diff --git a/deploy/db/prompts.py b/deploy/db/prompts.py
index d693730..f62021d 100644
--- a/deploy/db/prompts.py
+++ b/deploy/db/prompts.py
@@ -2,12 +2,19 @@
 from .connection import query, execute, execute_returning
 
 
+def _serialize(row):
+    """Convert datetime fields to strings for JSON serialization."""
+    if row and row.get("created_at"):
+        row["created_at"] = str(row["created_at"])
+    return row
+
+
 def get_active(role):
     rows = query(
         "SELECT * FROM prompts WHERE role = %s AND is_active = true ORDER BY created_at DESC LIMIT 1",
         (role,),
     )
-    return rows[0] if rows else None
+    return _serialize(rows[0]) if rows else None
 
 
 def get(prompt_id):
@@ -40,10 +47,14 @@ def seed_defaults():
 
 def list_by_role(role):
     """List all versions for a role, newest first."""
-    return query(
+    rows = query(
         "SELECT id, role, name, is_active, created_by, notes, created_at FROM prompts WHERE role=%s ORDER BY created_at DESC",
         (role,),
     )
+    for r in rows:
+        if r.get("created_at"):
+            r["created_at"] = str(r["created_at"])
+    return rows
 
 
 def save_new_version(role, name, body, notes="", is_active=True):