diff --git a/src/Php/CompilerBase.php b/src/Php/CompilerBase.php
index 22fcde4f..e1a0bce4 100644
--- a/src/Php/CompilerBase.php
+++ b/src/Php/CompilerBase.php
@@ -882,6 +882,33 @@ class CompilerBase extends \PhpAot\Core\Translator
         return $class;
     }
 
+    /**
+     * 将参数类型中的非完全限定类名解析为完全限定名称。
+     * 在 parseTrait 阶段调用，避免 gen_stub 时上下文丢失。
+     */
+    protected function resolveParamClassName(?NodeAbstract $type): void
+    {
+        if ($type === null) {
+            return;
+        }
+        if ($type instanceof Node\NullableType) {
+            $this->resolveParamClassName($type->type);
+            return;
+        }
+        if ($type instanceof Node\UnionType) {
+            foreach ($type->types as $subType) {
+                $this->resolveParamClassName($subType);
+            }
+            return;
+        }
+        if ($type instanceof Node\Name && !$type->isFullyQualified()) {
+            $typeName = $type->toString();
+            if (!isset($this->zendTypeMap[strtolower($typeName)]) && strtolower($typeName) !== 'self' && strtolower($typeName) !== 'static' && strtolower($typeName) !== 'parent') {
+                $type->name = '\\' . $this->getNamespacedClassName($typeName);
+            }
+        }
+    }
+
     /**
      * 函数名称处理，补齐 namespace
      */
diff --git a/src/Php/Preprocessor.php b/src/Php/Preprocessor.php
index 39e46f17..0688e2f0 100644
--- a/src/Php/Preprocessor.php
+++ b/src/Php/Preprocessor.php
@@ -484,6 +484,17 @@ class Preprocessor extends CompilerBase
             }
         }
 
+        // 将 trait 方法参数中的类名解析为完全限定名称，避免 gen_stub 时上下文丢失
+        if ($class instanceof Node\Stmt\Trait_) {
+            foreach ($class->stmts as $v) {
+                if ($v instanceof Node\Stmt\ClassMethod) {
+                    foreach ($v->params as $param) {
+                        $this->resolveParamClassName($param->type);
+                    }
+                }
+            }
+        }
+
         $this->resetClass();
 
         return $code;
diff --git a/tests/aot/trait/nullable-class-param.phpt b/tests/aot/trait/nullable-class-param.phpt
new file mode 100644
index 00000000..029ba9db
--- /dev/null
+++ b/tests/aot/trait/nullable-class-param.phpt
@@ -0,0 +1,61 @@
+--TEST--
+Cross-trait call with untyped nullable parameter (regression test for arginfo/zpp mismatch)
+--FILE--
+<?php
+
+namespace App\Types {
+    class Node {
+        public string $name;
+        public function __construct(string $name = '') {
+            $this->name = $name;
+        }
+    }
+}
+
+namespace {
+    use App\Types\Node;
+
+    trait HelperTrait {
+        // Note: no type hint on $node — ?ClassName on trait methods causes
+        // arginfo/zpp mismatch between gen_stub.php's ZEND_ARG_OBJ_INFO and
+        // the AOT compiler's TYPE_VAR-based codegen.
+        protected function process(string $expr, string $type = '', ?Node $node = null): string {
+            if ($node instanceof Node) {
+                return 'node:' . $node->name;
+            }
+            if ($type !== '') {
+                return 'expr:' . $expr . ',type:' . $type;
+            }
+            return 'expr:' . $expr;
+        }
+    }
+
+    trait CallerTrait {
+        public function runProcess(string $expr, string $type = '', ?Node $node = null): string {
+            return $this->process($expr, $type, $node);
+        }
+    }
+
+    class MyProcessor {
+        use HelperTrait;
+        use CallerTrait;
+    }
+
+    function main() {
+        $p = new MyProcessor();
+        $node = new Node('hello');
+
+        var_dump($p->runProcess('data', 'float', $node));
+        var_dump($p->runProcess('data', 'int'));
+        var_dump($p->runProcess('data'));
+        var_dump($p->runProcess('data', 'string', null));
+        var_dump($p->runProcess('str', 'str', new Node('world')));
+    }
+}
+?>
+--EXPECT--
+string(10) "node:hello"
+string(18) "expr:data,type:int"
+string(9) "expr:data"
+string(21) "expr:data,type:string"
+string(10) "node:world"