diff --git a/harness/requirements.txt b/harness/requirements.txt
index d6afb22e..c92a61ca 100644
--- a/harness/requirements.txt
+++ b/harness/requirements.txt
@@ -7,7 +7,7 @@
 # paid-run behaviour with no repo diff. Bump the lower bound only after
 # you've re-run the smoke + a paid Sonnet cell against the new release.
 claude-agent-sdk>=0.2.87,<0.3
-pydantic>=2.0,<3
+pydantic>=2.13.4,<3
 pyyaml>=6.0,<7
 rich>=15.0.0,<16
 typer>=0.12,<1
diff --git a/pyproject.toml b/pyproject.toml
index 4958d966..e2c4122b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -49,7 +49,7 @@ classifiers = [
   "Typing :: Typed",
 ]
 dependencies = [
-  "pydantic>=2.7,<3",
+  "pydantic>=2.13.4,<3",
   "pyyaml>=6.0.3,<7",
   "ruamel.yaml>=0.19.1,<1",
   "typer>=0.12,<1",