[PHPStan] Add rule to forbid empty() usage and replace all existing empty() calls

.phpstan/ForbidEmptyRule.php

@@ -0,0 +1,68 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\AI\PHPStan;
+
+use PhpParser\Node;
+use PhpParser\Node\Expr\FuncCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+
+/**
+ * PHPStan rule that forbids usage of empty() function.
+ *
+ * This rule enforces that empty() should not be used in favor of explicit checks
+ * like null checks, count() for arrays, or string length checks.
+ *
+ * @author Oskar Stark <oskarstark@googlemail.com>
+ *
+ * @implements Rule<FuncCall>
+ */
+final class ForbidEmptyRule implements Rule
+{
+    public function getNodeType(): string
+    {
+        return FuncCall::class;
+    }
+
+    public function processNode(Node $node, Scope $scope): array
+    {
+        if (!$node instanceof FuncCall) {
+            return [];
+        }
+
+        if (!$node->name instanceof Node\Name) {
+            return [];
+        }
+
+        $functionName = $node->name->toString();
+
+        if ('empty' !== strtolower($functionName)) {
+            return [];
+        }
+
+        // Allow empty() in ai-bundle config file where validation logic can be complex
+        if (str_ends_with($scope->getFile(), 'ai-bundle/config/options.php')) {
+            return [];
+        }
+
+        return [
+            RuleErrorBuilder::message(
+                'Usage of empty() function is forbidden. Use explicit checks instead: null check, count() for arrays, or string length checks.'
+            )
+            ->line($node->getLine())
+            ->identifier('symfonyAi.forbidEmpty')
+            ->tip('Replace empty() with explicit checks like $var !== null && $var !== \'\' for strings, count($var) > 0 for arrays, etc.')
+            ->build(),
+        ];
+    }
+}

.phpstan/extension.neon

@@ -2,3 +2,4 @@ rules:
     - Symfony\AI\PHPStan\ForbidDeclareStrictTypesRule
     - Symfony\AI\PHPStan\ForbidNativeExceptionRule
     - Symfony\AI\PHPStan\ForbidTestCoverageAttributesRule
+    - Symfony\AI\PHPStan\ForbidEmptyRule

src/agent/src/MockAgent.php

@@ -174,7 +174,7 @@ public function getCall(int $index): array
      */
     public function getLastCall(): array
     {
-        if (empty($this->calls)) {
+        if (0 === \count($this->calls)) {
             throw new LogicException('No calls have been made yet.');
         }
 

src/agent/src/StructuredOutput/AgentProcessor.php

@@ -117,7 +117,7 @@ public function processOutput(Output $output): void
             $output->result->getMetadata()->set($originalResult->getMetadata()->all());
         }
 
-        if (!empty($originalResult->getRawResult())) {
+        if (null !== $originalResult->getRawResult()) {
             $output->result->setRawResult($originalResult->getRawResult());
         }
     }

src/platform/src/Bridge/Anthropic/ModelClient.php

@@ -47,7 +47,7 @@ public function request(Model $model, array|string $payload, array $options = []
             $options['tool_choice'] = ['type' => 'auto'];
         }
 
-        if (isset($options['beta_features']) && \is_array($options['beta_features']) && !empty($options['beta_features'])) {
+        if (isset($options['beta_features']) && \is_array($options['beta_features']) && \count($options['beta_features']) > 0) {
             $headers['anthropic-beta'] = implode(',', $options['beta_features']);
             unset($options['beta_features']);
         }