diff --git a/pyproject.toml b/pyproject.toml
index b46e17e..0a178f2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -41,7 +41,7 @@ dev = [
     "python-dotenv",
     "pydantic-acp",
     "pydantic-ai-harness[code-mode]==0.52.0",
-    "pydantic-ai-slim>=2.9.0,<=2.52.0",
+    "pydantic-ai-slim>=2.9.0,<=2.57.0",
     "pydantic-graph",
     "pydantic>=2.7",
     "pytest-asyncio",