diff --git a/pyproject.toml b/pyproject.toml
index 31ba317..e014b30 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -40,7 +40,7 @@ dev = [
     "python-dotenv",
     "pydantic-acp",
     "pydantic-ai-harness[code-mode]==0.15.0",
-    "pydantic-ai-slim>=2.9.0,<=2.23.0",
+    "pydantic-ai-slim>=2.9.0,<=2.27.0",
     "pydantic-graph",
     "pydantic>=2.7",
     "pytest-asyncio",