diff --git a/.env.example b/.env.example
new file mode 100644
index 0000000..68566bb
--- /dev/null
+++ b/.env.example
@@ -0,0 +1,2 @@
+# Copy this file to .env and add local configuration values as needed.
+# Never commit .env or credentials.
diff --git a/AGENTS.md b/AGENTS.md
index cbdb2c7..6af9dd9 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -100,4 +100,6 @@ publications without explicit human approval.
 - Add tests for new library behavior under `tests/`.
 - Use the configured Ruff and ty checks; do not introduce duplicate tooling
   without a project need.
-- Do not commit generated build output, virtual environments, or `.env` files.
+- Copy `.env.example` to `.env` for local environment configuration. Do not
+  commit generated build output, virtual environments, `.env` files, or
+  credentials.