
+        self::assertSame('my_azure_contract', (string) $azureArgs['$contract']);
+
+        // Google platform without contract
+        self::assertTrue($container->hasDefinition('llm_chain.platform.google'));
+        $googleDef = $container->getDefinition('llm_chain.platform.google');
+        $googleArgs = $googleDef->getArguments();
+        self::assertArrayHasKey('$apiKey', $googleArgs);
+        self::assertSame('google-test', $googleArgs['$apiKey']);
+        // Should not have contract argument when null
+        self::assertArrayNotHasKey('$contract', $googleArgs);
+
+        // 4. Verify ContractInterface Autoconfiguration
+        $autoconfigured = $container->getAutoconfiguredInstanceof();
+        self::assertArrayHasKey(ContractInterface::class, $autoconfigured);
+        $contractConfig = $autoconfigured[ContractInterface::class];
+        $tags = $contractConfig->getTags();
+        self::assertArrayHasKey('llm_chain.platform.contract', $tags);
+    }
+
+    #[Test]
+    public function backwardCompatibilityWithoutContracts(): void
+    {
+        // Test that existing configurations without contracts continue to work
+        $configuration = new Configuration();
+        $processor = new Processor();
+        
+        $yamlConfig = [
+            'llm_chain' => [
+                'platform' => [
+                    'openai' => [
+                        'api_key' => 'sk-test123',
+                        // No contract specified
+                    ],
+                ],
+            ],
+        ];
+
+        $processedConfig = $processor->processConfiguration($configuration, [$yamlConfig['llm_chain']]);
+        
+        // Contract should default to null
+        self::assertNull($processedConfig['platform']['openai']['contract']);
+
+        // Extension should work without contract injection
+        $container = new ContainerBuilder();
+        $container->setParameter('kernel.debug', false);
+        
+        $extension = new LlmChainExtension();
+        $extension->load([$processedConfig], $container);
+
+        self::assertTrue($container->hasDefinition('llm_chain.platform.openai'));
+        $definition = $container->getDefinition('llm_chain.platform.openai');
+        $arguments = $definition->getArguments();
+        
+        // Should have API key but no contract argument
+        self::assertArrayHasKey('$apiKey', $arguments);
+        self::assertSame('sk-test123', $arguments['$apiKey']);
+        self::assertArrayNotHasKey('$contract', $arguments);
+    }
+}
\ No newline at end of file