[BUGFIX] Properly resolve max tokens key for gemini

Author: o-ba

Classes/Provider/SymfonyAi/SymfonyAiPlatformAdapter.php

@@ -445,10 +445,18 @@ private function buildOptions(string $model, int $maxTokens, float $temperature,
     }
 
     /**
-     * Resolve the max-tokens option key expected by a Symfony AI bridge based on the used bridge
+     * Resolve the max-tokens option key expected by a Symfony AI bridge.
+     *
+     * Each bridge keeps the option naming convention of its underlying API:
+     *   - Gemini uses camelCase (Google REST API: "maxOutputTokens")
+     *   - OpenAI / OpenResponses use snake_case "max_output_tokens"
+     *   - Anthropic / Mistral / Ollama and most others use legacy "max_tokens"
      */
     public static function resolveMaxTokensKey(string $factoryClass): string
     {
+        if (str_contains($factoryClass, '\\Bridge\\Gemini\\')) {
+            return 'maxOutputTokens';
+        }
         if (str_contains($factoryClass, '\\Bridge\\OpenAi\\')
             || str_contains($factoryClass, '\\Bridge\\OpenResponses\\')
         ) {

Tests/Unit/Provider/SymfonyAi/SymfonyAiPlatformAdapterTest.php

@@ -29,6 +29,10 @@ public static function maxTokensKeyProvider(): \Generator
             'Symfony\\AI\\Platform\\Bridge\\OpenResponses\\PlatformFactory',
             'max_output_tokens',
         ];
+        yield 'Gemini uses camelCase per Google REST API' => [
+            'Symfony\\AI\\Platform\\Bridge\\Gemini\\PlatformFactory',
+            'maxOutputTokens',
+        ];
         yield 'Anthropic Messages API' => [
             'Symfony\\AI\\Platform\\Bridge\\Anthropic\\PlatformFactory',
             'max_tokens',