diff --git a/pyproject.toml b/pyproject.toml
index 4cc99f4..e8219c2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -37,7 +37,7 @@ dev = [
     "langchain-acp[deepagents]",
     "python-dotenv",
     "pydantic-acp",
-    "pydantic-ai-harness[code-mode]==0.4.0",
+    "pydantic-ai-harness[code-mode]==0.5.0",
     "pydantic-ai-slim>=2.0.0,<=2.4.0",
     "pydantic-graph",
     "pydantic>=2.7",