diff --git a/src/Php/CompilerBase.php b/src/Php/CompilerBase.php
index e1a0bce4..413f2ca8 100644
--- a/src/Php/CompilerBase.php
+++ b/src/Php/CompilerBase.php
@@ -883,30 +883,42 @@ class CompilerBase extends \PhpAot\Core\Translator
     }
 
     /**
-     * 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。
+     * 将 trait 方法参数中的类名 Name 节点升级为 Name\FullyQualified。
+     * 对于已由 parseTypeDecl() 解析的限定名（含 \），直接升级节点类型；
+     * 对于尚未解析的非限定名（如 NullableType 内层，parseTypeDecl 返回 TYPE_VAR 跳过了解析），
+     * 先通过 useAliases/useNamespaces 解析再升级。
+     * gen_stub.php 的 SimpleType::fromNode() 依赖 isFullyQualified() 判断是否需要再次解析，
+     * 若不升级为 FullyQualified，在上下文丢失后会被错误地追加当前 namespace 前缀。
      */
-    protected function resolveParamClassName(?NodeAbstract $type): void
+    protected function upgradeToFullyQualifiedName(?NodeAbstract $type): ?NodeAbstract
     {
         if ($type === null) {
-            return;
+            return null;
         }
         if ($type instanceof Node\NullableType) {
-            $this->resolveParamClassName($type->type);
-            return;
+            return new Node\NullableType($this->upgradeToFullyQualifiedName($type->type));
         }
         if ($type instanceof Node\UnionType) {
-            foreach ($type->types as $subType) {
-                $this->resolveParamClassName($subType);
+            foreach ($type->types as $i => $subType) {
+                $type->types[$i] = $this->upgradeToFullyQualifiedName($subType);
             }
-            return;
+            return $type;
         }
-        if ($type instanceof Node\Name && !$type->isFullyQualified()) {
+        if ($type instanceof Node\Name\FullyQualified) {
+            return $type;
+        }
+        if ($type instanceof Node\Name) {
             $typeName = $type->toString();
-            if (!isset($this->zendTypeMap[strtolower($typeName)]) && strtolower($typeName) !== 'self' && strtolower($typeName) !== 'static' && strtolower($typeName) !== 'parent') {
-                $type->name = '\\' . $this->getNamespacedClassName($typeName);
+            if (isset($this->zendTypeMap[strtolower($typeName)]) || in_array(strtolower($typeName), ['self', 'static', 'parent'], true)) {
+                return $type;
+            }
+            if ($type->isQualified()) {
+                return new Node\Name\FullyQualified($typeName, $type->getAttributes());
             }
+            $resolved = $this->getNamespacedClassName($typeName);
+            return new Node\Name\FullyQualified($resolved, $type->getAttributes());
         }
+        return $type;
     }
 
     /**
diff --git a/src/Php/Preprocessor.php b/src/Php/Preprocessor.php
index 0688e2f0..28be8982 100644
--- a/src/Php/Preprocessor.php
+++ b/src/Php/Preprocessor.php
@@ -484,12 +484,12 @@ 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
+        // 将 trait 方法参数中的类名升级为 FullyQualified，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);
+                        $param->type = $this->upgradeToFullyQualifiedName($param->type);
                     }
                 }
             }
diff --git a/tests/aot/trait/class-param.phpt b/tests/aot/trait/class-param.phpt
new file mode 100644
index 00000000..57eebe6c
--- /dev/null
+++ b/tests/aot/trait/class-param.phpt
@@ -0,0 +1,56 @@
+--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 App\Test{
+    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 $node): string {
+            if ($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): string {
+            return $this->process($expr, $type, $node);
+        }
+    }
+
+    class MyProcessor {
+        use HelperTrait;
+        use CallerTrait;
+    }
+}
+
+namespace  {
+    function main() {
+        $p = new App\Test\MyProcessor();
+        $node = new App\Types\Node('hello');
+
+        var_dump($p->runProcess('data', 'float', $node));
+        var_dump($p->runProcess('str', 'str', new App\Types\Node('world')));
+    }
+}
+?>
+--EXPECT--
+string(10) "node:hello"
+string(10) "node:world"