Merge pull request #426 from BerkayAkpolat/fix/gemini-structured-output

fix: gemini structured output REST API compatibility and error handling

Author: ilvalerione

src/Providers/Gemini/HandleChat.php

@@ -19,6 +19,7 @@
 use function array_key_exists;
 use function trim;
 use function is_array;
+use function json_encode;
 
 trait HandleChat
 {
@@ -60,9 +61,24 @@ public function chat(array|Message $messages): Message
      */
     protected function processChatResult(array $result): AssistantMessage
     {
-        $content = $result['candidates'][0]['content'];
+        if (array_key_exists('error', $result)) {
+            throw new ProviderException("Gemini API Error: " . ($result['error']['message'] ?? json_encode($result['error'])));
+        }
+
+        if (!array_key_exists('candidates', $result) || empty($result['candidates'])) {
+            throw new ProviderException("Gemini API returned no candidates. Response: " . json_encode($result));
+        }
+
+        $candidate = $result['candidates'][0];
+        $finishReason = $candidate['finishReason'] ?? 'UNKNOWN';
+
+        if ($finishReason !== 'STOP' && !isset($candidate['content'])) {
+            throw new ProviderException("Gemini API finished with reason: {$finishReason}. Full response: " . json_encode($result));
+        }
+
+        $content = $candidate['content'];
 
-        if (!isset($content['parts']) && isset($result['candidates'][0]['finishReason']) && $result['candidates'][0]['finishReason'] === 'MAX_TOKENS') {
+        if (!isset($content['parts']) && $finishReason === 'MAX_TOKENS') {
             return new AssistantMessage('');
         }
 

src/Providers/Gemini/HandleStream.php

@@ -71,6 +71,10 @@ public function stream(array|Message $messages): Generator
                 continue;
             }
 
+            if (array_key_exists('error', $line)) {
+                throw new ProviderException("Gemini API Error (Streaming): " . ($line['error']['message'] ?? json_encode($line['error'])));
+            }
+
             // Save usage information
             if (array_key_exists('usageMetadata', $line)) {
                 $this->streamState->addInputTokens($line['usageMetadata']['promptTokenCount'] ?? 0);

src/Providers/Gemini/HandleStructured.php

@@ -11,6 +11,7 @@
 use function end;
 use function is_array;
 use function json_encode;
+use function strtoupper;
 
 trait HandleStructured
 {
@@ -33,31 +34,57 @@ public function structured(
             $last_message = end($messages);
             if ($last_message instanceof Message && $last_message->getRole() === MessageRole::USER->value) {
                 $last_message->setContents(
-                    $last_message->getContent() . ' Respond using this JSON schema: '.json_encode($response_format)
+                    $last_message->getContent() . ' Respond using this JSON schema: ' . json_encode($response_format)
                 );
             }
         } else {
-            // If there are no tools, we can enforce the structured output.
-            $this->parameters['generationConfig']['response_schema'] = $this->adaptSchema($response_format);
-            $this->parameters['generationConfig']['response_mime_type'] = 'application/json';
+            $this->parameters['generationConfig']['responseSchema'] = $this->adaptSchema($response_format);
+            $this->parameters['generationConfig']['responseMimeType'] = 'application/json';
         }
 
         return $this->chat($messages);
     }
 
     /**
-     * Gemini does not support additionalProperties attribute.
+     * Adapt Neuron schema to Gemini requirements.
      */
     protected function adaptSchema(array $schema): array
     {
         if (array_key_exists('additionalProperties', $schema)) {
             unset($schema['additionalProperties']);
         }
 
-        foreach ($schema as $key => $value) {
-            if (is_array($value)) {
-                $schema[$key] = $this->adaptSchema($value);
+        if (array_key_exists('type', $schema)) {
+            if (is_array($schema['type'])) {
+                foreach ($schema['type'] as $type) {
+                    if ($type !== 'null') {
+                        $schema['type'] = strtoupper((string) $type);
+                        break;
+                    }
+                }
+            } else {
+                $schema['type'] = strtoupper((string) $schema['type']);
             }
+
+            $schema['type'] = match ($schema['type']) {
+                'INT' => 'INTEGER',
+                'BOOL' => 'BOOLEAN',
+                'DOUBLE', 'FLOAT' => 'NUMBER',
+                default => $schema['type']
+            };
+        }
+
+        if (array_key_exists('properties', $schema) && is_array($schema['properties'])) {
+            foreach ($schema['properties'] as $key => $value) {
+                if (is_array($value)) {
+                    $schema['properties'][$key] = $this->adaptSchema($value);
+                }
+            }
+            $schema['properties'] = (object) $schema['properties'];
+        }
+
+        if (array_key_exists('items', $schema) && is_array($schema['items'])) {
+            $schema['items'] = $this->adaptSchema($schema['items']);
         }
 
         return $schema;