diff --git a/codex/cli.py b/codex/cli.py
new file mode 100644
index 0000000..b111c88
--- /dev/null
+++ b/codex/cli.py
@@ -0,0 +1,3 @@
+import typer
+
+app = typer.Typer(help="codex — personal knowledge base for scientific papers.")