Add optional translation to system prompts

So that system prompts can be written in any locale

Author: paulinevos

src/agent/CHANGELOG.md

@@ -54,3 +54,4 @@ CHANGELOG
  * Add model capability detection before processing
  * Add comprehensive type safety with full PHP type hints
  * Add clear exception hierarchy for different error scenarios
+ * Add translation support for system prompts

src/agent/composer.json

@@ -30,6 +30,7 @@
         "symfony/property-access": "^6.4 || ^7.1",
         "symfony/property-info": "^6.4 || ^7.1",
         "symfony/serializer": "^6.4 || ^7.1",
+        "symfony/translation": "^6.4 || ^7.1",
         "symfony/type-info": "^7.2.3"
     },
     "require-dev": {

src/agent/src/InputProcessor/SystemPromptInputProcessor.php

@@ -18,6 +18,7 @@
 use Symfony\AI\Agent\Toolbox\ToolboxInterface;
 use Symfony\AI\Platform\Message\Message;
 use Symfony\AI\Platform\Tool\Tool;
+use Symfony\Contracts\Translation\TranslatorInterface;
 
 /**
  * @author Christopher Hertel <mail@christopher-hertel.de>
@@ -31,6 +32,7 @@
     public function __construct(
         private \Stringable|string $systemPrompt,
         private ?ToolboxInterface $toolbox = null,
+        private ?TranslatorInterface $translator = null,
         private LoggerInterface $logger = new NullLogger(),
     ) {
     }
@@ -45,7 +47,9 @@ public function processInput(Input $input): void
             return;
         }
 
-        $message = (string) $this->systemPrompt;
+        $message = $this->translator
+            ? $this->translator->trans((string) $this->systemPrompt)
+            : (string) $this->systemPrompt;
 
         if ($this->toolbox instanceof ToolboxInterface
             && [] !== $this->toolbox->getTools()

src/agent/tests/InputProcessor/SystemPromptInputProcessorTest.php

@@ -29,6 +29,7 @@
 use Symfony\AI\Platform\Result\ToolCall;
 use Symfony\AI\Platform\Tool\ExecutionReference;
 use Symfony\AI\Platform\Tool\Tool;
+use Symfony\Contracts\Translation\TranslatorInterface;
 
 #[CoversClass(SystemPromptInputProcessor::class)]
 #[UsesClass(Gpt::class)]
@@ -186,4 +187,31 @@ public function execute(ToolCall $toolCall): mixed
             A tool without parameters
             PROMPT, $messages[0]->content);
     }
+
+    public function testWithTranslatedSystemPrompt()
+    {
+        $processor = new SystemPromptInputProcessor(
+            systemPrompt: 'This is a',
+            translator: new class implements TranslatorInterface {
+                public function trans(string $id, array $parameters = [], ?string $domain = null, ?string $locale = null): string
+                {
+                    return \sprintf('%s cool translated system prompt', $id);
+                }
+
+                public function getLocale(): string
+                {
+                    return 'en';
+                }
+            }
+        );
+
+        $input = new Input(new Gpt(), new MessageBag(Message::ofUser('This is a user message')), []);
+        $processor->processInput($input);
+
+        $messages = $input->messages->getMessages();
+        $this->assertCount(2, $messages);
+        $this->assertInstanceOf(SystemMessage::class, $messages[0]);
+        $this->assertInstanceOf(UserMessage::class, $messages[1]);
+        $this->assertSame('This is a cool translated system prompt', $messages[0]->content);
+    }
 }

src/ai-bundle/config/options.php

@@ -125,13 +125,25 @@
                             ->end()
                         ->end()
                         ->booleanNode('structured_output')->defaultTrue()->end()
-                        ->scalarNode('system_prompt')
-                            ->validate()
-                                ->ifTrue(fn ($v) => null !== $v && '' === trim($v))
-                                ->thenInvalid('The default system prompt must not be an empty string')
+                        ->arrayNode('system_prompt')
+                            ->beforeNormalization()
+                                ->ifString()
+                                ->then(fn ($v) => ['system_prompt' => $v])
+                            ->end()
+                            ->children()
+                                ->scalarNode('system_prompt')
+                                    ->validate()
+                                        ->ifTrue(fn ($v) => null !== $v && '' === trim($v))
+                                        ->thenInvalid('The default system prompt must not be an empty string')
+                                    ->end()
+                                    ->defaultNull()
+                                    ->info('The default system prompt of the agent')
+                                ->end()
+                                ->scalarNode('translator')
+                                    ->defaultNull()
+                                    ->info('Service name of translator for the system prompt')
+                                ->end()
                             ->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')

src/ai-bundle/src/AiBundle.php

@@ -585,11 +585,12 @@ private function processAgentConfig(string $name, array $config, ContainerBuilde
         }
 
         // SYSTEM PROMPT
-        if (\is_string($config['system_prompt'])) {
+        if (\array_key_exists('system_prompt', $config)) {
             $systemPromptInputProcessorDefinition = (new Definition(SystemPromptInputProcessor::class))
                 ->setArguments([
-                    $config['system_prompt'],
+                    $config['system_prompt']['system_prompt'],
                     $config['include_tools'] ? new Reference('ai.toolbox.'.$name) : null,
+                    $config['system_prompt']['translator'],
                     new Reference('logger', ContainerInterface::IGNORE_ON_INVALID_REFERENCE),
                 ])
                 ->addTag('ai.agent.input_processor', ['agent' => $agentId, 'priority' => -30]);

src/ai-bundle/tests/DependencyInjection/AiBundleTest.php

@@ -27,6 +27,7 @@
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\Reference;
+use Symfony\Contracts\Translation\TranslatorInterface;
 
 #[CoversClass(AiBundle::class)]
 #[UsesClass(ContainerBuilder::class)]
@@ -447,7 +448,10 @@ public function testMultipleAgentsWithProcessors()
                         'tools' => [
                             ['service' => 'tool_two', 'description' => 'Tool for second agent'],
                         ],
-                        'system_prompt' => 'Second agent prompt',
+                        'system_prompt' => [
+                            'system_prompt' => 'Second agent prompt',
+                            'translator' => TranslatorInterface::class,
+                        ],
                     ],
                 ],
             ],
@@ -471,11 +475,13 @@ public function testMultipleAgentsWithProcessors()
         $firstSystemPrompt = $container->getDefinition('ai.agent.first_agent.system_prompt_processor');
         $firstSystemTags = $firstSystemPrompt->getTag('ai.agent.input_processor');
         $this->assertSame($firstAgentId, $firstSystemTags[0]['agent']);
+        $this->assertCount(2, array_filter($firstSystemPrompt->getArguments()));
 
         // Second agent system prompt processor
         $secondSystemPrompt = $container->getDefinition('ai.agent.second_agent.system_prompt_processor');
         $secondSystemTags = $secondSystemPrompt->getTag('ai.agent.input_processor');
         $this->assertSame($secondAgentId, $secondSystemTags[0]['agent']);
+        $this->assertCount(3, array_filter($secondSystemPrompt->getArguments()));
     }
 
     #[TestDox('Processors work correctly when using the default toolbox')]