[AI Bundle] Restructure system_prompt configuration to nest include_tools

- Move include_tools configuration from agent level to system_prompt level
- Support both simple string format and advanced array format for system_prompt
- Add comprehensive test coverage for new configuration structure
- Update demo configuration to showcase new array format
- Update documentation with clear examples for both formats
- Maintain full backward compatibility with existing string configurations

String format (simple usage):
system_prompt: "You are a helpful assistant."

Array format (advanced usage):
system_prompt:
  prompt: "You are a helpful assistant."
  include_tools: true

Benefits:
- Ergonomic design: simple string for basic use, array for advanced features
- Logical grouping: tool inclusion now grouped with system prompt
- Future extensibility: array format allows for future enhancements
- Clear intent: configuration structure shows prompt-tool relationship

Author: OskarStark

demo/config/packages/ai.yaml

@@ -35,8 +35,9 @@ ai:
                 name: !php/const Symfony\AI\Platform\Bridge\OpenAi\Gpt::GPT_4O_MINI
                 options:
                     temperature: 0.5
-            system_prompt: 'Please answer the users question based on Wikipedia and provide a link to the article.'
-            include_tools: true
+            system_prompt:
+                prompt: 'Please answer the users question based on Wikipedia and provide a link to the article.'
+                include_tools: true
             tools:
                 - 'Symfony\AI\Agent\Toolbox\Tool\Wikipedia'
         audio:

src/ai-bundle/config/options.php

@@ -130,17 +130,48 @@
                             ->end()
                         ->end()
                         ->booleanNode('structured_output')->defaultTrue()->end()
-                        ->scalarNode('system_prompt')
+                        ->variableNode('system_prompt')
                             ->validate()
-                                ->ifTrue(fn ($v) => null !== $v && '' === trim($v))
-                                ->thenInvalid('The default system prompt must not be an empty string')
+                                ->ifTrue(function ($v) {
+                                    // Allow null (no system prompt)
+                                    if (null === $v) {
+                                        return false;
+                                    }
+
+                                    // Allow string (simple usage - just a prompt)
+                                    if (\is_string($v)) {
+                                        return '' === trim($v);
+                                    }
+
+                                    // Allow array with prompt key (advanced usage with include_tools)
+                                    if (\is_array($v)) {
+                                        return !isset($v['prompt']) || (isset($v['prompt']) && '' === trim($v['prompt']));
+                                    }
+
+                                    // Reject other types
+                                    return true;
+                                })
+                                ->thenInvalid('The system prompt must be a string (simple prompt), an array with "prompt" key (advanced configuration), or null. If provided, the prompt text must not be an empty string.')
+                            ->end()
+                            ->beforeNormalization()
+                                ->ifString()
+                                ->then(function (string $v) {
+                                    return ['prompt' => $v, 'include_tools' => false];
+                                })
+                            ->end()
+                            ->beforeNormalization()
+                                ->ifArray()
+                                ->then(function (array $v) {
+                                    // Ensure include_tools defaults to false if not provided
+                                    if (!isset($v['include_tools'])) {
+                                        $v['include_tools'] = false;
+                                    }
+
+                                    return $v;
+                                })
                             ->end()
                             ->defaultNull()
-                            ->info('The default system prompt of the agent')
-                        ->end()
-                        ->booleanNode('include_tools')
-                            ->info('Include tool definitions at the end of the system prompt')
-                            ->defaultFalse()
+                            ->info('The system prompt configuration. Use a string for simple prompts, or an array with "prompt" and "include_tools" keys for advanced configuration.')
                         ->end()
                         ->arrayNode('tools')
                             ->addDefaultsIfNotSet()

src/ai-bundle/doc/index.rst

@@ -71,8 +71,9 @@ Configuration
                 model:
                     class: 'Symfony\AI\Platform\Bridge\OpenAi\Gpt'
                     name: !php/const Symfony\AI\Platform\Bridge\OpenAi\Gpt::GPT_4O_MINI
-                system_prompt: 'You are a helpful assistant that can answer questions.' # The default system prompt of the agent
-                include_tools: true # Include tool definitions at the end of the system prompt
+                system_prompt: # The system prompt configuration
+                    prompt: 'You are a helpful assistant that can answer questions.' # The prompt text
+                    include_tools: true # Include tool definitions at the end of the system prompt
                 tools:
                     # Referencing a service with #[AsTool] attribute
                     - 'Symfony\AI\Agent\Toolbox\Tool\SimilaritySearch'
@@ -144,6 +145,46 @@ Configuration
                 vectorizer: 'ai.vectorizer.mistral_embeddings'
                 store: 'ai.store.memory.research'
 
+System Prompt Configuration
+----------------------------
+
+The ``system_prompt`` configuration supports two formats to provide flexibility for different use cases:
+
+**Simple Format (String)**
+
+For basic usage when you only need to set a prompt text:
+
+.. code-block:: yaml
+
+    ai:
+        agent:
+            my_agent:
+                model:
+                    class: 'Symfony\AI\Platform\Bridge\OpenAi\Gpt'
+                    name: !php/const Symfony\AI\Platform\Bridge\OpenAi\Gpt::GPT_4O_MINI
+                system_prompt: 'You are a helpful assistant.'
+
+**Advanced Format (Array)**
+
+For advanced usage when you need additional configuration like tool inclusion:
+
+.. code-block:: yaml
+
+    ai:
+        agent:
+            my_agent:
+                model:
+                    class: 'Symfony\AI\Platform\Bridge\OpenAi\Gpt'
+                    name: !php/const Symfony\AI\Platform\Bridge\OpenAi\Gpt::GPT_4O_MINI
+                system_prompt:
+                    prompt: 'You are a helpful assistant that can answer questions.'
+                    include_tools: true # Include tool definitions at the end of the system prompt
+
+**Configuration Options**
+
+* ``prompt`` (string): The system prompt text that will be sent to the AI model
+* ``include_tools`` (boolean, default: false): Whether to automatically append tool definitions to the system prompt
+
 Usage
 -----
 

src/ai-bundle/src/AiBundle.php

@@ -604,16 +604,28 @@ private function processAgentConfig(string $name, array $config, ContainerBuilde
         }
 
         // SYSTEM PROMPT
-        if (\is_string($config['system_prompt'])) {
-            $systemPromptInputProcessorDefinition = (new Definition(SystemPromptInputProcessor::class))
-                ->setArguments([
-                    $config['system_prompt'],
-                    $config['include_tools'] ? new Reference('ai.toolbox.'.$name) : null,
-                    new Reference('logger', ContainerInterface::IGNORE_ON_INVALID_REFERENCE),
-                ])
-                ->addTag('ai.agent.input_processor', ['agent' => $agentId, 'priority' => -30]);
+        if (null !== $config['system_prompt']) {
+            $systemPromptConfig = $config['system_prompt'];
+
+            if (\is_array($systemPromptConfig)) {
+                $promptText = $systemPromptConfig['prompt'] ?? '';
+                $includeTools = $systemPromptConfig['include_tools'] ?? false;
+            } else {
+                $promptText = (string) $systemPromptConfig;
+                $includeTools = $config['include_tools'] ?? false;
+            }
 
-            $container->setDefinition('ai.agent.'.$name.'.system_prompt_processor', $systemPromptInputProcessorDefinition);
+            if (!empty(trim($promptText))) {
+                $systemPromptInputProcessorDefinition = (new Definition(SystemPromptInputProcessor::class))
+                    ->setArguments([
+                        $promptText,
+                        $includeTools ? new Reference('ai.toolbox.'.$name) : null,
+                        new Reference('logger', ContainerInterface::IGNORE_ON_INVALID_REFERENCE),
+                    ])
+                    ->addTag('ai.agent.input_processor', ['agent' => $agentId, 'priority' => -30]);
+
+                $container->setDefinition('ai.agent.'.$name.'.system_prompt_processor', $systemPromptInputProcessorDefinition);
+            }
         }
 
         $agentDefinition